Wave/Tidal
Marine energy is currently a hot topic in the media as it is a clean, abundant source of energy that the government is promoting to help meet the UK's renewable energy targets. The industry is still in its infancy so in August 2004 the government announced a £50 million Marine Deployment Fund, which will provide a mixture of capital grants, revenue support and research and development funds for the first commercial marine energy devices.
Marine energy refers to wave and tidal energy, which are two distinctly different forms of energy resource. As an island nation the UK has a vast marine energy resource.
Wave energy is concentrated in the movement of water near the surface of the sea. Waves are created by the wind as it blows over the sea and the amount of energy contained in the waves increases with the strength of the wind and the distance over which it blows. The waves approaching the west coast are very energetic because strong winds blow across the Atlantic Ocean. The North Sea, by comparison, is relatively sheltered so waves on the east coast contain less energy. The greatest amount of energy is available offshore as waves lose energy as they reach the shallower coastal waters; eventually breaking on the shore.
Tidal energy is caused by the gravitational forces between the sun, moon and earth. In the UK this creates a twice-daily rise and fall in sea height. The tides are completely predictable so, unlike wave energy that is weather dependent, the amount of tidal energy available can be forecasted exactly. Tidal currents are fast-moving streams of water below the surface of the sea. In areas that constrict flow, such as between islands, the water flow accelerates and produces high-speed currents. The currents flow in two directions as they flow towards the shore and away with the tide. The UK has many sites with strong tidal streams around its coastline as well as exhibiting some of the highest tidal ranges in the world.
Many studies have estimated the amount of marine energy available. Waves around the UK coast contain up to an annual average of 70kW of power per metre of wave crest and it is estimated that wave energy could provide approximately 20% of the UK's electricity needs. Tidal energy is very location dependent and is concentrated in particular sites. It is estimated that tidal energy could provide up to 6% of the UK's electricity needs. The significant areas of marine energy resource tend to be in locations where there is limited capacity available on the electricity network. The ‘Path To Power' report produced by the British Wind Energy Association includes maps illustrating this The East of England has the advantage of up to 3GW of capacity available for the connection of new generation.