How Is Wave Energy Used to Generate Electricity?

By Joan Whetzel
The power of waves produces usable energy.

Earth is composed mainly of bodies of water---about 71 percent of the earth’s surface is water. Ninety-seven percent of that is found in the oceans. Because the earth's surface is curved, the sun heats it unevenly. This causes winds to blow across the water and generate waves. The sun and moon also exert their gravitational pull on the earth, triggering wave-producing tides. Wave motion energy can be harnessed and generated into electricity.

Potential

The kinetic energy of the typical 4-foot, 10-second wave produces greater than 35,000 horsepower (26099.50 kW) of power for every mile of coastline. That's enough power to light one 100-watt light bulb for 260,095 hours, or about 30.8 years.

Geography

The best locations for wave-technology apparatus depend, in part, on the environmental and economic characteristics of the location. Environmental characteristics include incorporating wave-energy equipment into any port's breakwaters, so that it generates electricity directly to the port. Economic characteristics include lowered costs, because less space is required to produce electricity than is required by wind-energy equipment. Having no need for access roads also contributes to lowering production costs.

Benefits

Waves produce a net energy, after costs, equal to or better than wind, solar or small hydroelectric power plants. One reason is that waves can trek long distances without any major power loss, unlike wind. Waves have a kinetic energy about 1,000 times greater than wind, which means they generate the same amount of power capacity in a smaller space. Waves produce power around the clock, in contrast to wind, which produces power primarily in the mornings and evenings, and solar energy, which produces power only during daylight hours. Wave energy technology requires less space than wind farms, there's no need for road construction and there are no moving parts to wear out--all cost-saving factors associated with wave energy.

Function

Three methods are used to generate wave energy. With the first, a system of buoys rises and falls with the waves, causing an electric generator to produce electricity that is propelled along a power cable to shore. With the second, a water column apparatus uses waves to fill and empty the column, forcing the air inside to go up and down. This piston-like action rotates a turbine which produces electricity. The third method involves a tapped-channel arrangement which directs waves into a raised reservoir and generates hydroelectric power by allowing water to flow from the reservoir.

Effects

On the positive side, wave energy is renewable, produces no pollution and has no negative impact on the view. On the negative side, bottom-mounted buoy systems could impact an area's plants and animals or produce enough noise to negatively affect marine migration. The cost of generating electricity could be affected by the size of the waves, the distance needed to carry electricity to consumers or the difficulties of the system's maintenance. The presence of wave energy technology could also impact fishing, shipping and recreational boating.

About the Author

Joan Whetzel has been writing professionally since 1998. She has written juvenile nonfiction, movie and television scripts and adult nonfiction. Her juvenile nonfiction has appeared in such magazines as "Tech Directions," "Connect" and "Class Act." She was part of the production team that produced the documentary "Fuel for Thought" on Houston PBS. She has also written articles for Katy Magazine Online.