UNDERSTANDING WAVE POWER

POWER FROM WAVES?

Ocean waves are energy being transferred across the ocean surface and are described by a wave height and a wave period.

The red dots in the image below represent water particles which go around in circles and do not travel with the wave.

Real seas comprise waves with many different heights and periods which is why the ocean surface appears so irregular.

The power available in each sea state is calculated per meter of wave crest. This means that the numbers in the chart above should be multiplied by the device width to provide the incident power. The power in the wave varies with the square of the wave height so there is a large variation in the available power.

RESONANT POWER TRANSFER

We can describe a wave energy system as a simple oscillator. The natural period of oscillation is determined by its mass and spring constant. Maximum power is captured when the wave period matches the natural period.

VIABILITY - ENERGY CAPTURE

This chart shows the probability of each sea state for a northern Oregon location. The majority of wave periods are between 5-10s. The larger systems have longer natural periods and increase energy capture.

WELL MATCHED WITH ELECTRICITY DEMAND

In the US, and in many countries around the world, population and electricity demand in coastal areas is growing faster compared to national averages. In many locations around the world the variability of waves can be seen to match daily and seasonal electricity demand. The net effect is that electricity from wave energy can be used when produced with only minimal requirement to store the energy. In fact, the consistency of energy from waves and the better alignment with grid demand means that much less storage is required compared to an equivalent solar or wind project in most locations. Furthermore, in locations such as the US West Coast, wave energy tends to peak when solar energy is low, and thus wave and solar can actually complement each other to improve power flows within utility grids.