Making Waves: How Do Waves Work?
Waves are actually a concentrated form of solar energy! Uneven heating of the Earth’s surface causes wind. Waves are generated by wind blowing over a distance of water. That distance is referred to as the fetch. Because the Pacific Ocean is so vast, the fetch is very large, leading to an energetic wave environment on the Oregon coast.
How much wave energy is out there? It is estimated that if 0.2% of the ocean’s untapped energy could be harnessed, it could provide power sufficient for the entire world. That's quite a statement. But what does this mean to the average person? Here are some facts to give perspective:
W = watt
kW = kilowatt (1,000 watts)
MW = megawatt (1 million watts)
GW = gigawatt (1 billion watts)
- It takes 1 W to play an iPod
- When you turn on a lamp that has a traditional light bulb, it puts out 60, 75, or 100 W of energy.
- A household typically has a power consumption of 1 kW. If a house used that constant amount of power every hour for a year, it would use 8760 kWh/year (1 kW x 24 h/d x 365 d/y).
- Therefore it takes 8760 kWh of electricity to power your house for a year or 1.44 kWh to illuminate a 60W light bulb for a day (24 h).
- 1 GW is the annual energy consumption for the state of Delaware.
How to Get Energy from a Wave
Worldwide, over a hundred conceptual designs of wave energy conversion (WEC) devices have been developed but only a few have been built as full-scale prototypes or tested. Most have been in Europe. Currently there are four main types of WEC devices that generate or convert energy from waves:
- Oscillating water column
- Point Absorbers
Below is a list of several examples of each main type of wave energy converter. Click on them to see some details regarding each particular design.
For a more comprehensive list of existing and developing technologies and companies, visit the U.S. Department of Energy’s Marine and Hydrokinetic Technology Database, providing up-to-date information on marine and hydrokinetic renewable energy, both in the U.S. and around the world.
Oscillating Water Column
These devices generate power when a wave push against a horizontally-hinged flap, or waves are funneled into a structure that causes a water column to rise and fall. These devices may be fixed to the ocean floor, hang from a floating or shoreline structure, or built into harbor jetties. An example size would be put into 20 - 100 foot depths, and may be 65 feet wide.
These devices are oriented in the direction of incoming waves that cause articulated components to bend and drive generators. Appearing somewhat like semi-submerged "train cars," they are typically moored to the ocean floor on one end. An example of the size of this device is around 390 feet long and 11 feet wide, with about 7 feet above the surface of the water.
These devices have a partially submerged structure that funnels wave over the top of the structure into a reservoir. The water runs back to the sea powering a low-head hydropower turbine. An example prototype is roughly 100 by 200 feet, but may be scalable as large as 700 by 1,200 feet and 65 feet wide.
These devices capture energy from the "up and down" motion of the waves. They may be fully or partially submerged. The size depends upon the unit, but an example might be that around 8 to 10 feet rises above the surface and the rest, around 150 feet or so, extends below the surface.