Section 1 of 5Fossil Fuels and Nuclear Power
Coal
- Mined from the ground and burned in power stations; it is the most polluting of the three fossil fuels.
Oil
- Drilled for under the sea bed;
- burning it releases carbon dioxide and sulphur dioxide, which causes acid rain.
Natural gas
- Mostly methane, often extracted by fracking;
- it is the cleanest fossil fuel, although it still adds greenhouse gas.
Nuclear
- Uranium-235 or plutonium-239 undergoes fission with no carbon dioxide emissions, but it leaves long-lived radioactive waste.
Section 2 of 5Renewable Resources
Hydroelectric
- Stored water falls through turbines, transferring gravitational potential energy to kinetic energy; it is reliable,
- but dams flood valleys.
Wind
- Turbines in windy locations generate electricity with no fuel, but output is unreliable when the wind is weak.
Solar
- Photovoltaic cells convert sunlight directly into electricity, but output depends on daylight and weather.
Tidal and wave
- Barrages and underwater turbines use the movement of water, but suitable sites are limited and the technology is still developing.
Geothermal
- Water pumped into hot rocks returns as steam to drive a turbine;
- it is reliable, but few locations are suitable.
Biofuels
- Crops or waste matter are burned for energy, and their carbon is often considered neutral, although this is debated.
Section 3 of 5Evaluating a Resource
The table compares the main resources on the points most often examined.
Evaluating a Resource
Pollution
- Burning fossil fuels releases carbon dioxide, a greenhouse gas, and sulphur dioxide, which dissolves to form acid rain.
Reliability
- Wind and solar output depends on the weather, while fossil fuel and nuclear stations give a steady output on demand.
Efficiency
- Efficiency varies widely, with hydroelectric plants among the most efficient and solar cells among the least.
Sustainability
- Non-renewable resources are finite and become more expensive as they run out and demand continues.
| Resource | Renewable? | Main environmental concern | Reliability |
|---|---|---|---|
| Coal | No | Carbon dioxide and sulphur dioxide | High |
| Natural gas | No | Carbon dioxide emissions | High |
| Nuclear | No | Radioactive waste | High |
| Wind | Yes | Visual and wildlife impact | Low, depends on wind |
| Solar | Yes | Large land area | Low, depends on sunlight |
Section 4 of 5How a Thermal Power Station Works
1
A heat source, such as burning fuel or nuclear fission, releases thermal energy to heat water.
2
The water boils to form steam, which is directed at the blades of a turbine.
3
The turbine spins a generator coil through a magnetic field, inducing a potential difference.
4
The electricity is distributed to homes and businesses through the National Grid.
Section 5 of 5Exam Checklist & Tips
2.3.2 – Key Points for the Exam
- Renewable An energy resource that is replenished faster than it is used.
- Non-renewable An energy resource that is not replenished fast enough to keep up with use, so it is finite.
- Fossil fuel A fuel formed from the remains of ancient organisms, such as coal, oil or natural gas.
- Fission The splitting of a large nucleus, such as uranium-235, to release energy.
- Greenhouse gas A gas, such as carbon dioxide or methane, that traps thermal energy in the atmosphere.
- Acid rain Rain made acidic by dissolved sulphur dioxide and nitrogen oxides.
Common Mistakes
- Calling nuclear power renewable because it releases no carbon dioxide during fission.
- Stating that wind power gives a constant supply, when its output depends on the wind.
- Describing natural gas as pollution-free, when burning it still releases carbon dioxide.
- Assuming biofuels add no carbon dioxide to the atmosphere, when burning them releases it.