Pure energy from the deep?

Imagine standing on the beach and flying a kite. The power of a toy held on a line, struggling against the wind, can be felt in innocent fun and you can often see the kite gliding faster than the wind blows. And have you heard of hydrodynamic kites that generate clean electricity?

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Swedish engineers have recognised the energy of the ocean’s tides and it is very possible that the invention will soon revolutionise the energy industry. The designed device is called Deep Green, which is being developed by specialists from Minesto – a subsidiary of the Saab concern specialising in underwater technologies. Their latest creation is a hydrodynamic “wing” combined with a turbine and a generator. Such a set, when submerged, transforms the power of underwater currents into electricity.

Minesto is based on flying wings with a span of 8 to 14 metres, which, like a surfboard or kite, travel suspended under the water surface, among other things, circling from side to side, zigzagging, looping in eights, at times rapidly accelerating, descending and ascending. Free suspension on ropes allows them to “fly” underwater and, most importantly, not sink. To generate electricity, they will need wave speeds in excess of 2.5 metres per second and no other technology is capable of operating at less than 2.4 metres per second. In the future, scientists want to go down to 1-2.5 m/s. Depending on the size of such a power plant, between 150 and 800 kW of power could be obtained.

During the experiments in Lough Strangford, a kit consisting of a 14 metre span kite and a 1.15 metre diameter turbine produced a maximum of 850 kW in a sea current flowing at 1.7 metres per second. During this test Deep Green was anchored at depths of 90 to 120 metres. The rope holding it in place was 110 to 140 metres long, but practice has shown that it must always be more than 20 metres longer than the water depth at that point.

Work will start as early as January 2014 to determine specifically where and how the kites and turbines should be hooked up to best maximise energy generation. The next step will be to build prototypes, which will then be tested in huge tanks at WPI and the nearby Alden Research Laboratory.

Minesto announces that the industrial operation of the first underwater kite colony will begin as early as 2015. According to experts, it is an absolute breakthrough when it comes to the use of sea currents, which are capable of generating power much greater than that from wind turbines. Environmentalists are also pleased with the idea, as the invention does not threaten the environment, the turbulence caused by the kite does not reach the bottom, so Deep Green does not disturb the underwater ecosystem.

Source: minesto.com