Waves are generated by the wind blowing over a distance of water (a fetch). As short waves become steeper, they break down and their energy flows into longer, more stable waves. Some time after the end of a given fetch, a set of wind-waves will arrive as a low frequency swell. Since there is a lot going on at sea, a given spot in the ocean often has many sets of different wind waves and swells passing by at different directions.
Waves are in fact a concentrated form of solar energy. Uneven heating of the earth's surface causes wind. The wind causes the waves.
Energy Needs and Wave Energy
New forms of energy are needed. Oregon has a "Renewable Portfolio Standard" that states that Oregon's goal is for 25% renewable energy for all large utilities (PGE, Pacificorp, EWEB) and 10% and 5% renewable energy for small utilities by 2025.Energy exists in the ocean in several forms -- as salinity, temperature differential, currents, tidal, and wave. Wave is one of the largest of the marine resources, and most broadly accessible. Compared to other renewables, wave energy has a higher energy density, a higher availability (80 – 90%), and better predictability.
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 the statement. But what does this mean to the average person? Here are some facts to give perspective:
W = watt
kW = kilowatt (1 thousand 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 this 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 lightbulb for a day (24 h).
- 1 GW is the energy consumption for the State of Delaware
Looking at marine renewable energy:
- A wave energy buoy is rated in the same way as the light bulb. You can have a 40 kW buoy or a 150 kW buoy - i.e. that is how much power it can generate.
- Ocean Power Technologies' first utility scale PowerBuoy is rated at 40 kW. A 40kW buoy could power 40 homes, on average. Their utility scale PowerBuoy planned to be deployed at Reedsport will produce 150 kW.