Tidal Turbines
Sea change for tidal power – New underwater turbines could be cheap and eco-friendly
A British company has invented a simple tidal power system that is relatively easy to install and has little impact on its environment. The device could soon be added to our range of renewable energy resources, and be used to bring power to remote seaside locations.
The TidEl system uses floating turbines that are anchored to the seabed by chains. The underwater windmills drift back and forth with the tide, so they point in the best direction to get power from the spinning blades.
“It is a rugged but simple design,” says Ian Griffiths, a business manager for SMD Hydrovision, Newcastle upon Tyne, the company that invented the system. www.smdhydrovision.com
The group tested a one-tenth scale model of the generator by submerging the device in a huge water tank at the New and Renewable Energy Centre in Northumberland this January. Results presented at the Oceanology International 2004 meeting in London last week suggest that full-size twin turbines should produce about one megawatt of electricity.
The inventors hope to deploy a full-scale unit, with blades 15 metres long, at the European Marine Energy Centre in Orkney next year.
Tidal troubles
Drawing energy from the tide has a number of advantages over other forms of renewable energy, says Tim Green, an electrical engineer at Imperial College London. “It is much more predictable than the wind,” says Green. “This will probably be the next big push in the UK after we have our wind-power farms up and running,” he says.
So far tidal power has been slow to catch on. Most tidal power plants rely on huge barriers across river estuaries, such as the La Rance tidal generator near St Malo, France. Concerns about the visual and environmental impact of barriers have kept plans for a similar system in the Severn estuary near Bristol, UK, firmly on the drawing board, says Green.
“Our system has a very small environmental footprint, and zero visual impact,” says Griffiths. “This could make it easier to get permission to install the units,” he says.
“Other research groups are investigating the idea of mounting underwater turbines on masts,” says Green. “But they face problems. Masts must be designed to take enormous loads in rough weather, and costs spiral when they are sited in deeper water,” says Griffiths. “Using chains instead of a solid mast helps to cut this cost.”
Griffiths says it is hard to predict how much energy from the generators will eventually cost, but predicts that it could compare to that from wind power. “It is definitely a commercial prospect,” he says.
TidEl has received start-up funding from the UK’s Department of Trade and Industry, which may also help to fund the full-scale version. The department’s decision is expected later this week.
Nature 24th March 2004 Mark Peplow
