What are the renewable and non-renewable energy resources, and how do power stations generate electricity?
Renewable and non-renewable energy resources, how power stations generate electricity, and the advantages and disadvantages of different resources.
A focused answer to the WJEC GCSE Science Double Award Unit 3 topic on energy resources, covering renewable and non-renewable resources, how power stations generate electricity, and the advantages and disadvantages of each resource.
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What this dot point is asking
WJEC Double Award Unit 3 wants you to describe renewable and non-renewable energy resources, explain how power stations generate electricity, and give the advantages and disadvantages of different resources.
Non-renewable resources
Fossil fuels are burned to release energy but produce carbon dioxide (a greenhouse gas) and other pollutants. Nuclear fuel produces no carbon dioxide while running but creates radioactive waste that is hard to dispose of.
Renewable resources
Renewables usually produce little or no pollution while running, but many depend on the weather or location (so they can be unreliable) and often cost a lot to build at first.
How power stations generate electricity
In a fossil-fuel or biomass station, the fuel is burned to heat the water; in a nuclear station, the heat comes from nuclear fission. Wind and hydroelectric stations skip the steam stage: the wind or moving water turns the turbine directly.
Weighing up the resources
Choosing a resource means balancing several factors:
- Reliability: fossil fuels and nuclear give a steady supply; wind, solar, tidal and wave depend on conditions.
- Cost: fossil fuels have fuel costs; renewables have high start-up costs but low running costs.
- Environment: fossil fuels release carbon dioxide; nuclear produces radioactive waste; renewables are cleaner but can affect habitats or views.
There is no perfect resource, so a mix is usually used.
Renewables in more detail
Each renewable works in a particular way. Wind turbines are turned directly by the wind. Solar cells turn sunlight straight into electricity (no turbine needed), while solar panels heat water. Hydroelectric stations let stored water fall through turbines. Tidal and wave schemes use the movement of the sea, and geothermal uses heat from hot rocks underground to make steam. Biomass (such as wood or crops) is burned like a fossil fuel but is renewable if the plants are regrown, and is roughly carbon-neutral because the plants absorbed carbon dioxide as they grew. Knowing the basic mechanism of each renewable helps you answer questions that ask which is suitable for a given location.
Why a mix of resources is used
Countries usually use a mix of energy resources rather than relying on one. This is because each resource has drawbacks: fossil fuels pollute and will run out, nuclear creates waste, and renewables can be unreliable. By combining them, a reliable "base load" from fossil fuel or nuclear can be topped up by renewables when conditions allow, and the failure or downtime of one source does not cut off the supply. Over time, the aim is to increase the share of renewables to cut carbon dioxide emissions, while keeping the supply reliable. Being able to argue for a mix, weighing reliability against the environment, is a common evaluation question.
Try this
Q1. Name two renewable energy resources. [2 marks]
- Cue. Any two of: wind, solar, hydroelectric, tidal, wave, geothermal, biomass.
Q2. What turns the generator in a fossil-fuel power station? [1 mark]
- Cue. A turbine (turned by steam).
Exam-style practice questions
Practice questions written in the style of WJEC exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
WJEC style4 marksGive two advantages and two disadvantages of using wind power to generate electricity.Show worked answer →
A Unit 3 evaluation question worth 4 marks. Reward two advantages: it is renewable (will not run out), produces no carbon dioxide or polluting gases when running, and has low running costs (2). Reward two disadvantages: it only works when it is windy (unreliable), some people find turbines spoil the view or are noisy, and the start-up cost of building them is high (2). Markers credit two valid points on each side. A common error is to give two versions of the same point.
WJEC style3 marksDescribe how a fossil-fuel power station generates electricity.Show worked answer →
A Unit 3 describe question. Reward: the fuel is burned to release heat, which boils water to make steam (1); the steam turns a turbine (1); the turbine drives a generator, which produces electricity by electromagnetic induction (1). Markers credit burning the fuel to make steam, the turbine turning and the generator. A common error is to leave out the turbine or to say the fuel makes electricity directly.
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