Renewable Energy Sources

Wind Turbines. This involves putting lots of wind turbines in exposed places like on moors or round coasts. Each turbine has its own generator inside it, so the electricity is generated directly from the wind turning the blades, which turn the generator.   advantages:  The only pollution that is created is in the manufacturing process. Renewable.     No fuel costs and minimal running costs. No permanent damage to the landscape - if you remove the turbines, the view returns to normal.   disadvantages:  It's unreliable - if it isn't windy, there is no power.   They spoil the view - You need around 1500 wind turbines to replace one coal-fired power station. This number covers a lot of ground, making a big effect on the scenery. They can be very noisy, which is annoying for people living nearby. The initial costs are high. It's impossible to increase supply when there is extra demand.  

Wave Power. As waves come into shore, they provide an up and down air motion that can be used to directly drive a turbine, which then drives a generator.   advantages:  No pollution. Renewable. No fuel costs and minimal running costs.     disadvantages:  Blocks water ways and creates hazards for ships. Fairly unreliable - waves tend to drop as wind drops. Initial costs are high. Spoils the view. Never likely to provide energy on a large scale.  

Solar Cells. Solar cells generate electric currents directly from sunlight. Solar power is often used in remote places where there's not much choice.   advantages:  Renewable. Clean energy Energy is free and running costs almost nothing - although initial costs are high. Can be used to power electric road signs and satellites. In sunny countries solar power is very reliable, but only in the daytime. Solar power can still be cost-effective in cloudy places like Britain.    disadvantages:  10% efficient. Expensive to buy. It's often not practical or too expensive to connect them to the National Grid.    

Solar Heating Panels. Very similar to the solar cells, but with differences that should be remembered.  Similarities:   Uses the sun's light/heat directly. They look the same, and can be used in the same places. Differences:     Instead of converting the sun's light into electrical energy, it uses the sun's heat to heat water to be used around the house.  

Solar Power Tower. With mirrors, it directs the sunlight into water, which is heated, evaporates, and turns a turbine which generates electricity.   advantages:  Renewable. Clean energy. Completely sustainable.     disadvantages:  Cannot be used at night.  

Hydroelectricity. Hydroelectric power usually requires flooding a valley by building a big dam. Rainwater is caught, and allowed out through turbines, driving them directly. The turbines then drive generators to make electricity.   advantages:  Immediate response to demand. Fairly reliable - except for times of drought. No fuel and minimal running costs. Generating hydroelectricity produces no pollution      disadvantages:  Flooding a valley has a big impact on the environment. Some species lose their habitat, and reservoirs also look unsightly when they dry up. Location in remote valleys can reduce the human impact. Initial costs are high.  

Tidal Barrages. Tidal barrages are big dams built across river estuaries, with turbines in them. As the tide comes in, it fills up the estuary to a height of several metres - it also drives the turbines. This water can then be allowed out through the turbines at a controlled speed.   advantages:  No pollution. Reliable, as there is always going to be a tide. No fuel costs and minimal running costs. Potential for generating a significant amount of electricity. Excellent for storing energy ready for periods of peak demands.       disadvantages:  The main problems are preventing free access by boats, spoiling the view, and altering the habitat of the wildlife, e.g. sea creatures. The height of the tide is variable so lower (neap) tides will provide significantly less energy than bigger (spring) tides. They don't work when the water level is the same either side of the barge - in between the tidal changes. It can only be used in some of the most suitable estuaries.  

Geothermal. This is only possible where hot rocks lie quite near to the surface. Cold water is pumped down into the ground, around 7km, to hot rocks below the earth's surface. The water evaporates, and travels back up to the power station, when the steam turns the turbine. This creates electricity.   advantages:  Renewable. No real environmental issues.       disadvantages:  The cost of drilling several km down to the hot rocks is expensive. Can only be put in certain places, where the hot rocks are close enough to the earth's surface to drill down to.