sources of energy Flashcards
Coal
Coal is usually formed from the remains of tropical forests.
The wood is trapped beneath sediment and altered, over millions of years, by heat and pressure to form coal.
Limitations - burning releases carbon dioxide and sulphur dioxide so it contributes to global warming and acid rain.
It is very polluting, but it is possible to reduce the harmful emissions from the power stations.
The most energy efficient fossil fuel.
Oil
Oil forms from organic deposits in warm seas, mainly dead plankton.
As with coal it is changed beneath the ground by heat and pressure over geological timescale.
Very flexible source for producing other secondary sources of energy and plastic products.
Limitations - again burning oil releases carbon dioxide and sulphur dioxide.
Gas
Natural gas forms with oil deposits but the liquid and gas separate as they develop beneath the ground.
Limitations - burning gas also releases carbon dioxide and sulphur dioxide, but it is the ‘cleanest’ of the fossil fuels.
Replacing all UK coal burning power stations with gas power would reduce our CO2 emissions from power generation by 50%.
Nuclear
Nuclear power works by splitting uranium or plutonium atoms to release heat energy.
When some atoms split neutrons collide and split other atoms in a chain reaction.
Limitations - The reaction must be carefully controlled to prevent an explosion – Japan 2011
Nuclear waste can remain radioactive for thousands of years – disposal issues, terrorism
Solar
Solar power can be domestic (household) systems or power stations.
Domestic systems may heat hot water or use photovoltaic cells to generate electricity.
Power stations may be large banks of photovoltaic cells or water boilers as shown in the clip below.
Limitations - concerns about the chemicals used in cells and the large areas of land need.
One megawatt (one million watts per hour) can roughly power 1,000 homes.
wind
Wind turbines can be used to generate electricity on a variety of scales from single turbines in a garden to vast wind farms of hundreds of turbines.
Limitations - In the UK more wind farms are being built offshore as planning permission can be hard to get for onshore schemes – but 3 times cost
Offshore windfarms often have higher wind speeds but may disturb marine ecosystems.
Hydro-electric power
Damming a river and sending some of the water downhill through pipes and over turbines to generate electricity.
Limitations - Concerns that dams trap sediment and stop the migration of some species. Also large areas may be flooded.
wave power
These systems harness the power of waves to generate electricity.
Limitations - some scientists have concerns about wave power schemes disturbing marine ecosystems.
Tidal Power
These schemes harness the power of the tides coming in and out to drive turbines and generate electricity.
Limitations - some schemes used a barrage with turbines all the way across a river estuary, this can create problems for species moving through the water and shipping.
New schemes have reduced these problems.
Severn Barrage proposal (Cardiff to Western Super Mare - 10miles long and could provide up to 5% of UK electricity needs; equivalent to 2 nuclear power stations).
Biomass
This is using organic matter to create energy.
Varied energy source and includes biofuels (e.g. ethanol from sugar cane or corn, biodiesel from vegetable oils & animal fats), wood, biogas and using organic wastes like manure for fuel.
Limitations - adverse publicity due to land required to be cultivated – at expense of food crops and natural habitats are destroyed.
