Making ripples, cautiously: ocean energy

In March, three wave-energy converters arrived at the Portuguese port of Peniche from Scotland. Named Pelamis, after a sea snake, the 750kW generators are undergoing final assembly there before deployment later this year five kilometres off the coast of northern Portugal. They were developed by Edinburgh-based Ocean Power Delivery (OPD) and ordered by a Portuguese consortium led by Enersis, a leading renewable energy company.

Assuming the generators perform well, the consortium will take delivery of another 28 before year’s end. When complete, the $9 million project is expected to meet the average electricity needs of more than 15,000 Portuguese households while saving more than 60,000 tonnes of carbon dioxide emissions yearly from a fossil-fuel power plant.

The Pelamis is about 130 metres long and 3.5 metres wide, and consists of four cylindrical segments hinged horizontally as well as vertically. As the semi-submerged sections bob and twist in the waves, hydraulic rams in the joints pump high-pressure oil through hydraulic motors that drive electrical generators. Power reaches shore via an underwater cable. The devices are loosely moored to the seabed – ideally in waters about 50 to 60 metres deep to save the cost of long mooring cables – and face the waves head-on.

Portugal prioritises

Richard Yemm, OPD’s managing director, said the world’s first wave farm was being installed in Portugal, not the United Kingdom, because Portugal had been quicker to prioritise wave power and recognise its commercial potential.

“The Portuguese government has put in place a feeder market that pays a premium for electricity generated from waves compared to more mature technologies such as wind power,” Yemm said. “This allows the commercial investment in early stage projects which is crucial to move the technology forward. This is exactly the same approach that delivered the wind industry in Denmark and Germany, which today has a turnover of over €12 billion a year with 60,000 employed worldwide."

Cost-competitive

Earlier this year the Carbon Trust, an independent company funded by the UK government that promotes the reduction of carbon emissions, issued a report saying that ocean energy could provide a fifth of the UK’s electricity needs and become cost-competitive with conventional and other renewable energies.

The UK has a number of wave power companies, and several different technologies under development. One of the key drivers has been the European Marine Energy Centre, (EMEC) on Orkney in the North of Scotland. The centre provides a proving ground to test the efficiency of prototypes and demonstrate they are robust enough to survive hostile sea conditions, while having minimal impact on the marine environment.

Devices under test can be linked directly to the national electricity grid. The Pelamis prototype has clocked up more than 1,000 hours here.

Meanwhile, the UK’s first commercial marine power project is underway off the coast of Northern Ireland. SeaGen, developed by Marine Current Turbines Ltd, works like an underwater windmill – but rather than wind, its rotors are driven by tidal flows of water.

A yet more ambitious installation is planned to start in 2007, ten miles off the coast of Cornwall. The £15 million Wave Hub project involves building an electrical ‘socket’ in the sea bed, connected to the national grid via an underwater cable.

Sixteen companies expressed an interest in connecting to Wave Hub, from which three have been selected for the first phase. Nick Harrington, Project Manager said, “All three have developed very different technologies and will form a core group with which we can go forward.”

Among the three companies chosen is Ocean Power Technologies (OPT) Inc., of New Jersey, U.S. Attracted by the strong interest in renewables and a receptive financial community, OPT became the world’s first publicly listed wave power company when it joined the Alternative Investment Market in London in October 2003, raising GBP22 million.

With a large coastline and strong prevailing winds that whip up its waters, the UK has by far the highest potential for wave power in the European Union. Worldwide, less than 0.1 per cent of the energy of waves and tides could supply more than five times the current demand for electricity, ocean power enthusiasts say. But converting wave energy into electricity has proved difficult.

Setbacks

Although wave power technologies have existed for about thirty years, progress has been slowed by setbacks, a lack of confidence, and minuscule R&D funding in the 1980s and 1990s – when oil prices returned to acceptable levels following the 1973 Middle East oil crisis. Further obstacles include opposition to unsightly shoreline stations, and to offshore facilities that could impede shipping or fishing. The pounding of the waves, saltwater corrosion, and the build-up of barnacles and seaweed pose special challenges.

“It’s hard to talk about the outlook for ocean energy systems because a number of technological barriers still haven’t been overcome,” said Peter Tulej, who heads the Paris-based International Energy Agency’s Renewable Energy Unit. “Substantial research and development remains to be done. In the past 30 years, governments have allocated very little funding to ocean energy systems compared with other renewable energy technologies.

“I personally think that ocean energy systems will come to the market. But it will probably take 20 to 25 years for significant growth.”

Venture capitalists can lead the way where the public sector fears to tread. “Wave and tidal power are at an early venture capital stage, and the market potential is huge,” said Jonathan Johns, a renewable energy expert at Ernst & Young, the accounting and consulting firm. “The winning technology isn’t clear at the moment, so it’s a matter of placing your bets, as it were. Cash will probably be burned for long period of time.”

Cautionary tale

The story of the Wavegen wave power station is a cautionary tale. Developed by researchers from Queen’s University in Belfast and operated on the Scottish island of Islay by the Inverness-based company Wavegen, Limpet 500 (Land Installed Marine Powered Energy Transformer) has produced power for the UK grid since 2000.

The station uses the principle of an oscillating water column (OWC). It has a chamber that lets seawater in and out, and an air-driven turbine that powers an electrical generator. Water from incoming waves compresses the air in the chamber, and receding water decompresses it. The turbine turns the same way irrespective of the airflow’s direction.

Although the station was rated at 500kW, it has produced 15kW. Wavegen had to be rescued from bankruptcy last year, when it was taken over by Voith Siemens Hydro of Germany, a leading hydropower equipment company.

Voith Siemens Hydro recently announced that it would supply the technology for Germany’s first wave power station – with a nominal capacity half that of the Islay facility. The OWC station, to be built by the German power company EnBW at an undetermined location near Germany’s North Sea shore, is expected to go on line by the end of the decade and power about 120 homes.

Among other countries developing ocean power technologies are Canada, the United States, China, Japan, India, Australia, the Scandinavian nations, and France, which boasts the world’s first and largest tidal power station. Its 240mW barrage on the Rance estuary in northern Brittany has been in operation since 1966. There are few suitable sites in the world for barrages, which work much like hydroelectric dams, and they have been criticised for disturbing the environment.

In commercial terms, wave and tidal power is around ten years behind its counterpart in wind energy. The cost of generating electricity from wind has fallen by 80 per cent in the past twenty years, as a result of optimising the technology and achieving economies of scale.

Wave power is starting from a lower threshold, but in common with other renewable energy sources will need support to become a lower-cost source of electricity than fossil fuels.

Despite the considerable difficulties, Ernst & Young’s Johns – like the IEA’s Tulej – is optimistic on the long-term chances for wave and tidal power. “The overall market prospects are very good,” Johns said. “If you take a 2020 horizon, then they’ll be part of the energy equation.”