How are waves formed?
Waves are generated by the passage of the wind across the surface of the sea. Energy is transferred from the wind to the waves. Waves travel vast distances across the ocean and at great speed and the energy is concentrated near the water surface. The energy within a wave is proportional to the square of the wave height. Therefore a two-metre high wave has four times the power of a one-metre high wave.
The longer and stronger the wind blows over the surface of the sea, the higher, longer, faster and more powerful the wave-spectrum is.
In summer, moderate winds blow over short distances for short periods of time, generating only small waves. A typical summer sea will have an average wave height of less than 2 metres and an average power of approximately 15kW per metre of wave front width. However, in winter, during the passage of a storm, waves can build to an average height of over 15 metres and power levels exceeding 2,000kW/m of wave front width. Moreover, individual waves can combine to create a ‘freak’ wave of up to 30 metres height and instantaneous power levels of up to 20,000kW/m. A wave energy converter (WEC) must be designed to withstand the passage of storm and freak waves without incurring damage, whilst remaining a cost efficient generator in the smaller seas that occur most of the time.
Wave energy is clean and renewable! It is one of the last renewable energy forms which mankind has yet to harness, and its potential is huge. The technical and economically recoverable resource around the UK alone has been estimated to be between 50-90TWh per year or around 14-25% of the current UK electricity demand.
As a large, sustainable resource which is abundant around the UK, harnessing wave energy can reduce UK dependency on external sources of conventional fuels such as coal, oil and gas, and help to counteract the price volatility which can come from these finite sources. Wave energy also has the potential to substantially contribute towards the reduction of carbon dioxide emissions from fossil fuels at a global level.
Although wave energy is a form of concentrated wind energy, as it has often travelled over large distances it is regularly out of phase with the local wind conditions. Wave energy can therefore help to balance output variability from other renewable sources and maximise the efficient use of the electricity networks.
Click here to view the BWEA 'Why Marine?' Document
 T W Thorpe, A Brief Review of Wave Energy, 1999.
 DECC, UK Energy In Brief, reports 2008 UK electricity consumption was 350.5 TWh