Marine energy
Marine turbines are like underwater windmills than can extract energy from fast-flowing tides or deep ocean currents
A huge amount of energy is stored in, on and above the oceans. Strong sea winds can be exploited with offshore windfarms, while waves can be converted into electricity using articulated snake-like generators. Scientists and engineers are also exploring how to create electricity from the salinity difference between rivers and oceans and the temperature difference between the sea surface and the colder waters below.
One of the most promising marine energy technologies is the tidal turbine, which was advocated in Manchester by Peter Fraenkel of Marine Current Turbines (MCT). These devices act like underwater windmills, with blades that rotate as the tide flows through them. Tidal turbines create large amounts of power in those countries with very fast-flowing tidal streams – such as the UK and Canada – and in the future similar devices could be used to extract energy from deep ocean currents such as the Kuroshio in north-west Pacific.
Compared to wind and solar energy, tidal generation has the advantage of predictability. Being driven by the gravitational pull of the moon and sun, as opposed to the weather, their timing and strength is known in advance to a high level of certainty. A further advantage is the high energy density of the tides. With as much as a thousand tonnes of water passing through a turbine's blades in a single second, a relatively small device can create a relatively large amount of electricity.
Producing devices robust enough to withstand these forces is a formidable engineering challenge, but MCT's flagship device – the SeaGen – has already been proven to work on a commercial scale. Positioned in Strangford Lough, Northern Ireland, the first SeaGen turbine has generated more than 100 megawatt hours of electricity.
Click here for the full article and to see a video of Peter Fraenkel presenting the technology
