39 minute read
Off shore wind crunch
AMBITIOUS GROWTH PLANS PUT PRESSURE ON FLEET CAPACITY
The planned rapid expansion in off shore wind capacity in Europe, as well as the demands from the next generations of turbines, is expected to lead to supply bottlenecks within fi ve years
The EU plans to increase the region’s off shore wind capacity fi ve-fold, from 12GW to “at least 60GW”, while the UK plans to quadruple its own off shore wind capacity over the same period.
On top of that, the EU hopes to complement that with a further 40GW of ocean energy - including floating wind turbines - by 2050, which is when the EU plans to reach its goal of climate neutrality.
These bold plans form part of an EU Strategy on offshore renewable energy that it predicts will cost nearly €800 billion, although it was not clear how much of this will come from public funds. But Europe’s commissioner for energy, Kadri Simson, has no doubts about the strategy’s importance: he was quoted in the statement as saying that Europe must harness “all the potential of offshore wind and ... other technologies such as wave, tidal and floating solar.”
And although the timetable can be counted in decades, EU member states have only weeks to get started, the statement made clear. Offshore renewable energy development objectives must be integrated into their National Maritime Spatial Plans, which coastal states are due to submit to the Commission by March 2021.
Meanwhile, Europe’s largest offshore wind energy nation, the UK plans to lift offshore wind production capacity from about 10.5GW to 40GW over the same period. This increase in capacity falls outside EU targets following the UK’s departure from the EU.
To hit the EU’s 2030 target will require an average of nearly 5.5GW of additional generator capacity in each of the next nine years, which compares with 2019’s figure of 3.6GW, which WindEurope reported was a record. It says that Europe “is the leader in offshore wind” and welcomed the EU’s new strategy, saying that it will “shape the development of offshore wind in Europe for the next 30 years” and support “further expansion of floating offshore wind ... for the deeper waters in the Atlantic, Mediterranean and Black Sea.”
It is against this background that the offshore wind support sector must gear up to construct and service more and bigger offshore and floating wind turbines. A WindEurope spokesman commented to The Motorship that, at the moment, there are enough vessels - in fact, over capacity - to service ongoing installations and operations. But looking ahead, “at least 10 new vessels will be required, each capable of annually installing up to 100 turbines or their foundations.”
At present, the largest wind turbine is said to be the 14MW Siemens Gamesa SG 14-222 DD, which was launched in May 2020 and a prototype is expected in 2021. It will become commercially available in 2024 but it has already amassed a number of orders, including one placed in June for 100 units.
Yet there is expected to be a global shortage of installation vessels able to erect large turbines in the quantities that will be needed. A study published in late November by the Norwegian consultant Rystad Energy predicts that “as turbine and project sizes grow, demand for specialised installation vessels will soar.”
At present, there are “only four vessels capable of handling the next generation of turbines” out of a total fleet of 32 active turbine installation vessels and 14 dedicated foundation installation vessels, it says. Although more are on order, “the global fleet will be insufficient to meet demand after 2025,” it warns.
Rystad Energy’s vice president and product manager for offshore wind, Alexander Dobrowen Fløtre, told The Motorship that the vessel market is in a ‘chicken and egg situation’: “A big portion of the longer-term demand is still only in the concept stages, which may not be enough certainty for players wanting to invest in newbuilds.” Yet “the contracting models applied in offshore wind are typically of a shorter-term nature [than] oil and gas, which may also affect investors’ decisions.”
The consultant’s findings confirmed views expressed in May this year by Mary Thorogood, senior strategy specialist at the turbine maker MHI Vestas Offshore Wind. As a panellist for a webinar hosted by the organisers of the All-Energy exhibition and conference, she said that turbines are being made bigger “because our customers asked us to” even though there is “a global shortage of vessels to deliver the projects.”
Also taking part in that event was Benj Sykes who, among other roles, is industry chair of the UK’s Offshore Wind Industry Council. He spoke of “a tight squeeze in the vessel supply chain” and said that “no-one can be absolutely sure where supply and demand will balance... [but] we are going to need more vessels.”
At the International Marine Contractors Association (IMCA), its marine technical adviser, Andy Goldsmith, took a more nuanced view: the shortage is of “specifically designed vessels for particular tasks,” he told The Motorship.
8 The 14MW
Siemens Gamesa SG 14-222 DD will be the most powerful off shore wind turbine
OFFSHORE WIND VESSELS: THE DESIGN BASICS
Rotterdam-based naval architect C-Job is involved in a number of design projects for off shore wind construction vessels
Its general manager Maarten Veldhuizen set out some of the key considerations for these specialized craft.
He is also project manager for C-Job’s involvement in the 5,000 tonne-lift crane vessel Orion which will go into service with Belgium’s Dredging International (DEME) following repairs to damage caused when its crane collapsed on 2 May 2020 during trials at crane-supplier Liebherr’s facilities in the port of Rostock in Poland. The COSCO-built ship is one of the highest lift-capacity purpose-built offshore wind construction vessels and its crane is the first HLC295000 model that Liebherr has supplied.
Liebherr quickly blamed the failure on the hook, supplied by Ropeblock, which broke when the test load reached 2,600 tonnes. Ropeblock itself issued a statement at the time acknowledging that it had designed the hook but said that it had subcontracted its manufacture. “We are appalled at the impact that this incident has on our customer Liebherr, but certainly also on the industry as a whole,” it added. No updates have been issued since then.
C-Job was not responsible for the crane design and is not involved in the investigation or repair work following the accident, but the incident illustrates an important design parameter for the vessels: they must be able to survive a ‘loss of load event’.
This needs to be considered carefully, Mr Veldhuizen explained, because if the load is suddenly lost, the vessel will roll to the other side. That is what happened in the Orion incident and videos available online seem to suggest that the momentum from this roll caused the crane to fold over backwards.
Bearing in mind that this could happen at maximum load, maximum outreach and in the open sea, the ship must be designed with enough ‘uprighting energy’ to prevent it from capsizing and although Orion’s incident happened at partload, with the crane nearly vertical and alongside, Mr Veldhuizen said that the ship “did what it needs to do” during the incident.
Two other design features that are uniquely combined in wind turbine installation vessels are size and speed. Unlike installation vessels for oil and gas projects, those that support g p j pp wind farm construction must also transport the jackets and st also transport the jackets and other large components, which requires them to have a large ch requires them to have a large empty deck space, he said.
They also need to be fast, which means high installed st, which means high installed power, which is also essential for dynamic positioning (DP) ial for dynamic positioning (DP) when the vessel’s crane is in use, putting these vessels in use, putting these vessels alongside large crane vessels and drillships in terms of sels and drillships in terms of power requirements, he said. .
For a vessel such as Orion, “you need to make sure that if n, “you need to make sure that if anything fails you still can operate the ship”, although that operate the ship”, although that may be at a lower capacity. The crane might operate at a . The crane might operate at a lower speed and the DP system might have a lower system might have a lower performance, but they must both still function. both still function.
For the DP system, it should be rated at DP 2 or higher, Mr ld be rated at DP 2 or higher, Mr Veldhuizen said, which is defined in IMO circular MSC/Circ. efined in IMO circular MSC/Circ. 645 as requiring that “no single fault in an active system will cause the system to fail.”
With both DP and crane operations demanding power at the same time, a vessel’s machinery installation and control systems must be able to cope with fluctuating power demands, which is more difficult with larger engines, he said; Orion’s engines, for example, are rated at 44MW.
In a statement to The Motorship, Wärtsilä - which supplied Orion’s engines - said that its integrated machinery set-up for that project consists of genset and propulsion configurations together with automated electrical, energy storage and DP systems to meet those fluctuating load demands “in every operation mode of the vessel.” Energy and power management systems give the engines have a good load pick-up capability, the company said.
Uniquely for an offshore service vessel, Orion’s power comes from dual-fuelled LNG engines, but Mr Veldhuizen does not expect this to set a trend for future vessels. That will depend to a great extent on fuel infrastructure; in some regions, LNG may not be as readily available as it is in Europe, he said. The ship also features exhaust waste heat recovery p y equipment to improve its efficiency and reduce fuel equipment to improve its efficiency and reduce fuel consumption, although Mr Veldhuizen declined to say by consumption, although Mr Veldhuizen declined to say by how much. how much.
8 Deme’s 5,000
tonne-lift vessel, before the crane’s hook failed under test
8 Off shore wind
construction vessels must survive a ‘loss of load event’, says Maarten Veldhuizen
FLOATING TURBINES: THE NEXT WAVE FOR OFFSHORE WIND
Floating off shore wind “off ers the ability for large capacity expansion near to demand centres,” believes Mark Spring, Lloyd’s Register’s ‘voice on off shore wind’
He made his remark in an article on the class society’s website about a UK target of 40GW of off shore wind by 2030, which he described as “not realistic” under current UK policies and argued that it could only be met if it was supported by fl oating wind turbines, enabling development of deeper waters to the west of the country. The title of his article underlines his point: it is called ‘Floating off shore wind - a national prize or a lost opportunity?’
Another class society, DNV GL, recently made a similar point about the global situation. During a webinar in early December, DNV GL’s floating wind advisor Magnus Ebbesen presented a slide stating that “floating wind works as a boost for offshore wind” and predicted that, by 2050, floating offshore wind projects will account for 255GW of installed capacity worldwide, “more than 20% of the offshore wind market.”
Just a week later, the global nature of floating wind projects was reinforced by an announcement by Korea Hydro & Nuclear Power (KHNP) that it had agreed a memorandum of understanding that it said will lead to the world’s largest floating offshore wind power generation complex.
The MoU was signed on 15 December with OW Offshore of Spain and Kumyang, a Korean renewable energy company, for a scheme involving three 500MW wind farms located 72km off south east South Korea.
Mr Spring drew The Motorship’s attention to another floating wind energy project, X1 Wind, which is being developed in Spain. A scale model is under construction for
Image: X1 Wind
testing off Gran Canaria using a Vestas V29 225kW turbine that has been modified so that it operates facing away from the direction of the wind.
Although this unusual arrangement is generally avoided because of the ‘tower shadow effect’ on the wind flow, it is being trialled as a solution to the challenge faced by large turbines that their long blades risk hitting the tower as the bend in the wind. Strategies to avoid this lead to inefficiencies, the X1 Wind project’s website notes.
Testing will also validate the projects’ PivotBuoy singlepoint mooring system, which is expected to provide “costeffective and reliable floating wind mooring, connection, installation and operation” for the turbine.
Another important objective for the project is that construction and commissioning will be possible without needing a heavy-lift crane barge, with all subsequent maintenance carried out at sea level.
8 An artist’s
impression of X1 Wind’s innovative fl oating turbine and PivotBuoy support
JONES ACT SPURS US VESSEL PROJECTS
US waters are expected to see signifi cant development in off shore wind installations in the years ahead, but the nation’s Jones Act restricts the choice of vessels that can be used to build them
It requires goods shipped between US ports to be transported on ships that are built, owned and operated by US citizens so when the country’s fi rst commercial off shore wind farm was built in 2015-16 off Block Island, the Maltese-fl agged jackup Brave Tern was serviced by two US-fl agged jack-ups L/B Caitlin and L/B Paul so that it did not have to enter a US port.
Last year, however, the US House of Representatives passed the Expanding Access to Sustainable Energy Act, which includes an amendment to enforce Jones Act requirements for all offshore renewable energy production, including installation vessels. And in December 2020, the US Senate passed the National Defense Authorization Act, which includes an amendment to ensure full enforcement of the Jones Act and other federal laws in offshore wind development.
Now, at least two projects are set to meet these requirements. On 16 December, the keel was laid at Keppel AmFELS shipyard in Texas for a vessel on order for Dominion Energy. It confirmed in a statement that, “with several gigawatts of offshore wind capacity to be installed along the US east coast in the next decade, access to Jones Actcompliant offshore wind turbine installation vessels is of strategic importance.” The vessel is due to be in service by the end of 2023.
With a lifting capacity of 2,200 tonnes, the vessel’s crane - supplied by Huisman - will have a 130m boom mounted on the 144m hull. The ship will be 47m wide, have a depth of 11.6m and include accommodation for 119 people. It will be
Image: NETSCo
suitable both for laying foundations and installing turbines and has been designed to handle “next generation turbine sizes of 12MW or larger,” Dominion Energy said.
Coinciding with that announcement was another, from Northeast Technical Services Co (NETSCo), about a joint development project with Lloyd’s Register North America to design and develop a Jones Act-compliant wind turbine installation vessel (WTIV).
NETSCo will be responsible for the concept design of the WTIV while LR will check that the design complies with applicable rules and regulations. It will also evaluate the design against international codes and standards and the US Coast Guard’s Code of Federal Regulations.
From a practical point of view, a key design feature is that it will use hull shapes that are common in the US shipbuilding market, NETSCo’s statement said to ensure it could be built in US shipyards. It will also be focused on meeting the requirements of current developments along the US east coast and Great Lakes, in terms of its crane capacity, deck space and water depth.
“The offshore wind industry is expected to see exponential growth in the United States,” said Rafael Riva, LR’s Americas marine and offshore commercial manager, said, so “there will be a pressing requirement for such vessels.”
Jan Flores, NETSCo’s vice president, agreed, adding that this presents “a perfect opportunity for us to .... support the offshore wind turbine market.”
8 A concept
illustration of the NETSCo Jones Act-compliant installation vessel
IMCA TACKLES ‘RIDICULOUS’ TRAINING OBSTACLE
Vessel operators in the off shore wind sector have faced a “ridiculous situation” over qualifi cations specifi ed for their vessel crews, according to Andy Goldsmith, marine technical adviser for the International Marine Contractors Association (IMCA).
Speaking to The Motorship, he said that many vessel service contracts - for both construction and service craft - require all crewmembers to meet training standards set by the Global Wind Organisation (GWO), even though many of them - such as the cook or the ROV operator, he suggested - will not be doing work connected with the wind turbine itself.
GWO is a non-profit organisation of wind turbine owners and manufacturers and its website confirms that its basic safety training (BST) standard “is a requirement made by wind energy employers as a pre-requisite for their own staff and contractors before they are allowed on site.”
This adds extra cost and delay, Mr Goldsmith said, although he is hopeful that guidelines IMCA published in October will ease the situation. These include a ‘Basic Safety Training Matrix’ that defines the minimum level of health and safety training, and medical fitness needed to work on, and from, vessels engaged on an offshore renewable energy project.
In a statement at the time, Mr Goldsmith said that “basic safety training requirements cannot be generalised and are different for [onshore and offshore] personnel.”
He is also concerned about the different renewal cycles of GWO qualifications and traditional seafarer certificates. GWO states that its BST certificate “lasts 24 months, before the training must be refreshed,” while certificates issued under STCW typically run for five years, “so you could never get any equivalence,” Mr Goldsmith said.
He believes, however, that the approach taken in the new guidelines of defining what is required for each role has allowed discussions about equivalence to be set aside.
Developing these guidelines has been “a long struggle”, he told The Motorship, and IMCA is now pushing for them to be included in tender documents. GWO has accepted them, he added, and he is confident that they will be widely recognised, although they will only benefit future contracts.
8 Irrelevant training
adds cost and delay, says Andy Goldsmith
Nor-Shipping 2021 delayed until January
The 2020 Nor-Shipping exhibition and conference is to be postponed from June 2021 until 10-13 January 2022. Rather than potentially holding a scaled down, socially distanced exhibition, Nor-Shipping has opted to delay the event to ensure global decision makers have the opportunity to meet face-to-face.
The decision to delay the event has been taken reluctantly, in response to concerns that the the planned 2021 programme could not reproduce the impact, experience and value of Nor-Shipping 2019, stated NorShipping Directors Karen Algaard and Per Martin Tanggaard.
“Health and safety comes first,” stresses Algaard. “We are committed to following stringent standards with regards to minimising the risk of infection, and, at present, that means fewer people, less interaction and more distance between exhibitors and participants. We believe that isn’t in keeping with the essence of NorShipping. However, by delaying the programme a little we can offer everything we have become known for, and more, with a uniquely Norwegian flavour in January 2022. It gives us and, we hope, the entire industry something very special to look forward to.”
INDUSTRY SUPPORT
The decision has been taken in consultation with all Nor-Shipping partners and a number of exhibitors, who overwhelmingly supported a move to enable greater contact and connection. Of those approached, over 90% of exhibitors were in favour of the rescheduling, with many stating that any participation in a summer 2021 event could have been challenging. 100% of partners backed the decision. It was further noted that the opportunity to provide a “once in a lifetime” Norwegian winter experience could be a significant draw for participants, as well as an opportunity to tailor memorable exhibition stands and activities.
The Norwegian Institute of Public Health has stated an expectation that social distancing measures will be in place until either the end of summer or autumn 2021. As such, Algaard says a postponement is the sensible move - for both the event and the industry it showcases and supports.
Nor-Shipping is currently working on a selection of digital initiatives to take place during 2021. Further details of these, and the 2022 event, will be released in the near future.
EXERGY STUDY ASSESSES LNG ENGINE PERFORMANCE
An exergy study undertaken on a dual-fuel 4-stroke engine demonstrated signifi cant combustion and turbocharger losses as well as an opportunity to recover about 9% of the waste heat from the charge coolers when the engine was operated at full load
Exergy, also known as available energy, is a concept arising from Second Law of Thermodynamics which quantifi es the maximum amount of work obtainable from a given system.
PhD student Beichuan Hong and his supervisors Professor Anders Christiansen Erlandsson and Dr Andreas Cronhjort from the KTH Royal Institute of Technology in Sweden set out to take a more practical approach to understanding the theoretical concept of exergy on engine component design than has been achieved in the past.
“Many previous studies have discussed engine performance from the exergy perspective,” said Hong. “However, since exergy is an advanced concept from thermodynamics, it usually explains the engine procedures in theoretical terms as irreversibility or entropy generation. This approach is not always easy to grasp. Therefore, people usually apply it at the macroscopic level without linking it to specific engineering problems.
“Although marine engines are quite energy efficient, it is important to look at the theoretical efficiency limit, and, as a system, the parts which hinder us from reaching that limit in practice. By taking a comprehensive view of the engine, we attempted to give some answers,” said Hong.
Their study examined the exergy losses inside the engine components of a 10-cylinder, V-bank Wärtsilä 31DF engine with a two-stage, serial turbocharger. The high and low pressure turbochargers were sequentially arranged with charge cooling after each compression stage, and the system used an air bypass valve and exhaust waste gate valves to improve the charging efficiency and for component protection.
The engine was operated at 25%, 50%, 75% and 100% load at a working speed of 750rpm. The exergy losses were characterized as: combustion-related, heat dissipation or gas exchange losses. A 1D simulation model of the engine was developed and validated on the commercial platform, GTSuite. Dynamic sub-models were separately calibrated, including, for example, gas flow property across the inlet valve, heat transfer in the cylinders and pipes and mechanical friction at the crankshaft.
“Instead of focusing on a particular engine component, we reviewed the engine performance at the systematic level and analysed the inefficiencies as well as the reasons why these losses occur,” said Hong. “In short, this project tried to demonstrate how far we are from the ‘ideal’ engine and where the potential for further improvement is.”
The researchers found that combustion exergy destruction dominated for the engine, contributing more than half of the total exergy destruction. The flow exergy destroyed in gas exchange, as the second highest contributor, was slightly higher than the rest of the exergy destruction types, and it increased at high load. Heat dissipation maintained the same level of loss by engine mechanical friction and was less sensitive to fuel mode and operating loads.
FUEL EXERGY
The engine was evaluated in dual-fuel mode with compressed natural gas (CNG) (using a premixed charge ignited by pilot diesel) and in conventional diesel mode. “Such an engine configuration enabled us to compare the difference between the two combustion modes,” said Hong.
Based on a calibrated 1D simulation, the researchers found that combustion irreversibility was the largest source of engine exergy losses amounting to at least 25% of fuel exergy. The exergy destruction was characterised as resulting from chemical reactions, heat conduction and mass transfer of the non-equilibrium combustion gases, with the chemical reactions always making up the largest proportion of the exergy destruction.
“According to our analysis, dual-fuel mode had a higher efficiency than diesel mode. For example, at the full-load operating point with the same brake mean effective pressure (BMEP), the energy efficiency at dual-fuel mode was 48.6% while diesel mode it was 47%. One reason for this is that the CNG fuel has a higher energy density (i.e. lower heating value) than most common fossil fuels. Also, the combustion of CNG premixed charge is easier to concentrate at top dead centre. This makes the combustion process faster and more homogeneous in gas mode, leading to less entropy generation.”
The fuel exergy losses cause a reduction in indicated
8 The exergy
study examined the exergy losses inside the engine components of a 10-cylinder, V-bank Wärtsilä 31DF engine with a two-stage, serial turbocharger
mean effective pressure (IMEP) and exhaust energy which further limits the amount of flow energy used to drive the turbines or other waste energy recovery systems. To have a loss of over 25% of fuel exergy indicates it is still very promising to optimize in-cylinder processes for faster combustion, lower heat loss and better work extraction even though the engine is already energy efficient, says Hong.
WASTE HEAT
There were two categories of waste heat considered: the flow energy contained by the exhaust after passing through the turbines and after-treatment and the energy carried by the coolers. For these, the total waste heat accounted for more than 30% of the fuel energy. However, the exergy analysis indicated that the energy quality of these waste heat sources was not high, said Hong.
“Theoretically, for the tested marine engine system, converting waste heat to mechanical work may recover a maximum of 9% of the fuel energy (e.g. 492kW in diesel mode for 5500kW engine output power). An alternative solution for this situation is that it could be directly used as a heating to integrate Computational Fluid Dynamics simulations with
system. In the case of a co-generation system the efficiency of energy recovery could be much higher.”
GAS EXCHANGE LOSSES
Exergy destruction in the gas exchange system was caused by flow losses resulting from piping restrictions caused by valve throttling, by fluid friction in the pipes and by the flow energy recovery of the turbochargers. Most of the exergy destruction occurred in the turbocharging system where the high-pressure turbocharger contributed around 40% of the total flow exergy destruction. Unlike the flow losses in the piping system, the flow exergy in the turbocharger was not entirely wasted, because it contributed to the work extracted by the turbine and the air boosting by the compressor.
“While intake and exhaust valves accounted for almost 20% of the flow exergy destruction, 70%-80% of the flow exergy destruction in the gas paths occurred at the turbocharging system. For each charging stage, the compressor always caused more exergy destruction than the turbine side. However, the flow losses by the valves also rose with load due to the increasing mass flow,” said Hong.
Unlike the flow losses in the engine piping system that are simply wasted, the work extraction by the turbine and the air boosting by the compressor also caused exergy destruction. “Our exergy analysis shows that the current two-stage turbocharging system in the tested marine engine has a pretty high efficiency for extracting the flow exergy. However, the turbines also destroy 15% of flow exergy whilst recovering the rest and sending to the compressor. Perhaps, exergyrelated R&D goals like reducing entropy generation could be a consideration in further research on the turbomachinery side,” said Hong.
“Of particular interest to us is the quantification of available energy inside the exhaust flow. The flow exergy is equivalent to 65% of the crank shaft output power. Hence the management of exhaust energy recovery indeed plays an important role in improving marine engine efficiency. When we compared the marine engine results to a truck engine pre-study, we found that 20% of flow exergy destruction occurs at intake and exhaust valves, while for truck engines, it was around 7%. This was rather unexpected and implies the sensitivity of the valve motions. Also, further analysis is needed to investigate the effects of Miller timing strategy on flow exergy utilization.”
Therefore, the next step of Hong’s research plan focuses project is to understand how to reduce flow losses and optimize the usage of flow exergy. One part of our project is
on the flow exergy in the exhaust system. “The aim of this measurement data for modifying the potential design flaws, especially for the configuration of the exhaust system such as the pipe geometry and valve profiles. This study will also enhance our understanding of engine exhaust exergy, especially how it relates to the performance of the turbine or other waste heat recovery systems.”
FAST FLOW SENSORS
Apart from its engineering application, one of Hong and his supervisors’ ongoing studies involves characterising exhaust energy pulses using fast measurement techniques. “One big challenge for fast flow exergy measurement comes from the development of fast flow sensors. The flow sensors are expected to survive in the marine engine exhaust and keep their high sampling accuracy. For fast pressure sensors, there are many commercial ones that can be used. However, for fast temperature and flow velocity measurement, we need to design and fabricate one ourselves. Luckily, our colleagues from KTH Fluid Physics Laboratory are collaborating with us to develop high-accuracy engine pulse-orientated sensors,” said Hong.
Engine simulation approach Wärtsilä supported the study with both data and supervision, and the company states: “The study presents its results and findings based on simulation model provided by Wärtsilä and not on real engine measurements. This means that the accuracy of result is dependent on calibration input of the simulation models operating conditions. In real testing and . In real testing and measurements, the result is varying contingent on varying contingent on operating and ambient conditions. As such, the final tions. As such, the final result is dependent on accuracy level of the model acy level of the model where absolute values are not the most relevant ot the most relevant findings but rather the behaviour and principle iour and principle of energy and exergy losses that occur in that occur in medium-speed engines. The study is part of the study is part of the continuous development process within Wärtsilä and cess within Wärtsilä and provides valuable input to further improve the rther improve the efficiency of our engines and continue to have the continue to have the highest efficiency among medium speed.” dium speed.”
8 One insight from
the simulation-based study was that the marine engine produced a higher proportion of fl ow exergy destruction at the intake and exhaust valves compared with a truck engine study
8 PhD candidate
Beichuan Hong was supervised by Prof Anders Erlandsson and Dr Andreas Cronhjort (pictured) from the Royal Institute of Technology (KTH) in Sweden
CRANE SHIP FOR BIGGEST WINDFARM LIFTS
Heavy-duty capability and sustainability fi nd new levels in the monohull off shore construction ship ordered from a Chinese yard by Jan De Nul, writes David Tinsley
Growing investment in vessels that can meet accelerated and ever-more exacting demand from the off shore renewables market fi gures prominently in the multifaceted fl eet development and renewal strategy of the Luxembourg-headquartered Jan De Nul construction and dredging group.
A highlight of the programme is a 237m newbuild incorporating a 5,000t lift-capacity crane, and engineered to Ultra Low Emission vessel (ULEv) standard, on which steel cutting commenced during early December. Designed to effect installation work afloat rather than in jack-up mode, the ship is due to enter service in 2022 under the name Les Alizés (Trade Winds).
The project denotes further penetration of the high valueadded shipbuilding sector by China, with the contract having been assigned to China Merchants Heavy Industry’s Haimen shipyard, Nantong City.
The rationale for the considerable handling capacity embodied by Les Alizés is the global trend in the offshore wind energy sector towards ever-larger wind turbines. These can stand at heights of more than 270m, carrying blades as much as 120m in length, and mounted on foundations weighing up to 2,500t.
With a cargo deck area of 9,300m2, the newbuild will be able to load out, transport and install multiple units of the heaviest components in one trip, yielding direct benefits in planning, project execution and fuel consumption. As an alternative to a jack-up vessel, the DP2-fitted crane ship will effect installation afloat, extending the operating scope to deeper waters and more challenging seabed conditions.
Besides the capability to build the next generation of wind farms, the ship has the wherewithal and layout to undertake the decommissioning of offshore oil and gas platforms.
Design, engineering and manufacture of the ship’s 5,000t capacity tub-mounted crane (TMC) is the responsibility of Dutch specialist Huisman, which has assigned construction to its Xiamen facility in China. The company said the unit is the largest of its type and application ordered to date for installation on a monohull vessel.
The TMC is designed to allow continuity of operations with both main and auxiliary hoist in extreme weather, and will incorporate Huisman’s dual main hoist system for upending large structures. It will also feature a segmented slew bearing, an electric drive system, and an automation package that will allow for future crane upgrading.
Ingeteam has been appointed as the electrical system supplier and integrator, covering power generation and distribution, propulsion motors, and power management system, plus the alarm monitoring and control arrangements. Primary products from the Indar range will be manufactured at the company’s premises in the Basque region of northern Spain.
The six Indar main generators of 8,640kVA, supplying AC current at 11,000V, have been specified with 12-cylinder MAN medium-speed, common-rail engines of the V32/44CR type, each rated at 7,200kW, giving a primary power concentration of 43,200kW. The Indar 315V AC motors for the multiple, main azimuthing propulsors and manoeuvring thrusters will all be driven by Ingedrive MV100 DFE frequency converters.
Exhaust gas treatment technology employed on the ship has two elements, whereby a diesel particulate filter, claimed to offer a 99% effectiveness in removing nanoparticles, is followed by a tailored MAN selective catalytic reduction(SCR) system. This not only ensures Tier III NOx compliance but also meets the even stricter Euro Stage V limit. The enhanced NOx reduction rate is essential to achieve the Ultra Low Emission vessel (ULEv) categorisation sought by the owner. Furthermore, the arrangements will satisfy Clean Ship ND07 and Green Passport EU certification criteria.
The common-rail system’s flexibility permits the engine to be programmed to run in accordance with different fuel consumption-versus-power characteristics, optimising efficiency at the respective load points. The optional ECOMAP feature that has been chosen applies various engine ‘maps’ to improve fuel economy while meeting IMO emission limits.
The main propulsors are four electrically-driven Schottel rudder propellers of the SRP 610FP type, each rated for an input power of 3,000kW. With this configuration, Les Alizes should be able to make transits at up to 13 knots. So as to ensure precise positioning in DP mode, two retractable SRP 610R units of 3,250kW apiece and two STT 7FP transverse thrusters of 2,600kW will be adopted. The Schottel package also includes the proprietary Leacon sealing system, designed to continuously check the seals for leaks and prevent water from entering the gearboxes.
Jan De Nul also has a jack-up offshore installation newbuild taking shape in China. Ordered from COSCO Shipping Heavy Industry, the Voltaire has been specified with a 3,000t crane and is seen as complementary to Les Alizés.
8 The 5,000t crane
is the dominant feature of the Jan De Nul newbuild at Haimen, China
NEW TITAN FOR WINDFARM DEVELOPMENT
Versatility and customisation are pivotal to a new concept of off shore windfarm construction vessel from a leading Danish designer, writes David Tinsley
Building on milestone references in wind turbine installation vessel (WTIV) design, Copenhagen-headquartered consultancy Knud E Hansen (KEH) has developed a new self-elevating class to meet evolving market demands in terms of pieceweight scale, transport capacity, construction productivity, and energy effi ciency.
Although proposed with a nominal technical specification, the Atlas C generation is intended as a design platform that can be customised to meet clients’ precise objectives and requirements. This applies principally to the equipment and engineering arrangements. Furthermore, it is seen as the basis for a new portfolio of wind turbine installation vessels of varying sizes.
KEH reports that negotiations are ongoing with operators in the offshore wind sector involving the tailoring of the platform to individual needs.
With a jacking deadweight of 18,000t, a cargo deck area of 6,800m2, and a crane rated for 3,000t at 37m outreach, the WTIV will be capable of carrying and deploying six of the new-generation wind turbines in the 14-16MW power range, and five of the next-generation turbines of 20MW-plus. The deadweight and crane capacity will also enable the transportation and handling of at least four of the extra-large monopole/transition pieces required for turbines in the 1416MW category.
In keeping with the objective of design versatility, the cargo deck incorporates uniform girder spacing both longitudinally and transversely, such that foundations for turbine parts can be standardised and installed in many different locations and orientations.
A multi-generator layout is at the heart of the dieselelectric power and propulsion system, applying key precepts of operating flexibility and service dependability. Power can be efficiently and precisely matched to actual load requirements at any point across the operating profile, while ensuring the requisite power availability and redundancy for challenging offshore conditions and assignments. An energy storage system will confer increased efficiency and environmental benefits.
In its initial proposal, the Atlas C-class incorporates eight identical gensets, each producing 3,340kW of electrical power, divided between two independent engine rooms. A direct-current (DC) grid system, allowing the genset engines to be run at variable speed, would be coupled to a 4MW battery pack for load levelling and peak shaving. As the batteries can supply instant power, the need to have a ‘spinning reserve’ with generators in standby mode, such as during DP operations, is obviated. Furthermore, the adoption of a battery system provides for the recovery of up to 60% of the energy used in jacking the vessel.
The main propulsors are four azimuthing stern thrusters, fitted in nozzles to maximise thrust, and driven by permanentmagnet motors. To achieve the required manoeuvring and position-holding performance, the foreship will be equipped with two tunnel thrusters and two retractable bow thrusters.
The hull elevates on four three-chorded trusswork legs, supporting the vessel, its payload and the installation process in water depths up to 80m. Raising and lowering is effected by a powerful, electrical rack-and-pinion jacking arrangement. The elevating system is designed for 5,000 load cycles, reckoned to be significantly more than many competing solutions and intended to ensure that the leg racks last the lifetime of the vessel.
The inverted cones, or spud cans, at the base of the legs have been developed to minimise seabed penetration, reduce the load on the seabed when the vessel is jacked-up, and help retract the legs where the bed is muddy. Moreover, the cans are fitted with buoyancy boxes to reduce the draught in port.
Such is the provision for tailoring of the Atlas C series that generators, engines, thrusters, cranes and jacking systems can all be modified and selected in strict accordance with clients’ needs and wishes and availability from manufacturers.
The three-deck main superstructure located forward houses the operations centre as well as the accommodation for crew and contractors in 130 cabins, surmounted by a fullwidth bridge, above which is arranged a heli-deck.
A smaller variant of the C-class series is under development as the Atlas A-class, envisaged with a 1,600t crane and capacity to transport four 14MW turbines for mounting on pre-installed foundations.
KEH’s track record on the design front includes the 130m jack-up Mayflower Resolution (now the MPI Resolution), completed in 2004 as the first-ever purpose-built, selfelevating turbine installation vessel , and the 161m sisters Pacific Orca and Pacific Osprey, which ranked as the largest jack-up WTIVs worldwide on delivery in 2012.
Credit: Knud E Hansen 8 The Atlas-C class,
a titan for windfarm projects
THE GAS TURBINE DILEMMA
One sub-heading in the January 1971 issue of The Motorship came in a review of trends in machinery demand, contributed by a Mr Muller, a design director of Sulzer. “Crude oil and LNG as fuels”, it read.
A number of Sulzer-engined tankers were due to enter into service that would be equipped to burn the same crude oil as was carried as cargo. The system being developed by Sulzer, and which was described as a “major development” was concerned mostly with the safety issues involved in burning a fuel that was described as “highly volatile”.
However, it was the novel practice of using boil-off gas from a soon-to-be-delivered LNG tanker that was raising eyebrows 50 years ago. Rather than today’s LNG technology, this pioneering installation was a Sulzer 7RND90 two-stroke engine, normally burning liquid diesel oil, via conventional injection equipment. The addition was an additional gas injection valve, lowing the LNG for combustion against the upcoming stream of scavenge air. This was thought to provide optimum mixing between the two fuels, allowing a fuel mix of up to 95% LNG.
Alternatives to the large diesel engine were still being seriously considered. The January 1971 Motorship published a paper from an Australian shipowner in which costings for a pair of ro-ro ships, powered by either medium-speed diesels or gas turbines, each of 17,500hp, were compared. Large two-stroke diesels and steam turbines had been discounted for various reasons. Taking into account fuel costs, lubrication, maintenance, installation and manning levels, the gas turbine system - a GE series 5000 - was shown to save just under $40,000 per year, a saving of about 15% of the total cost of the diesel installation.
In another article, the choice of twin Pratt & Whitney gas turbines for each of a class of four German-built container ships was explained by manager Denholm. Although it was acknowledged that fuel costs would be higher, the gas turbines lent themselves to automated operation, reducing manning levels, while the compact size allowed about another 80 TEU to be carried. But the greatest justification came from increased reliability and easier maintenance, it being calculated that the gas turbine powered vessels could permit at least one more voyage per year, more than covering any increased fuel costs.
8 Marine version of a Pratt & Whitney 30,000hp
aero-derivative gas turbine
8 Dart Europe, one of a trio of then-largest
containerships afl oat
With such an emphasis on propulsion, and the annual summary of ships completed, there was not much space for ship descriptions, but several pages were given over to the Dart Europe, first of the ‘second-generation’ fully-cellular container ships operating a weekly Transatlantic service. These ships, at the time the largest boxships afloat, were of 1556 TEU capacity, barely counting as feeder ships by today’s standards. This modest capacity in a ship of 231m length and 30.5m beam can be explained by most of the boxes being carried below deck, seven tiers in most holds. Above, just a single tier, 10 boxes across, was carried on the forward hatch covers, two tiers centrally, and three tiers aft.
A service speed of 22 knots could be achieved the written consent of Mercator Media Ltd.
with the Sulzer-based propulsion plant, comprising a Cockerill-built 10RND90 main engine of 29,000 bhp at 122 rpm, driving a six-bladed 6.3m diameter propeller. Although equipped to Lloyd’s Register UMS notation, the automation systems were kept simple, with the main engine being controlled from either the bridge, a control station in the engine room or controls on the engine itself - there was no separate control room.
The Transatlantic container trade was anticipated three Dart containerships were expected to carry a substantial proportion of that traffic. MOTORSHIPTHE
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