National and Global Energy Resources

Humans draw on a fixed set of energy resources to power transport, generate electricity and provide heating. You need to be able to name and describe each one.

The main energy resources are: fossil fuels (coal, oil and gas), nuclear fuel, bio-fuel, wind, hydro-electricity, geothermal, tides, the Sun and water waves.

Each resource is exploited to fill an energy store humans can use. Fossil fuels and bio-fuels are burned to release energy; nuclear fuel releases energy from unstable nuclei; the others transfer energy from natural motion, heat or light in the environment.

(Note) You do not need to describe how each resource is used to generate electricity. Focus on what each resource is, whether it is renewable, its uses, its reliability and its environmental impact.

The single most important distinction is whether a resource runs out.

A renewable energy resource is one that is being, or can be, replenished as fast as it is being used. A non-renewable resource is finite: it is used up faster than it forms and will eventually run out.

Non-renewable	Renewable
Coal	Wind
Oil	Hydro-electricity
Gas	Geothermal
Nuclear fuel	Tides
	The Sun (solar)
	Water waves
	Bio-fuel

Nuclear fuel (such as uranium) is non-renewable because the supply of suitable fuel is limited, even though a small mass releases a large amount of energy. Bio-fuel is renewable because new crops can be grown to replace what is burned, provided replanting keeps pace with use.

Energy resources support three broad uses: transport, electricity generation and heating. Most resources are suited to particular jobs.

Resource	Main uses
Fossil fuels (coal, oil, gas)	Transport (petrol, diesel), electricity generation, heating
Nuclear fuel	Electricity generation
Bio-fuel	Transport, heating, some electricity generation
Wind	Electricity generation
Hydro-electricity	Electricity generation
Geothermal	Electricity generation, heating
Tides	Electricity generation
The Sun (solar)	Electricity generation, heating water
Water waves	Electricity generation

Fossil fuels dominate transport because petrol and diesel are energy-dense and easy to store and carry. Most renewable resources are used mainly for electricity generation rather than transport.

A resource is reliable if it can supply energy whenever it is needed, regardless of the weather or time of day.

• Fossil fuels and nuclear fuel are very reliable. Fuel can be stored and burned or used on demand, so they meet peaks in demand at any time.
• Bio-fuel and geothermal are reliable, as fuel can be stored and geothermal heat is constant, though geothermal is only practical in certain locations.
• Tides are less reliable but highly predictable: they follow a known cycle, so output can be planned even though it varies through the day.
• Wind, solar and wave power are the least reliable, because they stop or drop when the wind falls, the Sun is not shining, or the sea is calm.

Do not confuse reliable with renewable. Renewable is about running out; reliable is about supplying energy on demand. Wind is renewable but unreliable; nuclear is non-renewable but reliable.

Every resource affects the environment, but in different ways and to different degrees.

Resource	Main environmental impact
Fossil fuels	Burning releases carbon dioxide (a greenhouse gas that adds to global warming); coal and oil also release sulfur dioxide, causing acid rain; oil spills damage habitats
Nuclear fuel	No carbon dioxide released in use, but produces radioactive waste that must be stored safely for a very long time; risk of accidents
Bio-fuel	Considered close to carbon-neutral because crops absorb CO₂ as they grow, but growing them can require clearing land and habitats
Wind, solar, wave, tidal, hydro	No fuel burned, so little or no CO₂ in use; impacts include habitat disruption, visual effects and, for hydro and tidal, flooding or altering coastal and river habitats
Geothermal	Low emissions; limited to suitable geological sites

Fossil fuels have the largest impact through carbon dioxide emissions. Renewable resources release far less in use, but building and manufacturing the equipment still uses energy and materials, so no resource is completely free of impact.

Over recent decades, use of renewable resources has been rising while reliance on fossil fuels is gradually falling. The drivers are concern about carbon dioxide emissions and global warming, improving technology, and the finite nature of fossil fuels.

Several pressures explain why the change is slow:

• Renewable equipment is expensive to build, even though the "fuel" (wind, sunlight) is free.
• Many renewables are unreliable, so fossil-fuel or nuclear back-up is still needed for demand peaks.
• Existing transport, heating and power systems are built around fossil fuels and are costly to replace.

Science can identify environmental problems such as rising carbon dioxide levels and suggest solutions, but whether those solutions are used depends on political, social, ethical and economic factors as well.

This is why the debate is not settled by science alone: cost, reliability, jobs and public opinion all shape which resources a country actually chooses.

1. Confusing renewable with reliable

These describe different things. Renewable means the resource will not run out; reliable means it can supply energy on demand. Wind is renewable but unreliable, and nuclear is reliable but non-renewable.

2. Calling nuclear fuel renewable

Nuclear fuel is non-renewable. The supply of suitable fuel such as uranium is finite, even though a small amount releases a large quantity of energy and no carbon dioxide is emitted in use.

3. Describing how a resource generates electricity

The specification does not require descriptions of how resources are used to generate electricity, so writing about turbines and generators wastes time. Focus on renewable status, uses, reliability and environmental impact.

4. Saying renewables have no environmental impact

Renewables have lower impacts, not zero. They can disrupt habitats, affect the landscape, and their manufacture uses energy and materials. Only claim reduced impact, not none.

5. Forgetting the non-science factors

When asked why fossil fuels are still used, include political, social, ethical and economic factors such as cost, reliability and existing infrastructure, not only the environmental science.