Researchers at the Okinawa Institute of Science and Technology Graduate University have developed a novel ocean current turbine which, they say, can match the efficiency of wind turbines while providing much more consistent and reliable output and taking up no land.

The design consists of a turbine anchored to the seabed with a line. The turbine “flies” like a kite in the ocean current at about 100 metres below the surface. At this depth, currents flow steadily and calmly regardless of surface storms.

The turbine is turned by three blades which rotate in the current.

Although ocean currents are slow, averaging 1 to 1.5 metres per second, water is more than 800 times as dense as air. As a result, even a slow current contains energy comparable to a strong wind. And currents do not stop or change direction, so they provide much more reliable and consistent energy than wind.

The design only comprises a float, a counterweight, a nacelle to house electricity-generating components and three blades. The low number of components makes for easy maintenance, low cost and a low failure rate.

The researchers have tested a prototype of the system and envisage an energy farm consisting of 300 turbines, each 80 metres in diameter. This would output about 1 gigawatt – the equivalent of a nuclear reactor.