Energy resources

1. An energy resource is anything that holds a store of energy which people can transfer usefully, either by burning a fuel or by capturing a natural flow of energy such as wind, moving water or sunlight.
2. Energy resources are put to three main uses on Earth: generating electricity, heating homes and workplaces, and powering transport.
3. Every resource is placed in one of two groups, depending on whether it can be replaced as fast as it is used.
4. A renewable resource is replenished naturally, so the wind keeps blowing, the tides keep turning and the Sun keeps shining however much energy is taken from them.
5. A non-renewable resource exists in a fixed amount, so every tonne of coal or uranium that is used leaves less for the future.
6. The fossil fuels (coal, oil and natural gas) and nuclear fuel are the non-renewable resources you need to know.
7. Biofuel, wind, hydroelectricity, tides and the Sun are the renewable resources you need to know, and waves and geothermal energy also belong to this group.
8. The deciding question is how fast the resource is replaced, not whether it is clean or whether it can be used twice.

Fossil fuels

1. Fossil fuels formed over millions of years from the buried remains of plants and sea creatures, which is far too slowly for them to be replaced on a human timescale.
2. Energy is released from their chemical energy store when they are burned in oxygen.
3. In a fossil-fuel power station, the fuel is burned to heat water in a boiler and turn it into high-pressure steam.
4. The steam spins a turbine, the turbine turns a generator, and the generator transfers energy electrically to the national grid.
5. Coal was burned mainly in power stations, though the last coal-fired power station in the UK, at Ratcliffe-on-Soar in Nottinghamshire, closed in 2024.
6. Oil is refined into petrol, diesel and jet fuel, which makes it the main fuel for cars, lorries, ships and aircraft.
7. Natural gas is burned in most UK home boilers for heating and cooking, and gas-fired power stations generate a large share of the country's electricity.
8. Fossil fuels are reliable, because fuel can be stockpiled and burned whenever it is needed.
9. A gas-fired power station can also be started up within minutes, so it can respond quickly when demand rises.
10. Burning any fossil fuel releases carbon dioxide, a greenhouse gas that adds to climate change.
11. Burning coal and oil also releases sulfur dioxide, which causes acid rain, and burning coal produces smoke and ash.

Nuclear fuel

1. A nuclear power station uses uranium as its fuel.
2. Inside the reactor, uranium nuclei split, and energy from the nuclear store heats water into steam.
3. From that point on, the steam drives a turbine and generator in the same way as in a fossil-fuel power station.
4. A small mass of uranium releases an enormous amount of energy, so a reactor can run for months between refuelling.
5. Nuclear power stations release no carbon dioxide while they are operating, which makes them attractive for cutting emissions.
6. Nuclear fuel is still non-renewable, because the uranium ore mined from the ground is finite.
7. The used fuel is radioactive waste that stays dangerous for thousands of years, so it must be stored securely for a very long time.
8. Building a nuclear power station is very expensive and slow, and closing one safely at the end of its life (decommissioning) takes decades.
9. Reactors take a long time to start up, so they are used to supply a steady output all day and night rather than to meet sudden rises in demand.

Biofuel

1. Biofuels are made from material that was alive recently, such as wood pellets, sugar cane, oilseed rape or methane gas from rotting food and animal waste.
2. Like fossil fuels, they release energy from a chemical store when burned, so they can heat water to drive turbines, fuel boilers or be blended into petrol and diesel.
3. They count as renewable because new crops can be grown each year to replace what is burned.
4. Burning a biofuel releases carbon dioxide, but the growing plants absorbed a similar amount of carbon dioxide from the air, so biofuels are described as close to carbon neutral.
5. Biofuels are reliable, because the fuel can be stored and burned on demand.
6. Growing fuel crops takes up large areas of farmland that could otherwise grow food, and forests are sometimes cleared to make room for them.

Wind, water and the Sun

1. A wind turbine has large blades that are turned by moving air, and the rotating shaft drives a generator directly without any fuel or steam.
2. Wind farms are built on hills and out at sea, where winds are strongest, and the UK now has some of the largest offshore wind farms in the world.
3. Wind is unreliable, because turbines generate nothing on a still day and must be shut down when winds are dangerously strong.
4. Some people object to wind farms because they change the look of the landscape and make noise.
5. A hydroelectric power station traps a river behind a dam, and water released from the high reservoir flows down through pipes to spin turbines.
6. Hydroelectricity is reliable and can start generating within seconds, because the water stored behind the dam can be released whenever it is needed.
7. Building a dam floods a valley, destroying habitats and sometimes homes, and only mountainous areas such as Scotland and Wales have suitable sites.
8. Tidal power uses the rise and fall of the sea, either with a barrage across an estuary or with underwater turbines turned by tidal currents.
9. Tides happen twice a day at times that can be predicted years ahead, so tidal power is predictable even though its output rises and falls during each day.
10. A tidal barrage blocks an estuary, which can harm the mudflats where wading birds feed and can obstruct shipping.
11. The Sun is used in two ways: solar cells transfer energy from sunlight directly into an electrical supply, and solar heating panels use sunlight to warm water for a building.
12. Solar power needs no fuel and has very low running costs, but it produces nothing at night and much less on cloudy winter days.
13. Wave power uses floating generators that are moved up and down by waves, and geothermal power uses heat from hot rocks underground, though few places in the UK have rocks hot enough.

Comparing energy resources

1. When you compare two resources, judge them against the same factors so that each point sets one resource directly against the other.
2. Reliability is whether the resource can supply energy at any time: fossil fuels, nuclear fuel, biofuel and hydroelectricity can, while wind and solar depend on the weather.
3. Response time is how quickly output can be raised: hydroelectric and gas power stations respond in seconds or minutes, while nuclear and coal power stations take many hours.
4. Effect on the environment covers carbon dioxide emissions, other pollution, waste and damage to land or habitats.
5. Cost is split into the cost of building the system and the cost of running it, since wind and solar are cheap to run because their energy source is free.
6. Location matters because hydroelectricity needs high valleys, tidal power needs a suitable estuary or coastline, and wind farms need exposed sites.
7. No single resource wins on every factor, which is why the UK uses a mixture of resources to keep the supply secure.