The Motorship January 2021

JANUARY 2021

Vol. 102 Issue 1188

Knud E Hansen:

Atlas C WTIV design

Next gen WTIVs:

New power generation

MAN ES ME-LGIP:

Bjarne Foldager interview

Shaft power feature: New PM solutions

ALSO IN THIS ISSUE: Exergy study | Turbocharger insulation | High temp superconductors | Alfa Laval SOFC project

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CONTENTS

JANUARY 2021

8

4

NEWS 24 Alfa Laval SOFC project

Alfa Laval is leading a Danish-funded project to introduce an ammonia SOFC fuel cell into the maritime market.

12 PM EMG variant

KSOE and HHI are seeking to develop a permanent magnet version of a newly developed direct on Engine Mounted Generator.

24 Jones Act-compliant WTIV

NETSCo expects is designing and developing a Jones Act-compliant wind turbine installation vessel (WTIV) to meet expected demand for offshore wind power.

30 REGULARS 8 Leader Briefing

Mark Bell, the general manager of SGMF, worries that descriptions of LNG as a bridging fuel risk sending ship owners mixed messages.

26 Design for Performance

A simulation-based exergy study into a 4-stroke LNG-fuelled engine at Sweden’s Royal Institute of Technology has identified significant combustion and turbocharger losses.

18

FEATURES

10 ME-LGIP retrofit option

MAN ES’ Bjarne Foldager sees demand increasing for LPG-burning ME-LGIP in the LPG gas carrier retrofit market.

12 Talkin’ about revolutions

Advances in shaft generator technology offer operational and environmental benefits, but there are trade-offs in terms of complexity.

16 Tomorrow’s world

High-temperature superconductors offer potential power distribution and motor efficiency advantages, Stevie Knight hears.

18 New power generation

Closed bus solutions offer efficiency and CAPEX advantages for the new generation of WTIVs, but require improved fault detection.

20 Offshore wind crunch

The growth in offshore wind generation, and larger turbine sizes, will require new larger wind turbine installation vessels after 2025.

30 Ship Description Online motorship.com 5 Latest news 5 Comment & analysis 5 Industry database 5 Events

Social Media Linkedin Facebook Twitter YouTube

Knud E. Hansen has developed a new concept of offshore windfarm construction vessel.

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The Motorship’s Propulsion & Future Fuels Conference will take place on 18-20 May 2021 in Hamburg, Germany.

Stay in touch at propulsionconference.com

JANUARY 2021 | 3

NEWS REVIEW

VIEWPOINT

ALFA LAVAL AND HALDOR TOPSOE JOIN DANISH AMMONIA SOFC DEVELOPMENT PROJECT

NICK EDSTROM | Editor nedstrom@motorship.com

Reasons to be Cheerful Happy New Year to our readers in the 101st year of The Motorship.

While the ongoing Covid-19 pandemic continues to dominate our daily lives personal and business activities, the accelerating pace of technological change continues to dominate our agenda.

The pandemic has indirectly accelerated the pace of technological change, and the maritime industry’s willingness to consider innovative solutions.

One such area is the rapid progress in bring autodocking solutions to market – Volvo Penta launched an autodocking solution for leisure vessels in January, and this was swiftly followed by Wärtsilä SmartDock Suite, which encompasses autonomous dock-to-dock operations.

Meanwhile, the accelerating pace of investment in the Energy Transition in major energy importing markets, such as Germany, Japan and South Korea, is likely to eventually result in new and expanded opportunities for energy transportation.

The main beneficiary of this expansion in the short-term is likely to be the LNG market, but demand for other alternative fuels may also rise. We feature an interview with MAN Energy Solutions’ Bjarne Foldager, in which he discusses the outlook for LPG as a marine fuel.

The operational advantages of LPG over IMO 2020-compliant fuels has led to the near-complete shift towards dual-fuel LPG-fuelled propulsion for newbuild chemical tankers destined for the propane trade. Meanwhile, shipowner interest in retrofit conversions for chemical tankers has accelerated since the completion of BW LPG’s first such conversion in 2020.

Meanwhile, the Energy Transition is also likely to see the sea become an increasingly important source of energy for advanced western societies. We discuss the likely impact of ambitious European announcements around ramping up offshore wind power generation over the course of the next decade, as well as the potential of floating offshore wind platforms to open up new deepwater locations.

This investment is likely to spur new orders for wind turbine installation vessels, as technical advances in the size of offshore wind turbines exceeds the load bearing capacity of many existing vessels.

We assess how OEMs are addressing the challenges of increasing voltage and crane heights to meet requirements of the next generation of offshore wind turbines in a special feature.

One of the latest ‘Hydrogen Republic’ research projects in Germany is investigating the possibility of integrating electrolysers directly into offshore wind turbines.

The emergence of new fuels for which four-stroke genset solutions have not been launched is likely to drive interest in shaft power solutions. Stevie Knight assesses the latest developments in the area, including KSOE and HHI’s latest direct-on EMG solution.

Meanwhile, research into wind turbine technology is driving advances in unrelated fields, such as high-temperature superconductors, which may benefit from scaled up demand. Stevie Knight discusses the potential applicability of advances in the field for commercial maritime in a special feature.

4 | JANUARY 2021

Alfa Laval, DTU Energy, Haldor Topsoe, Svitzer and the Mærsk Mc-Kinney Møller Center for Zero Carbon Shipping are entering into a joint project to accelerate the development of solid oxide fuel cell (SOFC) technology.

The project will initially focus on the development of ammonia-based SOFCs. The project is being funded by a grant from Denmark’s EUDP (Energy Technology Development and Demonstration Program). The partners will pursue a high-efficiency solution with the scalability to support marine industry decarbonization.

The project, SOFC4Maritime, will target optimal utilization of future green fuels via application of SOFCs for power production on marine vessels. When based on fuels such as ammonia, hydrogen or bio-methane, SOFCs hold great promise as a replacement for today’s fossil fuels. Such alternatives are needed in the maritime industry, which must transition to greener power over just a few decades.

By electrochemically converting fuel into electricity, SOFCs can potentially produce power with higher efficiency than internal combustion engines running on the same fuel without creating polluting emissions or particulates.

Ammonia-based SOFCs are especially attractive, since ammonia can be produced in large scale using renewable

8 The Alfa Laval Test and Training Centre

electricity and no biomass resource. As such, the initial focus of the research will be ammoniabased SOFCs. Alfa Laval, a marine supplier with more than a century of expertise, will head the development initiative. Haldor Topsoe will provide the underlying SOFC stack technology, while DTU Energy will support in system layout and component testing. Svitzer will bring a shipowner perspective and the Mærsk McKinney Møller Center for Zero Carbon Shipping will ensure a broad industry overview, end-to-end analysis of various energy pathways and a detailed techno-economic analysis.

“Addressing shipping’s environmental challenges - and climate change in particular - will require a diverse range of strong technologies. By partnering with fellow marine industry experts, we can investigate the possibilities and bring them to fruition in time to make a difference.” Sameer Kalra, President, Alfa Laval Marine Division.

“We are eager to pursue this project, which will provide essential information and enhance the feasibility of future pathways to zero carbon shipping based on SOFCs.” Bo CerupSimonsen, CEO, Mærsk McKinney Møller Center for Zero Carbon Shipping.

For the latest news and analysis go to www.motorship.com/news101

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NEWS REVIEW

OFFSHORE ELECTROLYSER NEXT STEP IN GERMANY’S “HYDROGEN REPUBLIC” The development of a 14MW offshore wind turbine with an integrated electrolyser for hydrogen production is one of three key projects presented on 13 January by Germany’s Federal Ministry of Education and Research as a result of its “Hydrogen Republic of Germany” ideas competition.

Siemens Energy and Siemens Gamesa are funding the development of a scalable solution that integrates an electrolyser array into the base of the world’s most powerful offshore wind turbine, the SG14-222 DD. The direct-drive, permanent magnet turbine, with a rotor diameter of 222 metres, is expected to be in serial production by 2024.

The direct coupling of the wind turbine and the electrolyser is intended to minimize the costs of hydrogen production by eliminating the cost of connecting to a power grid.

The companies intend to provide a full-scale offshore demonstration of the hydrogenproducing solution by 2025/2026, with Siemens Gamesa investing €80 million and Siemens Energy investing €40 million over the next five years.

Siemens Energy notes that currently 80 million tons of hydrogen is produced globally each year. This is expected to

BRIEFS CalMac win for BMT

Caledonian Maritime Assets Limited (CMAL) has awarded a contract to design and engineering firm, BMT, to provide consultancy services for the concept design of a new passenger ferry for the Gourock, Dunoon and Kilcreggan routes in Scotland. The £155,000 contract is part of the Gourock Harbour Infrastructure & Vessels Project, which is a partnership between Transport Scotland, CMAL, CalMac and Argyll and Bute Council.

6 | JANUARY 2021

8 Siemens Energy hopes to obtain funding from Germany’s €700 million “Hydrogen Republic” schemes for its offshore electrolyser development project

increase by about 20 million tons by 2030. Only 1% is currently generated from green energy sources. The bulk is obtained from natural gas and coal, emitting 830 million tons of CO2 per year. This is more than Germany and more than the global shipping industry.

Replacing this current polluting consumption would require 820GW of wind generating capacity, 26% more than the current global installed wind capacity. By 2050, production will have grown to about 500 million tons, with a significant shift to green hydrogen. This would require between 1,000GW and 4,000GW of renewable capacity by 2050 to meet demand.

The H2Mare initiative, led by Siemens Energy, consists of multiple sub-projects with over 30 partners from industry and academia. Other activities include the development of ways

to generate secondary products such as green methanol or green ammonia offshore (offshore Power-to-X). The partners also want to further advance water vapor electrolysis and seawater electrolysis technologies and to produce carbon dioxide and nitrogen from the air or seawater for Power-to-X production.

The Federal Ministry of Education and Research announced €700 million over the next five years for three “Hydrogen Republic” projects: H2Mare, H2 Giga and TransHyDE. H2 Giga is devoted to technologies supporting the serial production of water electrolysers, a move seen as necessary to make green hydrogen production competitive. Although there are already large electrolysers on the market, they are still mostly manufactured by hand. This is time-consuming, costly and error-prone, says the Ministry. H2

Giga developments will also address recycling and the flexible operation of electrolysers so that they can be stopped and started as quickly as possible and can be operated at different performance levels.

The project aims to make Proton Exchange Membrane (PEM), alkaline electrolysis (AEL) and high temperature electrolysis (HTEL) plant ready for assembly line production.

Electrolysis technology using ion-conducting membrane (AEM) will also be further developed.

The TransHyDE project aims to develop hydrogen transport infrastructure. It is anticipated that Germany will require hundreds of millions of tons of hydrogen annually to achieve carbon neutrality, a goal anticipated to be reached by 2050. Although some of this hydrogen will be produced in Germany, much will be imported from regions with more solar and wind resources. The project will test and scale up one transport technology each in four demonstration projects: hydrogen transport in high pressure vessels, liquid hydrogen transport, hydrogen transport in existing and new gas pipelines and the transport of hydrogen bound in ammonia.

US autodock debut

MR tanker order

H&W eyes WDV deal

Wärtsilä has launched a new semi-autonomous ship movement solution, SmartMove Suite, which pairs sensor tech with navigation systems.

The new solution has been successfully operated aboard MV American Courage, a 194-metres long Laker vessel, since March 2020 on a river in Ohio, USA. The vessel is the largest ship ever capable of performing automated docking and dock-to-dock sailing operations.

Japan Engine (J-ENG) won an order from Penglai Zhongbai Jinglu Ship Industry Co., Ltd for 2 x 6UEC50LSH-Eco-C2 engines for two MR tanker newbuildings. The vessels will be delivered to Singaporebased agribusiness Wilmar Ship Holdings. The order, which includes options for two further vessels, is noteworthy as J-ENG will act as engine licensor. The engines are due to be delivered from the end of 2021.

InfraStrata, the owner of Harland & Wolff in Belfast, signed a Letter of Intent with London-based Triumph Subsea Services for a 200m-long multi-role newbuild Windfarm Development Vessel with an option of a second ship in December 2020. The vessel is intended to meet UK localisation requirements for offshore windfarm installations, with the capability also to undertake subsea cable laying as well as ‘green’ hydrogen schemes.

For the latest news and analysis go to www.motorship.com/news101

RIDE THE WAVE

Of the LNG marine expansion

All the key role players in the marine industry have started to invest in LNG technology and infrastructures, as well as in new dual fuel or gas only engines for ships and new LNG bunkering vessels too. Vanzetti Engineering ARTIKA Series submerged pumps and VT-3 Series reciprocating pumps are the default choice for low and high pressure marine engine fuel gas systems, stripping and spray applications, booster, ship to ship bunkering, cargo and more.

VANZETTI ENGINEERING. Widening the horizons of LNG sustainability. www.vanzettiengineering.com

LEADER BRIEFING

ARE SHIPOWNERS TAKING LNG AS A BRIDGING FUEL TOO FAR? The idea of LNG as a bridge fuel should not deter ship owners from making the right choices today, writes Mark Bell, general manager, Society for Gas as a Marine Fuel (SGMF) Like any community the LNG as a marine fuel sector has developed its own language. In the early days it was all chickens and eggs as the sector grappled with the early investments needed from shipowners and fuel suppliers.

More recently phrases like ‘bridge’ and ‘transition’ have become common as people attempt to place LNG in the context of the wider decarbonisation of shipping. But advocates of LNG may have misdirected the very people they are trying to reach.

It is fair to say that LNG is not a perfect solution. It is undoubtedly a good option until better fuels come along. It outperforms all other current options in environmental terms, with dramatic improvements in emissions of local air pollutants as well significant reductions in CO2. Those benefits are not enough to reach the targeted 50% reduction in greenhouse gas emissions across the global fleet by 2050.

And the escape of highly potent greenhouse gas methane needs to be addressed. But LNG is a good first step and the only compliant step available to shipowners today.

But the idea of a bridge can be problematic. At our Gas Fest 2020 event, a series of online discussions hosted by SGMF in November 2020, the need for clear communication was highlighted by a group representing ship owners, engine developers, fuel suppliers and class societies.

SEEKING CERTAINTY Erroneous perceptions around LNG have real consequences.

Ship owners need certainty over a long period before they invest in ships. The image of LNG as ‘only’ a bridge fuel, combined with a widespread view of zero-carbon fuels as being closer to viability than they really are, could paralyse investment decisions. That in turn could mean that shipowners do not take steps to reduce emissions today, and thus miss future environmental targets.

The ‘bridge’ metaphor has perhaps failed to convey any helpful specifics about how these future steps are linked to the use of LNG today. The history of shipping is really a succession of ‘bridge fuels’, from oars to sails to steam to diesel. Although methane is also a hydrocarbon, its significant emission benefits mean LNG could be a useful bridge fuel a long time yet. Other non-carbon carriers such as nitrogen (in ammonia), or even pure hydrogen, will require costly and lengthy investment.

Appreciating the longevity of LNG and the wait for other alternatives is critical for shipowners when considering whether to build gas-fuelled ships now or to opt straight for carbon-neutral fuels Placed in the wider context of shipping’s decarbonisation, LNG has both a foundational role for other fuels and its own long-term future. The spread of gas as a marine fuel - the infrastructure, the vessels, the safety measures and the international regulations - has laid a framework for other future fuels to follow. Methanol, which was finally included alongside LNG in the IGF Code in late 2020, is a case in point.

LNG frameworks are designed with other low flashpoint

8 | JANUARY 2021

fuels in mind, although they remain relatively distant prospects. SGMF exists to ensure the safe and sustainable use of any gaseous marine fuel, not just LNG. Much of the work by SGMF and its members is to ensure that best practice is applied, but also that emissions performance and practical considerations are understood.

But LNG also has a future in its own right. Use of LNG as fuel together with continuous technology improvements will gradually improve shipping’s emissions impact. The use of biogas or synthetic methane, first as a drop-in fuel and eventually replacing fossil LNG, will only improve the well-towake footprint for methane. With enough availability, vessels could exceed IMO 2050 targets through the progressive use of bridged methane - natural, then biological, then synthetic.

Fossil LNG is the vital first step in reducing carbon for shipping.

This view of LNG as a trailblazer for alternative fuels and part of the long-term solution could help to dispel the ‘us vs them’ tone that can emerge when advocates promote their future fuel preferences. Too often LNG is pitched against alternatives. But if shipowners view LNG as fundamental to the emissions reduction journey, rather than a stage to be skipped over, there is a better chance that we will reach the emission targets on the other side of the bridge.

8 Mark Bell, general manager at the Society for Gas as a Marine Fuel (SGMF)

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MOTORSHIP INSIGHT FOR MARINE TECHNOLOGY PROFESSIONALS

TWO-STROKE ENGINES

JAPAN, LPG RETROFIT AND NH3 OPPORTUNITIES FOR ME-LGIP Demand for MAN Energy Solutions’ ME-LGIP engine has exceeded expectations, Bjarne Foldager, Senior Vice President & Head of Two-stroke Business, MAN Energy Solutions told The Motorship

8 Bjarne Foldager, Senior Vice President & Head of Two-stroke Business, MAN Energy Solutions

The pace of adoption of the LPG-fuelled ME-LGIP engine since its launch at MAN ES’ two-stroke research center in Copenhagen in September 2018 has exceeded the company’s own expectations.

“Of course, when we launch technology like this, we are always concerned about the timing. But I think we actually got the timing right with [the ME-LGIP], because it has really attracted a lot of interest since Day One,” Foldager reflected.

As of 14 January, 66 ME-LGIP engines have been ordered or delivered, as the dual-fuel technology is proving a popular choice for shipowners keen to explore a more sustainable propulsion solution.

In fact, the engine has become the industry standard for newbuildings destined for the butane and propane trade. In 2020, 97% of all the LPG tankers that were ordered were ordered with the ME-LGIP engine. “The market uptake has exceeded even our [pre-launch] best case scenarios,” Foldager noted.

Much of the interest has been driven by the operational benefits of running dual-fuel engines. “The orders have not been limited to just one type of ship: we’ve received orders for everything from the large gas carriers to medium size carriers, but also smaller gas carriers, down to 5,000cbm ships.”

JAPANESE AND FUTURE AMMONIA MARKETS Foldager identified two potentially significant developments for the ME-LGIP engine that occurred in the last months of 2020.

10 | JANUARY 2021

The first has been the emergence of significant shipowner interest in ME-LGIP engines for vessels engaged in coastal trades in Japan. The interest in LPG is not being driven by the gas carrier market. In Japan, LPG is seen as an interesting alternative fuel for commercial shipping.

“There is growing interest in smaller sizes of ME-LGIP for ships trading around the coast of Japan. The infrastructure is there, the fuel is readily available and, you know, capex-wise, it’s quite competitive,” Foldager explains. “The ME-LGIP is not only seen as an environmentally-friendly solution, but it also turns out to be quite competitive and can give a competitive advantage.”

Foldager notes that this had resulted in the first orders for coastal vessels. “We have received the first orders from... some of these smaller entities for coastal ships.”

The emergence of demand for LPG-fuelled engines from outside the gas carrier market represents an interesting market development. The fuel was identified as a readily available potential alternative to LNG for vessels engaged in tramp trades before the ME-LGIP was launched.

“Outside the gas carrier market, it’s fair to say it is still early days,” Foldager commented, noting that new designs for MELGIP powered vessels were continuing to be delivered.

However, Foldager envisages the ME-LGIP playing a wider role in the energy transition.

Foldager noted that the ME-LGIP engine shares the same Diesel combustion principle as the ME-C, and as the upcoming AEngine. “The top of the ME-LGIP engine with the valves and the injection looks a little bit different from a

For the latest news and analysis go to www.motorship.com/news101

TWO-STROKE ENGINES normal engine, but it’s not a completely new engine. In fact, we only need to change relatively few things regarding the injection components to enable LPG combustion.”

RETROFITS The second development has been the completion of the first retrofit conversion of an ME engine to ME-LGIP on BW LPG’s BW Gemini in 2020. The vessel’s MAN B&W 6G60ME-C9.2 prime mover converted to a 6G60ME-C9.5LGIP LPG-propelled dual-fuel engine in October.

“The first ship [BW Gemini] that was converted completed its maiden voyage, if we can say that about a five-year-old vessel, across the Pacific, through the Panama Canal to Houston loaded, running on LPG bunkers at the same time, and it’s now on the latest voyage. According to the feedback we have received from the engineers, it’s running extremely well.”

Meanwhile, the second conversion for BW LPG has been completed, and the third conversion is undergoing sea trials in China at Yui Lian Shipyard.

Foldager notes that enquiries about retrofits has risen following the success of the first retrofit.

“The fact that we have now completed a successful retrofit makes an enormous difference. BW LPG in Singapore has signed off on retrofits for their 15 vessels in total to be upgraded or converted to LPG.” “I think the interest in converting existing vessels to be able to operate on LPG in the future is being driven by the fuel’s environmental benefits, but also because it offers competitive advantages.”

Foldager noted that each of the BW LPG upgrades are expected to deliver CO2 emission reductions of around 3,000 tonnes per year. The fuel offers wider environmental benefits, with sulphur emissions lowered by over 90%, and NOx emissions reduced by 10-15%, and CO2 between 13 and 18%.

Fuelling a very large gas carrier (VLGC) with LPG instead of HSFO offers operational savings of US$4,000 per day, Foldager said, citing the ceo of Singapore-based shipowner and operator BW LPG.

“These savings include fuel direct fuel cost savings from a more efficient engine, because when they upgrade the ships, they have also been upgraded to the latest standard of engine.”

Underlying everything, shipowners and their finance providers are taking an increasingly close interest in futureproofing investments.

New regulations at the IMO are also fuelling interest. “The likely introduction of EEXI requirements for existing ships by the IMO will make it even more beneficial to convert your ships into a more environmentally friendly solution. There is no doubt the ME-LGIP would offer a higher EEXI rating.”

8 A rendering of a MAN B&W 6S50ME-C8.2-LGIP dual-fuel engine

Long-term decarbonisation scenario insights MAN Energy Solutions’ perspective on the potential decarbonisation pathways the shipping industry can follow out to 2050 reflects wider societal choices and regulatory choices, as much as technological advances and future fuels.

The scenarios, which were published late in 2020, were developed by the Fraunhofer Institute for Systems and Innovations Research (ISI), using the institute’s MATISSESHIP simulation model. The study presented four alternative scenarios covering the period between 2020 and 2050.

Unlike some other studies that focused on technological or techno-economic analyses, the study also addressed regulatory issues (identifying the fragmentation of worldwide regulation as a potential risk factor towards broader adoption), social attitudes (including the risk of ‘dark green’ attitudes prioritising decarbonisation above economic growth) and the speed with which the necessary

building blocks for the adoption of alternative fuels (including bunkering infrastructure and the emergence of a retrofit market) as key variables.

Importantly, the scenarios were refined through a series of workshops, permitting industry experts to sense-check the outputs from the quantitative model and the qualitative scenarios. The first, A for All Aboard, offers a ‘Goldilocks’ scenario in which technological development is driving global economic growth, whilst meeting the Paris Accord’s 2 degree Centigrade target.

Low carbon fuels prevail after 2035.

The second, H or Hanging On to Old Ways, proposes a world in which public scepticism about climate change targets saps governmental and corporate will to implement changes. National pathways diverge, and alternative fuels such as ammonia or SNG fail to penetrate the fuel mix until 2040 as LNG predominates.

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The third, O or Out of Control, offers a pessimistic vision where climate change targets are abandoned, and most international governments turn their back on decarbonisation. The development of low carbon fuels is abandoned, with technological development focused on efficiency improvements for oil fuels.

The final scenario, Y or Yes We Can?, offers an equally downbeat vision in which environmentalists have all but halted economic growth, prioritising sustainability over consumption.

The study offers a number of interesting insights into the interrelationship between regulation and fuel choices. Critically, the most attractive scenario (for all but Deep Green environmentalists) is A. The study notes the transition from LNG to low carbon ammonia and synthetic natural gas (SNG) needs to happen by 2030 for such a ‘Goldilocks’ outcome to be achievable.

JANUARY 2021 | 11

SHAFT POWER

ADVANCES IMPROVE SHAFT GENERATOR CASE

Photo: HHI

Shaft generators can save operating costs, reduce emissions and raise a ship’s environmental profile, but they require more thought than ever writes Stevie Knight

As Jussi Puranen of The Switch explains, “although auxiliary engines are still needed as a backup, using a shaft generator means that these can stay idle most of the time, significantly reducing OPEX costs on fuel and genset maintenance”.

It mostly comes down to two-stroke’s specific fuel-oil consumption (SFOC) being lower than four-stroke auxiliaries but Puranen adds: “Conventional gensets run at full-speed regardless of the power demand - to maintain a constant grid frequency, while an SG system can operate in variable speed mode.”

While the biggest fuel savings are typically achieved by vessels moving at less than a flat out pace, the focus also needs to cover those (sometimes lengthy) periods when the ship is in busy waters or on the berth approach. This can present a few challenges - though it isn’t about the SG itself, says Puranen: that “can typically operate even near zero speed, but main engines typically have much narrower range”.

The parameters take some consideration, says Michael Kranz of Wärtsilä, that is, “which engine speeds will deliver what power”. While for most operational profiles a range down to 70% of the maximum rpm is broad enough, occasionally the requirement goes as low as 50%. That is possible for the shaft generator - for a price. “The physics

12 | JANUARY 2021

8 HHI and KSOE have got together to develop a ‘direct on’ Engine Mounted Generator, the first 1.3MW model being combined with a large 24.5MW main engine onboard SK Shipping’s new 318,000dwt VLCC

makes the difference: if you want to have the same power from a lower speed, you need higher torque; this requires a bigger machine”, says Kranz, “although that can kill your business case.” And, he adds, it might still be unfeasible for the main engine itself.

Further, there is a small, nubby issue “that’s often overlooked” says Jan Backman of WE Tech. “While a hotel load of a few hundred kilowatts - as you’d find on, say, an oil tanker - can be met from normal engine margins, that’s not the case for something like a big container ship providing reefer slots.” Puranen adds “in practice” it can often mean pairing with a 15% larger main engine.

For the new, emissions sensitive ships, shaft generation is also interesting because it can produce electricity from a fuel for which there isn’t, yet, a DF auxiliary explains Backman. For example, WE Tech is supplying SGs to a couple of new Geogas Maritime LPG carriers to be delivered this spring: these SGs allow LPG to cover all the electrical load in transit, limiting the diesel gensets to harbour and manoeuvring operations.

ADDED EXTRAS While the standard solution generates power for the grid, it’s not such a big jump to consider reversing the direction and supporting the main engine with the electric drive. “Using a

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SHAFT POWER

‘‘

Onboard electrical demand has been decreasing, the lights are modern, and the fans and other systems now have speed control shaft generator as a booster motor for peak shaving can allow you to select a smaller main engine,” says Puranen - a step down in engine size, rather than up.

It’s a fairly straightforward argument. He continues: “If 99% of the time the necessary propulsion power is under 90% of the maximum, it makes sense to produce that remaining 10% of the power by putting a shaft generator into reverse, using it as a boost motor for moving against a heavy head-wind or through ice.”

Of course, this power reversal means firing up the gensets or relying on a battery installation to feed the shaft generator.

Further, there’s ‘take-me-home’ mode, where if there’s a problem with the main engine, it’s possible to leave the shaft generator to drive the propeller. It’s a much slower, lowpower transit, but it can get the ship back to safety.

THRUSTERS The advantages also include better energy handling.

“Onboard electrical demand has been decreasing, the lights are modern, and the fans and other systems now have speed control,” says Kranz. So, it’s now primarily thruster draw that’s holding back efficiency.

For some vessels, shaft generators could make all the difference. A broad range of ships, such as bulk and gas carriers, have a relatively large 1.5MW or 2MW thrusters, “but their hotel load is about the same size or even lower” he explains. Given this, it’s possible to switch the power from one to the other, with full speed control via the variable frequency drive.

These VFD’s have been the saving of shaft generators, adds Thomas Hartmann of DNV GL, pointing out that older versions used to employ a constant gear ratio and were often rather simply connected to the grid, but “fluctuations in propeller shaft speed created fluctuations in frequency”. This strained parallel-positioned gensets on the ship’s grid and threw up more issues when using controllable pitch propellers. As a result, VFDs are now pretty much central to most modern installations.

They have also helped free up the dimensions of other

systems. “Sometimes you might want to invest in a slightly bigger SG than you need for everyday use, just to cover the demand,” says Kranz. Either “it means you don’t have to install oversized and expensive gensets for the sake of running your thrusters just for, say, thirty minutes once a week”, or alternatively, it could allow for broader utilisation of controllable pitch propellers, “as some ships can take most of the berth approach on SG’s and CPP’s in combinatory mode,” he says, “though you have to get into the relative merits during the design phase”.

FOUR-STROKE The most obvious home for SGs may be the big two-stroke ships - but they’re a long way from being the only application: LNG carriers have usefully paired SG’s with four-stroke DF engines burning boil-off gas for some time, says Kranz.

While admittedly not as efficient as their larger, low-speed cousins, four-stroke SG installations still hold a trick or two.

For example, these can position cost-effective induction generators on the gearbox spur. The ‘induced’ magnetic field requires a very close fit between squirrel cage and rotor - this isn’t easily accomplished on a typical in-line two-stroke; it requires a larger airgap to accommodate shaft movement.

Further, the gearbox tie-in also allows straightforward declutching of the engine and easy maintenance.

HYBRIDS Even more potential opens up by pairing the SG’s with a battery... “especially as now batteries are getting much cheaper and more effective,” says Puranen.

However, there is more than one hybrid configuration.

“There’s the familiar method - you buy a battery and inverter and tie it in via the main switchboard,” says Kranz. “but we saw that for a little extra money, you could extend the PTO/PTI and connect the battery to the main SG frequency converter.”

It does yield advantages. Routing the power via a DC bus to the dedicated inverters of big consumers such as bow thrusters or large compressors, “can increase efficiency by up to 35%”, says Backman, as it avoids distribution and conversion losses as well as allowing more control on start-up.

This approach can be applied to both two-stroke and fourstroke engines; Wärtsilä’s solution is currently being explored

by Finnlines, (part of the Grimaldi Group) onboard the two Superstar ferries employed on Baltic crossings. Kranz explains these newbuilds will have induction SGs paired with Wärtsilä 46F main engines: this incorporates thruster management, an SG that works as a generator or motor to give an engine boost mode, plus energy storage. “They also

Image: Wärtsilä

8 There is a broad range of potential shaft generators configurations, including hybrid and four-stroke main engines

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JANUARY 2021 | 13

SHAFT POWER

AT THE OTHER END Certainly, supplying a typical long-haul VLCC with a shaft generator is an excellent bet, as it can usually reduce fuel consumption “by around 5%” overall says Mun Hwa Jung of DNV GL Korea. Both OPEX costs and environmental savings are, potentially, even greater when it comes to dual-fuel ships.

Despite all this, physical dimensions also play a large part in determining whether SG installation is even possible, explains Byoung Hun Kwon of KSOE’s Advanced Research Center.

In fact, two-stroke in-line installations require extending the intermediate shaft by 2m or more.

As a result, Hyundai Electric & Energy Systems, KSOE and HHI have got together to develop a ‘direct on’ Engine Mounted Generator (EMG), the first 1.3MW model being combined with a large 24.5MW main engine onboard SK Shipping’s new 318,000dwt VLCC. Both Kwon and his HHI colleague Jung Ho Son underline, the EMG’s basic electrical generation principle is “proven technology”, but its main difference lies in the compact disclike structure layout and its direct coupling with the main engine.

This has given rise to developmental challenges, says Son. The EMG’s capacity is governed by size, but at the same time, a larger mechanism either in diameter or depth raises the static load on the crankshaft. This provides a physical limit, he explains, and so the design requires careful tailoring to the specific engine loads.

Further, it’s in the location usually occupied by a torsional vibration damper or tuning wheel. In fact, the extra mass of the EMG itself can mitigate the issue, but it needs careful integration with the engine or it stands to increase - rather than reduce - torsional vibration on the propulsion shaftline.

Given all this, the EMG’s output stability during main engine running conditions has been thoroughly tested and verified by DNV GL, HHI Group and SK Shipping.

It is a worthwhile development, despite the effort: “These features reduce the length of the installation space by 40% compared to a conventional SG,” adds Son, “with no intervening gearbox”.

The result is a net gain in tank capacity. Kwon explains that a study for a reasonably standard LPG carrier showed that exchanging the EMG for a shaft generator in a conventional engine room allowed for enlarging the cargo space, “which went up from 90,000m3 to 91,000m3, adding 1,000m3 of gas”.

Further, it promises to minimise shipyard costs. Being able to fit and test both the shaft generator and engine before delivery cuts down installation time and effort says Kwon: delivering a fully integrated unit makes the usually tricky alignment procedure far simpler and shorter.

PM MACHINES More recently shaft generators have been evolving to embrace Permanent Magnet (PM) machines of the kind developed by The Switch and WE Tech.

While smaller-sized PM units have been around more than a century, those of the necessary megawatt-scale suitable for shipping have only been plausible given the recent developments on permanent magnet material composition, resulting in a step up in power density.

These have no need for an external energy source as the magnetic field is inherent rather than powered, explains

14 | JANUARY 2021

Photo: The Switch

asked for efficient recharging of the battery,” explains Kranz.

“You can either connect to shore power, when available, or you can use the battery instead - so you don’t need to burn fuel at berth.”

Puranen, adding this yields a “significantly more compact and mechanically simpler, more reliable generator”. Further, the higher power density means “they’re easier to install inline where space is limited”, says Backman, adding that these generally require little-to-no maintenance.

However, “there’s no such thing as a free lunch”, says Hartmann, and Puranen admits there’s been something of a challenge to overcome. These PM machines’ magnetic field is intrinsic, so - unlike other varieties - they don’t stop working when the power is pulled.

As a result, the most efficient, in-line PM SG’s have come under extra scrutiny by the class societies. If there’s no clutch to decouple the generator “all the time the shaft is moving .... and even when there is a malfunction in the machine, it will carry on pouring energy into the fault”, says Hartmann.

Further, though ideally the SG should be disconnected inside a few minutes, “that’s just not plausible with the big in-line PM machines”, he adds.

Kranz notes that for the same reasons “when installing them in a single shaft vessel discussion is critical, as given some failure in the SG you have to stop the main engine and still fulfil the specific redundancy rules”.

“All PM machines may require some added electrical protection,” says Hartmann. However, DNV GL’s answer is to allow for a sliding scale of response. He explains: “In what’s called Class 3 redundancy, we balance the risk of failure by asking for more protection of the machine plus higher quality winding and other construction and testing requirements so that we get to a point where an internal fault is reasonably unlikely. Then we will accept that it takes longer time before the rotating magnetic flux can be stopped.”

So, PM shaft generators need care, but they’re an important part of offering. It’s worthwhile noting that when pressed, the KSOE and HHI teams told MS that a “permanent magnet machine version of the EMG” is under development. Given this, factory pre-integration with the engine stands to make a significant difference. Handling these large magnets is “not easy”, explains Hartmann; that may be an understatement: Kranz is only partly joking when he adds the unwary “might never see their toolbox again”.

8 Permanent magnets yield a significantly more compact and more reliable generator but there are particular challenges to overcome as the magnetic field doesn’t disappear when the power is pulled

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SHAFT POWER

VERY COOL: SUPERCONDUCTORS MADE SIMPLE Superconductors haven’t often been mentioned in relation to shipping. However, not only could the technology cut the space requirement for both onboard grid and motors, some alternative-fuel vessels might even give it a leg up, writes Stevie Knight To use HTS “you need to get below a temperature of around 90K (-193°C)”, says Manuel La Rosa of Neutron Star Systems, but at that transition point, “a whole lot of things get far easier, just because wires lose their resistance”. And achieving this is no longer far-fetched, even for commercial vessels.

Superconductors have certainly come a long way since HK Onnes discovered the effect by cooling mercury: the next big step forward was arguably the cuprate-based YBa2Cu3O7-d (YBCO) innovation of the 90s as this meant the required temperature could be reached by, for example, liquid nitrogen cooling, giving rise to the slightly misleadingly named ‘high-temperature superconductors’ (HTS).

Now, the technology has “reached the second generation” explains Dr Markus Bauer of THEVA, a company specialising in thin, flexible tapes. While earlier wires centred on drawing and annealing a silver cylinder filled with HTS material, these later developments coat either a nickel-based or stainless steel foil with a nonreactive buffer. On top comes a micronthick superconductor layer. Cabling solutions shape it into a standard spiral form and enclose it in cooling jacket, both electrical and thermal insulation, finishing it with a metal sheath.

The whole thing is surprisingly compact, coming - on average - to between 40mm and 60mm in diameter for a typical 5MW DC line. By contrast, standard copper wiring for the same power can be five times the girth says La Rosa.

Even an off-the-shelf cryocooler such as the one from Stirling isn’t that cumbersome, taking up just a few cubic metres at one end of the link.

But the reason for entertaining the idea is simple: the losses are very, very low.

In fact, according to research by Nexans, a typical 5MW (5kA,1kV) shipboard system loses just 0.56% at 20 Kelvin and that reduces even further for lower temperatures. Put that against a medium voltage 250V DC copper wire distribution: operating with DC transformers and the system accumulates a total loss of around 5%. By comparison, the HTS is more efficient - and it works out “far less bulky overall” adds La Rosa.

A portion of these gains result from discarding the typical high-voltage grid used to mitigate the resistance across long, 30m to 300m runs. Replacing power cables with HTS between generator and bus-bar, or bus-bar and motor allows low or medium voltage operation, ditching the standard converters and transformers necessary to ramp it up and down.

According to the Nexans report, that means a 100m-long, 5MW superconducting power distribution system in operation for 300 days per year can save between 150 and 250MWh per year over a conventional DC installation.

There are few considerations - the length of the run has to be long enough to be worthwhile, probably over 30m, as the coolant retains its low temperature more effectively given greater mass. Another is that the ambient links need care if

16 | JANUARY 2021

the system is to retain efficiency. Further, it requires time and energy for cool down - “hours or possibly a day” says Bauer, though because of its light operational load, that might just mean the system is kept running during shorter port stays.

What makes this of particular interest to shipping is that there’s a neat tie-in with alternative power. There are already a handful of fuel cell vessels under build, including cargo carriers running LNG - and some designs are looking at incorporating liquefied hydrogen.

Further, cruise ships have a large, fairly continuous onboard power draw - often over 40MW. “A number of cruise operators are investigating the possibility of fitting fuel cells,”

8 High-temperature superconductor (HTS) tapes

8 Transition temperatures have changed over time, taking off in the 90s

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SHAFT POWER says La Rosa, but tight space and distribution over hundreds of metres can present a challenge, so it’s possible that HTS could provide a solution.

The most significant point is these fuels are themselves cryogenically stored. For LNG-propelled ships, the tank temperature is already more than halfway to the HTS operating temperature, so the liquefied gas can be used for precooling the nitrogen, allowing a smaller unit for the last step down. Further, with liquefied hydrogen “cooling comes for free as the H2 has to be warmed up anyway before use”, explains Bauer.

Most importantly, HTS tape or wire can also replace copper windings and permanent magnets, doubling the magnetic field’s power and allowing the development of more compact motors. However, while the current rises with decreasing temperatures, it also falls in relation to increases in the magnetic field, says La Rosa. In cables that field is low, therefore temperatures where nitrogen is liquid (65 to 77 Kelvin) are sufficient. Motors, with their magnetic fields, demand a lower temperature to achieve a reasonable current, so neon or helium gas will probably be necessary to bring the temperature down to 20 or 30 Kelvin.

But as Bauer underlines once reached, maintaining this temperature is much easier than might usually be expected.

As he explains, replacing a motor’s traditional copper with HTS means “there’s virtually no resistive heat during operation... so only very low cooling power is required”.

Moreover, overall performance is also considerably enhanced since a fall in resistance is accompanied by a drop in reactance, allowing for improved stability across transient conditions.

It has to be said, this is not exactly new technology. Nearly two decades ago, Kawasaki came up with a 1MW, HTS pod motor and followed this with a 3MW variable speed unit which returned tested efficiencies of 98%. Siemens has also demonstrated a 4MW motor, but AMSC and Northrop Grumman’s 36.5MW machine for the US Navy in 2016 has been a massive jump in scale. La Rosa points out that the total system came in less than half the size of the conventional version... and a third of the weight.

Despite warship utilisation, merchant marine take up “has been comparatively slow” says La Rosa, although there’s headway in renewable energy applications: THEVA recently helped apply a 3MW generator to a wind turbine.

But as La Rosa and Bauer both explain, the markets are changing. There’s the rise of cryogenic fuels, and HTS systems are themselves developing.

So far, most HTS motors are divided into a warm and a cold side. This usually positions the superconducting field windings on the rotor, while retaining conventional copper on the stator.

La Rosa explains that the reduced mass of the HTS element results in less time and energy for cool-down. A disadvantage is that it requires connecting components at very different temperatures. Bauer explains it needs a cryostat to keep the boxed in, turning rotor at the right temperature - slightly tricky, but do-able. It also requires vacuum and superinsulation between warm and cool sides, though La Rosa adds this configuration is still useful for larger applications.

While bringing both rotor and stator windings to cryo temperatures might create an even lighter machine, significant AC and cooling losses means “there is a long way to go till it makes economic sense”, says Bauer.

However, all these options still have a common element that limits the achievable flux explains Bauer. If the iron teeth supporting the winding reach magnetic saturation, it leads to

a rapid temperature rise and corresponding losses. As a result, while this more conventional stator still lends some efficiency improvements, the reduction in scale is limited to about half that of a conventional machine.

A further, completely new development sees the stator windings wrapped around a non-magnetic core such as aluminium or GRP. This promises further advantages. While it demands more HTS material - and makes both heat and torque transfer more complex as it means getting rid of a solid lump of metal - this design avoids the vibration and harmonic field distortions generated by the iron teeth. Most importantly, it could also increase flux density four or five times, reducing the motor’s scale for the same output.

There are challenges ahead: there’s still a lack of familiarity and there’s no ready-made modelling solution to show how they’d perform as part of an onboard power plant... as yet. But while the superconductor chemistry itself is still fairly expensive, “it’s coming down” says Bauer. Production volume is rising with demand from other more exotic sectors, including ‘small’ nuclear fusion reactors and the space industry “so for the same capacity the price will eventually be comparable to copper”, he predicts.

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8 Cable section for high-temperature superconductor (HTS) cables

8 Superconductor crystalline alloy of oxides of yttrium, barium and copper - YBCO

JANUARY 2021 | 17

OFFSHORE WIND

NEW POWER GENERATION: NEXT-GEN WTIV SOLUTIONS Closed bus solutions and ring connections are among the power solutions being introduced aboard the latest generation of wind turbine installation vessels, Stevie Knight hears

8 Shimizu’s supersized jackup can carry and install three, 12MW turbines - or seven 8MW units - in a single voyage

Turbine sizes have already reached the 14MW mark, their growth triggering a blossoming of super-sized installation vessel designs with kit to match, capable of taking all the components to site and installing them from foundations to blades.

But taking OIM’s BT-220IU and Knud E Hansen’s Atlas C jackup with their respective 2,600t and 3,000t capacity cranes as an example, what are the implications for onboard power?

“The cranes are getting taller, the sizes larger,” says John Lindtjorn of ABB, pointing to Shimizu’s latest 142m, 28,000gt jack-up. This can carry and complete the installation of three 12 MW wind turbines in five days using a 2,500t capacity crane with a lifting height of 158m. The WITV’s legs will also extend far enough to enable operations in 65m deep waters.

To do all this, it relies on six gensets, four 4.63MW engines, with a pair giving 1.425MW: these power three, 3.8MW main propulsion drives, a couple of 3.2MW tunnel thrusters and a single retractable unit of the same output.

Despite the scaling up, “it’s all well within what’s possible”, Lindtjorn adds, but when you add costs and environmental concerns to the mix, things become a little more complicated.

“Typically, ships divide up the power plant so that a failure will be limited to one bus section,” he comments: “That makes fault handling fairly simple - every block takes care of itself.”

But, he points out, “this has an impact on efficiency, you tend toward low partial loading on each engine, more black smoke and soot, higher running hours and shorter

18 | JANUARY 2021

maintenance intervals”. Plus there’s no load sharing, so each section has to be sized for the potential peaks. All this impacts cost and environmental performance.

Alternatively, “you could have a closed bus, or further, a ring connection”, a strategy chosen by a number of these new generation WITVs, including the Shimizu jackup. This results in higher efficiency, a lower carbon footprint - and potentially smaller engines. With ships of this scale, that can make a big difference. Further, it yields flexibility “as you can configure your power in whatever way you want, to suit a given operation”, says Lindtjorn.

A similar argument has also driven the power configuration onboard Jan De Nul’s new 236.8m Les Alizés. The ship has a deadweight of 61,000t and can load foundations weighing up to 5,000t.

But it is very different from more traditional jackup designs because installation takes place while floating. Therefore, apart from the four, 3MW Schottel azimuthing thrusters at the stern - giving a maximum speed of 13kn - there are a sizeable pair of 3.25MW retractable units plus two 2.6MW bow thrusters offering DP support.

“A floating installation vessel utilising DP mode means that you don’t have to consider payload limitations due to the jacking operation... so you can carry more cargo, further out to site,” says Gunter Servaes of Jan De Nul - so it saves jacking and sailing time. However, he adds “on a DP vessel like Les Alizés; everything needs to work together continuously, so the harsher the conditions, the more power you need to minimise movement”.

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OFFSHORE WIND Feeding them are six main generators: these are MAN ES 12V32/44CR four-strokes, (supplied with particulate filters and SCRs), together yielding an impressive 43.2MW. Once again, a closed bus is central to “smart operation” says Servaes, allowing overall load balancing and helping the engines to operate within the optimal efficiency range.

However, as Lindtjorn explains, the flip side of closed bus systems is the entire configuration needs to be thought through. Firstly, to make sure the generators balance each other effectively and secondly, to stop problems cascading from one area to another.

A fault here is not just about reduced available power: “It can lead to dramatic changes capable of overloading the sources that are left, which can lead to a complete blackout,” he says.

Further, he adds, “as these big engines can be slow on larger load steps, you have to be lightning-fast to limit the impact and avoid a subsequent event”.

Problematically, it’s just not that easy to determine where the issue lies. “In a closed ring system, a fault might pull the power in all kinds of directions; it’s not sufficient to use current magnitude as a trigger to tripping the section,” says Lindtjorn.

Therefore ABB’s block based protection also notes the direction of the current, and from that, deduces which area has the issue. “The governing logic has to be extremely robust and the whole thing has to happen in milliseconds,” he adds.

However, it is an investment that pays for itself: “Robust protection means at worst you only lose one small part of the system, and for the same reason you can lower the dimension of the energy sources and propulsion.”

BATTERIES More can be gained from hybridisation - and this is the way most of these WTIVs are heading: “Rarely do we see people asking for a newbuild without energy storage now,” says Lindtjorn.

Again it comes down to costs. “If it’s a critical operation like DP, you either need to make more engine power available to cover the potential demand arising from a power failure... or you can put in a battery,” he says. Further, he adds: “Batteries don’t mind ramping up in an instant.”

“It also helps green the entire operational range, OIM’s BT220IU installation design, now under build for OIM Wind, will be using a 980kWh battery pack for peak shaving as well as spinning reserve. It allows “better use of the power plant and lower fuel consumption during lifting and lowering, sailing and in-field transit, as well as manoeuvring”, says Oddgeir Indrestrand, President of OIM Wind. He adds that elements such as permanent magnet thrusters – which have fewer moving parts – also assist efficiency.

For Les Alizés, a substantial energy storage element is central to the power configuration. The electric, 5,000t heave-compensated crane especially “makes for very steep power swings in the order of some megawatts per second”, says Servaes: batteries provide the necessary buffer.

But having the onboard ESS allows energy recovery during lowering. Instead of being burned off as heat, a large proportion of the potential energy is fed back into the bank.

Given both these things, battery scaling was “a challenge”, he admits: too fast, or too deep a discharge or charge stands to shorten cell lifetime “so we had to play with size and optimal levels”, explains Servaes.

FUTURE “The WITVs being designed right now are significantly more ambitious than even just a couple of years ago,” says Lindtjorn. And that applies to the fuel.

Partly driven by the green profile of the wind industry, they’ve also started to embrace fuel cells and hydrogen: admittedly “it’s quite early days for the technology, but our customers say they want to be ready for it”.

It is undoubtedly in OIM’s sights. It’s using Rolls-Royce Bergen B36:45 lean-burn gas engines to reduce emissions on the BT-220IU, says Indrestrand, but most importantly, “these are easily converted to ammonia or hydrogen... or new fuel mixtures as they become available”.

While the configuration will remain similar, integrating fuel cells - and probably larger batteries - on a DC power grid makes sense, says Lindtjorn. Not only is it possible to drop some of the filters and transformers, the footprint is significantly lower, plus, he adds, the engines can operate at variable speeds, cutting fuel and emissions.

Moreover, Lindtjorn notes: “If you have a DC backbone, you can more easily integrate jacking systems... the solution can be quite elegant with a bidirectional power flow and so on.”

So, what about truly huge lifts? With its 30,000t capability, the offshore decom vessel Moonraker stands to dwarf tower requirements “It’s suitable for float-over substation installation in even the largest wind fields, and with minor alterations it can be adapted for turbines,” says designer Morgan Howes-Roberts.

Onboard are eight, dual-fuel gensets, providing a hefty 71MW in total. While the vessel is a semisubmersible requiring ballast pumps, lifting rams and so on, the greater portion of the power can be directed to eight, 4.5MW azimuthing thrusters: “the priority remains the positioning”, Howes-Roberts underlines.

However, there are pragmatic challenges that come with scale. Moonraker - like others incorporating flexibility and reduced fuel consumption - has a closed-bus configuration and would normally be operated in this mode. But closedbus test criteria involve triggering a real, high-level shortcircuit explains Howes-Roberts: therefore, the system has to be designed not just for safety but for full functionality after the ordeal, adding costs commensurate with size.

Further, he adds, it also “introduces a certain nervousness... and very big bangs”.

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8 BT-220IU: It’s “the world’s greenest” installation vessel, future-proofed for running alternative fuels, says OIM

JANUARY 2021 | 19

OFFSHORE WIND

AMBITIOUS GROWTH PLANS PUT PRESSURE ON FLEET CAPACITY The EU plans to increase the region’s offshore wind capacity five-fold, from 12GW to “at least 60GW”, while the UK plans to quadruple its own offshore wind capacity over the same period.

On top of that, the EU hopes to complement that with a further 40GW of ocean energy - including floating wind turbines - by 2050, which is when the EU plans to reach its goal of climate neutrality.

These bold plans form part of an EU Strategy on offshore renewable energy that it predicts will cost nearly €800 billion, although it was not clear how much of this will come from public funds. But Europe’s commissioner for energy, Kadri Simson, has no doubts about the strategy’s importance: he was quoted in the statement as saying that Europe must harness “all the potential of offshore wind and ... other technologies such as wave, tidal and floating solar.”

And although the timetable can be counted in decades, EU member states have only weeks to get started, the statement made clear. Offshore renewable energy development objectives must be integrated into their National Maritime Spatial Plans, which coastal states are due to submit to the Commission by March 2021.

Meanwhile, Europe’s largest offshore wind energy nation, the UK plans to lift offshore wind production capacity from about 10.5GW to 40GW over the same period. This increase in capacity falls outside EU targets following the UK’s departure from the EU. To hit the EU’s 2030 target will require an average of nearly 5.5GW of additional generator capacity in each of the next nine years, which compares with 2019’s figure of 3.6GW, which WindEurope reported was a record. It says that Europe “is the leader in offshore wind” and welcomed the EU’s new strategy, saying that it will “shape the development of offshore wind in Europe for the next 30 years” and support “further expansion of floating offshore wind ... for the deeper waters in the Atlantic, Mediterranean and Black Sea.” It is against this background that the offshore wind support sector must gear up to construct and service more and bigger offshore and floating wind turbines. A WindEurope spokesman commented to The Motorship that, at the moment, there are enough vessels - in fact, over capacity - to service ongoing installations and operations. But looking ahead, “at least 10 new vessels will be required, each capable of annually installing up to 100 turbines or their foundations.”

At present, the largest wind turbine is said to be the 14MW Siemens Gamesa SG 14-222 DD, which was launched in May 2020 and a prototype is expected in 2021. It will become commercially available in 2024 but it has already amassed a number of orders, including one placed in June for 100 units.

Yet there is expected to be a global shortage of installation vessels able to erect large turbines in the quantities that will be needed. A study published in late November by the Norwegian consultant Rystad Energy predicts that “as turbine and project sizes grow, demand for specialised installation vessels will soar.”

20 | JANUARY 2021

Image: Siemens Gamesa

The planned rapid expansion in offshore wind capacity in Europe, as well as the demands from the next generations of turbines, is expected to lead to supply bottlenecks within five years

At present, there are “only four vessels capable of handling the next generation of turbines” out of a total fleet of 32 active turbine installation vessels and 14 dedicated foundation installation vessels, it says. Although more are on order, “the global fleet will be insufficient to meet demand after 2025,” it warns.

Rystad Energy’s vice president and product manager for offshore wind, Alexander Dobrowen Fløtre, told The Motorship that the vessel market is in a ‘chicken and egg situation’: “A big portion of the longer-term demand is still only in the concept stages, which may not be enough certainty for players wanting to invest in newbuilds.” Yet “the contracting models applied in offshore wind are typically of a shorter-term nature [than] oil and gas, which may also affect investors’ decisions.”

The consultant’s findings confirmed views expressed in May this year by Mary Thorogood, senior strategy specialist at the turbine maker MHI Vestas Offshore Wind. As a panellist for a webinar hosted by the organisers of the All-Energy exhibition and conference, she said that turbines are being made bigger “because our customers asked us to” even though there is “a global shortage of vessels to deliver the projects.”

Also taking part in that event was Benj Sykes who, among other roles, is industry chair of the UK’s Offshore Wind Industry Council. He spoke of “a tight squeeze in the vessel supply chain” and said that “no-one can be absolutely sure where supply and demand will balance... [but] we are going to need more vessels.”

At the International Marine Contractors Association (IMCA), its marine technical adviser, Andy Goldsmith, took a more nuanced view: the shortage is of “specifically designed vessels for particular tasks,” he told The Motorship.

8 The 14MW Siemens Gamesa SG 14-222 DD will be the most powerful offshore wind turbine

For the latest news and analysis go to www.motorship.com/news101

OFFSHORE WIND

OFFSHORE WIND VESSELS: THE DESIGN BASICS Its general manager Maarten Veldhuizen set out some of the key considerations for these specialized craft.

He is also project manager for C-Job’s involvement in the 5,000 tonne-lift crane vessel Orion which will go into service with Belgium’s Dredging International (DEME) following repairs to damage caused when its crane collapsed on 2 May 2020 during trials at crane-supplier Liebherr’s facilities in the port of Rostock in Poland. The COSCO-built ship is one of the highest lift-capacity purpose-built offshore wind construction vessels and its crane is the first HLC295000 model that Liebherr has supplied.

Liebherr quickly blamed the failure on the hook, supplied

by Ropeblock, which broke when the test load reached 2,600 tonnes. Ropeblock itself issued a statement at the time acknowledging that it had designed the hook but said that it had subcontracted its manufacture. “We are appalled at the impact that this incident has on our customer Liebherr, but certainly also on the industry as a whole,” it added. No updates have been issued since then.

C-Job was not responsible for the crane design and is not involved in the investigation or repair work following the accident, but the incident illustrates an important design parameter for the vessels: they must be able to survive a ‘loss of load event’.

This needs to be considered carefully, Mr Veldhuizen explained, because if the load is suddenly lost, the vessel will roll to the other side. That is what happened in the Orion incident and videos available online seem to suggest that the momentum from this roll caused the crane to fold over backwards.

Bearing in mind that this could happen at maximum load, maximum outreach and in the open sea, the ship must be designed with enough ‘uprighting energy’ to prevent it from capsizing and although Orion’s incident happened at partload, with the crane nearly vertical and alongside, Mr Veldhuizen said that the ship “did what it needs to do” during the incident.

Two other design features that are uniquely combined in wind turbine installation vessels are size and speed. Unlike installation vessels for oil and g gas p projects, j those that support pp wind farm construction must st also transport the jackets and other large components, which ch requires them to have a large empty deck space, he said.

They also need to be fast, st, which means high installed power, which is also essential ial for dynamic positioning (DP) when the vessel’s crane is in use, putting these vessels alongside large crane vessels sels and drillships in terms of power requirements, he said..

For a vessel such as Orion, n, “you need to make sure that if anything fails you still can operate the ship”, although that may be at a lower capacity.. The crane might operate at a lower speed and the DP system might have a lower performance, but they must both still function. ld be rated at DP 2 or higher, Mr For the DP system, it should efined in IMO circular MSC/Circ.

Veldhuizen said, which is defined

Image: Liebherr

Rotterdam-based naval architect C-Job is involved in a number of design projects for offshore wind construction vessels

645 as requiring that “no single fault in an active system will cause the system to fail.”

With both DP and crane operations demanding power at the same time, a vessel’s machinery installation and control systems must be able to cope with fluctuating power demands, which is more difficult with larger engines, he said; Orion’s engines, for example, are rated at 44MW. In a statement to The Motorship, Wärtsilä - which supplied Orion’s engines - said that its integrated machinery set-up for that project consists of genset and propulsion configurations together with automated electrical, energy storage and DP systems to meet those fluctuating load demands “in every operation mode of the vessel.” Energy and power management systems give the engines have a good load pick-up capability, the company said.

Uniquely for an offshore service vessel, Orion’s power comes from dual-fuelled LNG engines, but Mr Veldhuizen does not expect this to set a trend for future vessels. That will depend to a great extent on fuel infrastructure; in some regions, LNG may not be as readily available as it is in Europe, he said. The ship p also features exhaust waste heat recovery y equipment to improve its efficiency and reduce fuel consumption, although Mr Veldhuizen declined to say by how much.

For the latest news and analysis go to www.motorship.com/news101

8 Deme’s 5,000 tonne-lift vessel, before the crane’s hook failed under test

8 Offshore wind construction vessels must survive a ‘loss of load event’, says Maarten Veldhuizen

JANUARY 2021 | 21

OFFSHORE WIND

FLOATING TURBINES: THE NEXT WAVE FOR OFFSHORE WIND

Image: X1 Wind

Floating offshore wind “offers the ability for large capacity expansion near to demand centres,” believes Mark Spring, Lloyd’s Register’s ‘voice on offshore wind’

He made his remark in an article on the class society’s website about a UK target of 40GW of offshore wind by 2030, which he described as “not realistic” under current UK policies and argued that it could only be met if it was supported by floating wind turbines, enabling development of deeper waters to the west of the country. The title of his article underlines his point: it is called ‘Floating offshore wind - a national prize or a lost opportunity?’

Another class society, DNV GL, recently made a similar point about the global situation. During a webinar in early December, DNV GL’s floating wind advisor Magnus Ebbesen presented a slide stating that “floating wind works as a boost for offshore wind” and predicted that, by 2050, floating offshore wind projects will account for 255GW of installed capacity worldwide, “more than 20% of the offshore wind market.”

Just a week later, the global nature of floating wind projects was reinforced by an announcement by Korea Hydro & Nuclear Power (KHNP) that it had agreed a memorandum of understanding that it said will lead to the world’s largest floating offshore wind power generation complex.

The MoU was signed on 15 December with OW Offshore of Spain and Kumyang, a Korean renewable energy company, for a scheme involving three 500MW wind farms located 72km off south east South Korea.

Mr Spring drew The Motorship’s attention to another floating wind energy project, X1 Wind, which is being developed in Spain. A scale model is under construction for

22 | JANUARY 2021

8 An artist’s impression of X1 Wind’s innovative floating turbine and PivotBuoy support

testing off Gran Canaria using a Vestas V29 225kW turbine that has been modified so that it operates facing away from the direction of the wind.

Although this unusual arrangement is generally avoided because of the ‘tower shadow effect’ on the wind flow, it is being trialled as a solution to the challenge faced by large turbines that their long blades risk hitting the tower as the bend in the wind. Strategies to avoid this lead to inefficiencies, the X1 Wind project’s website notes.

Testing will also validate the projects’ PivotBuoy singlepoint mooring system, which is expected to provide “costeffective and reliable floating wind mooring, connection, installation and operation” for the turbine.

Another important objective for the project is that construction and commissioning will be possible without needing a heavy-lift crane barge, with all subsequent maintenance carried out at sea level.

‘‘

Testing will also validate the projects’ PivotBuoy singlepoint mooring system, which is expected to provide “cost-effective and reliable floating wind mooring, connection, installation and operation” for the turbine For the latest news and analysis go to www.motorship.com/news101

OFFSHORE WIND

JONES ACT SPURS US VESSEL PROJECTS

Image: NETSCo

US waters are expected to see significant development in offshore wind installations in the years ahead, but the nation’s Jones Act restricts the choice of vessels that can be used to build them

It requires goods shipped between US ports to be transported on ships that are built, owned and operated by US citizens so when the country’s first commercial offshore wind farm was built in 2015-16 off Block Island, the Maltese-flagged jackup Brave Tern was serviced by two US-flagged jack-ups L/B Caitlin and L/B Paul so that it did not have to enter a US port.

Last year, however, the US House of Representatives passed the Expanding Access to Sustainable Energy Act, which includes an amendment to enforce Jones Act requirements for all offshore renewable energy production, including installation vessels. And in December 2020, the US Senate passed the National Defense Authorization Act, which includes an amendment to ensure full enforcement of the Jones Act and other federal laws in offshore wind development.

Now, at least two projects are set to meet these requirements. On 16 December, the keel was laid at Keppel AmFELS shipyard in Texas for a vessel on order for Dominion Energy. It confirmed in a statement that, “with several gigawatts of offshore wind capacity to be installed along the US east coast in the next decade, access to Jones Actcompliant offshore wind turbine installation vessels is of strategic importance.” The vessel is due to be in service by the end of 2023.

With a lifting capacity of 2,200 tonnes, the vessel’s crane supplied by Huisman - will have a 130m boom mounted on the 144m hull. The ship will be 47m wide, have a depth of 11.6m and include accommodation for 119 people. It will be

24 | JANUARY 2021

8 A concept illustration of the NETSCo Jones Act-compliant installation vessel

suitable both for laying foundations and installing turbines and has been designed to handle “next generation turbine sizes of 12MW or larger,” Dominion Energy said.

Coinciding with that announcement was another, from Northeast Technical Services Co (NETSCo), about a joint development project with Lloyd’s Register North America to design and develop a Jones Act-compliant wind turbine installation vessel (WTIV).

NETSCo will be responsible for the concept design of the WTIV while LR will check that the design complies with applicable rules and regulations. It will also evaluate the design against international codes and standards and the US Coast Guard’s Code of Federal Regulations.

From a practical point of view, a key design feature is that it will use hull shapes that are common in the US shipbuilding market, NETSCo’s statement said to ensure it could be built in US shipyards. It will also be focused on meeting the requirements of current developments along the US east coast and Great Lakes, in terms of its crane capacity, deck space and water depth.

“The offshore wind industry is expected to see exponential growth in the United States,” said Rafael Riva, LR’s Americas marine and offshore commercial manager, said, so “there will be a pressing requirement for such vessels.”

Jan Flores, NETSCo’s vice president, agreed, adding that this presents “a perfect opportunity for us to .... support the offshore wind turbine market.”

For the latest news and analysis go to www.motorship.com/news101

OFFSHORE WIND

IMCA TACKLES ‘RIDICULOUS’ TRAINING OBSTACLE Vessel operators in the offshore wind sector have faced a “ridiculous situation” over qualifications specified for their vessel crews, according to Andy Goldsmith, marine technical adviser for the International Marine Contractors Association (IMCA).

Speaking to The Motorship, he said that many vessel service contracts - for both construction and service craft - require all crewmembers to meet training standards set by the Global Wind Organisation (GWO), even though many of them - such as the cook or the ROV operator, he suggested - will not be doing work connected with the wind turbine itself.

GWO is a non-profit organisation of wind turbine owners and manufacturers and its website confirms that its basic safety training (BST) standard “is a requirement made by wind energy employers as a pre-requisite for their own staff and contractors before they are allowed on site.”

This adds extra cost and delay, Mr Goldsmith said, although he is hopeful that guidelines IMCA published in October will ease the situation. These include a ‘Basic Safety Training Matrix’ that defines the minimum level of health and safety training, and medical fitness needed to work on, and from, vessels engaged on an offshore renewable energy project.

In a statement at the time, Mr Goldsmith said that “basic safety training requirements cannot be generalised and are different for [onshore and offshore] personnel.”

He is also concerned about the different renewal cycles of GWO qualifications and traditional seafarer certificates. GWO states that its BST certificate “lasts 24 months, before the training must be refreshed,” while certificates issued under STCW typically run for five years, “so you could never get any equivalence,” Mr Goldsmith said.

He believes, however, that the approach taken in the new guidelines of defining what is required for each role has allowed discussions about equivalence to be set aside.

8 Irrelevant training adds cost and delay, says Andy Goldsmith

Developing these guidelines has been “a long struggle”, he told The Motorship, and IMCA is now pushing for them to be included in tender documents. GWO has accepted them, he added, and he is confident that they will be widely recognised, although they will only benefit future contracts.

Nor-Shipping 2021 delayed until January The 2020 Nor-Shipping exhibition and conference is to be postponed from June 2021 until 10-13 January 2022. Rather than potentially holding a scaled down, socially distanced exhibition, Nor-Shipping has opted to delay the event to ensure global decision makers have the opportunity to meet face-to-face.

The decision to delay the event has been taken reluctantly, in response to concerns that the the planned 2021 programme could not reproduce the impact, experience and value of Nor-Shipping 2019, stated NorShipping Directors Karen Algaard and Per Martin Tanggaard.

“Health and safety comes first,” stresses Algaard. “We are committed to following stringent standards with regards to minimising the risk of infection, and, at

present, that means fewer people, less interaction and more distance between exhibitors and participants. We believe that isn’t in keeping with the essence of NorShipping. However, by delaying the programme a little we can offer everything we have become known for, and more, with a uniquely Norwegian flavour in January 2022.

It gives us and, we hope, the entire industry something very special to look forward to.”

INDUSTRY SUPPORT The decision has been taken in consultation with all Nor-Shipping partners and a number of exhibitors, who overwhelmingly supported a move to enable greater contact and connection. Of those approached, over 90% of exhibitors were in favour of the rescheduling, with many stating that any

For the latest news and analysis go to www.motorship.com/news101

participation in a summer 2021 event could have been challenging. 100% of partners backed the decision. It was further noted that the opportunity to provide a “once in a lifetime” Norwegian winter experience could be a significant draw for participants, as well as an opportunity to tailor memorable exhibition stands and activities.

The Norwegian Institute of Public Health has stated an expectation that social distancing measures will be in place until either the end of summer or autumn 2021. As such, Algaard says a postponement is the sensible move - for both the event and the industry it showcases and supports.

Nor-Shipping is currently working on a selection of digital initiatives to take place during 2021. Further details of these, and the 2022 event, will be released in the near future.

JANUARY 2021 | 25

DESIGN FOR PERFORMANCE

EXERGY STUDY ASSESSES LNG ENGINE PERFORMANCE An exergy study undertaken on a dual-fuel 4-stroke engine demonstrated significant combustion and turbocharger losses as well as an opportunity to recover about 9% of the waste heat from the charge coolers when the engine was operated at full load Exergy, also known as available energy, is a concept arising from Second Law of Thermodynamics which quantifies the maximum amount of work obtainable from a given system.

PhD student Beichuan Hong and his supervisors Professor Anders Christiansen Erlandsson and Dr Andreas Cronhjort from the KTH Royal Institute of Technology in Sweden set out to take a more practical approach to understanding the theoretical concept of exergy on engine component design than has been achieved in the past.

“Many previous studies have discussed engine performance from the exergy perspective,” said Hong.

“However, since exergy is an advanced concept from thermodynamics, it usually explains the engine procedures in theoretical terms as irreversibility or entropy generation.

This approach is not always easy to grasp. Therefore, people usually apply it at the macroscopic level without linking it to specific engineering problems.

“Although marine engines are quite energy efficient, it is important to look at the theoretical efficiency limit, and, as a system, the parts which hinder us from reaching that limit in practice. By taking a comprehensive view of the engine, we attempted to give some answers,” said Hong.

Their study examined the exergy losses inside the engine components of a 10-cylinder, V-bank Wärtsilä 31DF engine with a two-stage, serial turbocharger. The high and low pressure turbochargers were sequentially arranged with charge cooling after each compression stage, and the system used an air bypass valve and exhaust waste gate valves to improve the charging efficiency and for component protection.

The engine was operated at 25%, 50%, 75% and 100% load at a working speed of 750rpm. The exergy losses were characterized as: combustion-related, heat dissipation or gas exchange losses. A 1D simulation model of the engine was developed and validated on the commercial platform, GTSuite. Dynamic sub-models were separately calibrated, including, for example, gas flow property across the inlet valve, heat transfer in the cylinders and pipes and mechanical friction at the crankshaft.

“Instead of focusing on a particular engine component, we reviewed the engine performance at the systematic level and analysed the inefficiencies as well as the reasons why these losses occur,” said Hong. “In short, this project tried to demonstrate how far we are from the ‘ideal’ engine and where the potential for further improvement is.”

The researchers found that combustion exergy destruction dominated for the engine, contributing more than half of the total exergy destruction. The flow exergy destroyed in gas exchange, as the second highest contributor, was slightly higher than the rest of the exergy destruction types, and it increased at high load. Heat dissipation maintained the same level of loss by engine mechanical friction and was less sensitive to fuel mode and operating loads.

26 | JANUARY 2021

FUEL EXERGY The engine was evaluated in dual-fuel mode with compressed natural gas (CNG) (using a premixed charge ignited by pilot diesel) and in conventional diesel mode.

“Such an engine configuration enabled us to compare the difference between the two combustion modes,” said Hong.

Based on a calibrated 1D simulation, the researchers found that combustion irreversibility was the largest source of engine exergy losses amounting to at least 25% of fuel exergy. The exergy destruction was characterised as resulting from chemical reactions, heat conduction and mass transfer of the non-equilibrium combustion gases, with the chemical reactions always making up the largest proportion of the exergy destruction.

“According to our analysis, dual-fuel mode had a higher efficiency than diesel mode. For example, at the full-load operating point with the same brake mean effective pressure (BMEP), the energy efficiency at dual-fuel mode was 48.6% while diesel mode it was 47%. One reason for this is that the CNG fuel has a higher energy density (i.e. lower heating value) than most common fossil fuels. Also, the combustion of CNG premixed charge is easier to concentrate at top dead centre.

This makes the combustion process faster and more homogeneous in gas mode, leading to less entropy generation.”

The fuel exergy losses cause a reduction in indicated

8 The exergy study examined the exergy losses inside the engine components of a 10-cylinder, V-bank Wärtsilä 31DF engine with a two-stage, serial turbocharger

For the latest news and analysis go to www.motorship.com/news101

DESIGN FOR PERFORMANCE mean effective pressure (IMEP) and exhaust energy which further limits the amount of flow energy used to drive the turbines or other waste energy recovery systems. To have a loss of over 25% of fuel exergy indicates it is still very promising to optimize in-cylinder processes for faster combustion, lower heat loss and better work extraction even though the engine is already energy efficient, says Hong.

WASTE HEAT There were two categories of waste heat considered: the flow energy contained by the exhaust after passing through the turbines and after-treatment and the energy carried by the coolers. For these, the total waste heat accounted for more than 30% of the fuel energy. However, the exergy analysis indicated that the energy quality of these waste heat sources was not high, said Hong.

“Theoretically, for the tested marine engine system, converting waste heat to mechanical work may recover a maximum of 9% of the fuel energy (e.g. 492kW in diesel mode for 5500kW engine output power). An alternative solution for this situation is that it could be directly used as a heating system. In the case of a co-generation system the efficiency of energy recovery could be much higher.”

GAS EXCHANGE LOSSES Exergy destruction in the gas exchange system was caused by flow losses resulting from piping restrictions caused by valve throttling, by fluid friction in the pipes and by the flow energy recovery of the turbochargers. Most of the exergy destruction occurred in the turbocharging system where the high-pressure turbocharger contributed around 40% of the total flow exergy destruction. Unlike the flow losses in the piping system, the flow exergy in the turbocharger was not entirely wasted, because it contributed to the work extracted by the turbine and the air boosting by the compressor.

“While intake and exhaust valves accounted for almost 20% of the flow exergy destruction, 70%-80% of the flow exergy destruction in the gas paths occurred at the turbocharging system. For each charging stage, the compressor always caused more exergy destruction than the turbine side. However, the flow losses by the valves also rose with load due to the increasing mass flow,” said Hong.

Unlike the flow losses in the engine piping system that are simply wasted, the work extraction by the turbine and the air boosting by the compressor also caused exergy destruction.

“Our exergy analysis shows that the current two-stage turbocharging system in the tested marine engine has a pretty high efficiency for extracting the flow exergy. However, the turbines also destroy 15% of flow exergy whilst recovering the rest and sending to the compressor. Perhaps, exergyrelated R&D goals like reducing entropy generation could be a consideration in further research on the turbomachinery side,” said Hong.

“Of particular interest to us is the quantification of available energy inside the exhaust flow. The flow exergy is equivalent to 65% of the crank shaft output power. Hence the management of exhaust energy recovery indeed plays an important role in improving marine engine efficiency. When we compared the marine engine results to a truck engine pre-study, we found that 20% of flow exergy destruction occurs at intake and exhaust valves, while for truck engines, it was around 7%. This was rather unexpected and implies the sensitivity of the valve motions. Also, further analysis is needed to investigate the effects of Miller timing strategy on flow exergy utilization.”

Therefore, the next step of Hong’s research plan focuses on the flow exergy in the exhaust system. “The aim of this

8 One insight from the simulation-based study was that the marine engine produced a higher proportion of flow exergy destruction at the intake and exhaust valves compared with a truck engine study

project is to understand how to reduce flow losses and optimize the usage of flow exergy. One part of our project is to integrate Computational Fluid Dynamics simulations with measurement data for modifying the potential design flaws, especially for the configuration of the exhaust system such as the pipe geometry and valve profiles. This study will also enhance our understanding of engine exhaust exergy, especially how it relates to the performance of the turbine or other waste heat recovery systems.”

FAST FLOW SENSORS Apart from its engineering application, one of Hong and his supervisors’ ongoing studies involves characterising exhaust energy pulses using fast measurement techniques. “One big challenge for fast flow exergy measurement comes from the development of fast flow sensors. The flow sensors are expected to survive in the marine engine exhaust and keep their high sampling accuracy. For fast pressure sensors, there are many commercial ones that can be used. However, for fast temperature and flow velocity measurement, we need to design and fabricate one ourselves. Luckily, our colleagues from KTH Fluid Physics Laboratory are collaborating with us to develop high-accuracy engine pulse-orientated sensors,” said Hong.

Engine simulation approach Wärtsilä supported the study with both data and supervision, and the company states: “The study presents its results and findings based on simulation model provided by Wärtsilä and not on real engine measurements. This means that the accuracy of result is dependent on calibration input of the simulation models operating conditions.. In real testing and measurements, the result is varying contingent on operating and ambient conditions. tions. As such, the final result is dependent on accuracy acy level of the model where absolute values are not ot the most relevant findings but rather the behaviour iour and principle of energy and exergy losses that occur in medium-speed engines. The study is part of the continuous development process cess within Wärtsilä and provides valuable input to further rther improve the efficiency of our engines and continue to have the dium speed.” highest efficiency among medium

For the latest news and analysis go to www.motorship.com/news101

8 PhD candidate Beichuan Hong was supervised

by Prof Anders Erlandsson and Dr Andreas Cronhjort (pictured) from the Royal Institute of Technology (KTH) in Sweden

JANUARY 2021 | 27

SHIP DESCRIPTIONS

CRANE SHIP FOR BIGGEST WINDFARM LIFTS Growing investment in vessels that can meet accelerated and ever-more exacting demand from the offshore renewables market figures prominently in the multifaceted fleet development and renewal strategy of the Luxembourg-headquartered Jan De Nul construction and dredging group.

A highlight of the programme is a 237m newbuild incorporating a 5,000t lift-capacity crane, and engineered to Ultra Low Emission vessel (ULEv) standard, on which steel cutting commenced during early December. Designed to effect installation work afloat rather than in jack-up mode, the ship is due to enter service in 2022 under the name Les Alizés (Trade Winds).

The project denotes further penetration of the high valueadded shipbuilding sector by China, with the contract having been assigned to China Merchants Heavy Industry’s Haimen shipyard, Nantong City.

The rationale for the considerable handling capacity embodied by Les Alizés is the global trend in the offshore wind energy sector towards ever-larger wind turbines. These can stand at heights of more than 270m, carrying blades as much as 120m in length, and mounted on foundations weighing up to 2,500t.

With a cargo deck area of 9,300m2, the newbuild will be able to load out, transport and install multiple units of the heaviest components in one trip, yielding direct benefits in planning, project execution and fuel consumption. As an alternative to a jack-up vessel, the DP2-fitted crane ship will effect installation afloat, extending the operating scope to deeper waters and more challenging seabed conditions.

Besides the capability to build the next generation of wind farms, the ship has the wherewithal and layout to undertake the decommissioning of offshore oil and gas platforms.

Design, engineering and manufacture of the ship’s 5,000t capacity tub-mounted crane (TMC) is the responsibility of Dutch specialist Huisman, which has assigned construction to its Xiamen facility in China. The company said the unit is the largest of its type and application ordered to date for installation on a monohull vessel.

The TMC is designed to allow continuity of operations with both main and auxiliary hoist in extreme weather, and will incorporate Huisman’s dual main hoist system for upending large structures. It will also feature a segmented slew bearing, an electric drive system, and an automation package that will allow for future crane upgrading.

Ingeteam has been appointed as the electrical system supplier and integrator, covering power generation and distribution, propulsion motors, and power management system, plus the alarm monitoring and control arrangements.

Primary products from the Indar range will be manufactured at the company’s premises in the Basque region of northern Spain.

The six Indar main generators of 8,640kVA, supplying AC current at 11,000V, have been specified with 12-cylinder MAN medium-speed, common-rail engines of the V32/44CR type,

28 | JANUARY 2021

Credit: Jan De Nul

Heavy-duty capability and sustainability find new levels in the monohull offshore construction ship ordered from a Chinese yard by Jan De Nul, writes David Tinsley

each rated at 7,200kW, giving a primary power concentration of 43,200kW. The Indar 315V AC motors for the multiple, main azimuthing propulsors and manoeuvring thrusters will all be driven by Ingedrive MV100 DFE frequency converters.

Exhaust gas treatment technology employed on the ship has two elements, whereby a diesel particulate filter, claimed to offer a 99% effectiveness in removing nanoparticles, is followed by a tailored MAN selective catalytic reduction(SCR) system. This not only ensures Tier III NOx compliance but also meets the even stricter Euro Stage V limit. The enhanced NOx reduction rate is essential to achieve the Ultra Low Emission vessel (ULEv) categorisation sought by the owner.

Furthermore, the arrangements will satisfy Clean Ship ND07 and Green Passport EU certification criteria.

The common-rail system’s flexibility permits the engine to be programmed to run in accordance with different fuel consumption-versus-power characteristics, optimising efficiency at the respective load points. The optional ECOMAP feature that has been chosen applies various engine ‘maps’ to improve fuel economy while meeting IMO emission limits.

The main propulsors are four electrically-driven Schottel rudder propellers of the SRP 610FP type, each rated for an input power of 3,000kW. With this configuration, Les Alizes should be able to make transits at up to 13 knots. So as to ensure precise positioning in DP mode, two retractable SRP 610R units of 3,250kW apiece and two STT 7FP transverse thrusters of 2,600kW will be adopted. The Schottel package also includes the proprietary Leacon sealing system, designed to continuously check the seals for leaks and prevent water from entering the gearboxes.

Jan De Nul also has a jack-up offshore installation newbuild taking shape in China. Ordered from COSCO Shipping Heavy Industry, the Voltaire has been specified with a 3,000t crane and is seen as complementary to Les Alizés.

8 The 5,000t crane is the dominant feature of the Jan De Nul newbuild at Haimen, China

For the latest news and analysis go to www.motorship.com/news101

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SHIP DESCRIPTIONS

NEW TITAN FOR WINDFARM DEVELOPMENT Building on milestone references in wind turbine installation vessel (WTIV) design, Copenhagen-headquartered consultancy Knud E Hansen (KEH) has developed a new self-elevating class to meet evolving market demands in terms of pieceweight scale, transport capacity, construction productivity, and energy efficiency.

Although proposed with a nominal technical specification, the Atlas C generation is intended as a design platform that can be customised to meet clients’ precise objectives and requirements. This applies principally to the equipment and engineering arrangements. Furthermore, it is seen as the basis for a new portfolio of wind turbine installation vessels of varying sizes.

KEH reports that negotiations are ongoing with operators in the offshore wind sector involving the tailoring of the platform to individual needs.

With a jacking deadweight of 18,000t, a cargo deck area of 6,800m2, and a crane rated for 3,000t at 37m outreach, the WTIV will be capable of carrying and deploying six of the new-generation wind turbines in the 14-16MW power range, and five of the next-generation turbines of 20MW-plus. The deadweight and crane capacity will also enable the transportation and handling of at least four of the extra-large monopole/transition pieces required for turbines in the 1416MW category.

In keeping with the objective of design versatility, the cargo deck incorporates uniform girder spacing both longitudinally and transversely, such that foundations for turbine parts can be standardised and installed in many different locations and orientations.

A multi-generator layout is at the heart of the dieselelectric power and propulsion system, applying key precepts of operating flexibility and service dependability. Power can be efficiently and precisely matched to actual load requirements at any point across the operating profile, while ensuring the requisite power availability and redundancy for challenging offshore conditions and assignments. An energy storage system will confer increased efficiency and environmental benefits.

In its initial proposal, the Atlas C-class incorporates eight identical gensets, each producing 3,340kW of electrical power, divided between two independent engine rooms. A direct-current (DC) grid system, allowing the genset engines to be run at variable speed, would be coupled to a 4MW battery pack for load levelling and peak shaving. As the batteries can supply instant power, the need to have a ‘spinning reserve’ with generators in standby mode, such as during DP operations, is obviated. Furthermore, the adoption of a battery system provides for the recovery of up to 60% of the energy used in jacking the vessel.

The main propulsors are four azimuthing stern thrusters, fitted in nozzles to maximise thrust, and driven by permanentmagnet motors. To achieve the required manoeuvring and position-holding performance, the foreship will be equipped with two tunnel thrusters and two retractable bow thrusters.

30 | JANUARY 2021

Credit: Knud E Hansen

Versatility and customisation are pivotal to a new concept of offshore windfarm construction vessel from a leading Danish designer, writes David Tinsley

The hull elevates on four three-chorded trusswork legs, supporting the vessel, its payload and the installation process in water depths up to 80m. Raising and lowering is effected by a powerful, electrical rack-and-pinion jacking arrangement. The elevating system is designed for 5,000 load cycles, reckoned to be significantly more than many competing solutions and intended to ensure that the leg racks last the lifetime of the vessel.

The inverted cones, or spud cans, at the base of the legs have been developed to minimise seabed penetration, reduce the load on the seabed when the vessel is jacked-up, and help retract the legs where the bed is muddy. Moreover, the cans are fitted with buoyancy boxes to reduce the draught in port.

Such is the provision for tailoring of the Atlas C series that generators, engines, thrusters, cranes and jacking systems can all be modified and selected in strict accordance with clients’ needs and wishes and availability from manufacturers.

The three-deck main superstructure located forward houses the operations centre as well as the accommodation for crew and contractors in 130 cabins, surmounted by a fullwidth bridge, above which is arranged a heli-deck.

A smaller variant of the C-class series is under development as the Atlas A-class, envisaged with a 1,600t crane and capacity to transport four 14MW turbines for mounting on pre-installed foundations.

KEH’s track record on the design front includes the 130m jack-up Mayflower Resolution (now the MPI Resolution), completed in 2004 as the first-ever purpose-built, selfelevating turbine installation vessel , and the 161m sisters Pacific Orca and Pacific Osprey, which ranked as the largest jack-up WTIVs worldwide on delivery in 2012.

8 The Atlas-C class, a titan for windfarm projects

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50 YEARS AGO

THE GAS TURBINE DILEMMA One sub-heading in the January 1971 issue of The Motorship came in a review of trends in machinery demand, contributed by a Mr Muller, a design director of Sulzer. “Crude oil and LNG as fuels”, it read.

A number of Sulzer-engined tankers were due to enter into service that would be equipped to burn the same crude oil as was carried as cargo. The system being developed by Sulzer, and which was described as a “major development” was concerned mostly with the safety issues involved in burning a fuel that was described as “highly volatile”.

However, it was the novel practice of using boil-off gas from a soon-to-be-delivered LNG tanker that was raising eyebrows 50 years ago. Rather than today’s LNG technology, this pioneering installation was a Sulzer 7RND90 two-stroke engine, normally burning liquid diesel oil, via conventional injection equipment. The addition was an additional gas injection valve, lowing the LNG for combustion against the upcoming stream of scavenge air. This was thought to provide optimum mixing between the two fuels, allowing a fuel mix of up to 95% LNG. Alternatives to the large diesel engine were still being seriously considered. The January 1971 Motorship published a paper from an Australian shipowner in which costings for a pair of ro-ro ships, powered by either medium-speed diesels or gas turbines, each of 17,500hp, were compared. Large two-stroke diesels and steam turbines had been discounted for various reasons. Taking into account fuel costs, lubrication, maintenance, installation and manning levels, the gas turbine system - a GE series 5000 - was shown to save just under $40,000 per year, a saving of about 15% of the total cost of the diesel installation.

In another article, the choice of twin Pratt & Whitney gas turbines for each of a class of four German-built container ships was explained by manager Denholm. Although it was acknowledged that fuel costs would be higher, the gas turbines lent themselves to automated operation, reducing manning levels, while the compact size allowed about another 80 TEU to be carried. But the greatest justification came from increased reliability and easier maintenance, it being calculated that the gas turbine powered vessels could permit at least one more voyage per year, more than covering any increased fuel costs.

8 Marine version of a Pratt & Whitney 30,000hp aero-derivative gas turbine

34 | JANUARY 2021

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The international magazine for senior marine engineers EDITORIAL & CONTENT Editor: Nick Edstrom editor@mercatormedia.com News Reporter: Rebecca Jeffrey rjeffrey@mercatormedia.com Correspondents Please contact our correspondents at editor@motorship.com Bill Thomson, David Tinsley, Tom Todd, Stevie Knight, Wendy Laursen Production Ian Swain, David Blake, Gary Betteridge production@mercatormedia.com SALES & MARKETING t +44 1329 825335 f +44 1329 550192 Brand manager: Toni-Rhiannon Sibley tsibley @mercatormedia.com Marketing marketing@mercatormedia.com EXECUTIVE Chief Executive: Andrew Webster awebster@mercatormedia.com

8 Dart Europe, one of a trio of then-largest containerships afloat

With such an emphasis on propulsion, and the annual summary of ships completed, there was not much space for ship descriptions, but several pages were given over to the Dart Europe, first of the ‘second-generation’ fully-cellular container ships operating a weekly Transatlantic service. These ships, at the time the largest boxships afloat, were of 1556 TEU capacity, barely counting as feeder ships by today’s standards. This modest capacity in a ship of 231m length and 30.5m beam can be explained by most of the boxes being carried below deck, seven tiers in most holds. Above, just a single tier, 10 boxes across, was carried on the forward hatch covers, two tiers centrally, and three tiers aft.

A service speed of 22 knots could be achieved with the Sulzer-based propulsion plant, comprising a Cockerill-built 10RND90 main engine of 29,000 bhp at 122 rpm, driving a six-bladed 6.3m diameter propeller. Although equipped to Lloyd’s Register UMS notation, the automation systems were kept simple, with the main engine being controlled from either the bridge, a control station in the engine room or controls on the engine itself - there was no separate control room.

The Transatlantic container trade was anticipated to double within the subsequent five years, and the three Dart containerships were expected to carry a substantial proportion of that traffic.

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