wind power

The future of offshore wind in Europe is in doubt

1 November 2008

A study by the Arthur D Little consultancy warns that although offshore wind is clean, green and supported by policymakers, it faces formidable barriers, including significant technical challenges, to securing its position in Europe's future renewable energy mix.

The report*, entitled All at Sea: the Future of offshore wind pinpoints the high failure rate of offshore wind turbines, and technical challenges in general, as the critical issue that must be addressed before any progression of the industry is possible. It recommends industry collaboration as the way to to overcome the challenges offshore wind faces.

The offshore wind market is small, (1 GW in 2007, about 0.01% of global capacity) but growing fast, probably sevenfold in the next five years. Virtually all of this growth will happen in Europe, half of that in the UK, where government policy is fully behind exploitation of the UK’s potential. The bad news is that it will require a staggering increase from the 194 turbines currently installed in the UK to around 3000, with another 4000 onshore.

So despite the image of offshore wind as an ideal form of green energy its future, says ADL, is by no means assured. Supply constraints, logistical difficulties and technical concerns present significant obstacles to the expansion of the sector. The first two barriers can be handled but the technical challenges are less widely recognised and present the biggest barrier to long-term growth.

The figures are clear. Onshore, wind turbines can achieve availability levels of 97%. Offshore, technical problems can reduce that number to 60%, made worse by long repair times. The wind industry must therefore find ways of developing equipment that is robust and reliable in an offshore environment, a step change that will require industry wide collaboration and a willingness to share resources and knowledge, and it will have to be driven by knowledgeable customers and by governments providing research funding and direct financial incentives.

The challenge begins with the need to convince investors to finance the high upfront costs. From the outset, offshore projects need to offer the prospect of a strong return to reduce the payback time. The business case then depends on building as many turbines as possible and, in order to maximise power yield per turbine, those turbines have to push the limits on size. Delivering projects of this scale and scope successfully means overcoming supply constraints, logistical difficulties and technical challenges.

The primary factors that are stretching capacity are consolidation following the last period of cyclical oversupply, sharply increasing demand, and the reluctance of suppliers to adopt risk-averse strategies where offshore wind is concerned. As a result, there are only two major offshore turbine manufacturers, Vestas and Siemens, and although REpower and Clipper are coming up on the rails with offshore-specific models, lead times of up to three years mean that the supply constraints are likely to ease only in the medium to long term. Similarly logistical difficulties such as the restricted supply of installation and maintenance vessels will, in time, be adjusted.

It is the third barrier, technical problems, that presents the biggest potential risk to the future of the industry. Technical failure rates in offshore wind can be high compared to onshore, reducing availability to 60%, and are difficult and expensive to fix. Analysis of maintenance records shows that while service teams for offshore wind farms are supposed to make two scheduled maintenance visits every year, unscheduled visits to many installations are made twenty times a year.

Onshore, serious technical failures are high-profile events, because they have the potential to cost lives as well as money. Most notable in the past year was the disintegration of a Vestas turbine near Arhus in Denmark due to ‘lack of maintenance’. Several incidents in the UK and Germany, including loose blades crashing into roofs of houses, have some questioning the viability of onshore turbines in inhabited areas of the country. This strengthens the case for offshore turbines but highlights the crucial need for current offshore designs to be radically improved.

Why do turbines fail?

The heart of the problem is that the technology being used offshore is generally onshore technology that has not been modified sufficiently to meet the different demands of an offshore environment. Failures are also harder to repair. The contrast with onshore reliability is dramatic.

And as sites move further offshore, this problem is likely to get worse. That could mean offshore developments in deepwater areas will be seen as unviable, and there is already evidence of caution. All the potential sites in the German North Sea have been allocated, but it is uncertain as to whether investment will follow. A leading industry figure in the German market informed ADL that offshore has ten years in which to prove itself, after which it may be partially or wholly curtailed in German waters.

Robust and reliable

ADL sees three areas that need attention if offshore wind technology is to become more robust and reliable – better design of individual components (e.g. smaller, two-stage gearboxes), the drive train (smarter integration of key components), and foundations, increased levels ot R&D mainly in design and maintenance methods, and more thorough certification testing for the offshore environment.

ADL believes that testing is the key. To date it has clearly been inadequate despite manufacturers’ claims that it is possible to test onshore without the expense of offshore testing. However, there is clear evidence that running a turbine in real offshore conditions for at least a year would bring to light many key problems and save considerable amounts of money.

Such testing has already been shown to be possible, albeit with government support. In Germany, for example, offshore testing is already taking place at Alpha Ventus (but on a partly commercial basis). All this work will need to be underpinned by collaboration. To date the industry has been characterised by a general atmosphere of secrecy and suspicion and, as a result, there has been a fragmentation of knowledge and a lack of research progress. This can be superseded if owners and developers put pressure on manufactureres for more rigorous testing, if turbine makers are prepared to invest with a long term future in mind, and if governmenst are prepared to free up funding for public R&D centres and projects such as Upwind.

*All at Sea: The Future of Offshore Wind Arthur D Little 2008.

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