|Switched on ... the marine turbine in Strangford Lough will eventually power 1,000 homes|
An underwater turbine that generates electricity from tidal streams was plugged into the UK's national grid today. It marks the first time a commercial-scale underwater turbine has fed power into the network and the start of a new source of renewable energy for the UK.
Tidal streams are seen by many as a plentiful and predictable supply of clean energy. The most conservative estimates suggest there is at least five gigawatts of power in tidal flows around the country, but there could be as much as 15GW.
The trial at Strangford Lough, in Northern Ireland, uses a device called SeaGen and generates power at 150kW. However, engineers have plans to increase power to 300kW by the end of the summer. When it is eventually running at full power SeaGen will have an output of 1,200 kW, enough for about 1,000 homes.
SeaGen was designed and built by the Bristol-based tidal energy company Marine Current Turbines (MCT), which also installed the test device at Strangford in May.
"The best way to think of it is an underwater windmill," said Martin Wright, managing director of MCT. "There are big masses of water moving on the Earth's surface as a result of the gravitational attraction of the moon. Therefore you have streams occurring where you have accelerated flow."
Tidal generators harvest the energy of these moving streams with the added advantage that the resource is, unlike wind, predictable.
The secretary of state for business, John Hutton, said: "This kind of world-first technology and innovation is key to helping the UK reduce its dependency on fossil fuels and secure its future energy supplies.
"Marine power has the potential to play an important role in helping us meet our challenging targets for a massive increase in the amount of energy generated from renewables."
The Department for Business, Enterprise and Regulatory Reform supported Seagen with a £5.2m grant, helping take its plans from the drawing board to the first demonstrator.
The cost of installing the marine turbines is £3m for every megawatt they eventually generate, which compares to £2.3m per megawatt for offshore wind. The costs will drop if the technology is more widely adopted.
Robin Oakley, head of Greenpeace UK's climate and energy campaign, welcomed the SeaGen trial: "Britain should be at the forefront of marine renewable energy development. Our windswept island has huge renewable resources and we should seize the opportunities to secure energy from around our coasts.
"Clean reliable tidal stream power can make a massive contribution to Britain, cutting CO2 and fuel consumption. But it also offers a chance for us to be world leaders in a new and potentially huge industry."
After SeaGen starts operating at full capacity, MCT plans to build a farm of turbines before 2011. "Our next site will be off the coast of Anglesey, the initial farm is about 10.5MW," said Wright. "The resource up there is around 350MW."
The Pentland Firth, the Channel Islands and the Severn estuary are also potential hotspots for tidal energy.
Wright said: "I hope it makes people believe that tidal power isn't 20 to 30 years away and a dream, but it is something that, if we get the right resources around it, could become a significant reality and contributor much quicker than that."