Energy Sources

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Hydro-electric Power (HEP)

Hydro-electric power is generated when water falls onto turbines, which are connected, to generators. Water is stored in a reservoir, which is created by damming a river. About 20% of the world’s electricity comes from HEP. Hydro-electric power is renewable.

Environmental Costs

Creating a reservoir causes a very large area of land to be flooded. This caused the habitats of fish, birds, people, and other animals to be destroyed.

Economic Costs

Hydro-electric power is a quite expensive method of generating electricity. This is because of the building of dams, pumps, turbines, etc. However, the water that they use is free. In the end, they more than pay for themselves.

Wind Power

Wind power is generated when the wind turns a propeller on a windmill. The propeller directly turns a turbine, which is connected to a generator. Windmills are specially designed to use as much of the energy in the wind as possible. It would take about 6000 windmills to replace one fossil-fuelled power station. Wind power is renewable.

Environmental Costs

Huge amounts of land are needed. These must be in windy places such as on mountain tops, or wide open spaces. They cause visual and noise pollution.

Economic Costs

Windmills are very expensive, but their 'fuel', wind, is free.

Solar Power

Solar cells are specially treated with chemicals which turn solar rays straight into electricity. Solar power is renewable.

Environmental Costs

Enough solar panels to generate a worthwhile amount of electricity would take up a huge amount of space.

Economic Costs

Solar cells, and so, panels are extremely expensive but, again, sunlight is free.

Geothermal Power

Rock underground are warmer than rocks on the Earth’s surface. In certain areas this energy is used to heat water. The water evaporates, creating steam which turns a turbine, which is connected to a generator. Geothermal power is renewable.

Environmental Costs

Geothermal power station stake up a lot of room. A lot of power is needed to drill the holes into the ground and as a side effect noise pollution.

Economic Costs

Geothermal power is relatively cheap compared to other sources, although drilling the necessary 7km holes is expensive.

Tidal Power

The tide can also be used to generate electricity. Tidal barrages are built. The tide comes in and directly turns a turbine, which works a generator, then goes out an does the same again. Tidal power is renewable.

Environmental Costs

There are few environmental costs with tidal power. However, the course of the tide, which would have previously removed pollution is being altered. Fish cannot swim upstream to spawn. The barrages also cause visual pollution.

Economic Costs

Tidal power is reasonably cheap. After, all waves cost nothing and the barrages are un-expensive.


Biomass is the use of biological materials to produce heat. Originally this was a renewable energy source, but now that wood is cut down faster than it can be replanted (and re-grow), it is classed as non-renewable. Usually wood or (in poorer countries) cow dung is used. Over half the world’s population uses this type of energy.

Environmental Costs

Excessive deforestation prevents trees from taking in Carbon Dioxide and giving out Oxygen through photosynthesis. Also, it causes soil erosion and climate change due to the above.

Economic Costs

Biomass is the cheapest energy source. This is why over half the world’s population has to use it. They are usually in the third world and cannot afford anything better.

Fossil Fuels

Fossil fuels are burnt. This heats water, which evaporates to create steam, which turns a turbine, which is connected to a generator. Fossil fuels are un-renewable.

Environmental Costs

Fossil fuels cause huge environmental damage. Fossil fuelled power stations release (in the form of waste gases) excessive amounts of pollution. These gases also damage the atmosphere, causing global warming, the hole in the ozone layer and kill plants and animals.

Economic Costs

Fossil fuels are very expensive. Large power stations have to be built and the actual fuel has to be bought.

Nuclear Power

Nuclear power is very powerful. Electricity is generated in a similar way to with fossil fuels. Nuclear fuels (for example, Uranium or Plutonium) are put in a nuclear reactor, which is used to generate heat. A heat exchanger is used to transfer this energy from the reactor to water, which turns to steam, which turns a turbine, which is connected to a generator. While un-renewable each piece of nuclear fuel is so powerful, generating so much electricity, that is does not make an awful lot of difference.

Environmental Costs

Nuclear power is also very dangerous. Nuclear radiation can cause cancer, mutations is offspring or even kill. In nuclear power stations, the radiation is carefully controlled, but there have been leaks such as the one at Chernobyl, Russia on the 26th April 1986. There is also a large problem about what to do with nuclear waste materials. It needs to be kept away from human contact, for hundreds, or even thousands of years, until it becomes safe.

Economic Costs

Nuclear power stations are very costly to set up. They require lead lining to prevent leakage. However, nuclear energy sources are nevertheless very cost efficient.

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