Guide to OSV Propulsion 2015

2015 • A supplement to Offshore Support Journal

guide to

osv propulsion

Betting on batteries

could usher in enviro-friendly era

Electric vessels avoid losses and are more fuel efficient New fuels and energy sources raise high hopes for hybrids

“Although we are at an early stage with hybrid, battery-powered ships, there is significant interest among stakeholders.”

Narve Mjøs, director, battery services and projects, DNV GL, see page IV

contents

IV

IV

regulars I COMMENT

digest II A cross-industry initiative is developing new engine technology

batteries IV Batteries could be about to revolutionise the OSV sector VIII Hybrid systems with batteries could take a number of forms

alternative fuels XII

XI Experience suggests LNG ships are as every bit as capable in DP mode XII Interest in LNG as a fuel for offshore vessels is growing on both sides of the Atlantic

prime movers – medium speed engines XVI Engine builders are developing more powerful, fuel efficient engines

prime movers – high speed engines X A range of choices is available for designers and operators of high speed X offshore vessels

electric propulsion XXII Electric power can provide numerous advantages and reduce losses

XXII

propulsors XXV New types of thrusters and podded propulsors have been developed

hybrid machinery XXVIII Hybrid solutions are securing a growing market share

dynamic positioning XXX Investment in DP technology remains strong

leading enginebuilders XXXII Engines delivered to anchor handlers and in PSVs in the last two years OSJ Guide to OSV Propulsion 2015

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COMMENT | I

HYBRID VESSELS LIKELY TO LEAD RECOVERY F

David Foxwell, Editor

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ew offshore vessels are being ordered currently, and few are likely to be ordered in the short to medium term, given the nature of the downturn in the industry. However, when the market recovers and vessels do begin being ordered in significant numbers again, far-sighted owners are likely to be looking for designs that distinguish them from their competitors, offer their clients more than other vessels and are more cost-effective, environmentally friendly and safer to operate. All of the abovementioned features point heavily in the direction of offshore support vessels (OSVs) with hybrid power and propulsion – with batteries at their heart. Plenty of offshore vessel owners already operate diesel-electric vessels, growing numbers on both sides of the Atlantic have adopted vessels with dual-fuel engines that can burn environmentally friendly liquefied natural gas (LNG) and some have already ordered vessels with a combination of these features. The ‘next wave’ will be hybrid ships with batteries.

As highlighted elsewhere in this special supplement, true hybrid vessels have many potential benefits for owners and charterers alike. They are especially flexible, and onboard power and propulsion machinery can be configured in a way that optimises the load profile, thus reducing wear and tear on engines, maintenance requirements and emissions.

Hybrid marine electrical propulsion with batteries can handle slow speed transit and dynamic positioning (DP) modes of operation equally well, and they provide a high level of redundancy and reliability and greater efficiency over a wide range of operating modes. Hybrid solutions also reduce fuel consumption and can reduce noise levels onboard a vessel, and they are suitable for a wide range of vessel types – they are ideal for vessels with dynamic positioning systems and those that are required to operate in environmentally sensitive areas, of which there are a growing number. Class societies working on the concept of hybrid power and propulsion – and most are – say they are suitable for a

range of vessels from platform supply vessels and anchor handlers to multipurpose vessels, crewboats and tugs.

In hybrid/battery-powered solutions that are beginning to be adopted, developments in battery technology and ship electrification have coalesced to offer owners ships that make more efficient use of energy sources onboard.

Only a couple of years ago, the idea of fitting an offshore vessel with batteries might have seemed like ‘blue sky thinking’. Not any longer.

The pace of change has quickened dramatically, and suddenly batteries are the next big thing. By the time that orders for the next generation of vessels start to flow, hybrid battery power could be de rigueur.

Research into battery technology is being undertaken around the world. Many major corporations are devoting huge resources to developing them, but for the time being, the marine industry has settled on lithium ion batteries, which have a number of advantages over other battery types, including zero hydrogen gas emissions, higher energy density than the alternatives, weight/volume savings, reduced maintenance, lower internal resistance (hence higher efficiency) and the ability to be scaled for large format marine applications.

They also offer the ability to provide vessels with standby/emergency and ‘transitional’ power, and –like the hybrid solution as a whole – they are well suited to use on DP vessels and others with variable loading. They also make ships more responsive and safer, the size of other power generation units can be reduced and they can store energy harvested from waste heat recovery, regenerative braking of cranes and other potential forms of renewable energy onboard, such as solar panels. As if that were not enough to recommend them, batteries onboard can also enhance the overall performance of LNG-fuelled hybrid ships, reducing ‘methane slip’ as it is known. As classification society DNV GL likes to claim, “the future is hybrid”, and hybrid solutions with batteries will surely be at the core of the next OSV revolution. OSJ OSJ Guide to OSV Propulsion 2015

II | DIGEST

Wärtsilä, MAN Diesel & Turbo and Winterthur Gas & Diesel are to collaborate on new engine technology

Wärtsilä unveils new engine

MAN Diesel & Turbo, Winterthur and Wärtsilä collaborate

As highlighted elsewhere in this special supplement, Wärtsilä recently unveiled a new medium speed engine, the Wärtsilä 31. Designed for significantly reduced maintenance requirements and fuel efficiency and flexibility, it is expected to have fuel consumption efficiency in the order of 165 g/kWh. The Wärtsilä 31 is designed to serve a variety of vessel types requiring main engine propulsion in the 4.2 megawatts (MW) to 9.8MW power range. In the offshore sector, the Wärtsilä 31 is ideally suited for anchor handlers, other types of offshore support vessel and drilling and semi-submersible vessels, where the requirements are for operational flexibility, high power density, long intervals between overhauls and high levels of safety.

The Wärtsilä 31 engine comes in three alternative versions: diesel, dual-fuel (DF) and spark-ignited gas (SG). The company said the multifuel capabilities that the Wärtsilä 31 will bring to the market “extend the possibilities for operators to utilise different qualities of fuels, from very light to very heavy diesel, and a range of different qualities of gas”.

Wärtsilä claims that the new engine will bring “remarkable increases in fuel efficiency and fuel flexibility, matched by significant reductions in maintenance costs”. For example, the first service on the Wärtsilä 31 is required after 8,000 running hours, whereas conventional marine engines require maintenance after 2,000 running hours.

The engine will be available in 8V, 10V, 12V, 14V and 16V cylinder configurations.

A cross-industry initiative led by Wärtsilä, MAN Diesel & Turbo and Winterthur Gas & Diesel to develop technology for use in two-stroke and four-stroke engines has been launched.

The Hercules-2 project aims to foster the development of environmentally sustainable, more efficient shipping. In this respect, it is in line with European Union policy and is therefore partly funded by the EU. Altogether, 32 marine industry partners from 11 different companies, 16 universities and five research organisations are co-operating in the project, with NTU Athens as co-ordinator. The R&D efforts focus on four main areas. These are: • application of alternative fuels and the optimisation of fuel flexibility to facilitate seamless switching between different fuels • development of new materials to support high temperature component applications • development of adaptive control methodologies to significantly improve an engine’s performance throughout its lifespan • achieving near-zero emissions via combined, integrated, after-treatment of exhaust gases.

OSJ Guide to OSV Propulsion 2015

“The greatest of the many benefits stemming from Hercules-2 will be the development of new technologies that have a positive impact on our customers’ profitability. Another is the significant contribution this project will make to more environmentally sustainable shipping,” says Ilari Kallio, vice president, R&D, engines, speaking on behalf of Wärtsilä.

“Hercules-2 is a strong platform that will create a basis for the development of technology applicable to ship engines in four to five years time. We have, therefore, positive expectations and look forward to collaborating with so many cross-industry partners,” said Søren H Jensen, vice president and head of R&D at MAN Diesel & Turbo.

The Hercules-2 project is due to run for three years.

Brunvoll thrusters for windfarm service vessels Brunvoll in Norway provided the thrusters for Esvagt’s Havyard 832 service operation vessels (SOVs), which were designed and built by Havyard Ship Technology in Norway.

The vessels are fitted with two Brunvoll 880kW tunnel thrusters and a single Brunvoll retractable azimuth thruster of 880kW. All three thrusters are fitted in the bow of the vessels.

Steerprop thrusters help Baltika manoeuvre Thruster manufacturer Steerprop played a key role in the ice-breaking and manoeuvring capability of the revolutionary oblique icebreaking rescue vessel Baltika, the design of which was developed by Aker Arctic. The vessel is propelled by Steerprop thrusters and is the first vessel ever built with an asymmetric hull design that allows it to break ice ahead, astern and sideways. Because of this, the relatively small ice-breaker is able to open a wide channel in ice.

Baltika departed from Murmansk earlier this year with a team from Aker Arctic onboard and sailed to the Kara Sea to carry out full-

scale ice trials. The testing programme included performance tests in two distinct ice thicknesses in ahead and astern directions as well as in the oblique ice-breaking mode.

Various operational tests were also included to verify the manoeuvrability and operational capability of the vessel. The vessel was monitored by an automatic measurement system set up to record ice loads on its hull.

Although ice conditions in the Gulf of Ob were at the upper end of the vessel’s designed ice-breaking capability, Baltika exceeded the required performance targets and expectation with a clear margin. The vessel could break ››› www.osjonline.com

DIGEST | III

››› 1.2m level ice in continuous motion when proceeding bow first and could achieve a speed exceeding 3 knots when moving astern. The oblique mode, which had never been tested in area operations before, worked extremely well.

During operational tests, Baltika demonstrated excellent manoeuvrability, clearing ice at the port of Sabetta. The vessel also demonstrated its ability to penetrate heavy compressive ice ridges without ramming them.

Baltika was built by Arctech Helsinki Shipyard in co-operation with Shipyard Yantar JSC in Kaliningrad, Russia, and is based on Aker Arctic’s oblique ice-breaker design, the Aker ARC 100. The vessel is 76.4m long and has a beam of 20.5m.

The diesel-electric power plant on board consists of three Wärstilä 9L26 generating sets with a combined output of 9MW. Baltika is propelled by three SP 60 PULL 2.5 MW Steerprop azimuth propulsors, two in the stern and one in the bow of the vessel. The DP system, which also includes the oblique ice-breaking mode, was developed by Navis Engineering. The vessel is classified by the Russian Maritime Register of Shipping in the Ice-breaker 6 ice class. In addition to icebreaking duties, the vessel is also fitted with a sophisticated built-in oil recovery system.

Rolls-Royce propulsion package for ice-class unit

DNV GL issues DP closed bus guide

Rolls-Royce has secured a contract to supply a power and propulsion package for a high end ice-class multipurpose vessel under construction at Keppel Singmarine for Singaporean ship owner New Orient Marine Pte Ltd. The propulsion package includes one 1,650kW and two 3,000kW tunnel thrusters, two US ARC 0.8 main azimuth thrusters and a single 3,000kW retractable thruster as well as four Bergen B32:40V12ACD and two Bergen C25:33L6ACD generating sets, which will supply the requisite power to the £132 million offshore vessel.

Designed by Keppel Offshore & Marine’s ship design subsidiary Marine Technology Development, the DP3 vessel will be built to Ice Class Arc 5 notation for operation in ambient temperatures down to -30°C. New Orient Marine, a subsidiary of Luxembourg-based Maritime Construction Services, is due to take delivery of its first ice-class vessel in July 2017. Rolls-Royce will start delivering equipment to Keppel Singmarine in January 2016.

Dynamic positioning (DP) vessels can now meet critical safety regulations while gaining operational flexibility, efficiency and cost savings through new design and monitoring methods, says class society DNV GL, which has issued guidelines for closed bus DP operations.

More and more operators are asking their drilling contractors to operate their DP units in closed bus mode in order to save on fuel and maintenance costs and to reduce the environmental footprint of the system.

It also enables a significant reduction in engine hours, with less wear and tear on the engine, and expanded windows for maintenance in a cold engineroom.

DP operations are strictly regulated, as loss of position can have dire consequences.

Loss of power is a main risk, and complete redundant design including generators and thrusters has been required. This comes at great cost during operations, and the industry has for many years worked on smarter solutions with equivalent safety.

The traditional systems are designed for open bus mode, meaning completely separated power systems, and when operated in closed bus mode, the closed bus-ties may create a failure propagation path, undermining fundamental design requirements defined in International Maritime Organisation and classification rules. A closed bus system is a much more complex and tightly integrated system, which is demanding to build, verify and operate safely. OSJ

Battery power for Eidesvik’s Viking Queen Eidesvik in Norway has entered into an agreement for the installation of a batterybased energy storage system on the vessel Viking Queen. This will be the first offshore vessel to be retrofitted with batteries. The company said it is possible to achieve a significant reduction in emissions on existing vessels if they are fitted with such a system.

Eidesvik said the solution was made possible through targeted co-operation between Lundin Norway, which has chartered the vessel, ZEM AS, the supplier of the battery system, and Eidesvik.

“Commercialisation of this groundbreaking technology is now possible because of Eidesvik’s participation in the R&D project FellowSHIP, in which the partners worked with battery technology for five years,” said the company. “The energy storage system will have a capacity of 650 kWh and can supply up to 1,600kW. The solution gives a fuel saving of approximately 18 per cent for the vessel. Further, NOx and greenhouse gas emissions will be reduced by approximately 25 per cent.” www.osjonline.com

Viking Queen is the first offshore vessel to be refitted with battery power technology

OSJ Guide to OSV Propulsion 2015

IV | BATTERIES

Batteries set to share the load offshore Hybrid power and propulsion with batteries could be about to revolutionise the design and operation of offshore support vessels

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nly two or three years ago, the idea of fitting batteries on an offshore support vessel (OSV) – or any other vessel – as a source of electricity for power and propulsion would have seemed unlikely, but a seeming revolution in marine propulsion seems to be gathering pace, with offshore vessels among the vessel types that are leading the way.

As highlighted previously in OSJ, batteries have been successfully tested on OSVs and have been proved to provide owners with a number of advantages. Newbuild vessels are being ordered with battery power, and existing vessels are being retrofitted with batteries. Were it not for the steep fall in the oil price, undoubtedly more would have been ordered with battery power, and when the market recovers from the trough in which it currently finds itself, it seems highly likely that hybrid propulsion systems with battery power included will be part of a new wave of more fuel-efficient, environmentally friendly offshore vessels.

Why, then, has the potential of battery power suddenly become recognised? As is usually the case in the offshore vessel sector, far-sighted Norwegian owners and vessel designers and builders are working with propulsion system providers to find new ways to build more efficient vessels. Other forms of hybrid machinery have already made their mark in the offshore vessel industry, and now, thanks to work carried out primarily in Norway, hybrid solutions with batteries are on offer – and they work.

Narve Mjøs: “hybrid ships with batteries have reduced fuel costs, maintenance and emissions and are more responsive”

OSJ Guide to OSV Propulsion 2015

As classification society DNV GL points out, the focus on hybrid propulsion systems is one reason why battery power is suddenly enjoying this level of attention. Another is a focus on ship electrification, where batteries can play a leading role and promise more efficient use of energy.

Speaking to OSJ earlier this year, Narve Mjøs, director, battery services and projects at DNV GL, highlighted the fact that all electric ships and hybrid ships with energy storage in batteries with optimised power control can significantly reduce fuel costs, maintenance and emissions. In addition, he explained, hybrid systems with batteries can significantly enhance responsiveness and enhance safety when vessels are operating in safety-critical situations.

Mr Mjøs noted that the initial focus of DNV GL’s attention on marine applications of batteries was primarily environmental. The environmental advantages of vessels burning liquefied natural gas (LNG) rather than conventional fuel have long been recognised (see elsewhere in this special supplement), but questions have been raised about a phenomenon known as ‘methane slip’ or the loss of unburned methane into the environment. One drawback of gas engines is their proneness to methane slip due to incomplete combustion of the methane in the engine – a problem exacerbated by the fact that the global warming potential of methane is 25 times higher than that of CO2. Engine manufacturers are working on ways to prevent methane slip, but in the meantime,

Remi Eriksen: “the price of batteries has fallen by some 60–70 per cent in the past four years”

Louise Dunsby: “batteries in a hybrid arrangement help meet shipowners’ desire to maximise efficiency”

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BATTERIES | V

Hybrid battery power has a number of advantages and made Viking Lady even more responsive

incorporating batteries into LNG-fuelled vessels can help reduce methane slip and deliver even better fuel efficiency, reduced emissions, reduced maintenance costs and optimised engine performance.

However, since this initial focus on compensating for methane slip, the class society has come to see batteries not just as a way to reduce emission of methane into the environment but as a way of improving performance and safety onboard.

Mr Mjøs highlighted the fact that Eidesvik in Norway – one of the first companies to appreciate the potential advantages of battery power – had found that its platform supply vessel (PSV) Viking Lady “was even more responsive” with batteries onboard. This proved to be particularly advantageous in heavy weather. “It gives the vessel instantaneous access to power, when it’s needed,” he said. “Diesel engines can’t give you that instantaneous response.” They also have other advantages, he added.

They can store energy harvested from waste heat recovery, regenerative braking of cranes and/or forms of renewable energy such as solar energy.

Evidently, owners and the supply chain are waking up to the potential advantages of hybrid battery power, and more and more propulsion solution providers are offering battery-based solutions. “Last year, DNV GL trained more than 100 participants in our introduction course to maritime battery systems,” Mr Mjøs told OSJ, noting that DNV had facilitated the establishment of the Maritime Battery Forum, which already has more than 50 members, including shipowners, yards and vendors as well as government agencies.

“Although we are at an early stage with battery-powered ships, there is significant interest among stakeholders, and the number of ships with battery technology is rapidly increasing worldwide,” Mr Mjøs told OSJ, noting that, in Norway, financial support for realisation of electric and hybrid ships can be made available from sources such as Innovation Norway, Enova and the NOx-Fund.

As Remi Eriksen, CEO and president of DNV GL, noted, the price of batteries has fallen by some 60–70 per cent in the past four years. “My guess is that this trend will continue,” he said, “with as much as a further 50 per cent reduction in price compared to the current level.”

Mr Eriksen also highlighted the advantages of batteries combined with LNG engines in a hybrid arrangement. “Battery hybrids enable a vessel to run its engines at more favourable loads. This reduces fuel consumption and therefore emissions to air,” he noted, also highlighting

What’s in a battery?

The high level of interest in and adoption of hybrid marine power and propulsion systems with batteries has been made possible by developments in lithium-ion batteries over the past few years – in particular, the adoption of high quality batteries for electric and hybrid vehicles and large-scale grid systems. It is these developments that have made battery systems a viable option for maritime applications.

As Egil Mollestad from Zem Energy, a battery developer based in Høvik in Norway explained, over the last decade, a range of lithium-ion based batteries has been developed and optimised for energy density, power density, cycle life, robustness, safety and cost.

The cells that form the basis of these batteries take different forms. They may be cylindrical, prismatic or in ‘pouch’ form and come in all sizes, from the small cells primarily used in consumer electronics to much larger units for commercial applications. Marine systems have mainly used lithium-ion www.osjonline.com

the benefits Mr Mjøs drew attention to – improved response time in safety-critical operations, extending engine lifetime and reduced engine maintenance – along with reduced noise and vibration on board.

Louise Dunsby, lead electrotechnical specialist in Lloyd’s Register’s marine technical policy group, agreed with Mr Mjøs and Mr Eriksen about the advantages and potential benefits of using batteries in a hybrid arrangement. She agreed that the development of battery and hybrid technology is helping the maritime industry overcome the challenges of emission regulations and shipowners’ desire to maximise efficiency.

However, she said, it is also helping shipowners address more stringent emissions regulations, with recent technological developments leading to an increasingly efficient alternative to traditional power sources.

In an ideal world, she suggests, it would be possible – and economically feasible – to change or ‘switch out’ the batteries on a ship with new ones, just as one does with a remote control for a television.

In reality, the batteries used in shipping are big enough to fill a large compartment – because ultimately the physical size of a battery directly relates to the power it can produce – and are far too big to change in and out, so research and development is focused on secondary or rechargeable technology.

Batteries of this size use a variety of chemical processes, she explained, the two most common being lead-acid and lithium-ion batteries. Both have been tried and tested over many years, are robust,

cells with nickel manganese cobalt oxide (NMC) cathodes and graphite anodes. Cells based on iron-phosphate cathodes have also been developed, he explained, and both represent a good compromise between energy, safety, power density, cycle life and cost.

“Today, cells are produced to a high quality standard, and it is very seldom that cells from quality producers experience any problems,” he explained. “The electronic control system that is required has also matured, and the industry knows how to install large battery systems in a safe and reliable way onboard ships. Huge production facilities have been built over the past few years to supply the automotive industry and as volumes increase in the maritime battery – and elsewhere – so the cost of production is expected to fall.”

In 2014, Zem Energy began work on a project to develop what it claims will be the first high power battery solution specifically for marine applications and has received support from Transnova and partners including DNV GL, which is helping Zem Energy ensure that its batteries comply with its guidelines for batteries for marine applications.

OSJ Guide to OSV Propulsion 2015

VI | BATTERIES

low cost and maintenance free and are considered safe with minimal risk of overheating. Lithium-ion batteries are favoured for their energy density, with lead-acid batteries being too large for propelling a vessel requiring a significant electrical load.

“There is plenty of research into other chemistries, such as lithiumoxygen and aluminium-graphite, and theoretically, it’s possible to make much more power-dense cells,” she explained, but for the time being, lithium-ion batteries are the focus of attention in the marine sphere, and practically speaking, other types of new technologies need to be developed further to make them efficient, stable and commercially viable.

Mrs Dunsby explained that, currently, batteries are being used in shipping as an auxiliary or short-term power source. “For most vessels, we still need conventional power sources to complement batteries, because they simply don’t last long enough – like electric cars, travel is limited because the batteries require charging after relatively short distances.

“For long journeys, the conventional power source would be used for propulsion and to charge the batteries, and the hybrid system would allow the batteries to take over at a particular time, for example, in coastal areas, or the system might be fully hybrid with a dynamic power management system, which selects the most efficient combination of power sources at any one time.”

When asked whether there must be some risks associated with using batteries on ships, Mrs Dunsby explained that the key challenge in developing new battery technology is that time-efficient charging capability is linked to the rate at which a battery self-discharges.

The quicker a cell can be charged, the more likely it is to discharge independently, creating heat, which is a potential fire risk.

Mr Mjøs agreed. “Batteries contain a lot of energy. There are important safety issues to be addressed,” he told OSJ. “We have developed class rules to address these issues. For the time being most batteries are air-cooled, but in the future we may see more liquid-cooled units. The size and weight of batteries is also potentially an issue for some vessels,” he explained. “Because of this they might not be quite so suitable for fast offshore vessels.”

Mrs Dunsby is also positive about responding to the challenges integrating batteries pose. “In theory, any technology can be de-risked to an acceptable level provided a sound approach is used to identify and mitigate hazards,” she said. “The most important thing is that ship designers and builders identify the specific risks as early as possible in the design of a vessel that will use a large battery – mitigating hazards early is much more efficient than reacting to them later,” she said.

Moreover, as she noted, “As soon as the world starts to take an interest in a technology, lots of interesting research starts happening, and if this research achieves a power-dense energy source, then the scope is revolutionary – industry could be completely changed, and the impact on the maritime sector could be immense.” OSJ

Soon to be delivered, Fafnir Offshore’s newbuild will have a hybrid battery arrangement

OSJ Guide to OSV Propulsion 2015

Trailblazers already adopting batteries There are a growing number of producers of lithium-ion batteries, but for the time being, the foremost in the marine sphere is a Canadian company, Corvus Energy, which was established in 2009 and has been a pioneer in the marine market. Batteries supplied by Corvus Energy were used in the FellowSHIP research programme headed by DNV GL, which saw a hybrid system installed on Viking Lady. This 500 kWh battery was installed in 2013, and an extensive monitoring programme has produced valuable efficiency and emission data documenting the benefits of batteries in such an application.

The first newbuild offshore supply vessel with a battery system, Østensjø Rederi’s Edda Ferd, entered service in late 2013. More recently, Eidesvik has decided to retrofit a battery energy storage system on its vessel Viking Queen – a project also facilitated by the FellowSHIP project and by co-operation between Eidesvik and Lundin Norway, which is to charter the newly upgraded vessel – which is being fitted with lithium-ion batteries from Zem Energy.

Another notable newbuilding with hybrid battery power is the soon to be delivered Havyard 833 WE ICE PSV that Fafnir has on order at Havyard in Norway – a vessel that secured the environmental award at the 2015 Annual OSJ Conference, Awards & Exhibition.

Arve Helsem Leine, design manager at Havyard Design & Solutions, explained that, working closely with Norwegian Electric Systems, the Norwegian designer had integrated batteries into the ship’s hybrid diesel-electric propulsion system. Norwegian Electric Systems developed and will deliver a Quadro Energy Storage Technology 2 (QUEST 2) battery system for the vessel, which will be the first vessel to be equipped with it. The battery pack supplies power to the main switchboards via an AC/DC converter.

“Installing our QUEST system on the vessel will reduce emissions and save fuel and money,” said Jan Berg, EVP business development at Norwegian Electric Systems. “We started development of QUEST 1 and QUEST 2 three years ago. Our thorough analyses of the vessel’s operating profiles now show that the savings will exceed our initial calculations.

Fuel consumption can be reduced by 5–20 per cent in transit, by 25–35 per cent in port and by up to 35 per cent in dynamic positioning mode. Battery technology is developing rapidly, and capacity and output are improving in relation to volume and weight all the time.” Overall, says Mr Leine, the combination of the Havyard 833 WE ICE’s hull design and hybrid battery power result in a PSV that will use 30–40 per cent less fuel than conventional PSVs during certain types of operation. This will also lead to a corresponding reduction in emissions of environmentally harmful gases such as CO2, NOx and SOx. To date, the largest such installation is the 2.7 megawatt/hr (MWh) battery system installed on Scandlines’ ferry Prinsesse Benedicte, which operates between Shælland in Denmark and Puttgarden in Germany. Since the ferry was first fitted with the batteries, Prinsesse Benedicte’s three sisterships have also been equipped with similar battery systems. The first large-scale all-electric battery-powered car ferry, Norled’s Ampere, came into operation in January 2015. This 120-car, 350-passenger vessel is equipped with a 1 MWh battery system that can be charged in the 10-minute period between each trip and at night when it is alongside. www.osjonline.com

Power Flexibility

for high-tech offshore vessels

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Find out more at www.mandieselturbo.com

VIII | BATTERIES

BATTERY POWER – WHAT FORM MIGHT FUTURE HYBRID SOLUTIONS TAKE? As interest in hybrid power and propulsion options with integrated batteries grows, it is interesting to consider what form future hybrid systems might take

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consumption of and emissions from an internal combustion engine depend on the engine load. Typically, engines are calibrated for optimum performance at high loads. For ship types that experience large load variations during operation – such as some offshore vessels – the introduction of batteries may allow the engines to operate optimally with respect to fuel oil consumption and/or emissions. “This can be achieved by selecting engine sizes that operate at optimal loads for most of the time, with additional power obtained from the batteries when required,” said Mr Brandsæter.

“When power requirements are low, the batteries can be charged using the excess energy generated by running the engine at the optimal load.

Alternatively, in operating conditions requiring very low loads, the ship may be able to operate on battery power alone. This can also

ike the automotive industry, classification society DNV GL divides battery-powered ships into three types: • full-electric ships (ES) • plug-in hybrid ships (PHES) • hybrid ships (HES).

On a full-electric ship, all the power for propulsion and auxiliaries would come from batteries. A plug-in hybrid ship, similar to a plug-in hybrid car, would be able to charge its batteries using shore power and has both conventional propulsion and electric propulsion. Such a ship can operate on batteries alone on specific parts of the route, when manoeuvring in port and during standby operations. A hybrid ship uses batteries to increase its performance and does not use shore power to charge its batteries.

As Andreas Brandsæter, a researcher working on hybrid power solutions at DNV GL, explained, the specific fuel

MECHANICAL PROPULSION WITH BATTERY HYBRID ELECTRICAL POWERPLANT

be beneficial for maintenance costs since engines operating at low loads may incompletely burn fuel, potentially leading to contamination of the lubrication oil and build-up of carbon residue on vital engine parts. Thus, the normal service intervals of an engine might be insufficient, leading to higher maintenance costs.”

An engine’s emissions are also strongly dependent on load, but it varies according to the type of emissions. Mr Brandsæter noted that, typically, emissions are normally higher at low engine loads. This is particularly evident for unburned methane (CH4) emissions, and as highlighted elsewhere in this special supplement, CH4 has a very strong greenhouse gas (GHG) effect, which is at least 25 times more potent than CO2. Moreover, a diesel engine (using either heavy fuel oil or low sulphur diesel) would be expected to have significant particulate matter (PM) emissions, especially at low loads. An accumulator may therefore also be used to reduce emissions by allowing the engines to run at optimised loads with respect to emissions.

HYBRID BATTERY PROPULSION

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To summarise, the benefits of hybrid ships include: • the fact that they can utilise energy from shore power • they enable engines to operate at optimum load • transient engine loads are avoided • greater redundancy is possible in the power system • it is possible to reduce emissions • noise and vibration levels onboard are reduced • energy harvesting and energy recovery may be facilitated.

Mr Brandsæter illustrates these advantages with an example in which he assumes that a ship’s power demand varies between 500kW and 1,100kW, with an average power demand of 800kW, meaning that the ship consumes 800 kWh in one hour of operation.

The ship has two generator sets installed, with a maximum total power output of 1,000kW. Although the average demand is 800kW, the ship cannot run with only one generator set because demand sometimes exceeds 1,000kW. Two

HYBRID BATTERY PROPULSION WITH DISTRIBUTED BATTERIES

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electrical load

OSJ Guide to OSV Propulsion 2015

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BATTERIES | IX

gensets must be running.

With both generator sets operational, total fuel consumption is 170 kg/hour, compared with 146 kg/hour if only one generator set is switched on.

However, if a battery was installed, the battery could take care of the variations, and the ship could run on only one generator set, with fuel savings of about 14 per cent.

As Sverre Eriksen, a principal engineer at DNV GL, explained, most conventional vessels traditionally have an electrical power system for the ‘hotel load’ and the auxiliary systems, and power for propulsion is taken care of by combustion engines or the ‘main engines’. The power for the electrical load is produced by generator sets consisting of an electrical generator driven by a combustion engine.

These engines are called auxiliary engines.

However, more and more ships that also use the electrical power for propulsion are becoming more and more common, and vessels that undertake operations that also require variable levels of power – such as offshore supply vessels (OSVs) – are making use of electrical propulsion.

At its most basic, a vessel might have conventional mechanical propulsion augmented with electrical

power from batteries. The figure reproduced here shows a battery integrated into the electrical system of a vessel with just this kind of conventional mechanical propulsion. In this particular case, the battery will be effective for smoothing the connected electrical load and helping to handle large load steps. When the large load steps are reduced, the number of auxiliary engines in use can also be reduced. In cases where the load can regenerate power, such as is the case on a vessel with one or more cranes, for instance, the battery can be used to harvest this energy.

The next step up in sophistication is hybrid battery propulsion. The second figure reproduced here shows batteries integrated into a power system for electrical propulsion. In this case, Mr Eriksen explained, the battery will provide power to the propulsion motors. The vessel may run on batteries alone, generator sets or in parallel operation using both batteries and generators. In addition to being a source of energy for propulsion, the batteries will smooth the load variations on the generator sets. As Mr Eriksen also noted, introduction of such a battery hybrid system will reduce the noise and vibration levels in the ship. This particular

HYBRID BATTERY, ELECTRICAL, MECHANICAL PROPULSION AND DC DISTRIBUTION

arrangement could also be used for ‘zero emission’ operation when entering a harbour.

The next step up in sophistication is hybrid battery propulsion with distributed batteries. As Mr Eriksen explained, one of the challenges in the electrical propulsion is its efficiency. In this arrangement, and as seen in the figure, the system has several power converters, each with a 2 per cent power loss.

However, if the batteries are distributed with the converters, as shown here, the losses are reduced. Another benefit of the distributed battery concept is that each propulsion unit is independent of a common source of energy. “This might be a smart solution for vessels that require a particularly high level of redundancy and reliability from the propulsion system, such as DP2 and DP3 dynamic positioning vessels.

The next figure reproduced here shows a hybrid battery, electrical, mechanical propulsion and DC distribution system in which the power system combines an electrical/ mechanical hybrid solution, a battery hybrid with plugin possibilities and DC distribution network.

The advantage of this concept is that, with a DC-distributed system, the speed of the prime movers

PURE BATTERY PROPULSION

for the generators can be adjusted to the load-dependent optimum fuel level. Hence, fuel consumption is reduced, and the environmental footprint of the vessel is minimised. This electrical/mechanical hybrid solution allows electricity to be generated by the main engine (power take-off (PTO)) or propulsion power to be produced by generator sets and batteries (power takein (PTI)). A boost mode is possible, which provides additional power when the main engine and PTI motor are running in parallel.

The final figure reproduced here shows power being supplied by a purely batterydriven vessel. The batteries are charged through an AC/ DC converter (either located on the vessel or onshore).

Two independent battery systems deliver power to the thruster. OSJ

KEY TO SYMBOLS Battery

Main engine

Genset G

Clutch

Shore plug

Propulsor

G

G

Motor AC/AC converter AC/DC converter DC/AC converter DC/DC converter

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OSJ Guide to OSV Propulsion 2015

ALTERNATIVE FUELS | XI

The track record of LNG-fuelled vessels such as Rem Eir suggests they are as reliable in DP mode as any other vessel

Track record suggests LNG works well on DP vessels With more and more owners considering doing so, experience suggests that adopting LNG propulsion does not mean accepting any limitations in all-important dynamic positioning capability

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ore and more owners of offshore support vessels are opting for liquefied natural gas (LNG) propulsion in order to take advantage of its reduced emissions and the cost benefits that can accrue from bunkering with LNG rather than fuel oil. Almost all modern offshore vessels are also dynamic positioning (DP) ships.

LNG-fuelled DP vessels have been in operation for several years and have a good operational and safety track record, but some owners have reservations about ordering them because of concerns about loss of DP in a safety-critical situation. However, a presentation by Terje Nordtun, a project manager at Wärtsilä Ship Design, at the 2015 European Dynamic Positioning Conference should put their minds at rest.

A platform supply vessel (PSV ) is used to transport deck cargo, various bulk cargoes and fluids (such as liquid mud, dry bulk mud, fuel and methanol) to and from offshore installations. Cargo is offloaded with the vessel either ‘backing in’ or alongside the rig in order to be dynamically positioned while cranes on the rig offload the cargo. This being the case, dynamic positioning is critical in keeping the PSV close to the rig – and avoiding a potential collision.

The minimum DP notation for redundancy to ensure safety in close proximity to rigs is DP2.

Mr Nordtun’s presentation at the conference was based on a review of more than a decade of experience with LNG-fuelled DP vessels, with a focus on Rem Eir, an LNG-fuelled PSV managed by Remøy Shipping.

At the time that it was delivered, it was the largest LNG-fuelled PSV in the world.

The first LNG-fuelled DP vessel was Viking Energy, which was delivered to Norwegian shipowner Eidesvik in 2003. This DP2, LNGfuelled vessel is a diesel-electric ship with a quartet of Wärtsilä 6L32DF engines, each of 2,020kW, forming the basis of the electrical powergenerating machinery. However, at the time that the conference took place in June 2015, there were 24 LNG-fuelled PSVs in operation or on order, of which 22 had dual-fuel engines. Among them is the dieselelectrically driven Rem Eir, which was delivered in November 2014.

With a length overall of 92.50m and breath of 20.00m, the vessel has a deck area of 1,090m2 and is a DP2 class vessel with an environmental regularity number (ERN), which describes the position-keeping ability of a vessel, of 99,99,99,99. This particular vessel makes use of Wärtsilä’s Low Loss Concept and combines the use of Wärtsilä 6L34 and 6L20 dual-fuel engines providing a total installed power of 7,350kW. Mr Nordtun explained that, prior to Viking Energy entering service and more recently, concerns had been expressed about whether LNGfuelled vessels might be less capable or reliable in DP mode. These www.osjonline.com

concerns included classification requirements for such an innovative vessel, including the requirement for an emergency shut-down concept, the bunkering procedure for the vessel, the need for redundant enginerooms and the need for a vessel hazard identification study (HAZID).

One key question that arises about any LNG-fuelled vessel is what would happen in the event of a collapse of LNG tank pressure or any other event leading to an interruption in the operation of the vessel’s propulsion and manoeuvring systems. Viking Energy was also intended for operation in very harsh conditions, which could lead to mixing of gas with liquid phase condensed gas and the potential for pressure drops. What would be the effect on dynamic positioning integrity were such a phenomenon to occur with the vessel station keeping close to an offshore installation in harsh conditions, and what could the potential consequences be of slow response (load acceptance) of engines in gas mode?

By more recent standards, this first ever LNG-fuelled PSV had a fairly basic LNG fuel supply arrangement. More recently, Wärtsilä has introduced its LNGPac concept – a complete gas-handling system for LNG-fuelled ships with LNG tank and related process equipment as well as the control and monitoring system. As Mr Nordtun explained, LNGPac also maximises LNG storage volume, makes the most efficient use of available space on a vessel, reduces the number of interfaces and enhances reliability whilst driving down costs.

As Mr Nordtun further explained, the key to maintaining redundancy in the fuel system on a DP ship with LNG propulsion is to ensure that the dual-fuel engine onboard can transfer instantaneously to diesel mode – at any load and at any time. “Diesel mode will act as a redundant fuel system for DP2 class requirements,” he explained. “A sudden failure in the gas supply during full power ramp-up does not compromise safety.”

“LNG as fuel is feasible for DP vessels,” Mr Nordtun concluded.

“It is a proven solution with a 12-year history encompassing 24 vessels.

Adopting LNG does not mean accepting any limitations in DP capability and performance. It is a perfect solution for PSVs making regular port calls, and vessel owners with LNG experience have not expressed any concerns related to vessel operation.

He said the future development of LNG-fuelled offshore vessels depends not on any concerns about DP performance but could be influenced by the additional investment cost for LNG ships and price development of LNG and MGO and by the development of emission control regulations – which provide an incentive for using LNG – and the need for more shore-based LNG infrastructure to be developed. OSJ OSJ Guide to OSV Propulsion 2015

Harvey Energy, Harvey Gulf’s first LNGfuelled vessel, could be the first of many such offshore ships in US waters

US OWNERS SET TO BENEFIT FROM SURGE IN GAS PRODUCTION Interest in liquefied natural gas as a fuel for offshore vessels is being driven by recognition of its environmental advantages and in the US by the sharp increase in production of low cost natural gas

OSJ Guide to OSV Propulsion 2015

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ALTERNATIVE FUELS | XIII

Chad Verret: “having operated LNGfuelled ships, building them is now high on Harvey Gulf’s list of priorities”

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hipowners in Norway have long understood the advantages of offshore vessels powered by engines that can burn liquefied natural gas (LNG), but with even stricter requirements in the US Emission Control Area (ECA) due to come into force in US waters in 2016 and America now a producer of abundant amounts of natural gas, the future looks bright for LNG ships in the US too.

As a study published late last year by America’s Natural Gas Alliance (ANGA) made clear, the abundance of LNG and its environmental credentials as a fuel could combine to see much greater use of natural gas as a marine and rail fuel in future.

The study, undertaken

by Gladstein, Neandross & Associates (GNA) on behalf of ANGA, sought to identify locations across three key areas – the Great Lakes, the Gulf of Mexico and the Mississippi River and its tributaries – with the best potential for demand growth to support LNG infrastructure investment.

What GNA found was significant. With continued co-ordination between end users, suppliers and stakeholders, potential US LNG demand from high horsepower users in the three regions could reach 1 billion gallons annually by 2029, which is approximately seven times all current domestic LNG use for transportation.

As is already the case in the US for power generation, manufacturing and onroad transportation, use of natural gas for marine and rail is being driven by abundant supplies, low cost and the fuel’s cleaner profile. A 2014 study published by the Maritime Administration in the US found that LNG as a marine fuel has clear environmental advantages and that, compared to established ship fuels, it emits 85 per cent less NOx and SOx, 90 per cent less particulate matter and 30 per cent less carbon dioxide. www.osjonline.com

Already, LNG-powered offshore vessels – and vessels of other types – are underway or under construction at yards in the US, from Harvey Gulf Marine International’s LNGpowered platform supply vessels (PSVs) to what will be the world’s first LNG-powered container ship, which is being built for TOTE in San Diego, there are currently 19 confirmed orders for LNG or LNG-conversion-ready vessels in North America. Such is the potential of LNG that GNA estimates that, in 15 years, more than 360 US-flagged vessels could generate 380 million gallons of LNG demand annually.

Of the three key areas studied in the report, GNA projected that the Gulf of Mexico will create the greatest level of demand for LNG vessel activity. “This presents a unique opportunity to develop the region into the world’s leading bunkering destination for LNG,” said ANGA, noting that, not far behind LNG adoption in the marine industry, major railroads across the US are at various stages of testing LNG as a locomotive fuel, with the study estimating that commercial locomotive adoption is likely to begin later this decade.

Here, too, fuel costs are driving innovation, because Class I railroads in North America consume approximately 4 billion gallons of diesel each year.

If they converted just a third of their operations to natural gas, they would be able to save approximately US$2.6 million each day, ANGA estimates.

As highlighted above, the momentum behind natural gas project development in high horsepower industries such as shipping is being driven by fundamental shifts in long-term supply of low cost natural gas in addition to recognition of its environmental benefits. Rapid technology advancements in unconventional drilling have unlocked vast resources of

natural gas that were previously too expensive to extract. Since the beginning of 2005, natural gas production in the US has increased 30 per cent, and the most recent 2014 figures from the Energy Information Administration (EIA) show a 56 per cent projected increase in total natural gas production from 2012 to 2040. This increased production will, it believes, supply enough domestic natural gas to provide power for generations, with the EIA, Massachusetts Institute of Technology and the Potential Gas Committee all projecting ample long-term domestic supplies of natural gas. The most recent projections show a range of technically recoverable gas using today’s technology of 2,203–3,545 trillion cubic feet.

As also highlighted above, the Gulf of Mexico is projected to be the key growth region, as it will be home to nearly 75 per cent of the study areas’ projected LNG-fuelled vessels. It has also been suggested that, as a result of ongoing European investment in LNG infrastructure and environmental market drivers, the Gulf of Mexico could also be an LNG bunkering destination for approximately 35 ocean-going vessels operating in international trades. These vessels could generate another 343 million

gallons (29 billion cubic feet) of annual LNG demand by 2029.

Significant new sources of LNG fuel supply will need to be developed throughout the study regions to support this anticipated demand growth, since current liquefaction is not capable of supporting such increases. An estimated US$1.5–2.5 billion in capital investments will be required to build out infrastructure capable of producing, storing and delivering the estimated 2.7 million gallons per day of LNG projected in the report by 2029, though some of this may be supplied by existing infrastructure.

ANGA’s optimism about the Gulf of Mexico market for LNG fuel is based in large part on the existence of the offshore oil and gas industry in the region, which supports a robust population of marine vessels supporting offshore oil and natural gas activity.

It notes that LNG will be available for domestic marine fuel use once the Cheniere export facility comes online in Louisiana, through agreements with LNG America, precluding the need to build baseload for new liquefaction investments, at least for initial projects.

Several other export facilities and LNG production facilities are also proposed for the region, including facilities that OSJ Guide to OSV Propulsion 2015

XIV | ALTERNATIVE FUELS

are being proposed in Port Fourchon and Galliano for offshore vessels.

Far-sighted companies such as Harvey Gulf International Marine that were among the first movers in the US when it came to building LNG-fuelled offshore vessels evidently concur with ANGA’s analysis. Having committed to the construction of six LNG-fuelled PSVs, Harvey Gulf recently acquired two shipyards in the US in order to use the expertise it has accumulated with LNG to ships powered by the environmentally friendly fuel too. The company has only just taken delivery of its first LNG-fuelled vessel, but sensing the scale of the opportunity in the US market, it is moving quickly to gain a foothold as a builder of LNG ships.

LNG first got Harvey Gulf’s attention when the front cover of OSJ sported a dual-fuel ship capable of burning conventional fuel and LNG in the same engines. “We were looking at green fuels and shale gas was kicking off in the US, so it just seemed to fit,” Mr Chad Verret, executive vice president, Alaska & LNG operations at Harvey Gulf, explained. However, when he went to the US Coast Guard with the company’s idea in 2011, he discovered there were no regulations in place to build an LNG-fuelled vessel. The technology had not previously been used in the US. “The Coast Guard was quite open and had been looking for a while at what was going on in Norway and how the Norwegian authorities had done it,” he explained.

Apart from the regulatory challenges, there were operational challenges to overcome too before Harvey Gulf could begin to operate LNG-fuelled ships.

There was no infrastructure for LNG fuelling in the region, so to start with, Harvey Gulf is delivering the gas by truck to an onshore fuelling terminal.

When it opens its own facility in Port Fourchon later this year, it will store the LNG on site, supplied via truck and later by OSJ Guide to OSV Propulsion 2015

Harvey Gulf plans to start bunkering ships at its Port Fourchon facility later this year

barge. “We did gas trials during the commission stage of the vessel delivery using three tanker trucks,” Mr Verret explained.

“In March 2015, we did a fullvolume bunkering operation filling the vessel tank to 67,000 gallons of LNG. The first time, there were a lot of Coast Guard personnel watching us, but by the third time, the oversight was much less. This means the level of confidence in us from the authorities was very high.

“Operationally we are learning a lot,” he added. “We optimised the bunkering process during the first month the vessel was operated, and I believe we’ll be even more efficient when the other five vessels are delivered by mid-2016.”

Thanks in large part to Harvey Gulf driving the process forward, the US Coast Guard now has an LNG marine fuel policy, with federal regulations expected once current policies have been tested. Mr Verret’s advice to others who want to go down the same route and switch to LNG is to “commit fully”, which, he said “is the only way you are going to get through.

Pushing classification society ABS and the Coast Guard the way we did helped them to move

forward.” Now, the US seems ready for a boom in building LNG-fuelled vessels.

Harvey Gulf’s timing was excellent, and as Wärtsilä, the company that supplies the dualfuel engines for Harvey Gulf’s vessels, noted recently, although low-sulphur diesel fuel has been the norm in the Gulf, since setting up the ECA in 2012, the authorities have stepped up pressure on operators to become greener. As a result, several other companies are looking to LNG as an alternative fuel, including Washington State Ferries, which transports 24 million passengers a year and may become an early adopter of LNG. The company believes it can reduce fuel costs by almost 50 percent, thus saving taxpayers’ money.

John Hatley, who is in charge of LNG initiatives at Wärtsilä, agreed that the shift to LNG is being triggered by economics, emissions and by safety and reliability. He believes that, even with the recent and dramatic drop in oil prices, LNG is still an interesting option. “Absolutely,” said Mr Hatley, who notes that payback can take less than four years. “LNG fuel is a cleaner, more cost-effective solution,

which is not as volatile price-wise as traditional fuels,” he said. The abundance of gas and shale gas in the US just adds to the reasons for switching to LNG. As highlighted in the September 2015 issue of OSJ, Harvey Gulf wants to use the yards to build LNG-fuelled ships – for its own account and for other owners – that will comply with the requirements of the forthcoming North American ECA. The new, stricter ECA requirements come into force in January 2016 and will require owners operating vessels in areas covered by it to meet a 0.1 per cent sulphur limit in the fuel they use. There are several ways that they can do so, and switching to LNG from conventional fuel oil is one of them – a decision that is potentially all the easier to make given the abundance of natural gas in the US and the fact that, historically, LNG costs less than fuel oil too.

Mr Verret told OSJ that the opportunity to build LNGfuelled ships and tugs to meet the requirements of the North American ECA was uppermost in the company’s thoughts when it acquired Trinity Yachts in New Orleans and Gulf Coast Shipyard, based in Gulfport, www.osjonline.com

ALTERNATIVE FUELS | XV

Mississippi, which built Harvey Energy, Harvey Gulf’s first dual-fuel vessel, and is currently working on five more vessels of the same type.

In a statement, the company said it had created a new affiliated company – Harvey Shipyard Group – to manage its shipbuilding assets and plans to build on its success in constructing the first LNGpowered offshore vessel in the US by building for other owners.

“These shipyard acquisitions will position Harvey Gulf as America’s only builder, owner and operator of dual-fuel (diesel/ LNG) offshore supply vessels and allow us to pass along the savings of lower operating costs and environmental protection to the marine transportation industry,” said Shane J Guidry, chairman and chief executive officer of Harvey Shipyard Group.

Mr Verret told OSJ that LNG-fuelled tugs are the initial focus of Harvey Shipyard Group’s attention, especially given the growing interest in exporting natural gas from the US from marine facilities at which tugs will be required.

It makes sense, he explained, that tugs servicing LNG export facilities should make use of LNG themselves, and Harvey Shipyard Group has already bid on projects in that area.

In the longer term, Mr Verret explained, Harvey Shipyard Group could turn its attention to building dual-fuel, LNG-burning offshore vessels for other owners, although in the short term, demand for offshore vessels is low given the low oil price.

He also highlighted the fact that studies demonstrate the abundance of natural gas in the US will ensure that, over the next decade the cost of the fuel is unlikely to rise more than 30 per cent from its current low level.

“That cannot be said of the cost of a barrel of oil,” said Mr Verret, noting that, in recent years, LNG has cost much less than conventional fuel and that LNG is expected to have a stable price www.osjonline.com

trajectory compared with other fuels in future.

The foregoing analysis of the expected development of the cost of LNG fuel is supported by analysis by classification society DNV GL in another recent report examining the feasibility of new fuels such as LNG and their affordability. In its position paper The Fuel Trilemma: Next Generation of Marine Fuels, DNV GL looked at the rapidly diversifying fuel market from the perspective of affordability, sustainability and safety, noting that these three factors will govern the success of any energy source chosen to meet regulatory requirements for CO2, SOx and NOx – requirements that are already pushing the limits of what can be achieved with conventional fuels and exhaust gas cleaning technology.

“In all cases, the cost associated with machinery, as well as the expected fuel price, will play an important role for shipowners as they make changes to their fleet,” said Christos Chryssakis, a senior researcher at DNV GL. “However, safety and sustainability have an impact

on affordability. Sustainability, assessed from a lifecycle perspective, will determine the availability of various fuels in the future and could constrain the energy mix locally or globally.

Novel design solutions may introduce a level of complexity that affects newbuilding costs and operational reliability. Even well known solutions such as LNG involve considerable ship design and equipment changes to ensure safe operation, and there are also external risks to be considered – a major accident could turn regulators and the general public against an otherwise promising fuel option.

“If it works in the Gulf, the potential to expand LNG fuelling to other forms of transport such as inland waterways, rail, mining, construction and trucking is huge,” said Mr Hatley. The fact that the shipping industry is notoriously conservative makes what Harvey Gulf has achieved all the more impressive.

“They took the plunge. Many companies think, ‘What I have works just fine, thanks very much,’ but Harvey Gulf wanted to be a pioneer and sees new

things as an advantage,” he said.

Mr Verret added that, in his view, Harvey Gulf’s customers will be the ones to reap the rewards with lower fuel costs and lower emissions. “I think we have taken a leadership role in taking technology from the North Sea in Europe and transferring it to the US for the benefit of our customers in the Gulf,” he said.

“Everyone is very curious, and now they say, ‘OK, maybe this works,’ whereas before, they thought LNG was just a quick fix. I think we will see a huge move towards LNG.” In fact, a move is already visible. Three years ago, there were no LNG vessels in the Gulf. Today, there are plans to introduce more than 40 LNG-fuelled ships in North America – 17 ferries, 12 tankers and bulkers, six offshore vessels, six container ships and one articulated tug barge. That could just be the start, Mr Hatley concluded. “I think that, because of the strong economics for gas in North America, there will be wider adoption here, and we may eclipse Europe in five years’ time.” OSJ

Overcoming infrastructure hurdles Undoubtedly, the biggest hurdle to be overcome before LNG can become more widespread as a marine fuel in the US is the development of bunkering infrastructure to support ships that use it.

Writing in a recent issue of Benedict’s Maritime Bulletin, Bryant E Gardner, a partner at Winston & Strawn LLP in Washington, DC, described LNG fuelling as a significant hurdle to widespread adoption of LNG and noted that, for the foreseeable future in the US, targeted portspecific development will probably be driven by ad hoc development through regular, localised contracts between suppliers and vessel operators, such as the Harvey Gulf development of a bunkering station in Port Fourchon to support its offshore fleet. “High volume onshore bunkering stations can be augmented by mobile vessel-to-vessel and truck-to-vessel bunkering options where needed,” he said.

However, as he pointed out, there is also a ‘regulatory gap’ for LNG bunkering and associated infrastructure operation to ensure consistent safety standards and guidelines across jurisdictions and proper training for crew, operators and first responders involved with LNG bunkering operations and contingencies.

He noted that meaningful development of LNG bunkering infrastructure could also encounter significant local political interest in decisions regarding large-scale trucking versus rail or pipeline transport and local liquefaction, and federal involvement will be required both to ensure uniformity and the achievement of nationally important onshore infrastructure in support of maritime commerce, although he said LNG industry participants have shown they are capable of handling the regulatory approval process for LNG import terminals and subsequently export terminals, which are of significantly larger scale than bunkering facilities.

OSJ Guide to OSV Propulsion 2015

XVI | PRIME MOVERS medium speed engines

More power – and fuel choices – available with fast-evolving engines Impending new emission standards will be a driving factor in the choice of engines for new vessels, but leading makers are ahead of the game and are ready with cleaner and more powerful options

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stable (including MaK models) are the most popular across all vessel types. However, not all fall into the medium speed bracket. Caterpillar’s highly popular 3500 series, with a specified speed range of 1,200–1,925 rpm, is considered as being in the high speed range and is described as such by its maker. However, Chinese manufacturer Weichai – which produces MAN engines under licence and which also has its own range of engines – describes its inhouse 170 series with a speed range of 1,000–1,500 rpm as a medium speed engine.

In terms of engine numbers, most vessels are equipped with multiple engines except for a small number of mainly safety standby vessels (nowadays usually known as emergency response and rescue vessels or ERRVs) that make do with just a single main engine. The installation of two or more engines is a traditional configuration but one that is, in any case, essential on dynamic positioning capable vessels because of the redundancy requirements of class societies. While there has been a tendency for the number of engines to increase in recent years, two or four is still the most usual number.

he offshore support vessel (OSV) sector comprises a wide range of vessel types, but with regard to propulsion choices, many employ medium speed engines for all but auxiliary and emergency generator purposes, when a high speed engine may be chosen. High speed engines are also abundant, especially on smaller vessels, but only a very small number of vessels are fitted with low speed engines.

Over the years, the number of enginemakers has diminished due to mergers and acquisitions. Even so, nearly 20 different makes have been installed on offshore ships built over the last two decades. Although some names have disappeared, there are newcomers too, such as Hyundai Heavy Industries’ in-house Himsen brand, and the entry of Chinese yards into the offshore sector has also seen some less familiar engine brands appearing in the reference lists.

The six leading manufacturers of medium speed diesels in terms of ship numbers powered are Caterpillar (including MaK), Wärtsilä, Rolls-Royce, Niigata, Yanmar and MAN Diesel & Turbo.

Between them, these six manufacturers feature on around 90 per cent of OSVs built between 1995 and today (including newbuildings on order).

Exactly what constitutes a medium speed engine varies according to accepted ideas and manufacturers’ own descriptions. Most sources suggest a speed of between 300 rpm and 1,000 rpm is the accepted range of medium speed engines, although Niigata has several engines that run at between 310 rpm and 420 rpm, which the Japanese maker rates as low speed, and its medium speed range has models that run at between 900 rpm and 1,200 rpm.

Wärtsilä chose Nor-Shipping 2015 in June Without a doubt, engines from the Caterpillar to launch its latest engine, the Wärtsilä 31 OSJ Guide to OSV Propulsion 2015

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medium speed engines PRIME MOVERS | XVII

Environmentally friendly, fuel-efficient diesel-electric machinery has been widely adopted on many offshore vessels

Another feature of the OSV sector is the fact that dieselelectric propulsion has become more common compared to direct mechanical propulsion. This means that most engines installed today are running gensets rather than gearboxes.

Another recent development that has taken place in the offshore vessel market is the advent of hybrid propulsion systems where diesel-electric and direct or geared drives are combined.

For the past five or six years and until the price of crude began to slide, the offshore sector was, for many builders, the most buoyant in the industry. As a consequence, fourstroke engines and medium speed variants in particular have dominated sales in terms of numbers. As a rule, the basic four-stroke engine types found on ships have counterparts for use in land-based applications both in power generation and transport – a factor that permits more R&D and testing to be carried out on engines because of larger production numbers.

Although the vast majority of four-stroke marine diesel engines run on oil fuels, much of the recent development by major producers has focused on the development of dual-fuel and pure gas-burning versions of their engines. Along with ferries, offshore vessels are considered the most suitable ship types to be fitted with engines burning liquefied natural gas (LNG).

Norway has incentivised this development with NOx tax penalties for oil burners and NOx fund subsidies for those owners prepared to pioneer LNG-fuelled ships. There are no similar incentives in US waters, although the emission control area (ECA) means there is a reason to consider engines and fuels that can allow operation without the need to install exhaust gas cleaning systems or burning expensive distillates. As highlighted elsewhere in this special supplement, the ECA will become a major factor influencing engine choice for newbuildings planned for US waters – next January, the new, stricter rules come into force.

In Norway, LNG as a fuel for medium speed engines has been used for more than 12 years since Stril Pioneer was delivered in 2003. February this year saw Harvey Energy become the first LNG-fuelled offshore vessel in the US. Harvey Gulf International Marine, the owner of Harvey Energy, is committed to the new fuel to the extent that it is establishing its own bunkering facilities and has also recently ventured into shipbuilding in order to build LNG-fuelled vessels for other companies.

The number of LNG powered engine models is increasing and whereas once the choice was limited to either a Wärtsilä dual-fuel engine or a Rolls-Royce pure gas Bergen engine, today, the choice is expanding rapidly. As well as more models from the early pacemakers, MAN Diesel, Caterpillar (MaK), Doosan, Himsen, ABC and Niigata and others either have dual-fuel engines in production or engines that are close to commercialisation. Not all have yet notched up OSV references, but since all are active in the sector, the likelihood that they will soon gain a first reference must be quite high.

Wärtsilä chose Nor-Shipping 2015 in June to launch its latest engine, which will be available in dual-fuel, oil or pure gas spark ignition versions. It will be produced in 8-cylinder to 16-cylinder configurations and has a power output ranging from 4.2 megawatts (MW) to 9.8MW at 720 rpm and 750 rpm.

The Wärtsilä 31 engine is described by its maker as having “significantly reduced maintenance requirements, while raising fuel efficiency, fuel flexibility and operational optimisation to totally new levels”. Its fuel consumption efficiency in its diesel version is as low as 165 g/kWh, and it is claimed to have the highest cylinder power in its segment – 610kW/cylinder. www.osjonline.com

The engine is designed to serve a variety of vessel types requiring main engine propulsion in the 4.2–9.8MW power range.

In the offshore sector, it is targeted at anchor-handling tug/ supply (AHTS) vessels, other OSVs, drilling and semi-submersible vessels where the requirements are for operational flexibility, high power density, long intervals between overhauls and high levels of safety. The multifuel capabilities that the Wärtsilä 31 brings to the market extend the possibilities for operators to use different qualities of fuels, from very light to very heavy diesel, and a range of different qualities of gas. The first service is required after only 8,000 running hours, as opposed to a typical 2,000 running hours for some other production engines.

The introduction of an advanced fuel injection system, combined with newly developed air injection technology, enables efficient and economical use of low sulphur fuel oils (<0.1 per cent sulphur) without any restrictions on low load running, making the Wärtsilä 31 especially suited for operating in ECAs. The engine is optimised to comply with current and anticipated IMO and EPA emissions legislation when coupled together with the Wärtsilä NOx reducer without any penalty in fuel consumption. The advanced UNIC engine control system, the advanced injection system and variable valve timing makes it possible to achieve the engine’s optimal running performance at any load.

The modular design reduces the time spent on maintenance as fewer parts are used in the engine, and instead of dismounting and overhauling individual components, larger assemblies can be exchanged. The shift from single parts to exchange units, such as power units, injectors and HP fuel pumps, enables more efficient maintenance resulting in less downtime. The modular design also facilitates engine conversions to use different fuels, for example, from diesel to gas, merely by replacing modules and without any machining.

Speaking at Nor-Shipping 2015, Roger Holm, senior VP, ship power engines at Wärtsilä, described the years of development work that went into it. “With this product, Wärtsilä is capable of providing customers with the marine industry’s most advanced, powerful, fuel efficient, fuel flexible and environmentally sound engine,” he claimed. “With this breakthrough development, which is based on the introduction of the very latest technology, we can now open the doors to a new level of optimisation that is valid throughout the entire life of the vessel.”

Just weeks before Nor-Shipping, MAN Diesel & Turbo OSJ Guide to OSV Propulsion 2015

XVIII | PRIME MOVERS medium speed engines

reported the latest developments in bringing its L35/44DF engine to market and announced that the engine had received type approval from all major class societies and was undergoing factory acceptance tests. The L35/44DF engine was first unveiled by MAN at SMM in Hamburg in 2012 as a retrofit option for the L32/44CR-T2 engine that formed the centrepiece of the maker’s stand.

MAN Diesel & Turbo’s development objective with the new engine was to produce a high efficiency/high specific power output unit that complied with IMO Tier II emission limits in diesel mode and IMO Tier III limits in gas operation. A high degree of fuel flexibility (HFO, MDO, MGO and natural gas) was another primary objective. With an output of 530 kW/cylinder, the inline L35/44DF is available as 50Hz or 60Hz variants and in 6–10-cylinder configurations, equivalent to total power outputs from 3.2MW to 5.3MW. The L35/44DF engine was specifically developed for the retrofit of L32/44CR-T2 engines with the advantage of a high level of component synergies and the same crankcase, which can be remachined onboard. Subsequent engine operation is mainly intended for gas mode with a separate pilot ignition system that is independent of the primary, common rail injection system. However, the common rail system is retained and fully functional as a backup system in the event of any problem while operating in gas mode.

Describing the reaction of the class representatives at the type approval test, Dr Günter Heider, a senior manager at MAN Diesel & Turbo and head of test and validation, fourstroke diesel and gas engines, said, “Among the features that were specifically appreciated and praised were the quick changes over from gas to diesel mode at 100 per cent load, the restriction-free gas load performance at an overload of 110 per cent and the engine’s logic and clear modular design.”

Before the launch of the Wärtsilä 31, Rolls-Royce claimed the highest power per cylinder in the segment with the 600kW output of the new Bergen B33:45, which was launched nine months earlier at SMM in 2014. The engine was designed with the main objective being a reduction in lifecycle costs, which would be achieved by a modular design, and a 20 per cent power increase over the current B series while still retaining the same footprint.

Inline engines will be the first to be produced, with V engines to follow later. Inline 6, 7, 8 and 9-cylinder units span a power range from 3,600kW to 5,400kW and V engines 6,000kW to 8,400kW running at 450–750 rpm as a direct propulsion engine or 720/750 rpm for 60/50Hz generator set drive. The engine can run on all types of oil fuels, and a gas variant is planned for the future. Specific fuel consumption is 175 g/kWh at 85 per cent MCR and 177 g/ kWh at full load.

Drawing on the tie-up with MTU, some of the development of the engine was done using the German branch’s CFD expertise, and the engine control system is the electronic OSJ Guide to OSV Propulsion 2015

engine management system from MTU, which was developed inhouse. It monitors and controls all key engine functions and exhaust after treatment.

The B33:45’s foundation is a more rigid SG iron block than the current B-series and has permitted reduced vibration levels of 10–11 m/sec. It supports the balanced crankshaft, which is the same for both propulsion and generator applications. Cylinders are individual units that can be removed complete within a service height of 2.52m above the crankshaft centreline. Connecting rods are of marine three-piece type allowing piston removal without disturbing big end bearings. The strengthened camshaft design has one section per cylinder for ease of replacement.

A totally new turbocharger is matched to the exhaust system, which provides multipulse charging with charge air taken through a two-stage intercooler and gives high turbo efficiency. Another feature is a reduction in the amount of external pipework, which ensures a safe yet simple fuel system design. This has been achieved by putting the oil bores into the cylinder heads, and the passages are joined by simple transfer blocks. The system is common rail ready, with the conventional system providing maximum flexibility for different applications.

Meeting IMO Tier III NOx emission requirements was another important goal and is achieved with urea selective catalytic reactor technology. NOx levels within IMO limits have been successfully validated running from 10–100 per cent load.

The control unit is integrated into the engine controller, and compact selective catalytic reduction (SCR) units will come in various sizes to match the engine power selected.

To date, none of the three engines described have secured offshore orders, a reflection perhaps on how few vessels have been ordered since the oil price fell so steeply, but all are evolutions of engines favoured in the OSV sector. The same is true of Caterpillar Marine’s MaK M34DF dual-fuel engine, based on the popular M32 which, like the MAN engine, can be retrofitted by converting the older base engine in situ. OSJ

The Bergen B33:45 was designed with reduced lifecycle costs firmly in mind and a 20 per cent increase in power

www.osjonline.com

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Baudouin has developed a particularly strong relationship with Penguin and its crewboats

XX | PRIME MOVERS high speed engines

WHEN SPEED MATTERS, THE CHOICE IS GREAT

M

oving crew rapidly to offshore facilities can be undertaken other than by vessels, for instance, by helicopter, but this is not a practical or economic option in many areas of the world.

Although the fast transfer sector began in the US oil and gas sector, today, it is common in offshore wind for maintenance and workboats to be constructed along similar lines.

Crewboats themselves come in many different sizes and capabilities, which means that their propulsion options also vary. Those options – be they for vessels capable of working regularly in heavy seas or for craft able to provide rapid transport in more benign conditions – are delivered by a range of engine and final drive suppliers.

Crewboat propulsion is dominated by two engine manufacturers, Cummins and

OSJ Guide to OSV Propulsion 2015

Caterpillar, although there are several other enginemakers in the market, such as Yanmar, MTU, Baudouin, MAN, Scania, Volvo Penta and GE. The engines are almost exclusively high speed units, and the final drive of most crewboats generally comes down to a choice of two options – conventional mechanical drive through gearboxes or waterjets.

Around one in six crewboats is fitted with waterjets as opposed to conventional propellers, and the number of vessels with waterjets built annually has increased since the turn of the century, but the growth has been gradual and appears to have plateaued over the last five years.

Although MTU is considered a German maker and now part of the Rolls-Royce family, the genesis of many of the company’s 2000 and 4000 series of products used in crewboats is US-based, as the

original Detroit Diesel has been passed through several hands before ending up at MTU. That the engine family is well known in the US where crewboats have been part of the offshore scene for longer than in Europe or Asia is a major factor in its continued popularity. The same is also true of the Caterpillar and Cummins engines, which dominate the sector.

Caterpillar’s range of engines is spearheaded today by the C32 ACERT engine most usually connected via a gearbox to a fixed pitch propeller but with the occasional waterjet-propelled vessel built. The C32 is a 12-cylinder engine available in four different power ratings, and with engine speeds between 1,600 rpm and 2,300 rpm, it can produce from 492kW up to 1,194kW. The range of vessel types

Very few vessels in the offshore sector are capable of speeds in excess of 20 knots, and the vast majority of those are crewboats or fast supply vessels

fitted with the C32 engine is extensive and varied, and none can be said to be typical. A recent delivery is the SeaZip 4, the fourth Damen Fast Crew Supplier 2610 in the Dutchbased SeaZip Offshore Service fleet. The catamaran hulled vessel is one of the first Twin Axe Bow service vessels to be deployed in the offshore oil and gas industry, as all other vessels of this type – including SeaZip 4’s three sister vessels – provide services for the offshore wind industry. Harlingen-based SeaZip Offshore Service has a partnership agreement with Heerema Marine Contractors (HMC) and has contracted service vessel SeaZip 4 for its annual project activities in the North Sea. The 26.3m aluminium hulled vessel has 90m2 of deck space and accommodation for four crew and 12 passengers. It can achieve www.osjonline.com

a service speed of 25 knots thanks to a pair of Caterpillar C32 TTA engines each rated at 895kW at 1,800–2,000 rpm and linked through Reintjes ZWVS 440/1 two-speed gearboxes to fixed pitch propellers. Since late May, SeaZip 4 has provided logistic services to support operations in the North Sea, which HMC carries out for various international clients.

More power than the C32 engines can deliver is available from the Caterpillar 3512 engine, which is also a 12-cylinder V engine available in four power ratings but is a slower revving engine with a choice of 1,600 or 1,800 rpm, resulting in a power range from 900kW to 1,305kW. The more powerful 3516 has – as the designation suggests – four additional cylinders being a V16 engine. These two engines are also highly popular choices for slower vessels such as platform supply vessels.

The potential of the larger 3516 engine is exemplified by the crew supply vessel Mr Steven, built this year by Gulf Craft of Franklin, Louisiana, for SeaTran – a local operator formed in 2014 by the amalgamation of three crew transfer operators.

Mr Steven is fitted with four Caterpillar 3516C engines each connected to twin disc MGX61500JC gearboxes and driving a Hamilton Jet HT810 waterjet. Total power output is 7,680kW, and the maximum light ship speed is 32 knots. Fully loaded, the maximum speed is 26 knots.

Mr Steven provides an interesting comparison with the slightly older (by six months) Captain Elliot built by the same builder for the same owner.

In most respects, the vessel’s dimensions and capabilities are identical except for the fact that the older vessel has accommodation for 62 passengers and the newer ship 72 passengers. The main difference between the two lies in the choice of engines. Instead of the Caterpillar engines of Mr Steven, Captain Elliot is fitted with www.osjonline.com

four Cummins QSK60-M engines but has the same gearboxes and waterjets. Captain Elliot’s engines are very slightly more powerful, as each is rated at 1,986kW as opposed to 1,920kW. The vessels’ speeds are identical, and both vessels have DP2 dynamic positioning capability.

Cummins is a sector leader when it comes to numbers of ships fitted with its engines.

The company’s KTA series has been available for over a quarter of a century, and the KTA38 is arguably the most popular engine in the sector. A V12 engine with an output of 1,120kW at its most powerful rating and speed, the KTA38 is usually installed in a propeller drive system. The V16 KTA50 is a more powerful engine and is commonly paired with waterjets. Cummins’ advanced Quantum System versions of the K engines – the QSK50 and QSK60 – have yet to achieve the volume sales of the KTA38 and KTA50 engines but are growing their presence in the sector.

A quartet of MTU 16V4000M73L engines each producing 2,880kW linked to four Hamilton HT 900 waterjets feature in the 70m long Incat-built vessel Muslim Magomayev. The vessel is the first that Incat Tasmania has purpose built for the oil and gas industry and is now operating in the Caspian Sea. This first of type DP2 class vessel is owned

by Caspian Marine Services and operates fast crew transfers for 150 offshore workers to multiple installations in the Caspian Sea. The semi-small waterplane area twin-hull design, along with active ride control, is said to increase comfort and reduce stress on passengers.

Muslim Magomayev is capable of carrying 150 passengers and 14 crew, along with deck cargo, in up to 40 knot winds and seas of 3m significant wave height. Its 16m beam is far narrower than is usual for an Incat catamaran but was determined by the

BS Camburi is fitted with a trio of Caterpillar C32 main engines, coupled to Doen DJ290 waterjets

width of the Volga-Don Canal.

Anticipated design speed was 36 knots with an efficient service speed of 30 knots at full load and 90 per cent maximum continuous rating.

MAN diesel engines are the prime movers for more ships than any other, but the German maker is best known for its massive low speed two-strokes and medium speed engines than for high speed units. At SMM in 2014, MAN’s high speed division launched its latest and most powerful engines for commercial marine applications.

Replacing the existing D2862 LE 431 and D2842 LE 421 with their 662kW output, the D2862 LE 44x is now taking the lead, with a performance of up to 735kW (1,000hp).

The 12-cylinder V engine is available in two versions: the IMO Tier II-compliant D2862 LE 441 and the D2862 LE 444, which fulfils EPA Tier 3 commercial. By adapting the turbocharger and the valve timing, MAN was able to raise the mean pressure and increase the power rating by 73kW compared to the most powerful engines available until now.

With a capacity of 24.24l, a

bore of 128mm and a stroke of 157mm, the engine can achieve a maximum torque of 4,380Nm at 1,100–1,600 rpm.

The MAN D2862 LE and the medium duty D2842 LE engines have been installed on around 30 crewboats since 2006, mostly on craft built in Vietnam for Bourbon Offshore subsidiaries. In all but one case, the engines power waterjets.

French enginemaker Baudouin has developed a particularly strong relationship with the Penguin Shipyard in Singapore, supplying multiple engines for several vessels built there, and at the wholly owned subsidiary Kim Seah Shipyard in Indonesia. Some of the vessels are operated by other subsidiaries of the yard. The engine of choice is the 12 M26.2.

Baudouin’s 12 M26.2 is, like many of the engines favoured by the sector, a 12-cylinder V engine with a displacement of 31.8l and a power range from 662kW to 883kW at 1,800 rpm and 1,950 rpm respectively. A more powerful and higher revving M26.3 model based on the older version was launched last year but has yet to notch up an initial reference in the sector. OSJ OSJ Guide to OSV Propulsion 2015

XXII | ELECTRIC PROPULSION

Electric solutions avoid losses and provide wide-ranging benefits In the last couple of years, propulsion system providers have taken the dieselelectric concept a step further and brought new solutions to market that keep the advantages of this kind of machinery, tackle issues associated with it such as losses and add in a host of other benefits

D

iesel-electric power is almost considered the norm for many types of offshore support vessels (OSVs), with most ships having four or six diesel gensets and a pair of main propulsion motors, sometimes driving through a gearbox but often directly linked to the main propulsors, especially where the thrust is provided by azimuth thrusters rather than conventional propellers.

Multiple gensets allow total power output to be matched to demand with the engines running at optimum speed.

When less power is needed, there is no need for all the engines to be running, thus allowing for fuel

savings. The number of engines also confers a high degree of redundancy on a diesel-electric ship where even one engine will permit the vessel to maintain some controlled motion in all but the heaviest of seas.

The flexibility that dieselelectric propulsion can bring does come at a price, with open seas propulsion efficiency being adversely affected by energy losses in the additional equipment that is necessary. However, for an offshore vessel, where open seas propulsion accounts for perhaps just one-third of the use of the engines, this is much less of a problem because of the optimum running of engines that can be

Edda Ferd was the first application of Siemens BlueDrive PlusC concept

managed at other times. A further benefit comes in the flexibility of layout, as there need not be a clear direct line between engine and propellers. Thus, engines can be located in line of one and another or offset in a layout that can take account of other needs of the vessel.

As diesel-electric has become more popular, so system makers have striven to improve the efficiency and reduce costs simultaneously. The result is a proliferation of concepts from enginemakers and others. Among these are Wärtsilä’s Low Loss Concept (LLC) (see elsewhere in this special supplement), Siemen’s BlueDrive PlusC, MAN’s EPROX (electric propulsion excellence) and ABB’s Onboard DC Grid (also highlighted elsewhere in this supplement).

Wärtsilä LLC dates back to 2004 when a system was ordered for the VS4420 platform supply vessel (PSV) Normand Skipper and has been in continuous development since. Before the advent of the system, the usual way to reduce the harmonic distortion in the distribution network caused by the frequency drives of the propulsion motors was to place a 12-pulse transformer between each frequency drive and the switchboard. Wärtsilä devised a way to overcome this problem by splitting the distribution bus

into two sections and placing a single transformer between the two buses.

With Siemen’s BlueDrive PlusC system developed in 2011, individual speed control of each engine over the whole engine speed region is possible.

BlueDrive PlusC is based on fully integrated power distribution, with the main switchboard and all drives collected into one compact unit. The main switchboard has in/out AC voltage and supplies clean power to other switchboards. Engine speed is controlled to optimise fuel consumption and reduce loaddeviation issues.

Over the past few years, DC distribution systems have been promoted as an alternative that has benefits in simplifying the distribution and reducing components and an added advantage if batteries are to be incorporated into the system. As Siemens and others have noted, battery technology is seen by many as a very promising energy efficiency measure for OSVs and many other vessel types. While they can be integrated into a DC distribution system more easily, their use is not confined to DC grid systems alone. Siemens’ revolutionary propulsion system uses variable rotational speed with optimal operation of the diesel generator in combination with batteries to significantly

www.osjonline.com

ELECTRIC PROPULSION | XXIII

reduce fuel consumption and the emissions of NOx and greenhouse gases. Siemens claims that the variable speed propulsion concept reduces total energy consumption by 15 per cent compared with earlier diesel-electric systems and by 23 per cent compared to gas/ dual-fuel engines. Total NOx and greenhouse gas emissions are lower compared with vessels using conventional diesel-electric or gaspowered solutions. The company says a comparison with the results obtained with dual-fuel offshore vessels with the same operating profile showed that greenhouse gas emissions were 27 per cent lower for the variable speed diesel engine alternative.

MAN has taken a rather different approach with its EPROX system. In a recent presentation, Bernd Friedrich, head of power trains and auxiliary equipment at MAN Diesel & Turbo SE, highlighted the highly flexible and redundant features of a conventional multi-engine diesel-electric arrangement but drew attention to some of the issues with such an arrangement, notably the question of losses between the fuel and combustion to the shaft power achieved.

He described MAN’s new system in which, as he put it, “good old DC is coming back” and existing components are arranged in a new way. As he explained, a DC system removes the switchboard usually found in a conventional AC arrangement, and the alternators are connected via rectifiers. The propulsion motors are connected and their speed controlled via inverters. The diesel engines can operate independently, and no synchronisation of the alternators is required. In the EPROX, it is also possible to integrate energy storage devices such as batteries, with the batteries connected to the DC grid via DC/DC converters. These energy storage sources can be used to reduce transient loads on the engines and help provide a faster, more dynamic system response. Load peaks are ‘shaved’ and buffered www.osjonline.com

by the batteries. Mr Friedrich concluded that this new energysaving solution would facilitate significant reductions in fuel consumption by operating the engines at variable speed.

Energy storage would provide an additional degree of freedom in diesel-electric plant design, and he described additional measures that could be used to improve a diesel engine’s dynamic performance, such as jet assist and boost injection.

The first use of a battery onboard an OSV was on Eidesvik’s Viking Lady two years ago. Eidesvik has been an enthusiastic supporter of innovation, and the ship itself has been used as a test bed for liquefied natural gas, fuel cell and battery technology. The battery system onboard Viking Lady was supplied by Canadian battery specialist Corvus and comprises 68 packs each rated at 6.5 kWh for a total capacity of 442 kWh. It is used to aid the DP system of the ship.

In May this year, Eidesvik announced a new battery retrofit project, this time on the dualfuelled Viking Queen – a 2008built 6,200 dwt PSV powered by four Wärtsilä 6L32DF engines.

The project will be supported by the vessel’s charterer, Lundin Norway, and Eidesvik along with the system supplier, Norwaybased Zem Energy, a newcomer to the marine scene as far as battery systems are concerned that has been selected to supply the battery system.

The energy storage system (ESS) will have a capacity of 650 kWh and can supply up to 1,600kW, which it is hoped will give a fuel saving of approximately 18 per cent for the vessel, with associated reductions in emissions.

To Zem Energy, the contract for delivery of a high efficiency battery system for Viking Queen represents a breakthrough, as CTO Egil Mollestad noted.

“Zem has, through several years of research, development and advisory work, built

comprehensive competence on battery systems. Therefore, we are now able to deliver competitive solutions to the maritime industry. We are proud that such a leading offshore company as Eidesvik has chosen us,” he said.

Salman Farmanfarmaian, Zem Energy’s co-founder, said the company is working with Nidec ASI, which is supplying the power electronics, and with Wärtsilä to integrate into the ship’s power management system. The battery system will be housed in two containers and will weigh around 32 tonnes. Mr Farmanfarmaian also said that the battery pack will have active cooling and that, for several years, Zem Energy has been continuously testing different battery cells to understand, quantify and model their behaviour – notably the heat generated by different load cycles and their effect on the battery’s degradation. “For this application, we believe it is important to actively cool each and every battery cell individually,” he said, adding that the cold northern waters certainly help to achieve an effective cooling solution.

Eidesvik is not the only offshore operator showing an interest in batteries. In April this year, operator Østensjø Rederi announced that, along with Corvus Energy and Siemens, it

would extend a partnership with a second offshore vessel project. The new 150m MPSV, to be named Edda Freya, will incorporate a 1050 VDC, 546 kWh Corvus ESS consisting of 84 Corvus Energy AT6500 advanced lithium polymer battery modules.

This new project follows on the heels of the Edda Ferd hybrid PSV project completed by the same partners in 2014.

The Corvus ESS will again be integrated with the Siemens BlueDrive PlusC electric propulsion solution that will provide efficient hybrid propulsion to the new MPSV and also provide backup power in the case of blackout. The two vessels are part of Østensjø Rederi’s environmental concept Mindset. The vessels optimise the use of diesel generators and the ESS to significantly reduce fuel consumption and emissions, allowing a 20–25 per cent energy saving over comparable vessels.

As also highlighted elsewhere in this supplement, the most recent member of the ‘battery pack’ is Icelandic operator Fafnir Offshore, which was another OSJ award winner, having picked up the OSJ Environmental Award for their battery-powered PSV, a Havyard 833 WE ICE design that has its battery supplied by Norwegian Electric Systems (NES). OSJ

Eidesvik has announced a new battery retrofit project on the dual-fuelled Viking Queen

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FAILURE

IS NOT

AN OPTION. Heading north towards the frozen Arctic, Chief Officer Sunil and the rest of the Polarcus Naila crew ready themselves for their next seismic survey. But however brutal and unforgiving the environment, mechanical failure and downtime are still unacceptable. The stakes are simply too high.

WATCH THE FILM: storiesfromsea.com

catpropulsion.com © 2014 Caterpillar. All Rights Reserved. CAT, CATERPILLAR, BUILT FOR IT, their respective logos, ”Caterpillar Yellow,” the ”Power Edge” trade dress as well as corporate and product identity used herein, are trademarks of Caterpillar and may not be used without permission.

PROPULSORS | XXV

THRUSTER EVOLUTION

REVOLVES AROUND EFFICIENCY Having long enabled offshore support vessels to manoeuvre and maintain positon in dynamic positioning mode, new types of thrusters and podded propulsors have recently been developed that promise even greater levels of efficiency and reliability

The latest addition to Roll-Royce’s thruster portfolio is a range of azimuth units powered by permanent magnets

I

f a couple of recently delivered offshore vessels had to be identified that highlight the importance of thrusters on offshore vessels, those vessels would surely have to be Viking Neptun, which was delivered to Eidesvik Offshore in Norway earlier this year, and the semi-submersible offshore accommodation vessels Posh Xanadu and Posh Arcadia, the first of which was delivered in January by PaxOcean Engineering of Zhoushan.

Each of the accommodation vessels will have no fewer than nine Brunvoll thrusters, including two AW100 azimuth propulsion thrusters located aft, two FU100 tunnel thrusters (one forward and one aft) and five azimuth retractable AR100 thrusters for manoeuvring – three are installed across the forward part of the vessel and the remaining two one each side aft. Between them, the thrusters have a total power output of 20,876kW. Now on long-term charter to Technip, Viking Neptun is the largest in Eidesvik’s fleet and the largest built by Kleven Verft in Norway. Designed by Salt Ship Design, the vessel is 145m long with a breadth of 31m and accommodation for 150 people. It has two main propellers from Wärtsilä (driven by a twin-in and single-out gearbox) and seven Brunvoll thrusters. The vessel has eight engines from Wärtsilä and a maximum speed of 17.2 knots.

In truth, however, the thrusters on these impressive vessels are fairly conventional units, whereas the focus of ongoing development www.osjonline.com

efforts at manufacturers and on products launched in the last six months or so has been much more revolutionary.

Among the latest additions to the growing range of thrusters intended for main propulsion is ABB’s Azipod D, which adds to its portfolio of smaller podded propulsion systems such as Azipod C. The D range, which comes in various options with or without nozzles, was described at its launch as “an advance in gearless thruster technology that will maximise flexibility of a wide range of vessels such as offshore support vessels, increasing charter opportunities while lowering maintenance costs and cutting fuel consumption for a variety of missions”.

The podded propulsor is described as 25 per cent more fuel efficient than its predecessor and is available in power ranging from 1.6 megawatts (MW) to 7MW. ABB claims its use can enhance propulsion efficiency when a vessel is in dynamic positioning (DP) mode. It can be adapted to fit varying hull shapes and incorporates a new air and water cooling system, helping reduce the thruster’s weight.

Rolls-Royce presented the latest addition to its range of thrusters at Nor-Shipping 2015 in Oslo, unveiling a new azimuth thruster powered by permanent magnet (PM) technology. The group already has PM-driven tunnel thrusters in its portfolio. Permanent magnet OSJ Guide to OSV Propulsion 2015

XXVI | PROPULSORS

technology for thrusters is not unique to Rolls-Royce, however – Brunvoll, Schottel and Voith have also designed and built similar products, although most are rim drive variants without a central shaft.

The first application of PM technology for thrusters was on tunnel thrusters with a permanent magnet motor in a rim, which drives the propeller in the centre. The permanent magnet motor consists of two main parts – a stator that carries a number of electrical coil windings and a rotor fitted with a number of very strong permanent magnets. A rotating magnetic field is created by the stator, which interacts with the fields of the permanent magnets on the rotor and generates force to drag the rotor around, providing the mechanical power.

The launch of the azimuth thruster with PM drive follows a programme of sea trials in which a pair of thrusters demonstrated efficiency savings of 7–13 per cent depending on ship speed and in comparison to azimuth thrusters powered by a conventional diesel-electric system. The trials took place on the research vessel Gunnerus, the Norwegian University of Science and Technology (NTNU) research ship, based in Trondheim.

Helge Gjerde, Rolls-Royce’s senior vice president for propulsion, commercial marine, said the performance of the thruster had exceeded the company’s expectations in terms of efficiency.

“The sea trials are continuing, but initial findings have significant implications. PM thrusters will become a valuable supplement to conventional thruster technology,” he said.

Apart from improved fuel economy, other benefits of the PM-driven azimuth thruster include more power through a propeller of the same diameter, reduced noise and vibration and scope to remove and maintain PM thrusters without the need for drydocking.

The trials on Gunnerus follow operation of Rolls-Royce’s first commercial permanent magnet tunnel thruster by Olympic Shipping, the Norwegian offshore vessel operator. The tunnel thruster, now in operation onboard Olympic Octopus, a multifunction anchorhandling tug/supply vessel of Rolls-Royce UT 712 L design, has clocked up more than 4,000 trouble-free running hours.

Another recent arrival in the offshore sector is the Voith Linear Jet (VLJ) propulsion system. Successful tests on the VLJ were carried out off the Isle of Wight in the UK at the end of 2014. VLJs were selected as the main propulsion system on the 21m catamaran Trearddur Bay, which was designed for Holyhead Towing Company subsidiary Turbine Transfers by BMT Nigel Gee. The VLJ is a new type of propulsor combining the best properties of conventional propellers with the best properties of conventional waterjets. At first sight, it looks to be a conventional propeller housed inside a nozzle, but it actually comprises a fully submerged custom-shaped deceleration/acceleration nozzle with a stator section aft of the rotor. The stator section cancels rotorinduced swirl and through that optimises the acceleration of the jet stream and the rudder inflow. The submerged position eliminates the requirement for a long inlet tunnel resulting in linear inflow and outflow and low marine growth sensitivity. The resulting benefits of this are increased efficiency and reduced noise and vibration levels.

The crew transfer vessel the system was tested on will take service technicians to offshore windfarms at sites all around Europe, initially at the Westernmost Rough site off the Humber for Dong Energy. The craft has achieved a trials speed of 30 knots – above expectations when compared to 26.5 knots for a near sister with jet propulsion. The efficiency of the VLJ would allow the craft to achieve the economical service speed of 25 knots required by Turbine Transfers even if the currently installed 10-cylinder 900kW engine was replaced with an 8-cylinder 720kW unit.

OSJ Guide to OSV Propulsion 2015

“The vessel is achieving more thrust at high speeds and when stopped in the water and pushing on a turbine than with conventional systems while achieving significantly lower noise and vibration levels,” said Alistair Knowles, a marine superintendent at Turbine Transfers. “It also adds to our green credentials through substantial fuel and emissions savings in our operations.”

VLJs are expected to be of interest in the workboat sector, the fast ferry and military and para-military markets. They are also expected to have potential applications on yachts and superyachts.

In broad terms, the new propulsion system’s key benefits are lower fuel burn than vessels with waterjets or propellers. The high efficiency of the VLJ over a wide speed range means that, at 25 knots – where waterjets are not particularly efficient – the VLJ is significantly better. For vessels with fixed pitch propellers, power density becomes an issue above 30 knots, whereas the VLJ can be used for speeds of up to 40 knots without any such issues.

Other recent additions to the growing range and type of thrusters include the Verhaar Omega V-POD, an electric propulsion/manoeuvring system that can replace a conventional screw shaftline with rudder. The V-POD is a pod drive with electric motor in an underwater housing. It can be used in combination with a diesel-electric and LNG-electric generator set and is said to have a high level of propulsion efficiency. The company says it overcomes some of the disadvantages of existing pod drives, such as high costs and low efficiency. It is also designed to be easy to install and occupies a minimum of space. Depending on the application, it is available as a pushing or pulling design and can be supplied with or without a nozzle.

Wärtsilä recently passed the final step in securing type approval from Lloyd’s Register for its new WTT11 tunnel thruster.

The WTT11 thrusters are electrically driven and can be delivered with a controllable pitch or fixed pitch propeller. Late last year, the company secured approval from classification society DNV GL for the design of its WST-14 thruster, which is part of the Wärtsilä steerable thruster (WST) compact series aimed primarily at tugs, anchor-handling vessels and coastal and inland waterway cargo vessels. The key benefits of the series include superior performance, easy installation, a high level of integration and ice class compatibility. OSJ

Wärtsilä’s WST-14 thruster is aimed primarily at tugs, anchorhandling vessels and coastal/inland waterway vessels

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XXVIII | HYBRID MACHINERY

Hybrid solutions of all types securing growing market share Propulsion system providers and manufacturers of gears, electric drive and energy storage devices have responded to rapidly growing interest in hybrid solutions of all types with a fast-growing number of potential solutions

W

ith 2020 almost in sight, classification society DNV GL recently revisited its Shipping 2020 report, published in 2012. Three years later, it says hybrid propulsion systems have emerged much more quickly than it anticipated.

Speaking at Nor-Shipping 2015 in Oslo in June, DNV GL CEO Tor Svensen noted that, when the report was published, the rise of hybrid vessels had not been anticipated. However, a significant reduction in battery prices and improved energy storage capacity means that hybrid systems are now becoming a real option for the shipping industry. They are, he explained, best suited for vessels with large variations in power demand, coastal trades and operations within emission control areas, although not all ‘hybrid’ machinery solutions necessarily make use of batteries.

“Pilot projects indicate that hybrid technology is robust and leads to fuel savings of 15 per cent for an offshore vessel,” he explained. “A hybrid engine system allows the ship to operate at its most efficient point, regardless of power requirement or load. There are already 33 hybrid vessels in operation or on order, and looking ahead, it is possible this number will top 100 by 2020,” said Mr Svensen.

As class society Lloyd’s Register noted recently, a number of hybrid vessels are already in service in other sectors. These include the LR-classed ferry Hallaig, the first diesel-electric hybrid ferry in the world. Developed under the Low Emission Hybrid Ferries Project, the ferry has a pioneering hybrid dieselelectric propulsion system with two 16R5 EC/90-1 Voith Schneider propellers (VSPs) providing a total power of 750kW and two lithium-ion batteries. The lithium-ion batteries are connected to a 400V switchboard to power the propellers and are connected directly to a DC link without requiring either additional electronics or voltage conversions.

Another interesting hybrid unit is the Svitzer ECOtug, of which four examples have been built for Svitzer by ASL Marine. The 33m long, 13m beam vessels are powered by diesel-electric hybrid

engines that can achieve a maximum bollard pull of 75 tonnes.

They were preceded into service in 2012 by the revolutionary E-KOTUG, a 32m long vessel with hybrid technology that allows its main engines to be shut down while the vessel is in transit. It can rapidly switch from hybrid mode using its electrically powered motors to conventional mode using its diesel engines. For low power operations, E-KOTUG can run on battery power alone.

Norwegian Electric Systems was heavily involved in the design of Fafnir Offshore’s Havyard 833 WE platform supply vessel (PSV), which is due to be delivered later this year. As highlighted elsewhere in this special supplement, the vessel has a diesel-electric and battery-based hybrid propulsion system. Norwegian Electric Systems’ vice president (sales) Paul Winson said a hybrid system of this type can avoid some of the problems otherwise encountered when owners need to meet class rules requiring ever greater redundancy (which typically means increasing the number of gensets or more redundant switchboards and more busbars, which leads to more components and more inefficiency). A hybrid approach such as that on Fafnir Offshore’s newbuild also addresses issues relating to the low loads associated with operating in dynamic positioning (DP) mode. A hybrid system can address both issues, he explained, with the gensets running at 80 per cent loading or higher while charging up the battery bank and providing power for other systems. “You are only looking at the batteries stepping in while the engines get going and synchronise so they only have to take the strain for minutes, not hours,” he explained.

ABB’s Onboard DC Grid was introduced in 2011 and made its debut on the PSV Dina Star in 2013. This kind of optimised propulsion concept enables power to be distributed through a single DC circuit.

Significant power savings result, with safety and redundancy enhanced over traditional AC systems. Distributing electricity in DC form allows engines to be operated at different speeds, substantially reducing fuel

LEFT: A Wärtsilä LLH tested on the PSV Viking Lady provided fuel savings of 15 per cent RIGHT: Karina was the first example of a new type of fast supply intervention vessel with hybrid machinery

OSJ Guide to OSV Propulsion 2015

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The first application of ABB’s Onboard DC Grid was on the PSV Dina Star

consumption and emissions compared with established propulsion systems. The dynamic response of the engines is also said to be improved, and batteries and other energy-storage devices can be integrated into the system.

More recently, Wärtsilä launched its Low Loss Hybrid (LLH) energy system, which it believes will offer significant fuel savings and reduce emissions. Unveiled at ONS 2014 in Stavanger, the Wärtsilä LLH utilises different power sources in combination with energy storage devices to operate the prime movers closest to their optimum performance. In addition to annual fuel savings of up to 15 per cent, depending on the type and configuration of the engine and mission profile, the LLH ensures a substantial reduction in exhaust gas emissions. The company notes that the control system for hybrid arrangements such as this is one of the keys to its success. A key feature of the LLH is its ability to reduce transient engine loads that cause increased fuel consumption and added emissions. Furthermore, by increasing the power redundancy, the system allows the engine to operate closer to its optimum design point where it has highest efficiency and least emissions. Reduced maintenance and increased system performance through rapid response from the energy storage system are also among the benefits offered. A LLH system was tested aboard the PSV Viking Lady and confirmed fuel savings of 15 per cent.

It is not just batteries that are contributing to the fast growth in hybrid vessels, however. Gearing designers, electric drive and energy storage device specialists are also contributing to advances in the hybrid propulsion systems. Their challenge is to maximise efficiency in each mode of operation so that fuel consumption and emissions can be minimised. Moreover, say manufacturers such as Rolls-Royce, electric or hybrid propulsion promises operators an inbuilt flexibility that reduces emissions and optimises fuel economy but also releases more space and lowers weight, noise and vibration as well as maintenance costs.

Interestingly, says the company, hybrid systems are best suited to tonnage featuring frequent transient operations, such as offshore support vessels. It has developed a range of electric propulsion systems that can also accommodate batteries or be plugged in to a shore connection of variable frequency.

Earlier this year, Norwegian marine drive specialist Kumera delivered its Norgear advanced multistep hybrid gear solution for an anchor-handling tug/supply (AHTS) vessel newbuilding contracted by Buksér og Berging for delivery from Vard Brevik.

The innovative hybrid gear plays a key role helping minimise the vessel’s environmental impact. By enabling different operating modes for different duties, it can reportedly achieve fuel savings of 40–50 per cent, depending on the duty.

A number of other gearbox designers are also targeting the market for hybrid drives, including Reintjes, which is offering its RHS series of hybrid gearboxes for fixed pitch propeller applications. The hybrid package typically includes the gearbox itself, with the combined electric motor and generator already www.osjonline.com

flanged to the gearbox and a separate frequency converter. Main input and output shafts are vertically offset, and the gearbox incorporates integrated hydraulic clutches to control drive options.

Another German contender, ZF Marine, has strengthened its programme to support hybrid drive installations. Its 5000 series, introduced in 2012, offers higher power transmission capability and a wide range of gear ratios (up to 5.5:1 in the case of the ZF 5300 model). More complex transmission systems are available to serve integrated power and propulsion configurations where more than one power take-off (PTO) or power take-in (PTI) is required. The 5000 series has a supplementary PTI arrangement to accommodate flexible input and output variants in a compact space, making it suitable for hybrid operations exploiting power from auxiliary sources. More recently, ZF Marine extended the range of its hybrid-ready transmissions with the ZF 3300 PTI. Designed to be powered via a standard diesel engine input or other power sources through a PTI, the new transmission provides a hybrid-ready solution suitable for high speed pleasure and commercial applications. The ZF 3300 PTI is designed with the flexibility to be integrated into a wide variety of hybrid vessel propulsion solutions and is rated up to 1,940kW at 2,450 rpm, offering a wide range of basic ratios from 3.00 to 5.00. As with most ZF Marine transmissions, the ZF 3300 PTI can be configured to suit any application in the appropriate power range.

As briefly highlighted in OSJ earlier this year, De Hoop shipyard in The Netherlands recently completed Karina, the first example of a new type of fast supply intervention vessel with another form of hybrid machinery. The design goal for the vessel was to be able to maintain speed irrespective of how much cargo it is carrying or what draught it is operating at and to transport cargo and offshore personnel in the most fuel-efficient way. At low speed (up to 13 knots) and in DP mode, the vessel operates in diesel-electric mode, with electrical power generated by a shaft generator. In the higher speed range, propulsion is provided by two diesel engines (both Cat 3516s), which are directly coupled through a gearbox to the shaft. The gearbox has a PTI for a 350kW motor to propel the vessel at low speed. No reversing gear is fitted, and astern propulsion is only possible in diesel-electric mode. With this particular type of hybrid propulsion system, full rpm control of all propellers, including the bow thruster, is available, while at low speed, only one engine is running, which saves fuel and reduces maintenance. Switching between diesel-electric and diesel-direct is automatic, and De Hoop claims that the arrangement results in fuel savings of up to 40 per cent.

Recognising the way that the market is developing, Volvo Penta recently announced an agreement to work on diesel-electric projects with Callenberg Technology Group. Under the agreement, the companies, who have worked together for years, will explore approaches to future hybrid electric projects. The company cited growing marine genset sales and becoming more competitive in the market for diesel-electric projects as key factors in their decision to work together. OSJ OSJ Guide to OSV Propulsion 2015

XXX | DYNAMIC POSITIONING

DYNAMIC POSITIONING MARKET SET TO GROW Investment in dynamic positioning remains strong despite the oil bust and is poised to expand further

A

ccording to a recent report published by research company Markets and Markets, the global dynamic positioning (DP) systems market is expected to reach US$1.48 billion by 2020, growing at a rate of 4.36 per cent year on year.

Increasing use of DP vessels for offshore drilling by the oil industry and the growing demand for class 3 DP equipment are the key driving factors that are aiding the growth of the market.

According to the report, the Asia-Pacific region will account for the major share of the market in 2015. China, Japan and South Korea are expected to be the fastest-growing countries in this region from 2015 to 2020.

Saudi Arabia and the UAE in the Middle East are identified as emerging economies, which are expected to witness an increase in demand for DP systems.

The growing maritime industry in the Middle Eastern region and the growing use of DP systems for offshore vessels are expected to be key drivers for the growth of the market in this region. Additionally, the ongoing dynamic growth of the shipping industry in Africa and Latin America is expected to present companies with significant opportunities in this market.

The report’s publisher reaches this conclusion about the technology’s future: “In a nutshell, this market has

OSJ Guide to OSV Propulsion 2015

enormous potential for new technological advancements and is expected to grow at a steady rate during the forecast period.”

The key to the expansion of the DP market as a whole has been the boom in the offshore support vessel market, which has driven demand for such systems onboard the various types of workboats required by the oil and gas industry, and despite the slow-down in this market caused by the so-called ‘oil bust’, this investment seems to be ongoing, with major players in the market continuing to invest and innovate.

One example of this is Farstad Shipping’s newbuild subsea and construction vessel Far Sleipner. The vessel has a Rolls-Royce power plant and is the first vessel equipped with its latest generation DP3 system.

Designed and built by Vard, the new vessel is equipped with Rolls-Royce bridge controls, DP3, engines and propulsion.

Børge Nakken, Farstad Shipping’s vice president for technology and development, said, “The DP3 positioning system onboard Far Sleipner ensures that the vessel stays in position, even in the event of an unforeseen situation – for instance, if one out of two separate machinery systems fails. This enables the vessel to complete its task in a safe and efficient manner.”

He pointed out that the main difference between a DP2

and a DP3 system is related to redundancy and tolerance for system failure. All key components of the systems are doubled up in a DP3 system.

This ensures that, for instance, neither flooding nor a fire in one part of the vessel will make it lose position and require the operation to be halted.

Far Sleipner is designed for subsea construction and inspection, maintenance and repair operations down to depths of 3,000m. It has an overall length of 142.6m, beam of 25m and a deck area of 1,800m2.

The vessel is arranged for three remotely operated vehicles and has accommodation for 130 people in single cabins. The vessel will go straight into a charter contract for Technip.

Another technological milestone comes from Navis

Engineering. Its DP control system and autopilot onboard the ice-breaking rescue and emergency vessel Baltika have been approved as meeting performance expectations, following a searching set of Arctic ice trials in the Kara Sea. Developed by Finnish company Aker Arctic Technology, Baltika is the first ship ever built with an asymmetric hull that allows it to break ice not only ahead and astern but also at an oblique angle. In this way, the ice-breaker can open a channel in ice where the width is disproportionate to the vessel’s relatively small size.

The innovative, multifunctional vessel is equipped with the Navis NavDP 4000 DP system and the Navis AP4000 heading control system (autopilot).

Navis Engineering’s DP control system and autopilot onboard the vessel Baltika have been approved following a searching set of Arctic ice trials

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DYNAMIC POSITIONING | XXXI

Navis Engineering and Aker Arctic have a scientific and technical co-operation agreement covering the joint development of technology for DP systems for ice-breakers and ice-class vessels.

Ice trials were conducted around the northern tip of Novaya Zemlya and across the Kara Sea to the Gulf of Ob. The trials involved performance tests in two distinct ice thicknesses in ahead and astern directions as well as in the oblique mode. Various operational tests were also carried out in order to determine the manoeuvrability and operational capability of the vessel.

Although the ice conditions in the area were at the upper end of the vessel’s designed

ice-breaking capability and the ice in the Gulf of Ob was considerably stronger than typical sea ice, Baltika exceeded performance expectations, with the set targets being surpassed by a clear margin. The vessel broke ice of 1.2m thickness in continuous motion when proceeding bow first and achieved a speed exceeding 3 knots in the astern direction.

As well as its asymmetrical hull, the 20.5m wide vessel features an asymmetrical arrangement of its three azimuth thrusters, enabling it to break ice and form a channel up to 50m wide in the oblique mode.

The Navis NavDP 4000 is fully capable of DP control during

DP in ice still a challenging issue Dynamic positioning is used routinely in open water, but as highlighted on a number of occasions in OSJ, using DP in ice presents a very different, very much more complex technical challenge.

DP in ice was one of a number of issues addressed at the 2015 European Dynamic Positioning Conference in London in June.

Nils Albert Jenssen, a well known expert on DP from Kongsberg Maritime, told the conference about the challenges of using DP in ice. He explained that there actually several classes of Arctic area.

These include the ‘workable Arctic’, in which there is open water almost all year round and no sea ice, but where there may well be icebergs, and cold temperatures and darkness are an issue, such as the Barents Sea and East Coast of Canada. Here, he explained, conventional DP technology works. Then there is the ‘stretch Arctic’, where there is a considerable open water season but intrusion of first-year and potentially multiyear sea ice in the winter (such as in the Russian Arctic and Chukchi Sea), where DP technology needs to be modified to take conditions into account. Last, but no means least, is the ‘extreme Arctic’, with a limited open water season together with severe first-year and multiyear sea ice as well as glacial ice (such as northeast Greenland). Here, he said, DP systems face a real challenge.

Kongsberg has been conducting research into DP in ice for several years and has developed a special DP ICE mode with increased ability to track external forces that could affect a DP system. It has been tested at model scale at the HSVA basin in Germany. As he noted, other research projects are underway to learn more about ice dynamics and DP vessels.

What he described as the “great DP challenge” is to develop the missing numerical tools to dimension Arctic DP vessels. Research projects on dynamic ice loads have been undertaken, such as the EU project DYPIC, which was used to develop a simplistic model, and other models are under development at Memorial University St John’s in Canada, under a project that is due to be completed in 2018. There is also an eight-year programme known as SAMCoT www.osjonline.com

the oblique operational mode, in line with Baltika’s distinctive ice-breaking action. Feedback about the Navis NavDP 4000

has been positive, with crew acknowledging its operational simplicity and reliability after the trials. OSJ

Far Sleipner is the first vessel equipped with Rolls-Royce’s latest generation dynamic positioning system DP3

with ambitions to develop a ‘numerical ice basin’. This project, due to come to fruition in 2018, is being led by NTNU Norway.

Describing some of the lessons learned from towing tests, Mr Jenssen said ice loads could sometimes be “very high” with very rapidly developing, very high peaks of considerable duration. “Will conventional, open water DP work in ice,” he asked? “Probably not.”

Describing Kongsberg’s ice-mode DP, he explained that much of the work focuses on new mathematical models that can be used to model ice effects. The work that the company is doing includes the development of a Kalman filter that is more reactive to measurements, providing a more responsive estimation of external forces, taking into account potential vulnerabilities to position reference uncertainties.

The controller that Kongsberg hopes to develop would be similar to those for open water DP, with thruster allocation as for open water DP and thruster ‘biasing’ to increase responsiveness. Describing some of the lessons learned from the tests at HSVA, he said that the ice mode DP works. “You need to follow the ice drift direction,” he explained.

Describing some of the operational challenges to be addressed before ice-capable DP systems could be fielded, he highlighted the need for DP failure mode and effects analysis to include ice management as a failure mode. As highlighted above, the heading of a vessel would have to follow the ice drift direction. DP capability plots are not available, however, as they are for open water operations, and ice under a vessel’s hull may cause potential hazards.

“In ice, manoeuvring and position changes will be more difficult to execute,” he told the conference, and could take the form of a sequence of position and heading changes and what he described as “active use of alternative rotation centres”.

“DP technology for ice conditions is available but not qualified at full scale,” he said. “We have no operational experience of DP operations in heavy ice conditions in the Arctic, and adequate numerical tools are not yet available. Ice model tests are needed to qualify vessel and DP systems.

“Arctic DP operations are feasible,” he concluded, provided there is also effective ice management, operations are well planned and understood and vessels and DP systems are designed for Arctic conditions.

OSJ Guide to OSV Propulsion 2015

XXXII | LEADING ENGINEBUILDERS

LEADING ENGINE BUILDERS

BY DELIVERIES 2013/2014 The tables reproduced here show the engine manufacturer for platform supply vessels and anchor handling tug supply vessels on ships delivered in calendar years 2013 and 2014

Recent PSV deliveries

Recent AHTS deliveries 0

20

40

60

80

100

120

0

20

40

60

80

100

120

140

160

180

Caterpillar

Caterpillar

Cummins

Niigata

Niigata

W채rtsil채

Rolls-Royce MAN W채rtsil채 Yanmar Yanmar Cummins MTU Rolls-Royce MAN Daihatsu

GE

Mitsubishi HI

Daihatsu

GE

Wuxi Wandi

2013

2014

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OSJ Guide to OSV Propulsion 2015

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