Minesto, a Swedish company which is a spin-off from Saab, has obtained funding to test underwater tidal power kites off the coast of Northern Ireland.
The underwater tidal kite consists of a turbine, generator, rudder, which is attached to the bottom with a tether. According to Minesto, it can produce energy in deep water with low flow velocity where no other known tidal technology can operate. Each tidal power kite will produce 0.5 megawatt and will fit into a standard shipping contaner.
The world’s largest tidal power station is to be constructed off the west coast of South Korea at Incheon.
GS Engineering and Construction has signed a memorandum of understanding with Korea Hydro and Nuclear Power to begin construction next year with a view to completion around 2017.
The power station will have a capacity of 1.32 gigawatts – 3.4 times greater than the capacity of the Rance Tidal Power Station in France which is currently the world’s largest tidal power station. The facility will provide 4.5% of South Korea’s demand for household energy.
Incheon is a city of 2,500,000 close to Soeul. It has the second biggest tide differences in the world, next to the Bay of Fundy in Canada.
A tidal turbine near the mouth of Strangford Lough in Northern Ireland has begun producing electricity at full capacity for the first time.
The SeaGen system is generating 1.2MW, the highest level of power produced by a tidal system anywhere in the world, and is claimed to be the first truly commercial ocean tidal system to achieve full production.
Martin Wright, managing director of SeaGen developers, Marine Current Turbines, said "There are no other tidal turbines of truly commercial scale; all the competitive systems so far tested at sea are quite small, most being less than 10% the rotor area of SeaGen."
The system works like an "underwater windmill" but with twin 16 metre rotors driven by tidal currents rather than the wind.
Another British company, Lunar Energy, is constructing the world’s largest tidal power plant – a giant 300-turbine field in the Wando Hoenggan Water Way off the South Korean coast. The plant will provide 300MW of renewable energy by 2015. An installation of a 1MW pilot plant is expected by March 2009.
A team of engineers from Oxford University has come up with a new design for underwater tidal turbines which they believe will be more robust, more efficient and cheaper to build and maintain than anything in operation today.
The tidal turbines in operation today are like underwater windmills, with their blades turning at right angles to the flow of the water. In contrast, the Oxford team’s device is built around a cylindrical rotor, which rolls around its long axis – like the blades of a manual lawnmower - as the tide ebbs and flows. A pair of these rotors would be connected with a generator in the middle. A turbine with a rotor 10 metres in diameter and 60 metres long could produce around 12MW of power.
"To do that, you only need three foundations and one generator," said Martin Oldfield, senior research fellow of engineering science at Oxford University. "To do that with a [windmill design] would require five foundations and 10 generators."
The device is mechanically far less complicated than anything available now, making less expensive to build and maintain. "The manufacturing costs are about 60% lower, the maintenance costs are about 40% lower," said Malcolm McCulloch, head of the electrical power group at Oxford’s engineering department.
The researchers have successfully tested a one-tenth scale version of turbine. They are now planning to build a half-sixze version that could generate electricity for the grid. Farms of the devices could be in production by 2013.
Researchers at te University of Southhampton are proposing to build a floating “Energy Island” which would harness energy from the wind, sea currents, waves, the sun and the by Ocean Thermal Energy Conversion. OTEC uses the temperature difference between surface and deep-sea water to generate electricity. Although it has an efficiency of just 1-3%, researchers believe an OTEC power plant could deliver up to 250MW of clean power. between four and eight energy islands would produce power equivalent to a nuclear power plant.
One method of using tidal motion to generate electricity is employed in this power plant on the Rance Estuary in France.
A different method is being tested in New York. Underwater turbines generate electricity from the tidal motion.
