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Energy

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Over the last 200 years an ever-increasing proportion of our energy has come from non-renewable sources such as oil and coal. While demand for energy rises these resources are running out and scientists are exploring the potential of renewable sources of energy for the future.

Renewable and non-renewable energy resources

All life on earth is sustained by energy from the sun. Plants and animals can store energy and some of this energy remains with them when they die. It is the remains of these ancient animals and plants that make up fossil fuels [fossil fuel: Fuels such as coal, gas and oil which are mined from the earth and burned to produce energy. They are formed from broken down animals and plants that died a very long time ago. ].

Fossil fuels are non-renewable [non-renewable: A resource that cannot be replaced when it is used up, such as oil, natural gas or coal. ] because they will run out one day. Burning fossil fuels generates greenhouse gases [greenhouse gas: Naturally occurring gases in the atmosphere such carbon dioxide, methane and nitrous oxide. They are believed to have increased through burning more oil, petrol, and coal. ] and relying on them for energy generation is unsustainable [unsustainable: Resources which cannot be used forever and cannot be replaced or recycled after they are used. The use of fossil fuels is unsustainable for example. ]. Hence the need to find more renewable, sustainable ways of generating energy. Renewable or infinite energy resources are sources of power that quickly replenish themselves and can be used again and again.

Some resources can be thought of as both renewable and non-renewable.

  • Wood can be used for fuel and is renewable if trees are replanted.
  • Biomass, which is material from living things, can be renewable if plants are replanted.

Non-renewable energy resources

Type of fuelWhere it is fromAdvantagesDisadvantages

Coal (fossil fuel)

  • Formed from fossilised plants and consisting of carbon with various organic and some inorganic compounds.
  • Mined from seams of coal, found sandwiched between layers of rock in the earth.
  • Burnt to provide heat or electricity.
  • Ready-made fuel.
  • It is relatively cheap to mine and to convert into energy.
  • Coal supplies will last longer than oil or gas.
  • When burned coal gives off atmospheric pollutants, including greenhouse gases.

Oil (fossil fuel)

  • A carbon-based liquid formed from fossilised animals.
  • Lakes of oil are sandwiched between seams of rock in the earth.
  • Pipes are sunk down to the reservoirs to pump the oil out.
  • Widely used in industry and transport.
  • Oil is a ready-made fuel.
  • Relatively cheap to extract and to convert into energy.
  • When burned, it gives off atmospheric pollutants, including greenhouse gases.
  • Only a limited supply.

Natural gas (fossil fuel)

  • Methane and some other gases trapped between seams of rock under the earth's surface.
  • Pipes are sunk into the ground to release the gas.
  • Often used in houses for heating and cooking.
  • Gas is a ready-made fuel.
  • It is a relatively cheap form of energy.
  • It's a slightly cleaner fuel than coal and oil.
  • When burned, it gives off atmospheric pollutants, including greenhouse gases.
  • Only limited supply of gas.

Nuclear

  • Radioactive minerals such as uranium are mined.
  • Electricity is generated from the energy that is released when the atoms of these minerals are split (by nuclear fission) in nuclear reactors.
  • A small amount of radioactive material produces a lot of energy.
  • Raw materials are relatively cheap and can last quite a long time.
  • It doesn't give off atmospheric pollutants.
  • Nuclear reactors are expensive to run.
  • Nuclear waste is highly toxic, and needs to be safely stored for hundreds or thousands of years (storage is extremely expensive).
  • Leakage of nuclear materials can have a devastating impact on people and the environment. The worst nuclear reactor accident was at Chernobyl, Ukraine in 1986.

Biomass

  • Biomass energy is generated from decaying plant or animal waste.
  • It can also be an organic material which is burned to provide energy, eg heat, or electricity.
  • An example of biomass energy is oilseed rape (yellow flowers you see in the UK in summer), which produces oil.
  • After treatment with chemicals it can be used as a fuel in diesel engines.
  • It is a cheap and readily available source of energy.
  • If the crops are replaced, biomass can be a long-term, sustainable energy source.
  • When burned, it gives off atmospheric pollutants, including greenhouse gases. If crops are not replanted, biomass is a non-renewable resource.

Wood

  • Obtained from felling trees, burned to generate heat and light.
  • A cheap and readily available source of energy.
  • If the trees are replaced, wood burning can be a long-term, sustainable energy source.
  • When burned it gives off atmospheric pollutants, including greenhouse gases.
  • If trees are not replanted wood is a non-renewable resource.

How long will fossil fuels last?

Estimates from international organisations suggest that if the world's demand for energy from fossil fuels continues at the present rate that oil and gas reserves may run out within some of our lifetimes. Coal is expected to last longer.

Estimated length of time left for fossil fuels

Fossil fuelTime left

Oil

50 years

Natural gas

70 years

Coal

250 years

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