As the global population continues to increase and existing fuel supplies begin to run out, countries will have to find ways to increase energy supplies.
Renewable technologies offer a way to increase energy supplies, however they are often more expensive or less efficient at producing energy than fossil fuels. Therefore they often require government subsidies.
Biomass - this is recently-formed material derived from living things, eg chicken droppings. 'Energy from waste' plants burn biomass and non-recyclable rubbish to generate electricity. The UK has many 'energy from waste' plants, eg Allington Quarry in Maidstone, Kent.
Hydroelectric power (HEP) - HEP is generated when river water is trapped behind a dam and used to turn turbines. The UK generates 1.5% of its electricity this way. Most suitable locations for dam building have already been used.
Wave power and tidal power - the UK is an island nation, yet it generates very little energy using the sea. Wave energy harnesses the power of small movements on the surface of the sea. The technology is new and currently expensive. Tidal energy harnesses larger movements of the tides. There are plans for tidal lagoons to be built in the UK.
Geothermal power - this uses heat within the Earth to generate electricity. This is easier where geothermal heat is more accessible, eg Iceland. There are few suitable locations so geothermal energy is rare in many countries. Ground source heat pumps are a similar idea, but they use the heat from the Sun that is stored within the surface of the Earth.
Solar power - the UK government wants to increase the use of solar power by 2020. Solar panels can be fitted onto buildings or within fields. They turn sunlight into electricity. New technology is making solar panels able to generate electricity on cloudy days, which would be good for the UK.
Wind power - wind turbines convert air movements into electricity. In the UK wind speeds are consistent and so this is a good way to generate electricity. The UK generates more wind energy using turbines on the land (onshore). As an island nation, the UK could build more turbines in the sea (offshore) though these are more expensive than onshore turbines.
Wind turbines - a renewable source of energy
Global energy use is still dominated by non-renewable energy. The use of non-renewable can be made more efficient. This could increase energy supplies as less fuel would be used.
Fossil fuels - coal and gas power stations can now re-use wasted heat in. These are called combined-cycle systems. Re-using heat makes the most out of the fossil fuel. Also, some power stations now burn small amounts of biomass alongside fossil fuels. This is called co-firing and it makes the fossil fuel last longer. Fracking could exploit shale gas, which would increase supplies of fossil fuels.
Nuclear power - uranimum fuel rods still have some uranium left within them after they have been used. Reprocessing recovers the uranium from spent fuel rods so that it can be reused. This doesn't create new supplies of uranium, but it does use the existing supplies more efficiently. This means that uranium supplies will last longer.