The Toronto Star and Ocean Power Magazine discuss the many ways that oceans and lakes could help us generate electricity.

The background is a recent study published by two Ryerson University researchers in the June 2011 edition of Renewable and Sustainable Energy Review entitled “Review of Marine Renewable Energies: Case Study of Iran”.

The authors note that the waves in the world’s oceans contain enough energy to supply two-thirds of the world’s need; and that doesn’t include the energy produced by lake and ocean tides and currents, by the chemistry of ocean water, or by the heat stored in its depths.

“Most people overlook the potential from bodies of water to capture renewable energy,” says mechanical engineering professor Alan Fung, who co-authored the paper with Farshid Zabihian.

Take simple turbine technology. A cubic metre of water, moving at the same velocity and over the same surface area as a cubic metre of air, generates 1,000 times more energy, says Fung.

That’s worth looking at.

Unlike wind and solar energy, ocean and lake energy can be obtained at any time and can be stored free of charge. Bodies of water offer predictable amounts of energy, and in some cases, require smaller infrastructure (and less capital investment) to extract  the energy than other renewables.

The paper looks at the potential for waves, tides, currents, thermal energy and salt to produce energy and different technologies that might exploit these hidden energy sources.

As Earth Energy reported recently, Scotland is going ahead with the world’s largest tidal power project.  A 300 kW wave power plant went into commercial operation in the Basque region of Spain earlier this month.

Meanwhile, the US Government and Lockheed Martin are experimenting with ocean thermal energy conversion (OTEC) in Hawaii. This technology leverages the oceans natural thermal gradient to generate power. In geographical areas with warm surface water and cold deep water, the temperature difference can be leveraged to drive a steam cycle that turns a turbine and produces electric power.

Lockheed is completing the final design phase of a 10-MW closed cycle OTEC pilot operation which will go on-line in the 2012-2013 time frame. This system is being designed to expand to 100-MW commercial systems in the near future.

Here is a video explaining how OTEC works.


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