Not all hydroelectric power has to come from dams.

Today, about 20 percent of the world’s power is hydroelectric. Nearly all of that water-generated energy is made by forcing rivers to flow through dams. But rivers make up just a small percentage of the water in the world. The ocean, however, occupies two-thirds of the Earth’s surface and is constantly moving. That motion can spin turbines to create power, the ocean is full of potential energy just waiting to be tapped.

Waves
The first major “wave farm” opened in Aguçadoura Wave Park off the coast of Portugal last year. Made up of worm-shaped devices that generate energy from the up-and-down motion of the waves, the farm produces enough energy to power 1,500 houses in Portugal with only three wave-energy devices (expansion is planned). Other wave parks, off the coasts of Scotland and Oregon, for example, are still in the planning stages.

Tides
Early tidal power functioned the same as damming rivers, and could seriously damage to the environment. Today, tidal power operates much the same as wind power, creating power as tides push water back and forth past a turbine. Tidal-power generation of this sort was tested successfully with six turbines in New York’s East River, and may soon start appearing in other rivers around the world.

Currents
The Gulf Stream flows at a rate of 8 billion gallons per minute—50 times more than all of the rivers in the world put together. Researchers at the Center for Ocean Energy Technology in Florida are working on a prototype turbine sturdy enough to withstand the rough underwater conditions, which they hope to test by this fall, though full-scale power generation could be as much as a decade away.

LEARN MORE   Check out GOOD’s interview with Matthew Simmons, an oil investor turned wave-energy advocate here.