Wave Energy

What is Wave Energy?

Wave energy has recently become an option for clean, green, sustainable energy.  Wave energy, also known as ocean energy or sea wave energy, is energy harnessed from the ocean or sea waves. The rigorous vertical motion of surface ocean waves contains a lot of kinetic (motion) energy that is captured by wave energy technologies to do useful tasks, for example, generation of electricity, desalinization of water and pumping of water into reservoirs.   There have been sporadic attempts throughout modern history since about 1890 to generate power from waves, though we have not yet been able to use it as a sole source of energy.

Exactly, waves are created by the wind that passes over the ocean’s surface. When the waves move slower than the wind speed that generates the wave, there is an energy transfer from the wind to the waves. The waves then move on that energy, opening up the potential for it to be harvested.  Waves hold a gargantuan amount of untapped energy, some of which we can use to power at least a portion of the world’s everyday electricity.

How Exactly Does Wave Energy Work?

Attentuator for Wave Energy Generation
Attentuator for Wave Energy Generation

There are a few ways to harness the energy from waves. There are point absorbers, attenuators, terminators and through overtopping.

    • The point absorber consists of a series of long unit, floating on the surface of the water following the movements of the wave.  It is this movement that is harnessed and converted to electricity in the point absorber.
    • Attenuators are situated parallel to the force and direction of a wave. They are held in place by mooring on the seabed. The motion of the device from the crest and trough of the wave exerts a force on a turbine that then feeds energy into the grid.
    • The overtopping terminator is a large device that is categorized as a wave capturer. This means that instead of using a wave’s kinetic energy to generate power like other wave energy devices, the terminator captures waves and takes advantage of their potential energy (Katofsky, 2008).   An animated visual provided by Lindoe Offshore Renewables Center provides a great side view of how the waves enter the overtopping terminator’s reservoir.

There are three locations where wave energy devices can be placed: shoreline, nearshore and offshore. Each exact location and wave energy device have benefits and drawbacks. Many experts are researching the viability of each option.  In order to harness wave energy and make it create and energy output for us, we have to go where the waves are. Successful and profitable use of wave energy on a large scale only occurs in a few regions around the world. The places include the states of Washington, Oregon, and California and other areas along North America’s west coast. This also includes the coasts of Scotland Africa and Australia.

In the United States, for example, the Pacific Northwest Generating Cooperative is currently building a wave energy plant (also called a wave-power park) in Oregon. This plant will use buoys, which sits on top of waves as they rise and fall, creating mechanical energy. Other countries are implementing wave energy plants, such as Australia, the United Kingdom, and Portugal. The world’s first commercial wave power energy plant is located in Portugal, opening in 2008.

What is the Future of Wave Energy?

Wave power has great potential, but there are still some kinks to work out. One challenge is the fact that waves, although consistent in the fact that the ocean is always moving (especially near coastal areas), are variable. Weather conditions and seasonal conditions affect wave height. Another challenge to effectively harnessing wave energy is figuring out a way to construct devices that can survive the harsh oceanic conditions. Temperature, salinity and storm damage can all be particularly problematic. The problem here lies that in order to make devices that can withstand these harsh conditions costs much increase for the devices, making them less economical. An additional issue that has been brought up is that save farms have the potential to displace fishermen.

Despite the challenges of harnessing wave energy, there are still plans to build wave energy farms throughout the world. Like solar and wind power, wave power is completely green, completely clean and completely sustainable. The challenge is to figure out how to do it effectively and exactly.