Two-thirds of the Earth’s surface is covered with oceans. And the human inhabitants of the other one-third of the Earth’s surface are looking for ways to harness the power of those oceans into alternative energy.

Ocean water itself is not a candidate for the alternative energy research to find gasoline alternatives. But it can still have a major role in reducing our dependence on fossil fuel.

How? By supplying the technology needed to generate electricity.

The oceans’ alternative energy potential can be developed in four ways:

Alternative energy from tides:

Ocean waves are the visible result of invisible currents of energy moving below the water’s surface. Tidal power is converted to electricity by underwater, windmill-like turbines which spin with the ebbing and flowing of the tides.

There is an effort underway to bring a single tidal turbine online in New York City’s East River, as part of that city’s efforts to develop its alternative energy resources.

Alternative energy from wave conversion:

Unlike tidal turbines, wave converters produce alternative energy by riding on, or just beneath, the ocean’s surface. As they bob up and down or from side to side, their motion pumps fluid to hydraulic engines; those engines power electric generators which pass electricity through undersea cables to onshore power grids.

Alternative energy from ocean thermal energy conversion (OTEC):

Ocean water is warmer at its surface than in its depths. OTEC uses the warm water to heat a fluid, which, as it vaporizes, expands and causes a pressure buildup in a turbine generator. The vaporized fluid is cooled by water pumped up from the depths and the cycle begins again. OTEC’s requirement of a 40 degree differential in the surface and deep waters limits its effectiveness as an alternative energy to tropical oceans.

Alternative energy from marine life:

A Spanish company has developed a way to extract vast amounts of “biopetroleum” from phytoplankton organisms–marine algae–and hopes to have a commercially viable fossil fuel substitute by 2007.

The oceans of the world as a major source of alternative energy? They could just be the “wave of the future”.