A FEW IDEAS FOR BETTER OFFSHORE CABLING /
page 40 April 2017
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I N N O V A T O R S
&
I N F L U E N C E R S
I S S U E
JOURNAL BEARINGS IN A WIND-TURBINE GEARBOX?
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Follow the whole team on twitter @Windpower_Eng
E D I T O R I A L
S T A F F
EDITORIAL
DIGITAL MEDIA / MARKETING
VIDEO SERVICES
Editorial Director Paul Dvorak pdvorak@wtwhmedia.com @windpower_eng
Web Development Manager B. David Miyares dmiyares@wtwhmedia.com @wtwh_webdave
Videographer Manager John Hansel jhansel@wtwhmedia.com @wtwh_jhansel
Senior Editor Michelle Froese mfroese@wtwhmedia.com @WPE_Michelle
Digital Media Manager Patrick Curran pcurran@wtwhmedia.com @wtwhseopatrick
Videographer Bradley Voyten bvoyten@wtwhmedia.com
Associate Publisher Courtney Seel cseel@wtwhmedia.com 440.523.1685 @wtwh_CSeel
DESIGN & PRODUCTION SERVICES VP of Creative Services Mark Rook mrook@wtwhmedia.com @wtwh_graphics Art Director Matthew Claney mclaney@wtwhmedia.com @wtwh_designer Graphic Designer Allison Washko awashko@wtwhmedia.com @wtwh_allison
Traffic Manager Mary Heideloff mheideloff@wtwhmedia.com Production Associate Tracy Powers tpowers@wtwhmedia.com
Senior Web Developer Patrick Amigo pamigo@wtwhmedia.com @amigo_patrick Web Production Associate Skylar Aubuchon saubuchon@wtwhmedia.com @skylar_aubuchon Web Production & Reporting Associate Jennifer Calhoon jcalhoon@wtwhmedia.com @wtwh_jennifer
Videographer Derek Little dlittle@wtwhmedia.com @wtwh_derek
FINANCE Controller Brian Korsberg bkorsberg@wtwhmedia.com Accounts Receivable Specialist Jamila Milton jmilton@wtwhmedia.com
Digital Marketing Director Virginia Goulding vgoulding@wtwhmedia.com @wtwh_virginia Manager Webinars Stacy Combest scombest@wtwhmedia.com @wtwh_stacy
2014 Winner
Marketing Manager, Social Media & Events Jennifer Kolasky jkolasky@wtwhmedia.com @wtwh_jen
2011, 2012, 2013, 2014, 2015, 2016
2013 - 2016
Director, Audience Development Bruce Sprague bsprague@wtwhmedia.com
2014 - 2016
WTWH Media, LLC 6555 Carnegie Avenue, Suite 300, Cleveland, OH 44103 Ph: 888.543.2447 • Fax: 888.543.2447 WINDPOWER ENGINEERING & DEVELOPMENT does not pass judgment on subjects of controversy nor enter into disputes with or between any individuals or organizations. WINDPOWER ENGINEERING & DEVELOPMENT is also an independent forum for the expression of opinions relevant to industry issues. Letters to the editor and by-lined articles express the views of the author and not necessarily of the publisher or publication. Every effort is made to provide accurate information. However, the publisher assumes no responsibility for accuracy of submitted advertising and editorial information. Non-commissioned articles and news releases cannot be acknowledged. Unsolicited materials cannot be returned nor will this organization assume responsibility for their care. WINDPOWER ENGINEERING & DEVELOPMENT does not endorse any products, programs, or services of advertisers or editorial contributors. Copyright© 2016 by WTWH Media, LLC. No part of this publication may be reproduced in any form or by any means, electronic or mechanical, or by recording, or by any information storage or retrieval systems, without written permission from the publisher. SUBSCRIPTION RATES: Free and controlled circulation to qualified subscribers. Non-qualified persons may subscribe at the following rates: U.S. and possessions, 1 year: $125; 2 years: $200; 3 years $275; Canadian and foreign, 1 year: $195; only U.S. funds are accepted. Single copies $15. Subscriptions are prepaid by check or money orders only. SUBSCRIBER SERVICES: To order a subscription or change your address, please visit our web site at www.windpowerengineering.com WINDPOWER ENGINEERING & DEVELOPMENT (ISSN 2163-0593) is published six times per year in February, April, June, August, October and a special issue in December by WTWH Media, LLC, 6555 Carnegie Avenue, Suite 300, Cleveland, OH 44103. Periodicals postage paid at Cleveland, OH and additional mailing offices. POSTMASTER: Send address changes to: Windpower Engineering & Development, 6555 Carnegie Avenue, Suite 300, Cleveland, Ohio 44103
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WINDPOWER ENGINEERING & DEVELOPMENT
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HERE’S WHAT I THINK
Editorial Director | Windpower Engineering & Development | pdvorak@wtwhmedia.com
Mini lessons in leadership – 2017
A
A|S|B|P|E Fostering B2B editorial excellence
American Society of Business Publication Editors
2016 National
DESIGN Gold
Revenue of $3 million or under
A|S|B|P|E Fostering B2B editorial excellence
American Society of Business Publication Editors
2016 Regional
DESIGN Gold
Revenue of $3 million or under
A|S|B|P|E
t a leadership conference some years ago, we participated in an exercise to show the value of a group’s collective wisdom. That problem scenario had our group on a spaceship that had crash landed on the moon. The recovery site was some distance away. Which of the objects suggested would we take with us for a several-day hike? The list included items such as a compass, matches, a gun, water, and so on. (In fact, the test is here: http://tinyurl.com/survive-on-moon) The exercise ran twice, first individually and then as a group exercise. When the scores were tallied, no one person in our group successfully made the journey to the rescue site. However, working as a team, we all “survived”. That was eye opening. It means that together, we are surrounded by wisdom and experience much greater than our own. And to tap into it, all you have to do is ask. With that in mind and this being the leadership issue, let’s tap into the wisdom of the Windpower Engineering & Development staff for their observations and lessons on leadership. Their task: Provide a brief lesson in leadership from someone you have worked for. Michelle Froese, Senior Editor: One of my first bosses was everything I admired at the time. She was a woman, she spearheaded a nonprofit environmental organization, and she was determined. I was young and impressionable. She was stern and demanding. But one summer day, she asked the staff to meet by a beautiful area we were working to preserve, gave us each a knapsack filled with snacks and a disposable camera, and told us to take the day off to recharge in nature. She said if she expected us to focus and work hard, she’d better remind us of the reason. You don’t always get what you wish for but you get what you work for, she’d say. Today, that area is still preserved and I take time to hike and enjoy it every summer.
Fostering B2B editorial excellence
American Society of Business Publication Editors
2016 Regional
DESIGN Award Winner Revenue of $3 million or under
APRIL 2017
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Mark Rook, VP of Creative Services: Lou Grasso was my boss in a marketing department back in the early 1990’s. He is one of the most talented illustrators and designers that I had the chance to work within the publishing industry. His actions and positive attitude made you want to do your best every day. I always strive to be as good as Lou.
Tom Lazar, Sales: Our company publisher, Mike Emich, was instrumental in helping me develop and hone my style through repetition and positive reinforcement. One particular time, I was having difficulty getting a prospective advertiser to respond to my typical sales efforts of calling and emailing. When I asked for advice, Mike asked, “Ever try just showing-up?” I had not. So, when in the area again, I did just that: I showed-up. I explained that I’d had a hard time reaching my contact, but was promptly introduced and able to make progress towards winning the business. It helped to know that Mike had worked through many of the same challenges. So with a positive result like that, trust was built further and has led to a successful six years. Lee Teschler, Executive Editor and colleague: A new boss who was so passionate about what we were doing that he’d buy stuff for the organization out of his own pocket, which in one case was a pretty expensive video camera. This was after its purchase request was given the thumbsdown by upper managers who thought they knew better how to run our day-to-day activities than we did. Neil Dvorak, brother: Probably the best boss I had was a Ken Jarrell. He had a way of getting the best out of people without using fear. One of his tactics, when holding meetings, was to let everyone tell what they were working on and where they were having problems. The rest of the group was encouraged to offer solutions. And they did, and that worked. Your editor: Mine came from a boss, Ron Khol, on a magazine early in my career. He would criticize with humor. For example, to critique the whole magazine staff, he occasionally wrote what he called The journal of constructive ridicule, in which he would point out our perceived editorial shortcomings. On one occasion, he felt a more immediate need to needle. He approached my desk with the magazine opened to an article I edited, pointed to a confusing caption, and said in his best, loud Yiddish accent, “So vad am I luking at? Vat... is...dis?” OK, point made, Ron. W
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APRIL 2017 • vol 9 no 2
CONTENTS
D E PA R T M E N T S 03
Editorial: Mini lessons in leadership
40 Transmission: A few ideas for better offshore cabling
06
Windwatch: Cool plasma lowers blade loads,
44 Fluids and filters: How a compact filter can
22
Insurance: Hedging against low wind:
Spar buoy, White etch cracks in bearings, Bat research, WINDPOWER 2017 preview
5 things you should know about weather risk transfer structures
improve gear oil debris analysis
48 Software: Connecting onsite wind techs with offsite support
50 Condition monitoring: Hear that clicking? Sonic analysis identifies tell-tale noises in a nacelle.
28
Safety: A few ideas for fall protection: How to stop dropped tools at height
71 Equipment world
34
Bolting: Smarter tool calibrations
72 Ad Index
F E AT U R E S
52 What turbine electronics are
repairable, and which are not
61
Many of the electronic controls in older turbines are unsupported by their manufacturers. But they are still repairable. Even better, they can be improved. Here are a few success stories.
What journal bearings may contribute to wind-turbine gearboxes
ON THE COVER
The planetary stage of the gearbox is rebuilt with journal bearings.
xx
A recent National Renewable Energy Laboratory program has evaluated a 1-MW gearbox with journal bearings. Results are encouraging for wider use and more reliable gearboxes.
56 Lessons learned lead to new ideas in gearbox bearings
Gearbox reliability has improved remarkably in the last 10 years, thanks to a better understanding of bearing loads. However, even the highest quality components have a limited life expectancy in the wind industry. It is important to have a consistent maintenance plan in place, and know the early signs of bearing damage to maximize gearbox and wind-turbine life.
66 Innovators and Influencers
In which we identify the people who move the wind industry forward.
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TAUNTONCOLLINS
SHENG
ROBERTS
PRIEBE
NEAGOY
LAWSON
GREULICH
CALDWELL
CONTRIB U TO R S
APRIL 2017
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MICHAEL CALDWELL was the fifth employee at Python Safety, Inc. specializing in Fall Protection for Tools, which was acquired by 3M in 2015. He is currently a Business Development Manager with 3M and is also the State Representative for Georgia’s 20th House district. Caldwell has written what’s become the most widely adopted dropped-object prevention plan in the world and travels around the globe speaking on this vitally important topic. JOHN GREULICH, Director of Sales at PSI Repair Services, has worked in a variety of leadership roles for PSI Repair Services over the past 26 years. During that time, he has served a wide range of industries including automotive, aerospace, defense, consumer products, paper and pulp, steel, semiconductor, transit, military, and wind energy. Throughout his tenure, Greulich has developed numerous solutions for customers with complex equipment failures. AARON LAWSON, Director of Engineering Services at PSI Repair Services, has worked in a number of roles in the electronics industry over the past 14 years. His specialties include electronics repair, shop leadership, and project management. Lawson’s vast knowledge propelled him into a director role, where he now oversees PSI’s highly regarded engineering services department, which has a major focus on the wind-energy market. CHARLIE NEAGOY is the VP of Business Development at Librestream Technologies Inc. He brings more than 20 years of experience in technical business development, sales, and product management to the company, where he is responsible for sales expansion via strategic partners and channels. Neagoy offers diverse industry experience, which includes digital, optical communications, aerospace, and industrial process measurement. Prior to Librestream, Charlie was VP of Partner Sales at Inlet Technologies (acquired by Cisco Systems in 2011), a provider of live video streaming, where he established relationships with companies such as ESPN, Apple, Microsoft, NBCU, and others.
MARYRUTH BELSEY PRIEBE has a special interest in clean tech, green buildings, and renewable energy. In recent years, Priebe has worked as the Senior Editor of The Green Economy magazine, is a regular blogger for several green business ventures, and has contributed to the editorial content of eco-living websites (including ecolife.com and greenyour. com). Visit Priebe’s site at jadecreative.com DON ROBERTS, CEO of DA Roberts LLC, is a professional mechanical engineer with 21 years engineering experience in utility-scale wind turbine design and operations, electrical power generation mechanical systems design, and commercial aircraft structural engineering. The most recent eleven years have focused on wind turbine asset management, with specialization in drivetrain reliability. Related skills include condition monitoring and analysis, gearbox borescope inspection, and failure analysis. Other responsibilities in wind energy have included component design, testing and analysis, operations and maintenance cost modelling, and condition monitoring system installation and testing. DR. SHUANGWEN (SHAWN) SHENG, a senior engineer at the National Renewable Energy Laboratory (NREL), has B.S. and M.S. degrees in electrical engineering and a Ph.D. in mechanical engineering. Shawn is currently leading the wind turbine condition monitoring, gearboxreliability database, and wind plant operation and maintenance research at NREL. In addition to having expertise in these areas, Shawn has an extensive track record of impactful information dissemination through various publications and conferences. GEOFFREY TAUNTON-COLLINS is a Weather Risk Analyst with GCube. He has a background in commercial property and is working as a dedicated resource to help develop GCube’s weather risk product worldwide — most notably for wind, solar, and hydro investments. He is focused on the U.S., European, and Latin American markets.
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AWEA WINDPOWER 2017 MAY 22 TO 25, 2017 Anaheim Convention Center Anaheim, California windpowerexpo.org
BRING YOUR ATTITUDE: WINDPOWER 2017 IS WHERE IT’S AT BEFORE MANY RURAL COMMUNITIES were connected to the electric grid, farmers depended on windmills to pump water for crops and cattle. Decades later, wind energy is still helping out on farmlands, providing a steady income for many farmers and ranchers when the rains don’t fall or the fields don’t produce as expected. And that income is sizeable. According to the American Wind Energy Association (AWEA), landowners received $245 million in lease payments in 2016 alone. Some are calling wind power “the new corn.” AWEA is simply calling it “big league” because wind energy is no longer just the choice of farmers,
but also that of some of the world’s most iconic brands such as Google, Microsoft, Amazon, Wal-Mart, General Motors, IKEA, and Yahoo! — just to name a few. It is also a choice of an increasing number of Americans. “American wind power is now the number one source of renewable capacity, thanks to more than 100,000 wind workers across all 50 states,” said AWEA CEO, Tom Kiernan, in a recent press statement. “Growing this made-in-the-USA clean energy resource helps rural communities pay for new roads, bridges, and schools, while bringing back manufacturing jobs to the Rust Belt.”
WINDPOWER 2017 gives attendees a chance to enhance their exhibit floor learning experience through targeted education sessions and one-on-one interactions designed to boost wind-related knowledge and business.
APRIL 2017
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W I N D W A T C H
At the close of 2016, the wind fleet totaled 82,183 MW in the United States, which means it is on track to double in output over the next five years, and supply 10% of the country’s electricity by 2020. With a two-thirds cost reduction over the last seven years, the wind industry is bringing new confidence, new development, and new opportunities. In fact, the tagline for this year’s AWEA WINDPOWER 2017 Conference & Exhibition, the largest wind energy trade show in North America, is a ‘Brand New Attitude.’ “We will introduce our Brand New Attitude in Anaheim this May, where you will find top-tier speakers, worldclass education, new and cutting-edge technology, and premium networking,” said Kiernan. “Wind power typically provides the least expensive energy available and isn’t a red or blue industry —, it’s red, white, and blue. Low-cost, homegrown wind energy is something we can all share in and agree on.” A shared experience is something AWEA is hoping attendees will do at this year’s WINDPOWER show. The organization is expecting thousands of wind professionals from across the industry, and over 425 exhibiting companies and organizations. Here you can tailor your experience through five different Education Stations.
•
•
•
Power Station (powered by Siemens). Gain a better understanding of how wind energy experts are pushing for global growth through market expansions and new commercial opportunities. Tech Station (powered by GE Renewable Energy) Hear from the top minds in business, academia, and government on innovations in wind that could fundamentally change the industry. Operations Station (powered by Vestas). Learn how to analyze management strategies to better
CLEAN THE WORLD
Stop by the Clean the World area on the show floor during exhibit hours (on Wednesday, May 24 and Thursday, May 25) to assemble hygiene kits and help make a difference in the community. Each kit compiled onsite at WINDPOWER will be themed just for kids. WINDPOWER ENGINEERING & DEVELOPMENT
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TOP: The Exhibition Hall during WINDPOWER 2016. AWEA has heard your requests, and this year the Hall will open at 9am each morning. RIGHT: Join fellow colleagues in assembling hygiene kits to support the local community in Anaheim through charitable work with the Clean the World Foundation.
•
•
Contribute to a positive impact on the local community while networking with fellow attendees. Join AWEA during WINDPOWER 2017, as they partner with Clean the World Foundation, a charitable organization that helps put soap and other hygiene products in the hands of the people and families who need it most. The charity also works to reduce waste from the hotel industry, which is one of the largest producers of solid waste in the world.
8
BOTTOM: Tom Kiernan, CEO of AWEA, speaking out for wind power during a panel session at last year’s event.
www.windpowerengineering.com
address operational lifecycle issues that challenge wind-farm owners and operators. Project Development Station (powered by UL LLC). Exchange ideas and discuss key topics for developing a successful wind-power project, including siting, permitting, forecasting, monitoring, connecting to the grid, and more. Thought Leader Theater (powered by Mortenson). This station brings together industry experts to discuss lessons learned and company successes so others can achieve the same.
What’s more is that every morning, General Sessions will be held live on the show floor, simulcast in each Education Station, and streamed online to reach thousands of additional industry participants. “At WINDPOWER 2017, you can take part in premier educational APRIL 2017
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ADVANCED BOLTING TECHNOLOGY
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W I N D W A T C H WINDPOWER 2017: A few conference highlights
View the full agenda at https://tinyurl.com/windpower2017
DATE EVENT
TIME
Monday, May 22 (Pre-Conference)
Wind 101 - Introduction to Wind Energy
1 to 5pm
Opening Reception
5 to 7pm
Tuesday, May 23
Welcome & Opening General Session
10 to 11am
Exploring O&M to Optimize Performance & Plan for the future
11:30 to 12:30pm
Transmission Expansion to Accomodate Increasing Winds
12:45 to 1:45pm
Workforce for the Future of Wind
1 to 2pm
Project Threats... Inside Job?
2:15 to 3:15pm
Large Wind-turbine Manufacturer Forum
2:30 to 3:30pm
How to Manage Turbine Performance
3:30 to 3:55pm
Wednesday, May 24
Improving the Value Proposition for Wind to Support Growth
10 to 11am
International Market Update: Opportunities & Challenges
11:30 to 12:30pm
Women of Wind Energy Networking & Awards
12 to 1pm
Wind power is in high demand from utilities and other buyers because it often provides the least expensive energy available, and this is a testament to American leadership and innovation. This makes it easier to network and meet new industry professionals. AWEA says over 33% of attendees will be WINDPOWER first-timers. Those who are new to the event may also want to secure a spot in the Innovation Pavilion, which will highlight the latest product innovators, small business owners, and entrepreneurs. “Wind power is in high demand from utilities and other buyers because it often provides the least expensive energy available, and this is a testament to American leadership and innovation,” said Kiernan.“Across the country, wind is welcome because it means jobs, investment, and a better tomorrow for rural communities. Let’s keep it up, propel new growth, and take our industry to the next level!” Now that’s the right attitude. And WINDPOWER 2017 is where is will happen. W APRIL 2017
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3214
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Visit us at Booth #
ICE
and informational sessions led by over 100 expert speakers and panelists, including top CEOs and Presidents,” said Jana Adams, Senior Vice President for Member Value and Experience at AWEA. “And every registrant has access to all exhibitors and session panels, which are available in one simple location…the show floor.”
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WINDPOWER ENGINEERING & DEVELOPMENT
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W I N D W A T C H
Blade-mounted flow actuator promises greater turbine power production A RECENT DEVELOPMENT PROMISES to allow larger, more efficient, and durable wind turbines by mitigating unsteady aerodynamic forces that generate fatigue and extreme loads on blades. Developer Aquanis says the device requires minimal modifications to a new blade. The design features a blade-mounted plasma flow actuator, a software controlled, solid-state electrical device that is simple and inexpensive. When a blade-embedded sensor detects deflection, software would signal the device to generate plasma that modulates the aerodynamic lift and drag forces, similar to the effect of trailing edge flaps in airplane wings. Each device weighs only a few ounces and would be placed on the outer 20 to 30% of the blade length near the tip. An electronic driver weighing a pound or two would mount
All remedies tried to date use moving parts and are costly and complex to implement. “The simplicity of our plasma actuator technology provides the basis for an inexpensive, no-moving-parts control system that will let wind turbines react instantly to changes in the wind,” said Aquanis CEO Neal Fine. And an improvement in aerodynamic efficiency can reduce material cost and extend the service life of utility-scale wind turbines. Aquanis’ Chief Technology The market for the device includes new Officer, John Cooney, holds wind-turbine construction, about 25,000 a model-scale prototype of utility-scale turbines per year with total a plasma actuator. capacity of 63 GW. This market is expected to grow 12% per year through 2025. Fine says he is targeting the top 10 wind-turbine manufacturers which include Vestas, Siemens, GE, Goldwind, Enercon, and Suzlon. Combined, these companies own about 70% of the global market. “However, they want to see wind tunnel data before they commit to anything,” he adds. And that is what the company is now working on. What’s more, the six-month NSF grant will fund development of a new design of the actuator that is expected to at least double its The simplicity of our plasma actuator technology provides the basis efficiency. Repowering is another target for an inexpensive, no-moving-parts control system that will let market. Although wind turbines react instantly to changes in the wind. Fine does not see modifying existing blades, the device could be a driver to inside the blade and provide 8 to 12 kV replace the blades especially if a refurbished signals to the plasma generators. The device turbine with a 10% longer blade and plasma is based on patented technology developed actuators can produce 20% more power, at the University of Notre Dame. Aquanis has an exclusive license to the patent portfolio for without exceeding the load limitation on the existing tower and foundation. the wind energy field of use. 12
WINDPOWER ENGINEERING & DEVELOPMENT
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THE BEST OPTION IS HAVING ONE CastrolÂŽ is the only lubricant supplier that offers fit for purpose technology options. We utilize multiple product-based solutions that can align with your O&M strategy and deliver continuity within your fleet. Our expert engineering services can provide insights to help you obtain the maximum value from your lubricants and your turbines. Ask us what options Castrol has for you. Learn more at AWEA Windpower, Booth 2220. Castrol.com/windenergy or 1-877-641-1600
BOOTH #2220
Š 2017 BP Lubricants USA Inc.
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W I N D W A T C H
TRUSTED LEADER IN OPERATIONS & MAINTENANCE
Aquanis says its electronic plasma actuators can modulate flow of air around a turbine blade, thereby reducing unsteady forces and maximizing aerodynamic performance.
With 30 years of experience and 10 GW of energy under contract in North America, EDF Renewable Services is the trusted leader to optimize plant performance, maximize availability, and minimize downtime. With services including full O&M, Asset Management, and 24/7/365 Monitoring, we bring an owner-operator sensibility to all projects. Our development group, EDF Renewable Energy, is a green energy leader, with over 9 GW of wind, solar, bioenergy and storage developed in North America.
EXPERTISE | COMMITMENT | INNOVATION
EDF Renewable Services 858.521.3575 | OMSales@edf-re.com www.edf-renewable-services.com
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EDF Renewable Energy 888.903.6926 | Communications@edf-re.com www.edf-re.com
The company says it has received a National Science Foundation Phase I Small Business Innovation Research (SBIR) grant of $224,969 for the development and testing of the device. The firm was also awarded an Innovation Voucher grant from the Rhode Island Commerce Corporation, which will provide $50,000 in funding to support the company’s research partners in Brown University’s School of Engineering. RICC also awarded the firm a $45,000 SBIR Phase I matching grant to supplement the NSF award.
They want to see wind tunnel data before they commit to anything. To explore a range of system designs, the company needs access to state-of-theart computational tools. The RI Innovation Voucher provides that, with access to Brown University researchers who have developed advanced computational fluid dynamics tools that will assist in Aquanis’ product design. W 14
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W I N D W A T C H
The MACC Spar concept
Filak’s team has designed a barge and a clever method for constructing a spar buoy large enough to support a six-megawatt turbine in deep water.
Andy Filak’s team has detailed a barge and construction method for a polymer concrete spar buoy large enough (~330-ft tall) to support a conventional 6-MW wind turbine in deep water. The barge would include ballast pumps, lifts for mounting the turbine to the buoy, and a position holding system for launching a turbine.
Purpose-built barge and buoy propose to take costs out of floating wind farms ERECTING OFFSHORE WIND TURBINES onto structures in relatively shallow water has been an expensive endeavor. For example, the cost for the five turbines at Block Island, the first in U.S. water, came with a price tag of over $250 million, more than $50 million per turbine. We can do better than that says a team of engineers led by Andrew Filak at AMF Concepts. Filak’s team has designed a barge and a clever method for constructing a spar buoy large enough to support a six-megawatt turbine in deep water, of which there is plenty surrounding the U.S. He recently shared detailed plans for the barge and buoy. Filak calls for using a marine advanced composite concrete to slip form − a sectionby-section forming method − the 330-ft tall buoy. Using geopolymer cement in the slip-formed concrete provides for a high compressive strength, 12,000 psi, about 80 MPa. Tensile strength comes from Baysalt rebar and Baysalt fiber. The rebar is a water proof, chemical resistant, and fire-proof material with a tensile strength several times stronger than conventional steel rebar. What’s more, the geopolymer cement binder will also meet carbon-reduction goals, emitting 80% less CO2 than conventional concrete. Spar-buoy construction starts on the land side of the quay. The first component is the end-bell starter section – actually, the WINDPOWER ENGINEERING & DEVELOPMENT
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bottom of the buoy. It has a 40-ft. diameter and 30-ft. height. Other sections are then formed on top of the bell section. An initial thought was to slip-form the entire buoy on land but the cost to lay-down the structure becomes uneconomical because of the weight of the spar and the cost of placing ballast at sea. Consequently, said Filak, the ocean going deck barge came into focus as a solution. The purpose-built barge would measure 148-ft wide and 440-ft long with a 27-ft height, from deck plate to bottom, and provide the facility for producing the buoy at the quayside. The developers’ consensus is that the spar-buoy substructure best meets the requirements for building deep water wind farms. Advantages include that it can be slip formed as a seamless and steel-free concrete structure. The substructure will have a minimum of a 100-year life due to the low porosity, high strength, and heat cured features of the geopolymer binder in the concrete. And because a modern turbine should work for about (optimistically) 25 years, the University of Maine says the foundation, not the turbine, is the costlier of the two units. Foundation reuse, up to four turbines over the life of the buoy, makes the spar design cost effective. Filak estimates that a buoy can be built and launched for less than $7 million each. More details from Filak’s team is here: http://tinyurl.com/ filak-foundation. Foundations that float, a topic covered in the February issue of Windpower Engineering & Development, is here: http://tinyurl.com/ foundations-that-float. W
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A few components of a complete turbine and buoy
MACC Spar 6MW, WTG SPAR BUOY The illustration highlights a few details on the design from Filak’s team. The spar buoy would be built on the barge at quayside and towed on the barge to its offshore location where the turbine, also onboard, would be added. He forecasts that the buoy should last through four generations of offshore wind turbines, making it the most cost effective structure yet.
www.windpowerengineering.com
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Update on what causes micro cracks that eventually fail turbine bearings
DIAGNOSIS:
Prohibited Vibrations! Drivetrain vibration measurements (mobile / online and offline) Based on ISO 10816-21 ISO certified vibration technicians
The photo on the left is bearing damage from the field caused by subsurface micro cracks. The other is of white etched cracks produced in Aaron Greco’s lab.
Video endoscopy
ONE BIG ROOT CAUSE FOR GEARBOX FAILURES has led scientists and engineers to look more closely at the white etched areas that form just under the surface of failed bearing races. What initiates these tiny cracks that eventually cause turbine shutdowns is still something of a mystery, but it is slowly giving way with close scrutiny. For example, the slipping-versus-roll ratio of bearing elements is now considered a prime driver for white etched cracks. And researchers are able to reproduce the cracks on samples with equipment in a lab. Those are just a couple ideas presented by Dr. Aaron Greco, Principal Materials Scientist, and post-doctoral student Ben Gould, at the recent Drivetrain Reliability Collaborative presented by NREL. The Argonne National Lab researcher acknowledged collaboration with Afton Chemical and SKF, and had more to say on this multi-lab effort to understand the white etching crack or axial crack issue. The term white etching refers to small and early cracking that is some form of micro structural alteration to the material field – a harder more brittle phase of steel − that surrounds the cracking. Its causes are more than just load. “I think the initial gut reaction is to say ‘well, we're just overloading the system,’ and that’s the cause but there are other issues that might be inducing the system,” said Greco. WINDPOWER ENGINEERING & DEVELOPMENT
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Greco said he sees most damage on the high-speed and intermediate speed shafts. When failure occurs in those locations, it can typically involve an up-tower bearing replacement. But when not caught early enough, it causes other issues such as bearings that deteriorate and put more wear on the system.
I think the initial gut reaction is to say ‘well, we're just overloading the system,’ and that’s the cause but there are other issues that might be inducing the system. There are many theories for the causes. “We've characterized them into mechanical conditions, which include loads, slips, frictional energy, and then others such as water corrosion, stray currents, and lubricant formulations. So these are all possible pathways that may cause white etched cracks. With the new test equipment, we can probe all
Five mega joules seem to be the cumulative frictional heat threshold below which no white etched cracks form.
of these different conditions. The ones of most interest are relate to loads and slips and the contact severity,” he said. There is a two-fold reason for developing a bench-top device, such as Greco’s bearing-material tester, the G2 machine that generates white etched cracks. “If you can replicate the failure
Greco’s bearingmaterial tester places a test sample in the center, while the surrounding rollers apply a load. The arrangement allows testing for hydrogen liberation, lubricant chemistry, water contamination, mechanical stress, surface shear (slip), and all that, at times, under the influence of electric current.
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in a controlled environment, you can understand the nobs to turn that cause bearings to fail, and better understand the root causes,” said Greco. The other reason: once you have a test method, you can start implementing or testing mitigation ideas, whether they involve materials, heat treatments, or lubricants. You can also start to validate the effectiveness of those mitigations.” “The machine we use is called a three ring, contact roller, and its benefits include a simple design that generates a bearing contact in its simplest form -- line contact between the roller and ring,” he added. It also allows wide control over the operating conditions so the researchers can change the slight roll ratio that's induced in the contact, along with the load condition, temperature, and more. “In the future we will be working with the NREL staff to understand the real conditions occurring up tower in a wind turbine that might be leading to this failure, and to coordinate bench-top testing with up-tower testing,” he said. W
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Project update: How the wind industry is protecting bats
MARK YOUR CALENDAR. April 17, 2017 is National Bat Appreciation Day. It is a date worth noting because bats are worthy of recognition. They are the only mammals that can truly fly (not glide), with a remarkable ability to navigate using echolocation. Perhaps of most significance to humans, bats keep the bug population in check by eating their body weight in insects each night. This means certain bat species can eat up to 1,000 mosquitoes in about an hour. Impressive, right? The wind industry thinks so, too. Although bats and wind turbines do not always mix well, no other energy industry is voluntarily researching and mitigating wildlife impacts (including wildlife not protected by federal law — such as many bat species) more than the wind industry. In 2003, the American Wind Energy Association, Bat Conservation International, the U.S. Fish and Wildlife Service, and the Energy Department’s National Renewable Energy Laboratory APRIL 2017
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jointly formed the Bats and Wind Energy Cooperative (BWEC). One result of the BWEC is the voluntary best-management practice that limits the operation of turbines in low-wind speed conditions during the fall bat migration season, when research has shown bats are most at risk of collision. It is expected to reduce the impacts to bats from operating wind turbines by as much as 30%. Another result of the BWEC is the development and research of devices that detect and deter bats from wind farms. A promising idea has come from Bat Conservation International (BCI), a wind program under the BWEC investigating the effectiveness of ultrasonic acoustic deterrents, or UAD devices. UADs emit a loud, high-frequency sound inaudible to the human ear but a deterrent to bats. The idea is that these devices, when mounted on a wind turbine, will make nearby airspace aurally uncomfortable to bats so they steer clear.
A BAT DETERRENT The U.S. Department of Energy has issued a $250,000 grant (augmented by $62,500 from the Massachusetts Clean Energy Center) to develop a blade-mounted, ultrasonic whistle on wind turbines to deter and protect bat species. The project, led by researchers at UMass Amherst, will address the challenge of deterring bats across an entire wind-turbine blade, and test whether a pulsed noise (similar to a bat call) can act as an effective warning. The ultrasonic whistle will produce a deterrence signal when air flows over the turbine’s blade.
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UNDERSTANDING BATS The Bats and Wind Energy Cooperative, or BWEC, is focusing on three main areas of research regarding bats and wind energy. 1. Pre-construction monitoring to assess bat activity levels and use at proposed wind sites. 2. Post-construction fatality searches to determine estimates of fatality, and find and compare patterns of fatality to other wind sites and in relation to weather and habitat variables. 3. Mitigation efforts that test the effectiveness of seasonal wind-farm shutdowns and deterrent devices on reducing fatality of bats.
For the offshore Energy Department study, acoustic bat detectors like this one on Maine’s Halfway Rock Lighthouse recorded bat activity at 36 coastline and offshore sites in the Gulf of Maine, Great Lakes, and mid-Atlantic Coast. (Photo: Steve Pelletier, Stantec)
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Researchers got the idea from certain moths that have an ability to obstruct or “jam” bat calls to avoid predation. If UADs prove effective on wind turbines, the devices could mean fewer operating restrictions for wind-farm owners, such as during bat migration season. The key is an effective and reliable UAD that can withstand the weather and environmental conditions experienced some 80-plus meters above ground. According to the BCI, it is planning three studies this year to investigate the effectiveness of a UAD-designed and manufactured by Renewable NRG Systems, a company that develops measurement products purpose-built for the renewable energy industry. One of the studies, funded by the U.S. Department of Energy, will compare the reduction levels of the deterrent devices with turbine operational minimization, specifically feathering blades in 5.0 m/s wind (or 2.0 m/s above the preset operating conditions). Research will also combine impact reduction strategies to determine whether there is an additive effect, showing that UADs further reduce bat fatalities.
www.windpowerengineering.com
Bats offshore As the U.S. offshore wind industry slowly develops, bat research has followed suit. A multi-year study funded by the Energy Department, and conducted by environmental consulting and engineering firm Stantec, is the most extensive study on bat activity offshore conducted to date. Researchers deployed specialized monitoring equipment to detect echolocation calls of bats at 36 coastline and offshore sites. The bat detectors were placed on a number of remote lighthouses, offshore towers, weather buoys, and three research vessels. The study aimed to identify relationships that help predict when and where bats are most likely to be found offshore. In turn, the industry can better plan offshore projects and develop operational constraints that reduce risks to bats. The study found, for instance, that offshore bat activity is highest near heavily forested coastal areas or islands and lowest in areas with fewer trees. Bat activity also increases during periods of warmer temperatures (peaking from July 15 through October 15) and in lower wind speeds. This means offshore developers may plan wind farms further away from shore, or decide to slow or stop turbines running during peak bat seasons. In 2015, the Energy Department awarded $1.75 million for five separate projects to support the development and testing of deterrent technologies that reduce the interactions between wind farms and sensitive bat species. Learn more about those studies at: https://tinyurl.com/bat-studies. Ongoing research and collaborative efforts are keys to protecting all bat species. In fact one recent study by W.F. Frick of Bat Conservation International (and published in “Biological Conservation”) has credited collaboration work for one conservation method — curtailment of wind turbines under high-risk conditions. The study pointed to a reduction of bat fatalities by 44 to 93% using this method, while minimizing the impact on power generation. Research continues to further refine and improve the effectiveness of such mitigation techniques. W APRIL 2017
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Wind work around North America Two years have passed since the Department of Energy released its WindVision report. It is a roadmap that set out a trajectory of 10% wind generation in the U.S. by 2020, 20% by 2030, and 35% by 2050. But is the wind industry keeping up? If the latest figures are an indication, wind energy is well on its way. In the United States, wind ranks number one and provides the largest source of renewable capacity, with over 82,000 MW installed at the end of 2016. Navigant Consulting recently forecasts a 40%+ increase, with another 35,000 MW of additional wind capacity expected between 2017 and 2020. American wind-power expansion is also poised to deliver 248,000 new jobs and $85 billion dollars in economic activity over the next four years. It seems wind energy is on the path to success.
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Xcel Energy has proposed its largest wind investment for 1,550 MW of new projects in the Upper Midwest. This includes seven new wind farms in Minnesota, North Dakota, South Dakota, and Iowa. Xcel Energy estimates savings of more than $4 billion in fuel and energy costs, and has proposed a combination of owned projects and PPAs worth more than $2.5 billion.
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Massive 600-MW project planned for Colorado
Mortenson will build and provide EPC services for the largest single-phase wind farm ever built in North America. The 600-MW Rush Creek Wind Project is set to include 300 Vestas’ V110 2.0MW turbines and an 83-mile transmission line near Limon, Colorado. Once complete, the project will increase Colorado’s wind energy production by more than 20%
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Repowering San Francisco
Wind developer, Salka LLC, plans to re-power California’s Altamont Pass wind farm by replacing 569, 100-kW wind turbines with 27 modern designs. Development of the new 55-MW Summit Wind Project will create about 100 jobs and finish by early 2018. The project is expected to generate more than 60% of its power during peak hours for San Francisco Bay Area consumers.
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Planning for Maryland’s offshore wind farm
US Wind is partnering with JDR Cable Systems on a 750-MW wind project offshore Maryland, the largest offshore wind project in the U.S. to date. JDR’s work will include project management, manufacture, and install of 122 miles of inter-array cable, and 112 miles of export cable and cable accessories. Cable manufacturing is expected to commence in 2018.
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Virginia project wins unanimous approval
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New work & wind power set for Québec
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After two years of study, Virginia Department of Environmental Quality has approved Rocky Forge Wind’s “Permit by Rule” (PBR) application — a wind project planned by Apex Clean Energy in Botetourt County. This marks the first PBR approval for a wind farm in Virginia. Rocky Forge is expected to pay $20 to $25 million in taxes over its lifetime.
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Pattern Development has completed the C$263 million construction-to-term financing for the 147-MW Mont SainteMarguerite Wind Farm, which is now in full-stage construction. The project is using 46 Siemens 3.2-MW direct-drive turbines, with components sourced from Québec. It will also employ a local workforce and about 250 or more during construction.
windpowerengineering.com
Partnering for more reliable gearboxes
Castrol, a global lubricant brand, has formed a joint venture with Romax Technology’s InSight business. Romax InSight is a predictive-maintenance and software provider, which monitors the condition of turbines and predicts gearbox breakdowns. Together, the companies plan to combine O&M experiences to advance gearbox performance and reliability.
GE equips first commercial solarwind hybrid project
GE Renewable Energy will supply equipment for the first commercial solar-wind hybrid power project in the U.S. The 4.6-MW community project in Red Lake Falls, Minnesota will use two 2.3-116 GE wind turbines. GE’s WiSE platform will integrate 1 MW of solar panels through the wind turbine’s converter directly, so both wind and solar share all the same balance of plant.
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I NSU R ANCE G e o f f r e y Ta u n t o n C o l l i n s Weather Risk Analyst GCube Underwriting Ltd.
Hedging against low wind: 5 things you should know about weather risk transfer structures
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s the global wind sector matures, the risk profile of development and operations is changing rapidly. Once confined to more developed and secure markets, the U.S. wind industry is now facing logistical and technical challenges of building and operating projects offshore, and in testing lower-wind onshore locations. Simultaneously, the sector is coming to terms with an overall increase in scale that has seen a considerable ramp-up in size and capacity. Towers reach over 100 meters, blades span over 80 m, and projects are hitting the 600-MW plus range — with even greater potential offshore. Wind-energy stakeholders and the industry have become fairly adept at managing these challenges and the threats they pose to the profitability of their assets, thanks in large part to backing from the insurance industry. In fact, the greatest threat to wind-energy profitability for today’s asset managers is no longer the risk of equipment damage or project downtime. This is good news because it shows a maturing industry. However, the sector faces one recent challenge: the impact wind resource fluctuations will have on asset and portfolio values. High-profile, low-wind speed events in established markets, coupled with the challenge of conducting reliable wind measurement campaigns in emerging markets, are now driving demand for a means of protecting project revenues. Safeguards against the impact of weather on wind project revenues are increasingly significant, and what is now known as weather risk transfer (WRT) mechanisms are gaining more interest.
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GCube’s Gone with the Wind report focuses on the challenges posed by weather-related under-performance of wind turbines. It was launched with the objective of fostering a greater understanding of the value that weather risk transfer or WRT mechanisms can add to a wind-power asset or portfolio.
Understanding WRT In a nutshell, weather risk transfer mechanisms provide project stakeholders with a means to stabilize future cash flows and minimize the impact of unexpected and adverse weather on revenue. WRT structures, if delivered effectively, help stabilize revenues and add value to a project when it comes to finance and refinance. WRT structures provide a financial hedge that protects against market or cash-flow fluctuations by means of compensation in the eventuality of below or above-par resource availability. A recent GCube report, Gone with the Wind: An Asset Manager’s Guide to Mitigating Wind Power Resource Risk, estimated that the global installed wind base is missing out on $56 billion in total asset value as a result of a failure to efficiently manage the financial impacts of weather risk. For those working in the wind sector, it’s no surprise that weather is the single greatest and most significant factor influencing availability and performance. With that in mind, here are five things you need to know about protecting assets from adverse conditions. 1. Expect the unexpected Access to high-quality wind resource data is now better than ever before. The availability and accuracy of longterm synthetic datasets continues to improve because the industry is developing increasingly advanced methods of onsite wind measurement.
www.windpowerengineering.com
APRIL 2017
4/14/17 11:23 AM
INSURANCE
A look at the structures The table provides a brief comparative summary of the Put, Collar, and Swap structures. Flip the page to see graphs that depict results of a hypothetical wind farm under each WRT structure. Of course, premiums and production will vary by wind regime and time period.
However, wind-energy developers and operators still find that long-term project performance differs considerably from pre-construction estimates. In some cases, this is a result of optimistic financial forecasting. More typically, it is the result of unforeseen climatic phenomena that undermine the efficacy of 12 or 24-month measurement campaigns. The threat posed by long-term resource fluctuations to renewableenergy asset performance and revenues is now indisputable and widespread. In the wind sector, this has been evidenced by a number of high-profile examples. One of the most severe examples occurred in Texas back in February of ‘08 when the power grid hit a state of emergency because of lack of wind. Texas recorded a resulting fall in energy production levels of 82%. More recently, the U.S. “wind drought” of early 2015 brought record lows to key markets in California and Texas, which averaged some of the lowest wind speeds in recorded history. In Europe, Scottish Power saw its profits tumble by around £40 million over six months due to less wind than anticipated in the first half of 2016. While in Australia, renewable-energy developer, owner, and operator, Infigen saw its revenues fall 23%, again as a result of low wind speeds. 2. Plan ahead The development of advanced weather risk coverage means the market has an increasingly viable response to unexpected challenges. While resource under-performance is occasionally inevitable, a WRT mechanism can safeguard asset owners against resulting drops in revenue. Simple, right? Well, the premise may seem straightforward but true to the nature of the wind industry, it has been slow to adopt WRT as standard practice. This is not so unusual. The conventional power and agricultural sectors also took time to mull over the value of weather risk transfer.
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The sticking points have been the capacity of risk management and insurance communities to offer an attractive WRT product, with clear advantages that asset owners and investors can fully buy into and understand. And unlike conventional property and casualty insurance, lack of resource is not yet a standard requirement imposed by regulators, lenders, or lenders’ insurance advisors. Until recently, the attitude of operators was typically a ‘wait and see’ approach, where asset protection was only sought after a major revenue shortfall. This reactive approach is diminishing in favor of a more proactive one. Wind operators are beginning to recognize the value of investing in their assets now and for the future. Furthermore, improvements in data collection and analysis mean that WRT contracts can now offer structures based on actual or ideal production by using SCADA data from the generating assets. This is far more effective than relying on meteorological data from offsite devices. It significantly reduces the “basis risk” that typically occurs with data used for a WRT contract that fails to match site performance. Additionally, increased contract lengths of around 10 years are now available, which are able to better match loan tenor lengths and sync with project lifecycles. 3. Size to fit So, how do weather risk transfer mechanisms work? Put simply, a WRT product provides cash in years of resource under-performance. It is adjusted to suit the preferences, needs, and availability of the buyer’s resource. Three basic structures are available: the put, collar, and swap. For a: •
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Put, buyers pay an upfront premium and then receive compensation in years of resource underperformance. Their contract will set out what constitutes a year of under-performance and the “trigger”
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Under the put structure, the buyer pays a premium upfront and receives compensation in years of resource under-performance. For example, if the trigger number is 140,000 MWh and production turns out to be 130,000 MWh, the buyer will be compensated for that 10,000 MWh shortfall. They will be paid 10,000 times the notional payment.
Under a collar structure, the buyer pays a negligible or no upfront premium at all. Instead, in years of resource over-performance, the insured will compensate the insurer — so whenever revenues are above the ‘call.’
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number for production. If production falls below this number, the insurer will pay out in proportion to just how far below it production has fallen. Collar, buyers pay a negligible upfront premium, or nothing at all. So, the insured may compensate the insurer in years of over-performance, while the reverse is true during project under-performance — the insurer pays the insured. When revenues are somewhere in between the agreed upon number for under and overperformance, neither party pays.
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Swap, the insured will pay little or no upfront premium but, in this case, there is only a single trigger so that one party will always compensate the other at the end of the settlement period. If revenues are above this trigger, the insured will compensate the insurer, and vice versa if revenues fall below the trigger.
A proper understanding of which structures best suits the risk exposure of a specific project or portfolio is critical because it determines how effectively
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APRIL 2017
4/14/17 11:23 AM
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INSURANCE
A swap structure is similar to a collar, in which the insured pays little or no upfront costs. The difference is that at the end of the settlement period, one party will always compensate the other. In this case, there is a single trigger point represented by the red line in the graph. When revenues are above this trigger, the insured will compensate the insurer and vice versa. This has the effect of providing stable year-on-year revenues.
a WRT mechanism performs longterm. One size does not fit all. Time and investment will be required from buyer and seller to determine a suitable structure and triggers. 4. Add value Those who may benefit from a WRT product fall into one of two groups: those who are financing or refinancing, and those who are doing neither but want to balance revenue flows and secure revenue certainty. In the first case, because WRT effectively safeguards a minimum amount of revenue for a wind farm, regardless of wind-speed variability, lenders can apply less conservative estimates for their expected revenues. This means lenders can offer more favorable debt service coverage ratios. The advantages of this enhancement to leveraging, coupled with lending rate reductions, will make projects more valuable to asset owners. GCube estimates that, for a 50-MW onshore wind farm worth $80 million, successfully mitigating or transferring weather risk could achieve a total net present value increase of $5.8 million. WRT is still an option for those not at the financing stage, such as 26
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risk-averse entities seeking to stabilize year-on-year revenues. In fact, benefits include an ability to minimize the impact of weather variability on the volatility of share prices and foster investor confidence. WRT buyers can also benefit from protection against rating downgrades and are typically better able to avoid profit warnings. 5. Protect investments Typically, more small-scale wind operators have researched the benefits of weather-resource transfer structures. WRT can provide vital protection for a single-asset owner, for whom the financial impact of below-par wind speeds in one location is proportionally far greater than it is for the owner of a large portfolio. While a larger portfolio owner can benefit from the geographical diversification of its assets, the prevalence of region-wide wind lulls (as experienced across much of the U.S. in 2015) means that even the largest portfolios remain unprotected from the financial strife of asset underperformance. Further, if a portfolio owner is seeking project financing through a special purpose vehicle, a WRT product
can deliver project-by-project financial advantages. And, finally, larger players typically have greater skillsets and resources to dedicate to the identification of suitable WRT mechanisms. This lets such companies access more options and make informed decisions about how insurance products can increase stability and revenue predictability across their portfolios. Resource variability and underperformance are serious concerns for the industry, with the frequency and severity of low-wind events affecting asset owners around the world. Indeed, their importance will only grow as wind and renewables make an ever-greater contribution to global electricity generation. For single-asset and large portfolio owners, WRT mechanisms can provide invaluable protection against the financial impact of unforeseen climatic phenomena. By enabling greater revenue certainty, these mechanisms let wind-power stakeholders focus on what really matters: running a profitable business and providing a cost-effective, long-term supply of clean energy, regardless of the unexpected. W
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APRIL 2017
4/14/17 11:23 AM
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S AF ETY
Michael Caldwell Business Development Manager 3M 3M/wind.com
Fall protection for tools, such as tool holsters and wristbands, make work environments safer and more productive by significantly reducing falling object incidents that could result in personal injury, equipment damage, and tool loss. Look for protection products that are third-party tested in harsh conditions. (All photos: 3M)
A few ideas for fall protection: How to stop dropped tools at height
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ropped objects are neither a recent problem nor exclusive to the wind industry. In 1903, for example, the New York Times published a frontpage article on construction of the East River Bridge, which still stands today. The article however, barely touched on the progress of the bridge, which was big news for the city at the time. Instead, it focused on the number of objects falling off the bridge during construction. The article mentioned numerous dropped and thrown tools, posing threats to boats and people below. It seems that when opposing sides of the bridge were built up close enough to one another, workers on each side were throwing tools back and forth. Certainly, it was a different time with a different safety culture. That was well over 100 years ago. But how much has changed?
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According to the Times’ article: “Dozens of placards were posted at various points on the bridge, cautioning.” Cautioning what? Safety, of course. Even back then signs were posted around a job site, much like you see today at construction sites, reminding site personnel to “Be careful” and “Put safety first.” In other words: watch your step and try to avoid dropping stuff. After a century of experience, we see that building a safety culture has proven easier said than done. The Occupational Safety and Health Administration (OSHA), the federal agency charged with the enforcement of safety and health legislation, has put together the top reasons for workplace death in the construction industry and has called it the “Fatal Four.” The Fatal Four includes getting struck by objects (i.e. dropped tools), standing or working between
www.windpowerengineering.com All photos courtesy of 3M
APRIL 2017
4/14/17 11:25 AM
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SAFETY
A hardhat tether provides extra safety and security to ensure a worker’s hard hat does not accidentally fall off.
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heavy equipment, electrocution, and workplace falls. OSHA maintains that eliminating the Fatal Four would save over 600 workers’ lives in America every year. This means that we still have a number of unnecessary deaths every year from preventable events. It some ways it seems little was learned from the safety mistakes of the East River Bridge, or other construction incidences since then. Granted, accidents happen but how is it that dropped objects are not better prevented some 100-plus years later? Fatalities aside, guess how many people are simply injured a year from a falling object at a work site? Maybe 1,000? How about 10,000? In 2015, over 42,000 people reported injuries from falling objects at job sites. And note, this number only represents reported injuries, and is not an accurate indication of actual incidences. OSHA representatives have maintained the actual number is likely four to five times that because most workers are unlikely to report unless an injury is serious enough. To break this down, a total of 42,400 injuries from dropped objects equates to 116 per day every day, including holidays and weekends. That is more than two per day per state. This means that today in Georgia, two people are going home because of getting struck from a falling object. Today, in Minnesota, two people are going home. Today in Ohio, California, Alabama, Maine, Oregon, Washington, and so on, two people are going home because of a preventable injury. There were two in each one of those states yesterday, and there will be two tomorrow. About every 12 minutes in the U.S. somebody gets hurt from something falling. It’s a mundane point but one worth repeating because the question becomes how long are you willing to gamble that you won’t be one of the 116 people today that gets struck by some object while passing by a job site? The question today is: what are we as an industry going to do about it? Let’s consider some of the things we have done about it.
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Hardhats Hardhats were designed for small bumps and minor impacts — not for dropped objects. They were first used in mines and confined spaces where workers might move or stand up too quickly and bump their heads on the surrounding rock-hard tunnel. Fast-forward to today and we’re still using hardhats at many job sites. Use of a hardhat should remain mandatory at all construction sites. But it should not be the only form of protection against dropped objects. Barricades To ensure additional safety, some companies will place barricades around construction sites or wind turbines to prevent personnel from walking below while work is happening above. But how far out are you typically barricading at a site? It’s easy to assume objects would fall in a straight line down but that’s rarely the case (which is another reason safety netting fails to work a lot of the time). There is equipment or other tools in between that can cause objects to bounce or unexpectedly deflect off another surface. So if barricades are a safety measure, the space and distance getting barricaded is an important consideration. Is it twice as far in every direction as workers are climbing up? Likely not. Typically the job site itself is not large enough. Just imagine the construction of the Freedom Tower in New York. If workers had barricaded out twice as far in every direction as they were climbing up, half of Manhattan would have been shut down for 10 years. This is unrealistic for most job sites. Lanyards & tethers Tethering tools has become one answer to the dropped-object problem. The concern is when this answer becomes a one-size-fits-all response. Five lanyards for five different tools is perhaps one thing, but what if you need 20 or 50 tools up tower? Then the typical answer is a bungee to tether every tool you may need with you.
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SAFETY
However, providing one bungee cord is like handing a wind technician one universal wrench to fix a turbine. One size fits all is not an ideal answer to ensure tool safety. But neither is sporting 20 to 50 tethered tools ideal for quick or safe access. What’s more, two-thirds of the dropped objects are tools not in use. In other words, most of the objects falling are those workers are paying no attention to. It might be a tape measure or water bottle set down that slides off-tower when a worker accidentally brushes past it, or some other object that is tossed next to these items, knocking one over the edge. The point is the objects that fall are typically not the tools workers are using or carrying with them. It is the stuff on the side. So what is the best method to ensure those objects are safely contained without more glorified rope (i.e. lanyards) or extra snaps and attachment points? One way is to completely change how we think about dropped objects — and that means leading with fall protection.
Fall protection for tools The idea here is that dropped object prevention is an extension of fall protection. Shifting the mindset and treating all objects at height as if they were people at height increases the burden of safety. And technically, fall protection measures safeguard personnel at height and should protect those on the ground, too. One of the first questions when properly planning and fitting for fall protection asks what kind of harness is required. This is because the type of harness is important and depends on the job, the person wearing it, and how it will attach to keep that person safe. Attachment points for tools are similar. In fact, think of them as a harness for tools. With this mindset, it is easy to reason that a different size, shape, and type of “harness” for a tool is needed depending on the job and the worker. And whether it is for a quarter-of-an-ounce shackle pin or an 80-pound portable generator, there is a different type of attachment to ensure the object stays safe at height.
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A cell phone or radio holster should attach to a harness and tool belt, and adjust for easy access.
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SAFETY
Attachment points make it possible to tether tools in seconds without defacing or structurally modifying tools. Once an attachment point is correctly installed on a tool, a tool lanyard can be used to tie the tool off.
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While there are plenty of zero-harm safety cultures at workplaces, there unfortunately are no set standards for dropped object prevention. Therefore, it is important to stress the significance and enforce implementation requirements. There is little point in purchasing a special attachment for a unique tool if it’s misused, so proper training is essential — for proper implementation and inspection prior to use. To drive this point home, consider this: if a manufacturer or someone on the job says a tether is rated for 10 pounds, it is important to question what this means. Simply nodding and assuming the rating means the tether is safe for use is not enough because it’s unclear if that 10 pound test was static or dynamically tested.
About every 12 minutes in the U.S. somebody gets hurt from something falling.
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One thing safety and fall protection does have going for it is that most workers have a strong sense of teamwork. In most cases, site workers are more likely and willing to use equipment that protects the people around them then they are to use gear that protects themselves. So a wind tech might forgo his own hardhat but chances are he’s unwilling to risk a wrench falling out of his hands and potentially harming someone below. Working at height is dangerous work for every person at a job site. When fall protection becomes greater than individual safety, behaviors begin to change rather quickly and in favor of stronger safety measures. After all, when it becomes your responsibility to ensure that the person next to you goes home safely, it becomes extremely important how you don a fallprotection harness and attach a wrench or spare tape measure. W
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BOLTI NG Michelle Froese Senior Editor Windpower Engineering & Development
Smarter tool calibration
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alibration is the process of configuring an instrument to provide a measurement within a set or acceptable range. It is used to ensure the accuracy of a tool, which is important in the wind industry. A couple loose bolts and the reliability of a wind-turbine’s tower or gearbox could come into question. Eliminating or minimizing factors that cause inaccurate measurements is a fundamental aspect of tool design. Just ask Chris McKerihen, a Mechanical Engineer with RAD Torque Systems, a division of New World Technologies Inc. The company is a Canadian manufacturer of pneumatic, battery-powered, and electronic pistol grip torque wrenches. “The aim of calibrating a tool, such as a torque wrench, is to ensure that it applies the torque the tool indicates it is applying. This may seem simple enough, but true calibration is a little more complicated than it sounds,” he says. The calibration process typically involves using the tool to test samples of one or more known values, called calibrators. “This is done by gradually increasing the pressure to the tool while it is in factory, on a calibration stand, and connected to a digital readout transducer,” says McKerihen. A RAD Smart Socket measures torque directly on a bolt up to 8,000 ft. lbs. It uses RAD Torque’s transducer technology with custom sockets to measure the torque applied to the bolt during a torque cycle. It is about the same size as a standard socket, has a built-in rechargeable battery, measures and displays peak torque, provides “pass” or “fail” indication, and logs all data (downloadable as XLS, CSV, or PDF files).
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Tool calibration is important but so is a tool’s weight and size. Large pneumatic or electric torque wrenches used on megawatt-sized turbine towers can weigh over 30 lbs. RAD Torque has used new materials and heat treatment processes just to keep the size and weight count down, while ensuring the reliability and safety of the tool remains high. For example, the company’s E-RAD 10K offers excellent power-to-weight ratio. It weighs only 15 kg with a torque range of 1,350 to 10,000 Nm.
A technician will then verify the torque output from the transducer and compare it to the test gage. “This is the easy part,” he says. “You’re testing and double-checking the tool to confirm that it does what the manufacturer says it does.” Easy maybe, but it is an important step. Factory torque charts and tool certification verify its quality. What such charts fail to account for, however, are the many variables users may find within their specific application. “The big variable is the bolted joint. How long is the bolt? How dirty is the bolt? And how hard is the washer?” McKerihen points out that a galvanized bolt is going to act differently than one that’s higher grade or lubricated. “There is no guarantee that the bolt used in your specific application is similar to the one for which the tool was initially calibrated. Many variables can affect calibration. So if anything changes in the environment, technically the tool should be recalibrated for those variables.”
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Torque is an indirect measurement of clamp load, he explains. “You can put the same torque value into seemingly identical bolts and achieve different clamp loads. At the end of the day, clamping force is the primary goal and marker of an accurately bolted joint.” McKerihen says it is still important to ensure that when a developer maintains, ‘This is a torque-critical application, and it must adhere to these standards,’ that you are using a calibrated certified tool. “However, a question still stands beyond a tool’s quality,” he adds. “And that is: are you sure you’re adhering to those standards for your specific job?” This is where it is key to understand the application and its requirements. “Some wind techs get too focused on specific torque values that aren’t necessarily representative to what matters in the end, which is clamp load. Accurate calibration comes down to a genuine understanding of the bolt, the joint, and the quality of that joint — and what it means to the selected torque value of your wrench,” he says.
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Some wind techs get too focused on specific torque values that aren’t necessarily representative to what matters in the end. To better understand applicationspecific calibration, RAD Torque engineers have attempted to replicate what may happen in the field. “In our own internal testing and calibration, we’ve built mock flanges and purchased different types of wind-tower bolts. What happens is once you’ve strained that bolt with an applied torque, it changes the dynamics of it. So the second time you tighten it, it acts a little differently.” When it comes to calibrating tools for an energy industry, this slight difference matters. “Under 36
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and particularly over-bolting is potentially dangerous and hazardous to equipment. The latter can eventually lead to a broken or fragmented bolt, and that can cost project owners a lot in future downtime,” says McKerihen. In these testing scenarios, the engineers have tried to characterize what happens in the field and how to best address how such variables affect calibration. “Really, the best way to ensure that a certain torque value has been delivered is with something like a smart socket, one that lets users calibrate their tool to a specific application in the field.”
tech kept getting a fail light. “He set his pressure on the ground based on the chart we provide here for 2,000-foot pounds. But up-tower, he kept getting fail, fail, fail. So, why was the tool failing?” asks McKerihen. Fortunately, the wind tech had a TV tool on hand. “It quickly read that his torque wrench was only capable of 1,700 foot pounds. Why? Because of the loss in the air hose going all the way up the tower. The tool quickly told him the answer.” This was an easy fix. The technician moved the regulator from the bottom to the top of the hose, and the tool worked immediately.
Traceable torque The smart socket is a small device that measures actual torque applied to a bolt during a torque cycle. According to McKerihen, it acts as an audit device that lets users calibrate a tool while in the field for their set application. “We call it the lie detector because it logs the action of every completed torque,” he says. “For example, a wind tower might have a flange of 144 bolts and the standards might specify that each one of those bolts must be torqued within a certain threshold — say, of maybe five percent of each other. By using something like a smart socket, there is now a data log and proof that from bolt one, the job is done accurately.” McKerihen provides another example of how a smart socket has helped in the wind industry, but this time on a transducer verification tool. The RAD Transducer Verification Pneumatic Tool (or TV tool) has a built-in transducer that is similar to the smart socket, and was designed to fix a problem in the bolting industry: incorrect air supply and tool operation, both of which can cause differences in a tool’s torque output. In this case, a technician ran a 100-meter long hose up the tower of a wind turbine at a manufacturing plant. The hose connected his pneumatic tool (set for use in the nacelle) to a regulator and compressor on the ground. But the APRIL 2017
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TOP: An ISO 17025 accredited calibration laboratory, in New World Technology’s manufacturing facilities, ensures maximum quality and calibration traceability without use of a third party. The company designs all tools according to CSA, CE, and UL safety standards. BOTTOM: Planetary gear-driven wrenches offer continuous rotation and controlled torque, which makes them faster and more accurate than conventional hydraulic wrenches. New World Technologies uses in-house machining facilities for every tool to ensure high quality, safety, and performance.
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“That’s a situation where that fail light and that device told the end-user he was doing something wrong,” says McKerihen. “But imagine if he was using a conventional tool, set the pressure, ran the 100-meter hose up-tower, and worked all day. No one would ever check or know that he was outside of the tolerance window.”
Really, the best way to ensure that a certain torque value has been delivered is with something like a smart socket, one that lets users calibrate their tool to a specific application in the field. Setting standards The idea McKerihen and his team of engineers at RAD Torque are trying to demonstrate to the wind industry and others (with help from the company’s own RAD Smart Sockets) is that accuracy varies from application to application. “Standards are certainly important and I’m not knocking them, but some of the standards are a bit antiquated. They are based on older thought processes or designs,” he says. “One bolt in one wind tower is not necessarily going to act like one in another wind tower, whether that’s because of brand, wear, weather, or another condition.” So why treat it that way if the goal is equipment reliability? McKerihen says it comes down to the acceptable tolerance window for the job at hand — and knowing what that is. In fact, if you check the fine print, most tools have instructions that read: Verify with experimental results. “But as engineers, all through university, you’re taught that such calculations have an exact value. But in the real world, in real applications, that’s typically not the case,” he says. “If the scenario is different, the loading will be. Always calibrate for your specific application.” W 38
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A RAD Transducer Verification wrench gives the operator a visual indication as to whether the tool’s torque output is deviating from the set target torque, reducing errors in the bolting process. High-torque accuracy can be achieved when using the real-time Bluetooth torque-graphing mode.
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T RA NSM I SS ION Maryruth Belsey Priebe W r i t e r, J a d e C r e a t i v e IQPC GmbH
A few ideas for better offshore cabling PEFLEX is a corrosion-resistant, cable-protection system used to protect freespan array and export cables on offshore wind farms. Its modular design enables quick assembly onshore or on a cable vessel. Once assembled, PEPFLEX is positioned from the wind turbine’s monopole to beyond the scour pit limit. Photo courtesy of Pipeline Engineering
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espite the critical role cables perform at wind facilities, the devices are too often an afterthought during project planning. A push for faster wind-farm installations and lower project caps and operation budgets means some components take less precedence over others in attempts to streamline project costs. While cables may fall to the bottom of the list for some onshore wind farms without much concern, the same does not hold true for offshore projects. Offshore developers in Europe have learned this the hard way. For instance, damage to cabling at both the Thanet and London Array wind projects have had British offshore wind-farm operators looking for ways to prevent such challenges. At the 175-turbine, 630-MW London Array project in the outer Thames Estuary, the problem occurred during export cable laying. While install of the nearly 450 km of offshore cable took place, a part was damaged and required replacement when one leg of the installation rig pressed the cable into the seabed floor. For the 100-turbine, 300-MW Thanet wind farm, about 12 km off the coast of Thanet district in Kent, England, a routine inspection found a kink in two export cables shortly after install. Repairs meant the wind farm could only operate at half power. The job also required conversion of a VBMS
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vessel (formerly, VSMC — a specialized offshore vessel supplier) to properly conduct the cable replacement because a chartered cable-laying vessel was unavailable on short notice. Unlike onshore wind-farm installations, offshore cabling routes are more difficult to access, let alone repair. In fact, simply locating a fault can sometimes pose a challenge. Unexpected costs of specialized vessels (given the small number available worldwide with suitable capabilities) and wind technicians (who excel at work offshore) can add up quickly. Another complicating factor is that intertidal operations for offshore wind-farm cabling have proven quite different than those typical in the oil and gas industry. Also, soil conditions vary greatly depending on the locale so one offshore wind project is not necessarily representative of another. Protecting cables The Thanet and London Array projects are two examples of offshore wind farms that have experienced unexpected cable problems, but they are not alone. Sweden’s 110-MW Lillgrund wind farm is another project that stopped operation for nearly two months due to cable faults. Project operators had to send high-quality, underwater cameras down to locate and assess the problem. At first they found that a cable section bent at an acute angle, and then operators identified another fault on a different point closer to the substation. Other offshore wind-farm operators have noted issues such as early cable erosion and insufficient protection against the current. Regardless of the cause, failures like these can severely impact a wind farm’s performance and revenue. An offline wind farm can cost upwards of $2 million a day, and then there are the added repair or replacement costs. As such, one area garnering attention within the offshore wind-cabling sector is the production of better cable-protection systems, and ideally one that can adapt to a cable already in use with little effort or added cost. One device now in use at a few
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APRIL 2017
4/14/17 11:49 AM
A Radical Change in Bolting is Coming Your Way Norbar Torque Tools Introduces a New Generation in AC Powered Torque Multipliers
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TRANSMISSION Subsea cable health is a particular challenge for offshore wind developers and operators because of the harsh environment it must endure and work in. The ORCHIDS project (Offshore Renewableenergy Cable Health monitoring using Integrated Distributed Sensor systems) is looking to enhance subsea cable-monitoring capabilities by combining emerging optical-sensing techniques to enable a smarter cable-management system. Photo courtesy of European Marine Energy Centre
TekTube works differently than most cableprotection systems by replacing the need for conventional steel J-tubes, which protect cables when they are connected to subsea foundations. The system’s pre-install capability lets it fit and secure onto cables onshore, which saves time on the installation vessel and improves efficiency of the overall operation. TekTube was successfully installed for the first time at the Westermeerwind near-shore wind farm in the Netherlands. Photo courtesy of Tekmar
offshore wind farms, including the London Array, is the PEFLEX subsea cable-protection system. PEFLEX protects subsea array cables and export cables against movement from wave action and turbulence through exposed monopole scour zones. It is intended to safeguard cables from impact, abrasion, fatigue from dynamic motion, and over-bending. It can also install without divers or an ROV to save additional project costs. PEFLEX is equipped with a series of durable interlocking polyurethane vertebrae half sections, interspersed with elastomeric sleeves. The system also uses J-tube and J-tubeless connections at the subsea entry point, and is clamped and fastened securely into place with Inconel strapping and banding. Another example of innovation in offshore cabling protection is a compound cable solution called a two-inone because it provides cable protection and replaces conventional steel J-tubes. J-tubes have been used in the oil and gas sector for many years as protection for power cables because they connect to a subsea foundation. The two-in-one is designed for jacket structures, gravity based foundations, and tripods. One company, Tekmar, has designed the TekTube, which can install onshore and reduce offshore time and costs. TekTube 42
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can secure to a wind-turbine foundation when still on land, sealed in place, and then transported offshore to the wind-power site where it accepts the power. According to Tekmar engineer Jack Simpson, saving install time is an important safety feature of this product. “Cabling represents about 7% of the cost of installing turbines, but historically 70% of the insurance claims — it is a very risky element.” He added that by reducing risk, it is also possible to reduce installation costs. "This one product costs a quarter of the price of most other cable-protection options. Installation is cheaper, too. This is a bit of a game changer in the industry.” Other ideas for protecting subsea cabling include bend restrictors that limit the curvature of cabling, and bend stiffeners, which prevent over-bending during installation. Also, suppression strakes designed with computational fluid dynamics principles help prevent damage from vibration forces over free spans. Smart cables The durability of cable hardware is one way to ensure proper install and fewer cable faults and failures. However, no device
offers full assurance against cable damage, especially in harsh offshore conditions. But there is a product that gets one step closer. Smart cable is fast becoming capable of several things conventional cable is not. For example, smart cables include capabilities such as continuous cable condition monitoring, pre-fault detection, and the ability to send information to a web-based status monitoring system. These systems typically consist of advanced cabling hardware, sensors, and control centers where all data points are monitored and analyzed. Over the past couple of years, Tecnalia, a firm working with PDL Solutions and JDR Cable Systems (and funded by the UK government), is working as a team to develop smart cables for use in the UK offshore wind sector. Their goal is to reduce the levelized costs of offshore renewable energy. The benefits of their smart cabling include the ability to monitor and indicate where insulation degradation is taking place, test the function of cables (without interrupting service), and pinpoint cable failure. More recently, Fraunhofer UK Research has teamed up with Synaptec (a developer of optical fiber networks), and the European Marine Energy Centre, to develop a new way to address marine cable and electrical infrastructure reliability. The team intends to enhance subsea cable-monitoring capabilities by combining emerging optical-sensing techniques that enable a smart cable system for use during manufacture, install, and end of life. “Subsea cable health is a particular challenge for offshore renewables due to the hostile environment in which they are placed and have to operate,” explained David Hytch, Offshore Renewables Specialist at InnovateUK. “Failure of cables can also lead to costly losses of revenue and hefty repair bills.” While no offshore cable or hardware system provides full protection against faults, a combination of monitoring capabilities can significantly decrease downtime and speed repairs. W
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F LU I D S & F I LT E R S Shawn Sheng National Renewable Energy Laboratory
Don Roberts DA Roberts LLC,
Improving the analysis of gear-oil debris with a compact filter
F A compact filter installed (below) and conventional element provide a size comparison. Photos by Don Roberts
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ilter debris analysis (FDA) is a condition-based monitoring tool used by industries to identify wear mechanisms in critical, oil-lubricated machinery. Often discarded during regular maintenance, the filter are traps with potentially valuable wear data that may not be collected or analyzed consistently using more standard, periodic oil analysis. Such analysis is good for trending oil deterioration. Using particles liberated from the filters, a laboratory can use several techniques, including a scanning electron microscope (SEM), to provide rapid, automated counting of large wear particles into size bins and classification by elemental composition. FDA is not currently a standard condition monitoring tool used in the wind industry. Utility-scale wind turbines have large gearbox oil filters, typically 15 to 30 in. (400 to 800 mm) in height, weighing 10 to 20 lb (4 to 9 kg). Because of the large filter’s size, costs of logistics and analysis are barriers to regular use of FDA. Thus, researchers from the National Wind Technology Center at the National Renewable Energy Laboratory conducted a test program with Hydac Technology Corporation and SGS Herguth Laboratories, Inc. to overcome these barriers as part of the Drivetrain Reliability Collaborative (formerly known as the Gearbox Reliability Collaborative). The accompanying photos show one possible, costeffective solution under field test. A side-stream filter consisting of off-the-shelf hardware supplied by Hydac uses a small version of the standard main gear-oil filter and would draw oil from a sample port upstream of the main gear oil loop. Logistics and analysis costs for the compact filter are significantly lower than for the large filter, with a potential payback within a few years in comparison with periodic large filter FDA. Field tests were conducted on nine, megawatt-class wind turbines from July 2015 through December 2016. Laboratory analysis demonstrated successful hardware operation and SEM particle classification for the main and compact filters, as shown in the pie and bar charts. The charts show good correlation obtained from one test turbine between the main gear oil and compact
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F LU I D S & F I LT E R S
filters with respect to particle size and classification. One source of data variation between the main and compact filters during the field trial was the preparation method of SEM patches for small and large filters caused by the more difficult
handling of the large filter; therefore, another advantage of the compact filter is more consistent sample preparation. As part of the analysis specification, classification rules are established, as shown in the table
Example of SEM classification rules. The classification rules provide an instruction set for the SEM to bin particles by composition using an energydispersive spectrometer (EDS) to evaluate the particles as shown in the photo below.
BELOW: SEM analysis results; main gear oil filter (top), and the compact filter (below) Source: SGS Herguth
BELOW: SEM/EDS classification of particles Source: SGS Herguth
Example of SEM Classification Rules (SGS Herguth)
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The tables, Elemental concentrations and size, shows their SEM classification. The data can identify specific wear components such as the bearings, gears, or wear mechanisms involved, such as sliding or cutting to further inform corrective maintenance. What is the benefit of filter collection and classification over standard oil analysis? The filter can provide a more consistent collection of particles over time between periodic maintenance intervals. Oil-analysis samples collected at a discrete moment in time limits the quality of the data by the quality of the sample. For example, samples collected on cold, settled oil will not have a representative particle distribution. And warm samples are colleted about 20 min. after the turbine stops because of the time it takes to climb an 80 to 100-m tower. The table Oil analysis tests presents a matrix of common wind turbine gear oil analyses that summarizes limitations for gearbox health monitoring in comparison with FDA. Using filter particle counts, sizes, and classification, outliers on a wind project can be identified for additional monitoring or maintenance. FDA may be most beneficial for some wind projects that do not already collect or monitor wear particles. Successful alternative traps include magnets and online chip detectors to collect ferrous wear particles, and filter baskets located under the filter elements, which collect ferrous and nonferrous particles.
Elemental concentrations and size
Elemental concentrations (above) and size (below) per particle classification.
Oil analysis tests
Source: SGS Herguth
LEFT: References: *Matt Spurlock, Practicing Oil Analysis (11/2006), **Guy Nadeau, William R. Herguth, Applying SEM-EDS to Practical Tribology Problems, Herguth Laboratories, Inc., Practicing Oil Analysis (7/2004)
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Performing online wear particle and vibration monitoring could be the next logical steps for a staged implementation of more expensive online condition-based monitoring after FDA screening has identified a need for more frequent monitoring. The research demonstrates FDA has distinct advantages over oil analysis, and may fit a key niche between oil analysis and more expensive online condition monitoring systems. W
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When combined into one comprehensive package, this arsenal of products provides protection, assurance, and maintenance predictability. In making this small investment you put yourself in control, leading to substantial time and money savings. With over 50,000 installations, HYDAC has the experience to meet your toughest requirements. Partner with HYDAC for all of your Wind Turbine applications. • BN4HX Filter Element – Designed for heavy duty wind environment and long maintenance intervals • Filter Housings, NF (simplex) or NFD (duplex) – A two-stage (course/fine filtration) design with integral bypass protection • GW Sensor – Placed in the filter housing for more precise measurement, it sends a signal if the element is suddenly retaining increased material • AS1000 Aqua Sensor – Reads humidity level in the gearbox and can set a parameter to send a signal when high • EY1356 Switch Sensor – A magnet collects material and closes the loop sending a warning signal of a possible issue NFD Filter Housing
NF Filter Housing
BN4HX Elements GW Sensor
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EY1356 Switch Sensor
AS1000 Aqua Sensor
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S O F T WA R E
Charlie Neagoy VP Business Development L i b r e s t r e a m Te c h n o l o g i e s I n c .
Onsight Connect video collaboration software runs on smartphones, tablets, desktops, and even smart glasses. It connects field workers with experts for a shared experience to more rapidly diagnose, inspect, and resolve problems in low-bandwidth and rugged environments.
Connecting onsite wind techs with offsite support
T
he time and distance that separates expertise from turbine assets is an O&M challenge. For example, what happens when a wind tech comes across an unknown problem during a routine turbine inspection? For remote wind farms, it is important to provide quality turbine inspections and fix problems quickly. At times, additional expert advice is needed and that can take up valuable time. A quicker answer may come from a combination of software and the Internet of things (IoT), which connects onsite and offsite personnel. The problem Imagine that during a routine wind-turbine inspection, a wind tech hears an odd noise coming from the gearbox. He is unsure of the cause and could use a second opinion to diagnose the problem. He takes a few photos, completes the
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inspection, and later emails the photos and a description of the problem to an expert working offsite. The next step may include a few back-and forth emails, maybe a phone call, and potentially another trip up-tower with a borescope. In some situations, the expert may have to travel to the wind site to inspect the problem in person. It is a workable problem, but one that takes extra time and cost. Fortunately, there is a quicker way. Companies in other energy and transmission industries are starting to diagnose asset and infrastructure problems faster by deploying “collaboration platforms.� Such platforms fast-forward communication efforts between onsite field personnel and offsite engineers or equipment experts. With the help of collaborative features, such as real-time audio and video, field techs virtually bring the eyes and ears of experts into the field to inspect, diagnose, and troubleshoot complex assets.
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SOFTWARE
A quick answer Now imagine our wind tech with the gearbox problem, only this time he’s equipped with live video-collaboration software that connects his footage and visuals to a remote expert. Instead of taking photos to email later on, he can work with a remote expert right on the spot. By using a collaboration platform, such as Librestream’s Onsight, the tech simply launches the Onsight app on his smartphone, connects using cellular or wireless networks, and video calls his expert at headquarters. Librestream is a software and tech company with the goal of helping companies collaborate on work and environments virtually. The Onsight collaborative platform connects workers in rugged environments with experts far away to rapidly respond to issues in the field. Unlike video chat or conference calling, it was built to meet rigorous
The key to clear images is an industrial-quality camera. The Olympus IPLEX features a unique PulsarPic image processor to produce highresolution images that can highlight very small defects. It is equipped with a 6.5-inch screen and an anti-reflective, daylight-view monitor.
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LEFT: A colleague, supplier, or customer might be on the other side of the world, but experts can stay in the office, sharing audio and video, circling and marking areas that need attention, adjusting lighting, and recording or capturing still images to develop a lasting knowledge base.
security requirements and operate in low-bandwidth environments. The software can also integrate within existing workflow processes and provide a saved knowledge base that leverages expertise as part of the IoT. So when a similar problem occurs in the future, the answer is still available and only a click away. Thanks to an easy-to-access app, the wind technician and equipment expert can initially work together on finding and fixing the gearbox problem. The two can also pass notes virtually, and telestrate or draw on the video screen. A telestrator is a device that lets its operator draw a freehand sketch over a moving or still video image. Now suppose the expert in this case wants to examine the external gearbox via the tech’s video. He can simply instruct the technician to inspect inside of the gearbox on the spot. With proper equipment onsite, this is possible and easy. The technician would set up his videoscope and a specialized collaboration hub. Librestream’s Onsight 400R Collaboration Hub, for example, is an IoT device that can connect nondestructive test or visual inspection instruments, such as a videoscope, and share live visuals with offsite personnel. The wind tech can plug the
RIGHT: Regardless of the format and resolution support, the Onsight 400R Collaboration Hub can stream live and clear visuals from external test instruments to remote experts. Teams can record a session, take high-resolution photos, or freeze and draw on the visuals together.
videoscope into the hub, insert the scope inside the gearbox, and instantly share images and video with the expert’s smartphone or computer. If an area is of particular concern, the expert can remotely zoom in or adjust the onscreen lighting from his own computer or smart device. He can also circle or mark areas on the screen that need attention, or capture still images to review later or to develop a recorded knowledge base. Such collaboration platforms can connect teams from anywhere, at any time, eliminating the challenges that time and distance once imposed. As the offshore wind industry grows in the U.S., so can the reach to global equipment manufacturers. For example, when a problem arises on an offshore turbine, a wind tech could quickly and easily connect with a manufacturer in Europe for O&M advice. This capability promises to save wind-farm owners costly travel and, most importantly, turbine downtime. W
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CO ND I TION MO NI TOR IN G
Paul Dvorak Editor Windpower Engineering & Development
Hear that clicking? Sonic analysis hears tell-tale noises in a nacelle.
A
condition-monitoring firm from Israel has devised a system that listens for ultrasonic noise from rotating machinery, such as that in a wind-turbine nacelle. It processes the signals using selfteaching algorithms, and notifies maintenance when something needs attention. Amnon Shenfeld, CEO of 3DSignals, says the capability is possible, thanks to advances in signal processing, machine learning, and artificial intelligence (AI). Deep learning is a recent field in AI. “There is a famous family of algorithms in computer science that deals with a teaching algorithm that recognizes phenomena. It has been used most recently around computer vision to recognize faces better than people can,” says Shenfeld. The system needs initial data sets for training, but once you teach the algorithms a few general characteristics or features, they have the capability to recognize other conditions without further training. His team decided to take the family of algorithms and apply the same level of understanding to the acoustic realm or soundscape because there are specific and well known behaviors in the ultrasonic domain for bearings. Video involves moving pixels while sound involves moving frequencies in time. “So mathematically speaking, you can apply similar algorithms to a soundscape of environment,” says Shenfeld. “An application could be hearing a motor, gearbox, or generator and decipher its rotational speed, and whether or not is it under stress. These are the applications that 3DSignals deals with today.” Where used He says his systems are used in hydro-electric facilities where in one case, the system recognized a valve failure that vibration and temperature sensors did not. In hydro plants, results were conclusive. “Acoustics picked up events earlier than vibration sensors, and there are many sound sources in a hydro plant,” says Shenfeld.
3DSignals says its sensor is five times more sensitive than a human ear.
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CONDITION MONITORING
The schematic provides a general layout for a 3DSignals acoustic conditionmonitoring system.
Ultrasonics can detect flaws earlier than vibration sensors because of their sensitivity. Vibration sensors must be close to the area of interest. “Most conventional vibration sensors are not sensitive enough to pick up flaws, but ultrasonic signals are the first signs of impending failures. So by the time a vibration sensor picks up a problem it may be too late. In some cases our system was the first and only one to report a failure,” he says. The existing sensor would have to mount about 10 ft from the equipment of interest, but newer sensors, available later in the year, could be positioned up to 30 ft. from equipment. “Sensors are our designs, our integration. Because the system can learn to detect rpm, an encoder for that function is not necessary. The rpm detection is patented.” Learning Shenfeld says an algorithm can detect rotating systems out of the box, by their physical parameters. “If we know the bearing size, its acceptable speed, and its number of elements, the system can recognize its acoustic signature. We know right away, how far from the ideal the signature is and, therefore, how healthy the system is,” he says. Consider a system that was not previously monitored, a gearbox or wind turbine of a particular model from specific manufacturer. “We first have reports of anomalies where the acoustic pattern out of the equipment differs from the expected acoustic signature. The system raises a flag with an alert initiated by some sort of acoustic anomaly. Then we alert a maintenance expert or engineer and let them listen to the gearbox before they leave their office.” Shenfeld says it is possible to collect feedback from experienced maintenance people as to whether the anomaly sounds critical or not, and what type of failure it might indicate. An alert would also say the problem is related to, for example, a lack of lubricant or misaligned shafts with a particular percent of confidence. Human input trains the algorithm so next time the same signature happens, or any anomaly, it is compared by the deeplearning algorithm. Wind techs have mentioned that even at ground level, they can tell by the sound the turbine is making, that something is amiss in the nacelle.
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“Lucky for us, mechanical engineers get intimate with their machines and over time they learn to recognize failure modes by the way things sound when not running right. In many cases, detecting and recording an anomaly to play back for a maintenance person takes just minutes. The expert decides what happens next. “The learning process depends on getting enough acoustic signature failures from different types of equipment. In most cases, an anomaly will tell an expert how soon they must get to the machine. “We start giving value on day one, and start getting insight to the types of failures, if we have enough previous acoustic data.” How many sensors for a turbine? Shenfeld says two or three sensors would be sufficient for a turbine nacelle − one sensor with the gearbox and second near the generator. “I am confident that after one emergency stop, the signature coming out of the bearings would indicate a type of damage. So a good test would be to collect a sound sample at the start.” Shenfeld thinks the timing is right for the introduction of this technology because experienced people are retiring and taking their experience and the close relationship with their machine with them. Although the system has not yet been applied to wind turbines, all applications so far have been with rotating equipment. So he is looking in the U.S. for wind farms that want to benefit from this technology. W Easily read analysis of machine events can be sent to smart phones and tablets for prompt attention by operations and maintenance personnel.
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Aaron Lawson
Director of Engineering Services
John Greulich
Director of Sales
PSI Repair Services
Many of the electronic controls in older turbines are unsupported by their manufacturers. But they are still repairable. Even better, they can be improved. Here are a few success stories.
An
analysis conducted by Wind Energy Update suggests that 50% of all failures in wind turbines are due to electronic problems. That’s a high percentage and it doesn’t get the same attention as the gear boxes, generators, or blades. Nonetheless, downtime, component failure costs, and the administrative expenses of replacing these parts add up to a substantial figure. What is repairable? When a new wind turbine component such as a power supply comes into our repair facility, the first question is: Can it be repaired? The question is answered best after conducting a root cause analysis and finding why the device really failed. A root cause is the actual issue that sets off a chain of events that eventually leads to the larger component failure. For example, a power supply that failed on a wind turbine might send a series of fault signals to the
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SCADA system, such as different communication errors because the power supply is no longer functioning. The actual root cause of that failure may be due to faulty electrolytic capacitors inside the power supply. The capacitors may be beyond their lifetime or maybe their operating temperature was exceeded. That’s the actual root cause of that power supply failure. Other examples of root cause in electronics are faulty or weak components. External causes could be grid transients, voltage spikes, under or over voltage, or lightning strikes. Poorly designed circuitry or under-rated components are additional causes. A root cause analysis also needs tools and techniques to uncover the actual causes of a problem. For example, a Pareto Analysis is used to determine the most prevalent failure modes from a group of failed components. Think of the root cause as the tip of the iceberg. The root cause is the underlying issue that you don’t see and can be a much larger problem. A few case studies A few real-world applications of failed electronic devices show the solutions that resolved the issues. Occasionally even usually reliable pitch-motor drives run into trouble. The original unit in this case had an extremely short lifetime, frequently less than two years. Analysis showed that capacitors would leak electrolyte on the circuit board causing a short circuit. Catastrophic failures meant many of the units received were unrepairable. To make matters worse for the client, replacing the drives is difficult because they are up tower in the hub. Technician labor made the drives expensive to replace. The original design used poorly rated capacitors and transistors. The inefficient design generated a lot of excess heat. Lastly, a threaded hole on the heat sink for a ground lug was easily stripped because it was just tapped into aluminum. Our redesign consists of manufacturing a power board with a set of new FETs (field-effect transistors). These FETs generate less heat than the originals due to lower On-Resistance and the improved capacitors can handle higher ripple current. Manufacturing the board means it was possible to repair some of these catastrophic failures that would otherwise be unrepairable. The redesigned circuit board uses thicker copper traces which helps pull heat from the transistors and capacitors. What’s more, the much higher efficiency of the redesign means the units run about 25°C cooler than the OEM design. The result has been that over 3,000 units are in the field with a meantime between failure improved by over 80%. Lastly, to prevent stripping the threaded hole, we drill out and install a steel insert which prevents damage.
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Fifty percent of all failures in wind turbine are due to electronic failures. Source: WU Onshore Asset Optimization & Reliability Benchmarking Report 2015. Data source: Sciemus
The pitch motor drive was not up to its task because of excess heat, a frequent problem in some turbine electronics.
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The phase module from an inverter assembly presented additional challenges. An accompanying image shows the catastrophic damage possible when an IGBT fails. It takes out the driver, circuit board, and some of the brackets and other system components. The replacement is a drop-in unit with an upgraded fault protection, such as advanced active clamping. It also uses a next-generation baseless IGBT design. An IGBT is an isolated gate bipolar transistor, essentially a large power transistor. That lowers the thermal resistance between the IGBT driver and its heat sink. A liquid cold plate, a heat transfer device works with a finned interior which helps quickly remove heat from the coolant and the heat sinks. The redesigned phase module also has thicker bus bars which help remove heat from the IGBT terminals and balances the emitter circuit impedance. A yaw motor module called for a different approach. The original unit was it failing at an unacceptable rate. A Pareto analysis on the first 30 failures pointed to the IGBTs as the main cause of failure. The OEM devised a solution in which they suggested retrofitting the cabinet with a 45-amp module. So far, so good, but the redesign is wider than the original, which called for modifications to the cabinets. It was bad enough the replacement unit was more expensive but the labor for the retrofit cabinet added more cost to the repair. The solution devised was to upgrade the original 30 Amp module to an equivalent 45-Amp module. Basically, we were able to take the larger IGBT used in the 45-Amp drive and fit it in the 30-Amp design
The Pareto analysis examined several components in the module to determine which failed most often. The 80% line indicates.... what does it indicate?
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The phase module rebuild included advanced fault protection, next generation baseless IGBTs, a liquid coldplate with finned interior, thicker bus bars to remove heat from the IGBTs, and a balanced emitter circuit impedance.
with the same form factor and now with the current capabilities of the 45--Amp drive. A power inverter, an obsolete unit, had failed often enough to exhaust the O&M team’s supply of replacements. Fortunately, enough information was available to make a dropin replacement possible. No changes were needed on the client’s system side. It was also possible to build in additional features not available in the original design, features such as high-speed fault detection, advanced active clamping , , over-and-under voltage protection, as well as short circuit protection. Another improvement on this unit was to mount the IGBT drivers directly to the IGBT which helps lower stray inductances.
The OEM solution to the failing yaw-motor modules was to fit higher current IGBTs into a larger cabinet which set off a cascade of additional modifications and costs.
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The rotor current controller on a generator showed that it had a much higher variation and failures rates than others. This controller mounts on the back of a generator and rotates in a high vibration, high-heat environment, which made the through-hole solder joints in these capacitors prone to cracking. The capacitors would start to arc and eventually burn up the circuit boards. A Pareto analysis pointed to snubber capacitors and the circuit board they mount to as the main failure mode. The accompanying image shows main failures in solder joints on the capacitors. The upgrade consisted of selecting a snubber capacitor with a tab style mechanical connection. This eliminates the throughhole solder joint and its failure mode. The redesigns are much more reliable. A similar but larger power inverter presented new challenges. The accompanying image shows catastrophic failures common to the units. Its IGBTs would short out and then burn up because of the high voltage and current available. Despite the mess on the left of the photo the apparent catastrophic failure was refurbished to a like-new condition. In the process, the heat sinks are resurfaced and we install new IGBTs, a new bus structure, as well as the bus capacitors. Then we repair the driver board and once fully assembled, test it
to its ratings for full power and current. Another Pareto analysis for a large number of pitch system battery chargers pointed to a transformer as the main cause of its failure. A few other components would also fail when the transformer power was exceeded. A postmortem – real dissections – revealed that primary windings were failing because it’s power was being exceeded. High ambient temperatures played a role as well. Upgrades to this unit consisted of a higher power transformer. It’s physically larger so we manufactured a custom adapter board to fit it on the original circuit board. Included were higher temperature ICs and a series of other components, such as electrolytic capacitors. Even when some devices do not look repairable, they might be. Consider a pitch thermistor module. This unit reads a thermistor from a pitch motor and sends out a fault if the motor temperature exceeds a set value. The original unit had a high failure rate due to the universal power supply in the design. It was rated for 24 to 240 Vac or dc. Although a universal device, it’s an overly complicated power supply for the application. The module’s needed only 24V. We improved the device by eliminating its universal function, making it run strictly off 24 Vdc, making it simpler and more reliable. The redesign has a much lower failure rate than the original.
The CAD model of the power inverter (top) allows conducting thermal studies. The production unit is below.
Lastly, an automated lubrication system suffered from an inefficient design that produced a lot of heat in its power supply which was failing the units at a high rate. The system is essentially a sealed plastic box without sufficient air flow to cool the power supply. A solution involved a dropin replacement unit custom designed for the application. It is more efficient than the original one which means it produces a lot less heat, making it more reliable than the original. And it’s a low cost alternative to the original design. W
The rebuild effort called for new IGBTs, a new bus structure, repaired driver board, and resurfaced heat sink.
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last repaired on 3/10/12
D E N R A E L S N O S S LE a r in g s e b x o b r a e g in as le a d to n e w id e se Michelle Froe
Senior Editor evelopment gineering & D Windpower En
y in th e la st ed re m ar ka bl ov pr im s ha il it y be ar in g G ea rb ox re li ab de rs ta nd in g of un er tt be a ks to m po ne nt s 10 ye ar s th an es t qu al it y co gh hi e th en er , ev du st ry . It lo ad s. H ow ev in th e w in d in cy an ct pe ex li fe ce pl an in ha ve a li m it ed te nt m ai nt en an is ns co a ve to ha m ag e to is im po rt an t s of be ar in g da gn si y rl ea e ow th pl ac e, an d kn e li fe . d w in d- tu rb in an x bo ar ge e m ax im iz
GEARBOXES HAVE LONG TAKEN BLAME as the typical cause for a wind-turbine failure, and for good reason. Many gearboxes fail to pass the five-year mark without need for component repairs or full replacement. But when the wind industry first got its start, few considered the high winds, vibration, or environmental conditions that turbines must withstand. “At the time, the same basic gearboxes used at cement mills or in industrial applications were simply hauled up some 300 feet in the air, placed inside a nacelle, and expected to work to the same standards,” said Richard Brooks, Manager of the Wind Energy Aftermarket at 56
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At the time, the same basic gearboxes used at cement mills or in industrial applications were simply hauled up some 300 feet in the air. The Timken Company. Timken engineers and manufactures bearings and mechanical power transmission components. “Little thought was given to customizing the gears or bearings.”
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Times have changed and today a gearbox is specifically designed for its intended application, such as for use in a wind turbine. However, the “gearbox legacy design issue,” as Brooks calls it, has led to years of lessons learned for the wind industry that continue to this day. “For example, a wind gearbox designed for a brand-new turbine today is exceptionally better than one even made five or seven years ago because of the accumulative knowledge engineers have gained and continue to gain over time.” Although this progress has led to more durable gearboxes capable of better handling the harsh conditions turbines face, there is still one fundamental challenge. This challenge primarily relates to differences in speed, according to Brooks. “A turbine’s rotor may be turning at about 15 rpm but the generators are going 1,500 rpm, which represents an increase of 80 to 100 times,” he says. Typically, a designer would select different types of bearings and lubricants for low and high-speed applications. “But here you have one gearbox handling different speeds and loads with one type of lubricant. This isn’t the best scenario.” Brooks says that in an ideal world, the turbine design would make use of two different gearboxes — one for low and one for high speeds — but that’s too complicated and not economical or feasible for the wind industry. “Nevertheless, you’re still stuck with a machine that must deal with compound 58
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A view inside a gearbox shows the three different bearing positions. Planet carrier and lowspeed bearings have the lowest rate of failure, while high-speed and intermediate bearings have the highest rate. Planetary bearings rank in between and typically offer a 10-year life expectancy before expected failure.
speeds in a harsh and complex environment, while facing high dynamic loads. Over time that leads to failures.” Brooks says the industry is likely never going to fully overcome this challenge in gearbox-driven turbines, but quality bearings properly maintained are one step in mitigating turbine downtime.
High-speed bearings Although there is some truth to the statement that a gearbox is only as good as its components, even the highest quality equipment has a limited life expectancy in the wind industry. Bearings offer no exception.
Bearings serve numerous roles in a wind-turbine gearbox and show different failure rates based on their position. For example, planet carriers and low-speed bearings work with some thrust load but generally have a low failure rate. “That’s not to say damage cannot occur or become an issue in low-speed bearing positions,” says Brooks. “Typically when the wind industry is discussing bearing failure rates, they’re more often than not talking about high-speed and intermediate bearings.” Brooks is referring to the bearings on the parallel shaft, and primarily the high-speed shaft that drives
The observed damage modes in intermediate bearings include smearing, inclusion axial cracking, or white etch axial cracking. If not addressed, over time smearing and inclusion will lead to an axial crack on the inner ring of a bearing.
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High-speed bearing solutions
The table offers a quick guide on how to best address high-speed bearing damage. For example, if a bearing is showing inclusion or white etch cracking, a case carburized design may be the answer.
the generator. The type of bearing used on the high-speed shaft will vary depending on the gearbox model and manufacturer. “You’ll either see a cylindrical with a ball bearing, a double tapered bearing, or a single tapered bearing of a special design,” he says. “Regardless, the high-speed shaft bearing has the highest failure rate of all the bearings found in a wind turbine.” The reason? “The main cause of failure in high-speed bearings is from axial cracks or white etch cracks, which are cracks related to a change in the microstructure of bearing steel.” Technically, there are three potential damage modes, but Brooks says that over time each results in the same problem: a spall or crack on the inner ring of the bearing.
The reason high-speed bearings get so much attention is their high failure rate, which occurs about every five years. Fortunately, repair costs are relatively low. “A replacement bearing set will cost a few thousand and it only takes a small crew of wind techs up-tower — no crane required — to complete the job in about a day.” So, a full repair may only cost about $10,000, says Brooks. “However, this scenario comes with a big ‘if’,” he adds. “You must detect potential cracks before the bearing begins generating debris and causing other problems. Once there are consequential damages, there is no choice but to replace the full gearbox and that cost is no longer low.” Brooks says detection can be done though online vibration analysis and oil testing with a sampling for Iron content. “Maintain a good lubricant practice, which incudes using the appropriate lubricant for this application,” he advises. “And do everything possible to keep water out of the gearbox. I know this is easier said than done given the environment wind turbines are in.”
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Typical damage modes in high-speed bearings 1. SMEARING, which is a type of surface damage that may alter the original surface texture and profile of the bearing. 2. INCLUSION AXIAL CRACKING OR SPALLING, which according to Brooks are caused by non-ferrous contaminants and can lead to granular weakening of the bearing coating or material. “The greater the inclusions, the more likely the bearing will develop cracks,” he says. 3. WHITE ETCH AREA AXIAL CRACKING OR FLAKING, which is a transformation of the bearing material’s metallic structure. The exact cause is highly debated in the wind industry. “We’ve been discussing white etch cracking for 10 years, and are still talking about it,” says Brooks. “It is an issue that has won the attention of engineers, bearing experts, gearbox manufacturers, and even major universities — some of which are using electron microscopes — to determine the cause of axial cracks, so it is a complicated issue.” APRIL 2017
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Planetary bearings While high-speed bearings have the highest failure rates and low-speed bearings have some of the lowest, planetary bearings rank somewhere in between. Life expectancy is about 10 years before failures typically set in, although this can vary depending on the make and model of the gearbox. “But regardless of gearbox model or bearing type, we generally find that deflections and loading problems are the primary issues with planet bearings,” he says. “This is because of the variable loads that come into the gearbox and cause undesired deflections. This is made worse when the main bearing wears and lets even more thrust and load than intended into the gearbox. Over time, these forces take a toll.” Spherical roller bearings were the planet bearing of choice about 15 years ago, but thanks to some lessons learned that’s no longer the case. “In fact, the standards now discourage use of spherical roller bearings in gearboxes,” says Brooks. That leaves cylindrical or taper bearings, a choice that varies per gearbox manufacturer. “If you compare tapered bearings to cylindrical versions, tapers do a better job of handling thrust damage — at least with proper installation.” Brooks cautions that tapers are a precision bearing and more challenging to assemble than cylindrical types. Proper monitoring is critical to watch for excessive wear, and he advises three steps for wear detection.
Wear detection of planetary bearings 1. Routinely test oil samples for iron content. “Ideally, this should be done online with a program that’s installed in the gearbox and continually monitors and checks for wear particles,” he says. 2. Install and monitor an online vibration analysis. 3. Check the position of torque arms in gearbox mountings. “If they have moved all the way backwards, this means the gearbox has likely experienced too much thrust,” Brooks points out. 60
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Damage to a planetary bearing can accumulate quickly. Unlike high-speed bearings, replacing a planetary bearing requires a more complex strategy than simply sending a couple wind techs up-tower for repairs. Typically a crane is needed on site, and potentially a full rebuild of the gearbox. “In fact, if you go back three or four years, if you had a planet bearing problem, that gearbox had to be fully removed from the nacelle and tower, which always required a crane,” says Brooks. “Service companies are now getting creative and figuring out ways to replace planetary bearings up tower when possible. This is saving costs.” When cylindrical bearings are damaged, Brooks recommends replacing them with a case carburized design, which is more durable to debris. Case-hardened steels exhibit higher fracture toughness than through-hardened steel. He says there are also a number of coating options that could help, such as a black-oxide or diamond-like carbon coating. “Or, you can consider a re-design to make the cylindrical more of a precision bearing or switch to a tapered bearing.” For damage to tapered bearings, Brooks also suggests using a case carburized design — or an integrated design, which is a newer option for gearbox manufacturers and service companies.
Integrated bearings A bearing typically has three pieces: the rollers, an inner race that is pressed onto a shaft, and an outer race that is pressed into the gear bore. But now there are options that integrate the inner race with the shaft or the outer race with the gear, or both, into one solid component. “Integrating essentially machines the bearing’s outer race into the inner bore of the gear,” explains Brooks. An integrated bearing reduces the total number of components in the assembly by directly machining bearing races into the surrounding components of a gearbox. It is an option for cylindrical and tapered gearbox planet bearings. “In some ways it brings complexity into the manufacturing process because bearings are not made at gear plants nor
TOP: Inclusion-related axial cracking in bearings typically appear as a “white etch butterflies.” Eventually, cracks will form and prorogate to the surface of the steel. BOTTOM: Borescopes let technicians look inside wind-turbine gearboxes for gear and bearing damage. The image is of a typical axial crack. A roller is on the left and the race is on the right.
are gears made at bearing plants,” says Brooks. “But there are a lot of advantages to integrating the two.” Most notably: integrated bearings show improved performance and greater power density. “Certain failure modes simply don’t exist with the integrated design,” says Brooks. “One example is referred to as creeping outer. This occurs when a bearing race is pressed into the gear so that, over time and under load, the bearing can potentially move and generate debris. Of course you don’t want that, and it cannot occur with a onepiece, integrated component.” For this reason, many brand-new gearbox designs are employing integrated bearings, whether cylindrical or tapered. “Lesson learned,” says Brooks. “It takes time, but with each new design we progress and gain more knowledge. In fact, a few companies are also starting to offer integrated retrofit rebuilds, which is a fairly new and exciting option in the wind industry.” W
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journal bearings What
A recent National Renewable Energy Laboratory program evaluated a 1-MW gearbox with journal bearings by durability tests. Results are encouraging for wider use and more reliable gearboxes.
to wind-turbine gearboxes
Paul Dvorak • Editor • Windpower Engineering & Development IF A WIND TURBINE GEARBOX is not yet fitted with upgraded roller-bearing arrangements in its planet stage, it soon will be when it is repaired because new designs have a higher load capacity. Arrangements include preloaded taper roller bearings or cylindrical rollers with raceways integrated to the planet gears. But even these arrangements will eventually suffer spalling damage from rolling contact fatigue and require replacement. Is it possible that a gearbox with journal bearings could better withstand the harsh conditions that wind turbines impose? Engineers at NREL and Romax Technology and other industry partners recently completed a U.S. Departmentof-Energy-supported project to test nextgeneration gearbox, generator, and power converter technologies aimed at reducing the levelized cost of energy. The gearbox layout incorporated flex pin and journal bearing APRIL 2017
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technology to improve planet load sharing and further the understanding of journals in this low-speed-high-load application. Within the project, the drivetrain was designed, built, and tested in a dynamometer at the National Wind Technology Center. Dr. Ashley Crowther, the Global Vice President of Engineering at Romax Insight, presented the promising test results to the recent Drivetrain Reliability Collaborative meeting at NREL. The program goal was to suggest a next-generation drivetrain that would move the wind industry forward. “We were looking into an advanced gearbox arrangement for the wind industry to test technology with the goal of reducing system costs and maintenance while increasing efficiency,” he said. Journal bearings in wind gearboxes are uncommon, although there are a few recently offered by European gearbox original equipment manufacturers (OEMs).
One goal for the next-generation gearbox is to boost drivetrain efficiency.
A previous NREL project provided a drivetrain for modification, with the main shaft supported by two tapered bearings and including a medium-speed generator.
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What
journal bearings
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The conventional gearbox was replaced with one fitted with journal bearings in a single stage, with four planets mounted on flexible or flex pins. For cost-effectiveness, the test gearbox had one stage, but during the concept research, NREL’s Program Lead, Jon Keller said the team looked at a series of ratios and found that the lowest cost of energy is possible with a two-stage gearbox with a ratio of about 30. The illustration, A cross section, shows the sun gear and flex pins, which support the spindles, and the journal bearings supporting the planets. In this application, the planet rotates on a thin film of oil over the journal material and the ring is stationary. The material is
steel coated with special alloys, proprietary to the manufacturer in Europe. The purpose of the flex pin is to improve load sharing through the four-planet system. A three-leg stool provides an analogy. All three legs contact the ground so the stool does not rock. But a four-leg stool could easily rock if the legs are stiff. Similarly, a planetary system with more than three planets can share the planet loads unevenly. The system deflection, small clearances, and as-built errors (typically within tolerance) all play into the magnitude of the uneven load sharing. But if there is some flexibility in the system, it would be like having a spring on each of the stool legs, letting it always rest on four legs. The flex pin offers a way of doing that in a four-planet system. An earlier article (http://tinyurl.com/bearings-journal or WPE&D May 2016) provides more detail on rebuilding the gearbox. Benefits and challenges The pin is allowed to bend so the planets on spindles can move or translate up and down. Although the flex pin is not a new concept, and Romax has designed these gearboxes before, it improves the design and allows for a more compact gearbox to combine with the journal bearings. Another benefit of the journal bearings is lower costs because of their simplicity compared to rolling-element bearings. Crowther’s team also suspects these types of bearings would improve reliability because they are made of fewer parts, and still need longer-term durability testing and field trials. However, the design greatly reduces
the number of parts and, in that respect, should improve reliability. For instance, the design removes between two and four rows of bearings (depending on design) from each planet and replaces them with one bearing. Journal bearings can also reduce weight and their assembly is easier than with preloaded designs. “So there are many benefits to the journal bearings, although we are certainly not partial to journals or rollers at the moment,” said Crowther. There are challenges in the design as well. For example, an interference fit holds pins in the carrier, and the combined pin and spindle is also an interference fit. It is important to understand the stiffness of the fit, and its effect on the system-level models. Modeling all of these items in simulation software is a challenge and a recommended area of improvement. Flex pins The flex pins let the gears float, so loads increasing with torque bend the pins. Due to the couples on the shaft, the spindle translates slightly, so the torques adjust to being near equal on each planet. Spindles do not tilt. That is important. The load sharing on a fourplanet design absorbs torque fluctuations and reduces tooth misalignment. The bar chart Torque versus load shows results, where 417 kNm is near rated load, and the relative load on each planet is close to 1. Lubrication The lubrication system had to provide oil to the bearing. An oil feed comes through the main shaft housing, into the carrier,
Tap
The journal bearing is oil lubricated, making it a full fluid-film bearing. It is hydrodynamic, in that it must generate its own oil wedge from spinning.
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The flex pin inside a spindle lets it translate slightly as planet loads change.
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High Pe
Plots from strain gages in the gearbox showed that load sharing improved with load to nearly equal load distribution at rated torque.
down the pin, and up the spindle to the planet. A rotating union allows pumping oil from a stationary section to the planet or rotating section. There are challenges here. “Due to constraints from modifying an older drivetrain, we could not quite get the pressure we wanted. The rotation also caused pressure fluctuations. But it worked reasonably well, generating one bar pressure using a well-known gearbox oil. To maintain cleanliness, the system used filters of 8.5 and 3 microns. In addition, we heated the oil to maintain 55°C for an ideal viscosity. This gave a flow rate of about 0.5 to 4 l/min to the journal,” said Crowther. The journal design is running at a relatively slow speed compared to other journal bearing applications. “We calculated design parameter for the journal bearings
considering an axial component of load due to the tilt of the drivetrain at 5° but there was no large load from a helix angle on the gears as is common. Then, there were radial loads on the journals from gear-mesh forces, as well as some small loads from pressure angles on the gears and the deviations in manufacturing” said Crowther. Modeling the journal called for understanding the deflections including the tilting of the gears, and particularly how it affects the tilt of the planet gear mesh. “We calculated the film stiffness, and that was research, but out of that and other work, Romax Technology did some modeling developments for Romax Designer. We researched the pressure distribution across the width of the journal. In the end, we were able to get a good stiffness calculation to finish the design” stated Crowther.
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Feat_Journal Bearings_4-17_Vs4.indd 63Half Page Ad for AWEA Anaheim 2017.indd 1 High Performance Wind Turbine Bearings
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What
journal bearings
to wind-turbine gearboxes
Pressure and temperature sensors were mounted at the end of the spindles.
Instrumentation It was necessary to measure many parameters to confirm the function of the design. Durability was judged at teardown and by a particle counter of debris in the oil. “For function, we wanted to know that we had the right pressure, cool running temperatures, and the ability to gather physical measurements such as component strains. The gearbox was instrumented for temperature and pressure at the end of the pin, which gave good information as to how the journal was running,” he said. Strain gages on the flex pin measured the bending and validated that it was acting properly. This also verified load sharing between the four pins. Functional tests The previous chart, Torque versus load, shows loads at low and rated torque, where load sharing becomes quite good. At low torque, uneven sharing does not matter because there is low stress on the bearings and gears. But as torque increases, the loads even up. “They were between 0.95 and 1.05 relative load, which is quite good. If designing a conventional gearbox with four planets and without flex pins, a load share factor of about 1.25 would be appropriate. Flex pins allow either a smaller gearbox or a higher reliability, or you can design for a trade-off in the middle,” said Crowther. Tooth load distribution, another important performance criterion, was assessed by using a tooth marking compound and tooth root strain gauging. The strain-gage measurements allowed working out the tooth load distributions, which were deemed adequate. “A 6 4 WINDPOWER ENGINEERING & DEVELOPMENT
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With a limited budget, the team settled on two tests: start-stops, which involved runs from standstill to 10 rpm in 10 seconds at no-torque load for 5,000 cycles. This approach would simulate about one year of operation in about 21 hours. These tests were followed by a dithering test, or an oscillation of the gearbox. “This latter test would simulate a turbine at idle or low breeze and could represent thousands of hours in a turbine’s life. So the dither test simulated slow rotations. It’s significant because a slow rotation does not generate the film thickness or pressure to lift the journals. The bearing operated in the boundary lubrication regime—surfaces rubbing against each other. The goal was to see how well the box would hold up,” said Crowther.
little contact showed to one side. The challenging factor of modeling the stiffness of the flex pin to the spindle interference fit was the driver behind that, if we were going into production we would correct the next gearbox easily,” he said. “The load factor, KHß, met requirements,” said Crowther. “It is the peak load over the main load, and the value decreased as torque increased, so it improves toward the rated torque but could be improved further,” he said. The performance tests ran the gearbox at steady state under load until everything settled. “Temperatures were quite cool. One thermocouple was in the load zone and one out, and temps rose pretty much together, but much lower than what would cause a gearbox shut down. So the bearings run cool and there is low wear. Maintaining the sump oil temperatures with heaters was the driver of the oil temperature more than anything,” Crowther concluded. A particle counter set to International TOP: Although the oil temperature rose with load, temperaStandards Organization (ISO) tures stayed within an acceptable range. standards, or bins, was part of the durability tests, which BOTTOM: Particle counts remained stable during the simulated year of starts and stops. provided the equivalent of 1 year of starts and stops, about 5,000 cycles. Through that testing the particle count remained stable. “During start-stop testing, we were not seeing particle generation that would wear this thing out, which was good. We had pretty low wear. The teardown also revealed minimal wear from the functional tests and the standard for durability testing,” said Crowther.
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The gears suffered expected tooth damage in the no oil + dithering test. Such damage would appear on any gearbox in a similar situation, but the journal bearings had little wear. Even with the oil pump off during the dithering test, the journal bearing did not get hot.
Lastly, a call was made to run it without oil pressure. “So we turned off the oil supply, not even having the one bar, to see what would happen. And then after, we did a teardown,” he said. During the teardown, the team looked for damage to the journal and other wear in the gears. It is not possible to see into the journals as with rolling element bearings, therefore it was not possible to use a borescope of the gearbox during testing to look for damage. “The gears did not perform so well for this harsh dithering test, as a result of running them without oil”, reported Crowther. “We saw terrible fretting corrosion. This durability test was horrible enough to impart significant damage to the gears. It goes to show how rough a test this was for the journals because any wind turbine gearbox would see gears with this type of fretting corrosion if you ran such a test,” said Crowther. Standard criteria of acceptable and poor journal bearing wear—pictures with ranges of dark bands on bearing surfaces—let the team judge or rate results. “Recall,” said Crowther, “that journal bearings fail from wear, not rolling contact fatigue life, because the load is not on a line, it is spread over a large area.” He reports that on teardown, the team saw some wear on the journal and spindle, but it was considered minor and acceptable. Other tests followed. One was without the oil supply, for 54,000 cycles at ± 0.5° at 2 Hz, another for 1 hour of dithering with 25% oil flow, and then 6 hours dithering with zero oil flow. The graph Accelerated dithering – zero oil flow, shows the pump pressure. “The oil temp is interesting because we thought that APRIL 2017
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journal bearing would get hot, but it did not,” Crowther said. “When the oil pump was turned back on, the debris that may have accumulated in the bearing because of wear came out and the count rose a bit.” The journal bearing showed acceptable wear and performed quite well. It exposed the soft copper layer (~700-µm thick) after wearing off the (~20 µm) coating material. Also, it is a bit to one side because of gravity. The little damage found on the journal bearings shows remarkable promise for this application. Crowther closed with several industry recommendations:
• Maintain some level of lubrication during shipping, erection, standby, curtailment, extended shutdown, and similar periods • Encourage turbine OEMs to work with gearbox OEMs to put more journal bearing gearboxes in service for long-term evaluation • Develop the supply chain to OEMs, qualify journalbearing suppliers, and determine the volume needed • Develop new certification calculations and design practices • Extend prove-out tests or long-term field performance in volume • Develop condition monitoring and inspection standards • Measure film thickness and validate analysis • Improve interference fit modeling and validations W
WINERGY ALREADY USES JOURNAL BEARINGS IN LARGE GEARBOXES Gearbox manufacturer Winergy recognized that journal bearings have proven their advantages in several other heavy industries, so why not in the wind industry? Last year, the company said that since March 2013, a 2-MW gearbox prototype with journal bearings has been in operation in a Vestas V90 turbine in Sweden. More recently, a spokesman for Winergy, Tobias van der Linde, reports that the Vestas turbine with journal bearings is still in operation and is performing well. Meanwhile, the company has put two more gearboxes into service in the 2 to 3-MW class, and for other turbine manufacturers. Several additional commissionings are planned for 2017. Van der Linde also reports that to company is building and testing journal windpowerengineering.com
bearing gearboxes for future multi-megawatt offshore turbines which are expected to enter service by the end of 2018. The company would not share technical data on the gearboxes but would say that no changes were needed on peripheral equipment such as the oil-supply system in comparison to gearboxes with roller bearings. Also, there is no higher oil demand, bearing temperatures stay constant at the rated power, and all tests show no wear on the bearings. Journal bearings are available in Winergy gearboxes and for the HybridDrive. WINDPOWER ENGINEERING & DEVELOPMENT
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On the next few pages you will be introduced to four people and one group who had the inspiration to tackle the technical problems unique to the wind industry.
T H ANK YOU
to Windpower Engineering & Development’s Innovators and Influencers of 2017
These innovators and influencers have had such a significant impact on the wind industry that the staff of Windpower Engineering & Development would like to recognize and celebrate their success in this Eighth Annual Innovators and Influencers special section.
2017
I N N OVATO R » D r. H a b i b Dagher, P. E.
Dr. Dagher is the founding Director of the University of Maine’s Advanced Structures and Composites Center, and leads the Department of Energy’s (DOE) New England Aqua Ventus I Offshore Wind Advanced Technology Demonstration Project. The Composites Center, a world leader in bringing advanced materials into construction, was established by the National Science Foundation in 1996. It has grown under Dr. Dagher’s leadership from four to 180 employees, and is now housed in a 100,000 ft2 laboratory, and has won over 40 national and international innovation and excellence awards. And if that is not enough, to drive innovation in offshore wind energy, he spearheaded the development of the Alfond W2 (Wind-Wave) Ocean Engineering Laboratory, a unique facility with a rotatable high-accuracy wind generator over a multidirectional wave basin, as well as the Offshore 66
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Wind Laboratory, the second largest wind blade testing facility in the U.S. To round out his career to date, Dr. Dagher led the design, deployment, and testing of the patented VolturnUS1:8, the world’s first floating wind turbine foundation, a hull made of concrete, carrying a working, grid connected turbine on a composite tower. This 1:8 scale testing program, funded through the DOE, included more than 30 partnering organizations. This successful deployment resulted in a new private company that is developing a 12 MW floating wind demonstration project called New England Aqua Ventus I, off the coast of Maine. Project participants include Emera Inc., Cianbro Corporation, DCNS Energies, and the University of Maine. This demonstration project will deploy two, 6-MW turbines using the VolturnUS floating concrete semi-submersible hull. In May 2016, the project was selected by the U.S.
DOE to receive $39.9 million to fund the construction planned for 2018. This will likely be the first utility-scale floating wind project in the Americas. The patented VolturnUS floating concrete hull technology supports wind turbines in water depths of 45 meters and more, it allows for local manufacturing, has a 100-year life, and independent cost estimates have shown it to significantly reduce the cost of offshore wind. Dr. Dagher earned his Ph.D. from the University of Wisconsin-Madison and joined UMaine in 1985. He was honored as White House Transportation Champion of Change in 2016, and was selected as Engineering New Record’s Top 25 Newsmakers for 2016. Dagher holds 26 patents with six pending. He has testified before the U.S. Senate on offshore wind energy as a pathway to national energy independence. W
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2017
I N N OVATO RS » Idealists from the wind project on Cutty Hunk island
Left to right, W – wind crew, F – film crew, Top row: Warren Rosenthal, Ed Rankin, Rodger Race, Allan Spaulding, John Rockwell (all W) Bottom row: John Wellemeyer (FM), Andrew Finley (FM), David Jenkins (WM), John Hiller (FM), Richard Goodman (FM), David Vassar (FM), Van Spaulding (FM) Photo by Elizabeth Zerbe
You will be forgiven if you are unaware of the significance of Cutty Hunk island to the wind industry. It’s a small dot of land at the end of a string of islands northwest of Martha’s Vineyard. In the late 1970s, about a dozen idealists with hands-on skills were seized by the idea of finding a better way than diesel generators to power the island. Their goal was to erect a wind turbine. The world was in the grip of the OPEC oil embargo at the time and prices for diesel fuel had already doubled. Like most islands, Cutty Hunk’s residents got their power from a station of four diesel generators, and the population of about 26 was paying about $15,000 annually for electricity. The exploits of these wind pioneers were, thankfully, recorded by film-maker and documentarian David Vassar of BackCountry Productions. “The Cutty Hunk windmill was the largest wind turbine ever built for the generation of electricity. It wasn’t built by General Electric or funded by the Department of Energy. It was built by hand with private money from small investors.” You can watch a 12-minute summary of Vassar’s film here: http://tinyurl.com/ vimeo-wind. Password: dveff. From it we can glean a few turbine details such as its 25m lattice tower, about a 10m diameter APRIL 2017
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rotor with stall flaps at the tips, and it was upwind facing. Another document tells that it was rated for 200 kW, but that sounds too high. Still, the turbine was fairly advanced for 1978. President of the group’s company WTG Energy Systems, Allan Wellikoff, said the turbine ran on an off for a couple years and other versions were built and flown in Scotland. When praised for the advanced design, he said, “While it is good to be first, the money comes from being second.” Although the turbine did not operate very long, it pointed the way for future developers. Eventually, the island experimented with three wind turbines, 50, 100, and 250 kW. The larger one, from Nordex, was deemed the most useful. What about the documentary? Vassar says the studio that now owns it is re-mastering it digitally and will eventually release it for a wider audience. One showing is scheduled for the Roxy Theater in San Francisco on April 23 and another for April 22, Earth Day in Texas. He hopes Nexflix will acquire rights and show to it to everyone. W windpowerengineering.com
The Cutty Hunk windmill was one of the largest wind turbine ever built for the generation of electricity. It wasn’t built by General Electric or funded by the Department of Energy. It was built by hand with private money from small investors.
The 12-min. video details some of the construction and assembly of the 200-kW turbine on Cutty Hunk island in 1978. WINDPOWER ENGINEERING & DEVELOPMENT
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2017
I N N OVATO R » Leader E li za b et h
B u rd oc k fosters U.S. offshore wind growth
Elizabeth Burdock didn’t get her start in wind energy, but if her resume is any indication of her grit and determination, she is just what the industry needs. Burdock is currently the Executive Director for the Business Network for Offshore Wind, a notfor-profit organization she helped develop to support and build the offshore wind industry in the United States. “Our goal is to inform, educate, and connect businesses, developers, and global experts in offshore wind. We want to develop a community for networking and collaboration,” she said. “And, really, my goal is to facilitate and build the entire U.S. offshore wind supply chain.” Burdock has been facilitating clean energy initiatives and working in the field of sustainability for more than 18 years. However, her journey to the wind industry began elsewhere, in housing development — and politics. As Senior Advisor at the U.S. Department of Housing and Urban Development during the Clinton Administration, she acted as liaison to the President’s Council on Sustainability, and as Executive Director of the White House Partnership for Advancing Technology in Housing. “The federal level gave me a good overview of clean energy because we looked at solar power, geothermal energy, and even smaller measures such as pre-fabricated drywall corners because they save costs on waste,” she said. “I learned that when we take energy efficiency and couple it with renewable energy, we can actually get to zero-energy homes.” This is when Burdock first became hooked on renewables. 68
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After she left the Administration, she worked for several lobbyists and soon established a D.C. Chapter of the Renewable Energy Business Network, which provided a platform for researchers and business professionals with an interest in renewables to connect, promote, and grow the industry. “Here, my passion for renewables and wind energy in particular grew, and it quickly became my life’s purpose,” she said. “A reason I am such a strong advocate for offshore wind is because of the jobs it creates.
energy), Burdock believes the industry is finally set to grow and expand on both coasts. “The market is getting established, and I say that with pride,” she says. “We began as a state-focused organization in Maryland in 2014, and are now a national organization recognized on an international level.” The Network, and Burdock in particular, spent a lot of time researching and learning from the offshore industry in the UK and Europe, with hope of accelerating development and saving costs in the U.S.
We’re about 20 years behind Europe, but the good news is that we can take from their experiences and learn from their challenges to move the industry forward much more quickly here. It is probably about three times that of what’s offered by other renewable sectors, such as solar or even onshore wind.” Topics still close to Burdock’s heart are fair opportunities and affordable living standards, and the wind industry can offer potential prospects both. “It is so important to me that we give everyone a chance, and offshore wind does just that — it employs lower skilled people to highly educated PhDs. The benefit is that we are truly creating a ‘green’ economy where everyone can work and live successfully and efficiently.” Now that America’s first offshore wind farm, the 30-MW Block Island project off the coast of Rhode Island, is up and running and states such as New York and Massachusetts have committed to offshore wind (New York plans to develop up to 2.4 GW of offshore wind by 2030 while Massachusetts requires large utilities to buy up to 1,600 MW of offshore wind
“We’re about 20 years behind Europe, but the good news is that we can take from their experiences and learn from their challenges to move the industry forward much more quickly here,” she said. One way the Network is doing this is through an annual conference, the International Offshore Wind Partnering Forum, which Burdock spearheaded. It brings global experts to discuss and collaborate on the latest technologies and developments in offshore wind. Now in its fourth year, it will take place in Maryland this April. “As the only organization in the whole country focused solely on offshore wind, we have become the primary voice for the offshore industry in the U.S., and it means so much to me,” said Burdock. “We’ve worked hard, gained credibility incredibly quickly, and I cannot wait to see what the industry — in the U.S. and North America as a whole — will look like in the next five years.” W
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2017
I N N OVATO R » H e n r i k St i e sd al
Most companies and inventors that develop viable ideas or products patent them to keep their financial benefits to themselves. But one guy from Denmark thinks that if you make a good idea public, a hundred other minds can easily improve on it and thereby benefit a wider number of people. Maybe a whole nation. Maybe more. In this case, the guy is Henrik Stiesdal, a former chief technology officer of Siemens, where he spent 27 years improving wind turbines, and the idea that he made open source is one for a floating foundation, in the illustration. It is a recent and potentially inexpensive design for a floating wind-turbines platform. More on his offshore platform idea is here: http:// tinyurl.com/wpe-stiesdal You might think that growing up on a windy farm is a requirement for wind pioneers. It has inspired others in previous Innovator sections and it worked for Stiesdal. After leaving the family farm, his early wind industry work turned into what some call the Danish Concept: an upwind rotor on a nacelle with automatic yawing, and two-speed stall-regulated turbines (two generators, for high and low-speed winds) with fail-safe systems. This setup is still found on a few refurbished turbines. An early prototype in 1991 was rated at 30 kW. “The Siemens claim to fame is that we have developed a simple and easy-toindustrialize machine that could significantly bring down energy costs,” said Stiesdal, while at the company. He is also responsible APRIL 2017
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for Siemens’ success with their direct-drive The Siemens claim to turbines, most of which are assigned to work fame is that we have offshore because of their improved reliability developed a simple and over conventional wind turbines. Stiesdal’s other significant credits easy-to-industrialize include the Vindeby Wind Farm, the world’s machine that could first offshore wind farm, and development significantly bring of the IntegralBlade manufacturing method down energy costs. which casts blades in one piece, eliminating the weak spots of previous methods. And later, the CombiStall blade, a wind load regulation scheme, and first variable-speed turbine for Bonus Energy A/S. He is now president of Stiesdal A/S, and still developing creative windturbine ideas. For instance, at a recent AWEA offshore event, he presented his latest design for a floating foundation. Called TetraSpar, the design is built from components borrowed from industry, and already in production, such as cylindrical welded braces and cast nodes from tower technology, and steel tanks from several industries. Stiesdal’s Wikipedia bio says he holds more than 650 patents related to wind-power The free idea technology, not bad for a kid Stiesdal says anyone who would like to improve inspired by wind on the family farm. W on this floating foundation is welcome to do so. windpowerengineering.com
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I N N OVATO R » To d d G r i f f it h – Designer of super-sized turbine blades
Griffith shows a cross-section of a 50-m blade, which is a first step on a path to 200-m blades and 50-MW offshore exascale wind turbines. The design exercise is a DOE ARPA-E-funded program at Sandia National Labs along with University of Virginia, University of Illinois, University of Colorado, Colorado School of Mines, and the National Renewable Energy Laboratory.
The modern worldwide wind industry is at least 30 years old, so you might think most wind-turbine designs have already been optimized and the industry need only plan more projects. Dr. D. Todd Griffith, a member of the technical staff and the technical lead for Sandia National Laboratories’ Offshore Wind Energy Program, disagrees. To make offshore wind economical, particularly on a large scale, he believes larger turbines with longer blades are still in order. “The U.S. has great offshore wind energy potential but offshore installations are expensive, so larger turbines will be needed to capture that energy at an affordable cost,” said Griffith. “But beyond 10 or 15 megawatts, conventional upwind blades will be expensive to manufacture, deploy, and maintain.” Most U.S. wind turbines are rated around 2-MW, although the largest commercially available turbine is rated at 9 MW, with blades 80 meters long. Impressive, but it is still less than ideal for a large offshore wind farm. So Griffith has begun work with a team at Sandia, which includes numerous university researchers and industry advisers from GE, Siemens, and Vestas. The challenge: Design a low-cost offshore 50-MW turbine with a blade more than 200 m long — that’s two and a half times longer than any existing wind blade. While a 50-MW horizontal turbine is well beyond the size of current designs, studies show that load alignment can significantly reduce 70
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the mass and forces on blades, making peak stresses and fatigue on the blades. This them durable in offshore conditions. reduces costs and allows construction of According to Griffith such an blades big enough for a super-sized turbine. “exascale” turbine would also be If anyone is up to the task of designing manufactured in segments for easier such a large blade structure, it is Griffith. transport, and would face downwind when His research contributions — just to name a operating. “At dangerous wind speeds, few — include work in the areas of turbine the blades are stowed and aligned with blade design, structural dynamics, field the wind direction, reducing the risk of testing, and structural health-monitoring damage. At safer or production worthy methods for wind-power systems. He is an wind speeds, the blades spread out to Associate Fellow of American Institute of maximize energy production,” he said. Aeronautics and Astronautics (he did PhD “Granted, what we are proposing to work at Texas A&M University in Aerospace do here is far beyond current designs Engineering), and is a recipient of an AIAA and very high risk,” he added. But it is Distinguished Service award for leadership in wind energy. Griffith has also Granted, what we are proposing to do here is far designed the Sandia beyond current designs and very high risk. 100-m series of blades and is also an essential step if it is to be done at all leading a U.S. national research project regardless of time frame. that aims to improve design and costGriffith is dedicated to wind energy and effectiveness of large-scale floating improving current turbine designs. In his offshore vertical-axis wind turbines. spare time, he chairs the ASME Wind Energy Part of Griffith’s success is his ability Technical Committee, writes research papers, to think outside the box. To deal with the load alignment of a 50-MW turbine, his and presents at numerous wind events in project team looked at palm trees and how Europe and the U.S. If that isn’t enough, he also acts as an adviser and mentor to student they sway in storms and high winds. The tree’s segmented trunk is lightweight and interns at Sandia when he is in the lab. It will be exciting to see how Griffith’s follows a series of cylindrical shells that research impacts the offshore wind bend in the wind, without losing strength industry in the U.S. Learn more at or stiffness. On a wind turbine, a similar http://energy.sandia.gov. W load-alignment approach could reduce www.windpowerengineering.com
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