Wave technology

Andrew Williams | 11 years ago

Following announcements by two UK-based companies, wave power looks set to become an increasingly important renewable energy source.  But how long will it be before it is commercially viable and what ecological benefits might it bring?

The UK wave power sector

According to the Department of Energy & Climate Change (DECC), the UK enjoys the richest marine energy resource in Europe, with around 35 percent of the continent’s total wave energy potential.  The Carbon Trust estimates that we could meet up to 15 percent of our electricity needs from marine sources, and that we could install 2 gigawatts of generation capacity by 2020, and up to 30 gigawatts by 2050.

As a result of this unique potential, many in the renewables sector are waking up to the fact that wave power could one day rival wind as a key source of renewable energy in Britain.  In its 2010 study Building a Low Carbon Economy – The UK’s Innovation Challenge, the Committee on Climate Change reports that the UK has become a world leader in the sector with ‘a quarter of the world’s wave technologies being developed to some extent in the UK.’

However, despite this early promise, the total amount of energy generated from wave power remains relatively modest.  A new report by the Centre for Alternative Technology reveals that, in 2008, renewables were responsible for only 6% of energy used (7% of gross supplied electricity), with just 0.75% from wind, wave and solar sources (although this accounted for almost 2% of gross supplied electricity).

The fact remains that wave power technology, which captures energy from wave movement and converts it into electricity, is still subject to uncertainties over the best system design and faces substantial challenges over issues including installation, maintenance and grid connection.

New projects

Against this background, two innovative UK projects are rising to the challenge of developing the technologies necessary to realise this massive, and as yet largely untapped, energy resource.

In November, EON-UK revealed that its prototype wave power device, the Vagr Atferd, (meaning ‘wave power’), had generated power in UK waters for the first time.  The news was hailed by Scottish first minister Alex Salmond as “another significant step” in Scotland’s journey to becoming the “green energy powerhouse of Europe.”

The 750kW device, currently on trial at the European Marine Energy Centre’s Billia Cross site in Orkney, is the first of its type to be tested anywhere in the world.   The 180m long Pelamis Wave Energy Converter weighs around 1,300 tonnes and works by using wave motion to produce electricity by driving a set of hydraulic rams at the hinged joints, which link the cylindrical sections of the device.

Meanwhile, the team behind Wave Hub, an energy scheme with the potential to generate enough electricity to power up to 17,500 homes, announced last month that it has been plugged into the National Grid for the first time.

Wave Hub is a £42 million grid-connected offshore facility for the large-scale testing of technologies that generate electricity via wave power.  It consists of an electrical hub on the seabed 16 kilometres off the Cornish coast, to which wave energy devices can be connected.  The 12-tonne hub is linked to the UK’s grid network via a 25km, 1300 tonne subsea cable.

Making bigger waves?

So, how long will it be before wave technology of this type is available on a large-scale?  According to Guy Lavender, Wave Hub’s Business Manager, commercial development depends upon a range of factors, from the availability of adequate finance to the establishment of a supportive regulatory and consenting regime for long-term development.

“It is important to recognise that device developers are at different stages of development.  Whereas some are confident of commercial deployment in the next five years, others believe that it could be 10 years before we see large-scale commercial arrays,” says Lavender.

Developers will also need marine licenses for commercial-scale projects, which can only be obtained after carrying out environmental impact assessments.

Assuming these hurdles are overcome, Lavender argues that a number of other constraints to scaling-up the technology remain.  These range from the technical challenges of offshore deployment and the development of nearshore grid capacity to the need to develop a supportive planning and regulatory system.

“Wave Hub responds to many of these issues by showing how an offshore infrastructure project can and has been delivered.  What is important however is that there is a clear commitment from the UK Government that this is an industry it wants to build.  Without that the UK risks losing its competitive advantage,” adds Lavender.

E.ON-UK’s approach is to gradually expose the Vagr Atferd to increasingly severe sea states to prove the machine can operate in the full range of conditions.  The expectation is that this testing stage will continue throughout 2011 and possibly beyond.

“We need to do this in a series of stages to manage exposure, build up confidence and gather the operating data that we and our partners need,” says Amaan Lafayette, Marine Development Manager at E.ON UK.

“We currently envisage a joint programme of 4 to 5 years, together with our partners Scottish Power Renewables, who have commissioned another machine to run alongside ours in a joint project,” he adds.

Ecological advantages

In the wake of ongoing debates about the environmental consequences of wave and tidal power, what advantages do smaller-scale devices, such as the Vagr Atferd and those tested at Wave Hub, have over larger-scale technologies of the type pictured in the proposed Severn barrage?

“In broad terms, grid-connected open-sea infrastructure like Wave Hub is less capital intensive than barrage technology and has less impact on the environment given that wave energy devices generally float on or just below the surface of the sea and only require mooring systems to keep them in place,” says Lavender.

At this stage, the environmental and ecological affects depend on the local area and are difficult to predict, especially as there aren’t yet many projects in the water available for monitoring and comparison.  However, by creating a ‘total barrier effect,’ it is difficult to deny that a barrage will also cause additional impacts over and above individual ‘non-connected’ devices.

“Fish will undoubtedly be [more] affected by a barrage than spaced devices, unless provision was made for them to pass through the barrage without passage through the turbines.  This would then have a knock on effect on the wider ecosystem by virtue of impacts on birds that may feed on the fish,” says Lafayette.

“Water quality [would also] be impacted as the sediment levels change, which will affect the turbidity of the water and this will affect the animals that live in the water basin or estuary,” he adds.

The potential ecological advantages of wave energy have also been welcomed by observers from the wider environmental community.

“[We] welcome the development of wave energy devices as an essential mechanism to address climate change.  While the site specific impacts are yet to be fully understood, we are confident that if placed sensitively and executed with care, wave energy devices such as Pelamis should be truly sustainable developments,” says Melissa Moore, Senior Policy Officer at the Marine Conservation Society (MCS).

“It is an exciting time for developing offshore wind, wave and tidal electricity in Scotland, and as an important report that MCS in Scotland helped to co-ordinate outlined, sustainable development of the industry is welcomed and can be done so without endangering important environmental interests,” adds Calum Duncan, MCS Scottish Conservation Manager.

“We support a ‘deploy and monitor’ policy that requires collection of adequate baseline survey data to identify environmental sensitivities prior to deployment and detailed monitoring thereafter, as part of an adaptive management approach that triggers mitigation measures if necessary. This is an unprecedented opportunity to make sure devices are installed and operated in a manner that minimises impacts on the marine environment whilst making their much-needed and most welcome contribution to a low-carbon future,” he adds.

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Andrew Williams