The latest wave power schemes are aimed at perfecting demonstration plants, but commercial generation is getting nearer
Developed by the UK's South West Regional Development Agency (RDA), the pioneering Wave Hub marine energy project has been safely installed on the seabed following a delicate operation to lower the 12t hub into 55 metres of water, 16 km offshore.
Wave Hub is creating the world's largest test site for wave energy technology by building a grid-connected socket on the seabed off the coast of Cornwall in South West England, to which wave power devices can be connected and their performance evaluated.
The idea is that groups of wave energy devices will be connected to Wave Hub and float on or just below the surface of the sea to assess how well they work and how much power they generate before being commercially produced and deployed. There are four berths available at Wave Hub, each covering two square kilometres. Wave Hub will have an initial maximum capacity of 20MW (enough electricity to power approximately 7000 homes) but has been designed with the potential to scale up to 50MW in the future. The first wave energy devices are expected to be deployed in 2011.
The £42m (EUR50m) project has been developed by the South West RDA and is a cornerstone of its strategy to develop a world class marine energy industry in South West England and the UK.
The RDA's Wave Hub general manager Guy Lavender said: "Wave Hub will be on the seabed for the next 25 years, helping the world gain invaluable knowledge about how we tap the vast energy potential of our oceans in the pursuit of clean, abundant, renewable energy and cementing the UK's position at the forefront of this green power revolution."
Wave Hub is connected to the shore via a 25km, 1300t subsea cable that has been laid from the beach at Hayle on the north Cornwall coast out to the Wave Hub site.
Wave Hub is being funded with £12.5 million from the South West RDA, £20 million from the European Regional Development Fund Convergence Programme and £9.5 million from the UK government.
Further north, wave energy company Aquamarine Power has recently visited the Western Isles in Scotland to explore the potential for installing a small demonstration wave power project off the west coast of Lewis. Representatives of the Edinburgh-based company came to Stornoway to attend the recent inception meeting of the Outer Hebrides Renewables Group where issues affecting the renewable energy industry such as grid infrastructure and transmission charging were discussed. The company now plans to make contact with as many local stakeholders as possible to take advice on the most suitable locations for a potential site to install a test array of up to ten wave power devices in the next five years.
"It has been great to visit Lewis to understand some of the issues facing the renewable energy industry here on the island. We are now keen to speak to as many local people as possible to help us identify potential areas for testing a small demonstration array of our Oyster wave power devices," said Sian George, head of Aquamarine Power's commercial development team.
"The Isle of Lewis has some of the best wave resource in the world. We think the marine renewables industry offers terrific potential for the island but at this early stage it is essential that we work closely with local communities and key stakeholders to ensure the sustainable and responsible development of any proposed Oyster project," she added.
Aquamarine Power has offices in Edinburgh and Orkney. The company successfully installed its Oyster 1 wave device at the European Marine Energy Centre (EMEC) in Orkney last summer and plans to deploy its next-generation Oyster 2 in Orkney next year.
Also in Northern Europe, Danish company Floating Power Plant is still testing its Poseidon power plant in Lolland, Denmark. The 350-ton floating platform uses a hydraulic power take-off system and is fitted with wind turbines. A patented buoy system ensures that Poseidon always faces into waves.
The current platform is a demonstration version, measuring 37 metres wide, 25 metres long and six metres high. However, once tests are completed next year, a 30,000t commercial version is planned (Fig.1).Depending on both waves and winds, Floating Power Plant says that a commercial platform could generate up to 50GWh/y.
In the US, Ocean Power Technologies has signed what it describes as a groundbreaking settlement agreement (SA) with 11 federal and state agencies and three non-governmental stakeholders for its utility-scale wave power project at Reedsport, Oregon.
This agreement represents a major step towards the grant of the first license ever issued by the Federal Energy Regulatory Commission (FERC) for a commercial-scale wave power project in the US. The SA supports the responsible, phased development by OPT of a 10-PowerBuoy, 1.5MW capacity wave energy station in a manner that protects ocean resources and stakeholder interests.
10-buoy wave farm
Manufacturing of the first 150kW PB150 PowerBuoy is already underway at Oregon Iron Works under its contract with OPT. The 10-buoy wave farm is expected to be connected to the grid after receipt of the FERC license and additional funding, supplying clean energy to approximately 1000 homes.
OPT says that this first-ever wave energy SA was reached after extensive technical, policy, and legal discussions regarding appropriate prevention, mitigation and enhancement measures, and study requirements. It covers a broad array of resource areas including aquatic resources, water quality, recreation, public safety, crabbing and fishing, terrestrial resources, and cultural resources. The SA includes an innovative adaptive management plan that will be used to identify and implement environmental studies that may be required, and to provide a blueprint for the application of this new information as the wave power station develops.
Oregon governor, Ted Kulongoski, said: "The manufacture of the first buoy has already created dozens of green-energy jobs in Oregon and when the 10-buoy wave power project is built, a whole new industry will be created to benefit our coastal communities."
"This agreement demonstrates OPT's commitment to develop wave power in a way that respects the environment and the needs of all who rely on ocean resources for many different uses," added OPT executive chairman George W Taylor.
In the Gulf of Mexico, Minnesota-based Independent Natural Resources has installed a commercial wave-powered demonstration version of its SEADOG offshore platform. The SEADOG pump captures ocean-wave energy to pump of seawater, consuming no fuel or electricity and creates no polluting by-products in the process. The pump uses buoyancy to convert wave energy to mechanical energy.
The main components of the SEADOG pump include a buoyancy chamber, buoyancy block, piston assembly, piston shaft, piston cylinder, and intake and exhaust valves. When positioned in the water the buoyancy block (filled with air) floats within the buoyancy chamber, moving up and down in relation to the ocean waves and swells. The buoyancy block is connected to the piston shaft which in-turn moves the piston assembly through the piston cylinder.
The company says each of the seven feet diameter pumps on the platform will send water up through three water wheels connected to a generator capable of producing about 60kW, 4kW of which will be used to run a standard reverse osmosis desalination machine to produce 3000 gallons of freshwater per day.