Power Generation 1. Tidal 2. Hydro 3. Wind 4. Solar 5. Nuclear 6. Fuel fossils 7. Geothermal

Tidal Power

How it works: Tidal Barrages

Tidal Power Generation The turbines spin much more slowly than wind turbines at just 10 to 20rpm and so there is little impact on marine life. Each machine will generate around 1MW of power and 10 to 20 machines will be grouped in 'farms' under the sea where currents are high.

Tidal Barrage: A series of Water Turbine

Tidal Multiple Turbines Underwater turbines are by definition out of sight and it is believed that their environmental impact is negligible thanks to their slow rotation rates of just revolutions per minute 10 times slower than that of ships propellers). In addition, tidal turbines do not affect navigation or shipping and so there are no hidden extra costs to consider.

Tidal Power The tide moves a huge amount of water twice each day, and harnessing it could provide a great deal of energy - around 20% of Britain's needs. Although the energy supply is reliable and plentiful, converting it into useful electrical power is not easy. A few years ago, "tidal power" meant "tidal barrage", but these days there are other options as well.

Tidal Power Generation Tidal power generation works differently to hydro- electricity, and wave power. A barrage (dam) is built across a river estuary - e.g. The Severn - and water is pushed through a turbine and generator (fitted into tunnels in the barrage) as the tide comes in and goes out. For shipping to be able to pass, locks are built into the barrage which can be opened to allow the safe passage. There are obvious benefits to this type of tidal power generation - e.g. the dam can act as a road bridge, and the nearby coastline is protected from powerful waves. However, there are also disadvantages to local wildlife as the ecosystem is drastically changed near to the dam. hydro- electricitywave powerThe Severn

Tidal Power Plants Tidal power is another way to generate electricity extracting energy from the sea (see also wave power). Twice a day enormous volumes of water rise and fall with the tides, and the UK is perfectly placed to take advantage of this free energywave power

240MW La Rance FranceLa Rance

Advantages Once you've built it, tidal power is free. It produces no greenhouse gases or other waste. It needs no fuel. It produces electricity reliably. Not expensive to maintain. Tides are totally predictable. Offshore turbines and vertical-axis turbines are not ruinously expensive to build and do not have a large environmental impact.

Disadvantages A barrage across a coast is very expensive to build, and affects a very wide area - the environment is changed for many miles upstream and downstream. Many birds rely on the tide uncovering the mud flats so that they can feed. Fish can't migrate, unless "fish ladders" are installed. Only provides power for around 10 hours each day, when the tide is actually moving in or out. There are few suitable sites for tidal barrages