|
|
|
||||||||||
|
WAVE |
|||||||||
Energy Availability The huge amount of energy within waves has long been recognised. For UK waters, around 30 GW of wave power is available for capture by wave energy converters: when estimates of converter spacing and efficiency are considered an average of about 7 GW of electrical power could be supplied. (Reference: "The UK wave energy resource" A. J. B. Winter, Energy Technology Support Unit, AERE Harwell. Published in Nature 30th October 1980.) More recent data is given in the Carbon Trust report: Variability of UK marine energy resources The energy density from waves is greater than that from wind or solar. Some examples of average annual power levels, per metre width of wave are: Lewis 43 kW/m Orkney 28 kW/m Scarborough 8 kW/m Cromer 5 kW/m The highest energy densities are on the west coast of the UK, where not sheltered by Ireland. The east coast has a lower energy density. There is also a good correlation during the course of a year, between the available wave energy and electricity demand. In other words, the waves are larger in the winter, when more electricity is consumed. This makes wave energy an attractive resource. The power of a wave, per metre width, is given by the equation: Power (in kW) = 0.49 . H2 . T Where H is the significant height in metres, and T is the period in seconds. Characteristics of Waves Waves transport energy from one location to another with good efficiency. In other words, the thing that produces the wave (usually the wind) can be a long distance from where the wave is observed.This has the beneficial effect that wave energy is relatively consistent from one hour to the next. Another characteristic of waves is that the speed of travel depends on their size. The water within waves moves with a circular motion. In other words, there is a vertical component, and a horizontal component. For efficient extraction of energy from the wave, both of these components should be harnessed. |
||||||||||
