The new proposed Anglo-Swedish technology resembling a kite will be used to capture energy from ocean currents with low speeds of between 1.2 and 2.2 metres per second. According to the manufacturer, Deep Green could “contribute to a substantial increase of power from the tides with its ability to produce energy from areas where other technologies are less efficient”. Minesto claim, for instance, that the new resources that could be harnessed using Deep Green could almost double the theoretical potential from water currents in the United Kingdom.
Deep Green consists of a turbine with a wing which acts like a kite. The kite is attached to the ocean bed by a tether, so it swings in the current and has a control system which determines the best trajectory to lead the hydrodynamic flow to the turbine at 10 times the current speed. The “kite”, with a wing span of 12 metres, has a capacity of 500 kW and can make the water go through the turbine at a speed of 16 metres/second at a current velocity of 1.6 m/s. Electricity is transmitted through a power cable inside the tether.
According to Minesto, since no tower or other complex offshore structure is needed, the final cost per produced kWh could range from 6 to 14 c€/kWh, which is comparable with the cost of a 2-MW offshore wind turbine placed in relatively deep waters (10-12 c€/kWh).
In 2007 the technology was evaluated and taken up in the Marine Energy Accelerator (MEA) program by The Carbon Trust in a bid to accelerate the move to a low carbon economy. “The Minesto device is now a key component in the Carbon Trust’s strategy to develop novel devices which represent the next generation of marine renewable energy”, said Tom Delay, chief executive of the Carbon Trust.
It is feasibility has been demonstrated by means of a scale 1:10 small prototype, while a 1:14 scale prototype is currently under construction and will soon be ready for testing off the coast of Northern Ireland.
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