The UK and European offshore wind industry could create jobs, supply chain opportunities and multi-billion-pound revenue streams, while increasing energy security and cutting carbon emissions. But there is a problem, which is now the subject of an intense research and development and demonstration (R&DD) innovation and efficiency drive. High installation, operation and maintenance costs must come down. Jon Herbert reports.

Overcoming the costs of producing renewable energy from offshore wind farms is currently a huge hurdle. However, the rewards are equally large.

In response, energy operators, researchers and government-backed bodies are in the middle of a major R&DD drive to bring forward technologies and more effective working methods that will make an environment that was previously conquered by the oil and gas industry a viable green opportunity to produce more power from the seas.

The UK currently has the world’s largest installed wind farm generating capacity, with new projects in the pipeline leading up to 2020. By 2020, when the EU’s 15% renewable energy target kicks in, the Government’s UK renewable energy roadmap expects to see wind generating capacity reach 18GW. If costs can be contained, this could rise to 40GW by 2030.

At that point, it is estimated that onshore wind turbines, currently the cheapest UK energy source, will cost 8.3 pence per kilowatt-hour (p/kWh), compared to 12.5 p/kWh offshore. However, with promises from Conservatives to end new onshore wind subsidies if they win the May 2015 general election, offshore wind is moving to centre stage.

The long-term target is even more optimistic, providing costs can be cut. The Carbon Trust foresees a quarter of a million offshore wind-related UK jobs by 2050, at which point annual revenues have been predicted to reach £19 billion, commensurate with a 7% carbon emissions reduction over 1990.

However, almost all cost problems and solutions are tied to the changing and challenging offshore environment in which the future wind industry must operate as it moves out to sea and over the horizon.

The answer lies in innovation and close co-operation.

Major advances are being made in a series of key areas — vessel and turbine manufacturing and installation technology, wind farm layout and cabling design, operations and maintenance organisation and practice, plus developing a skilled but cost-effective workforce.

Accelerating innovation

The UK currently has some 20 major offshore wind farms, including some of the world’s largest. Development has been in three phases: Round 1, Round 2 and the large Round 3. But the industry is, literally, getting into deep water.

Until recently, most turbines installed in UK waters have been at depths of less than 20 metres and within 25km of the shoreline.

However, to meet even 2020 targets some 3000 new, much larger, complex and hopefully more efficient and robust turbines will need to be installed in up to 60 metres of water as far as 200km out to sea.

The Carbon Trust notes that from the foot of the foundation to the tip of the blades — at 250 metres tall — these giants will stand higher than London’s iconic “Gherkin” building. Turbine rotors will have a diameter 50% larger than the London Eye.

Working in harsh metocean (meteorological and oceanographic) conditions — buffeted by waves, winds and currents — large arrays of these leviathans will need a completely new range of technology.

This will include new foundation concepts, large specialist installation vessels and new installation methods that are able to work swiftly in remote, heavy seas all year round. It is too expensive to lose winters to wild weather. The way forward is co-operation, partnerships and alliances based on new research, development and demonstration programmes.

Mixed fortunes

2014 has seen both optimism and pessimism for UK offshore wind. With a proposed assembly plant larger than the Wembley Stadium pitch, Siemens announced in February a £160 million investment in facilities in Yorkshire across two sites. The first is a new turbine assembly and service centre at the Green Port of Hull. The second is a new rotor blade manufacturing centre in nearby Paull.

With a further £150 million investment from Associated British Ports (ABP), up to 1000 new jobs will be created, plus construction employment opportunities. There will also be major knock-on benefits for the supply chain.

Prime Minister David Cameron welcomed the move as “a massive vote of confidence in our long-term economic plans”.

However, a month later, energy giant SSE withdrew from plans to invest £20 billion in four major wind projects, citing limited government subsidies and high cost hurdles. The company said it would “narrow significantly the focus of its near-term development plans for offshore wind”.

Energy Secretary Ed Davey dismissed cost claims and was adamant that offshore wind targets will be met. He added: “Are we the best place to invest in the world? Yes.”

Radical rethinking

To tackle the cost innovation problem, in 2008 the Carbon Trust brought together nine major offshore wind developers who jointly operate 77% of the UK’s licensed generating capacity. The outcome has been a collaborative R&D programme — the Offshore Wind Accelerator (OWA) — which took the target of cutting costs by 10% by 2015.

Since then, the initiative has spurred a series of industrially focused development routes that are now tackling costs at a fundamental level.

The OWA is based firmly on technical innovation. The most pioneering new concepts are being developed, de-risked and commercialised through the supply chain. One third of funding comes from the Department of Energy and Climate Change; the rest from industry.

Co-operation between utility companies that run wind farms, turbine makers and support and installation vessel operators has been identified as the critical key to progress and optimisation.

Vessel owners, for example, largely determine vessel technology, and this can have far-reaching implications for overall wind farm efficiency. As increasingly specialised vessels are essential, their design must tie in with the future needs of other partners.

Turbine manufacturers too must share information about their future needs as components get bigger. Parameters such as lifting heights, overall weight and out-reach distances that vessels must be capable of achieving during installation — plus manufacturing methods that determine later maintenance and repair needs — can define some 80% of subsequent operating costs, it is estimated.

It is essential to look years ahead and this is a major financial and cost consideration.

Conversely, the large upfront investments needed for bigger turbines can cut operating costs per unit of electricity generated, because of greater generating efficiency and the fact that fewer turbines are needed. That in turn can reduce dependency on weather conditions, an important variable with wind.

Confidence is a vital factor for long-term investments in innovation. If the parties are assured long-term contracts, they can invest with more certainty. Vessel operators are then in a better position to operate at lower costs.

Innovation is needed too to reduce transmission line losses in the long electrical and subsea cable systems that take power ashore. More research is also needed into the layout of large wind farms to minimise inefficient air disturbance effects in air between turbines.

One other major cost issue is the time lost at sea during routine operation and maintenance (O&M) work, whether due to events, bad planning or adverse weather. It has been calculated that more than 50% of O&M time is spent waiting for the right weather conditions.

Innovative examples

DONG Energy is a major energy developer and operator and is working on an 18-month project with an academic consortium from the University of Oxford in an industry-academia model — just one example of the progress that can potentially be achieved.

The team is investigating how new material for the “monopiles” on which turbines stand and new installation methods could reduce offshore wind power costs by a predicted 35% to 40% by 2020.

Monopole foundations typically weigh some 600 tonnes at present and most of the mass is steel. With modern Round 3 offshore wind farms consisting of circa 100 turbine structures, the material and installation costs are high.

Currently, steel thicknesses are some 100mm. If this can be reduced by even a small amount without compromising strength and the stiffness of foundations, the savings could be significant.

The PISE project (Pile Soil Analysis) is part of OWA. Other industrial contributors include RWE, Statoil, Statkraft, SSE, Scottish Power and Vattenfall. Imperial College and University College Dublin are also involved.

Cost-efficient workforce

One other area where cost cutting is being looked at closely is the offshore workforce. Workforce costs inherited from the oil and gas industries have been historically high. Alternative sources include growing recruitment from the armed forces, where retiring service people are used to thinking and working efficiently in adverse environments around the clock.

Meanwhile, the National Audit Office (NAO) has criticised the Government for handing out £16.6 billion of green energy subsidies on eight projects to the offshore wind industry without ensuring competition to reduce prices.

The NAO says this means that householders will pay hundreds of millions of pounds too much on domestic energy bills while energy companies made “excessive profits”. The spending watchdog estimates that householders will pay an extra £11 annually up to 2020.

It suggests a better method of payment might be phasing. This would mean the Government paying reduced subsidies for turbines that are built later when costs are likely to be lower. Fears that the UK could miss its EU green energy targets for 2020 are said to have made ministers panic.

Last reviewed 26 August 2014