Energy resources

Revision notes

Energy resources include fossil fuels, nuclear fuel and renewable sources such as wind, solar, hydroelectric, tidal and biofuel. They differ in renewability, reliability, environmental effects, response to demand and cost. Electricity generation transfers energy from these resources into electrical energy. A balanced comparison should use evidence about emissions, waste, land use, variability and security of supply.

Renewable and non-renewable resources

Renewable resources are replenished naturally on human timescales. Non-renewable resources are finite on human timescales. The classification tells you about resource replacement, not whether a technology has zero environmental impact.

Comparing energy resources

Useful comparison criteria include reliability, controllability, greenhouse-gas emissions, air pollution, land and habitat effects, waste, fuel availability and cost. Different resources involve different trade-offs.

Some renewable sources have variable output because they depend on environmental conditions. Other sources can be controlled more directly to match demand.

Evaluating evidence

A balanced evaluation should compare resources using the same criterion. For example, if discussing environmental impact, compare emissions, land use or waste for both resources rather than listing unrelated facts.

Exam technique

Avoid declaring one resource simply 'best'. State the context and the criterion. A strong answer gives an advantage, explains why it matters and then gives a relevant limitation or comparison.

Reliability and demand

Electricity demand changes throughout the day, so resource choice is not only about total energy available. A useful supply system must also consider when energy can be generated and how rapidly output can respond to changing demand.

Variable resources may produce little power when conditions are unsuitable. A complete evaluation can therefore include storage, backup generation or a mixture of resources, provided the answer stays focused on the evidence given in the question.

Reading comparison data

Tables and graphs often compare cost, output or environmental impact. Quote values where useful and compare like with like. A percentage difference, lifetime total or output per unit time may support a stronger conclusion than a vague statement such as 'one is cheaper'.