Energy resources differ in renewal, reliability and impact
Definition
Renewable energy resource
A renewable energy resource is replenished naturally at least as quickly as it is used, so it will not run out through use on a human timescale.
Definition
Non-renewable energy resource
A non-renewable energy resource is finite and is used faster than natural processes can replace it.
- Resources provide heating, transport and electricity but differ in reliability, response time, output, impact, location and cost.
- Renewable resources often depend on weather conditions and have lower efficiency rates non-renewable energy resources.
Fossil fuels and nuclear fuel are non-renewable
- Fossil fuels are coal, oil and natural gas.
- They can be stored and burned when required, giving controllable output.
- Combustion releases carbon dioxide and can release sulfur dioxide and particulates; extraction and transport can also damage habitats.
- Nuclear fuel produces large continuous outputs with no carbon dioxide from fuel combustion during operation.
- Nuclear stations are expensive to build and decommission, create long-lived radioactive waste and require strict safety systems.
Biofuel depends on sustainable replacement
- Biofuel is made from recent living material such as crops, wood or organic waste.
- Plants absorb carbon dioxide while growing, but cultivation, processing and transport can create net emissions.
- Fuel crops can compete with food production and use land, water and fertiliser.
- Biofuel is renewable only when new biomass grows at least as quickly as it is harvested.
Wind, water and sunlight are renewable flows
- Wind has no fuel emissions during operation but is intermittent and needs exposed sites.
- Hydroelectricity can start quickly and give large output, but dams flood land and alter rivers.
- Tidal power is predictable, but suitable coastal sites are limited and barrages disrupt estuaries.
- Solar energy produces electricity or heats water, but output varies with daylight, season and cloud.
- Manufacture and construction still have environmental impacts even when operation uses no fuel.
Choose resources for the required use
- Transport favours energy-dense fuels or stored electricity because vehicles carry their supply.
- Heating can use gas, electricity, biomass, solar thermal energy or heat pumps.
- Electricity networks combine resources because demand changes and no single source is ideal everywhere.
Example
- A windy coastal community could use wind power to reduce operational emissions.
- Intermittency means it also needs storage, backup generation or connection to a wider grid.
- Tidal output is more predictable but requires a suitable site and may damage estuary habitats.
Exam technique
- Compare both resources against the same criterion, such as reliability or emissions.
- Separate operational emissions from construction, extraction and decommissioning impacts.
- Link local conditions to output and then to demand.
Common Mistake
- Nuclear fuel is non-renewable.
- Biofuel is not automatically carbon neutral.
- Renewable resources can still cause environmental damage.
An energy mix balances constraints
- Renewables reduce dependence on finite fuels, but variable output can require storage and backup.
- Non-renewable stations can provide controllable output, but create fuel, emission or waste problems.
- The best mix depends on geography, demand, technology, acceptable impacts and timescale.
Self review
- Define a renewable resource.
- Give two advantages and two disadvantages of fossil fuels.
- Why is biofuel not automatically carbon neutral?
- Compare wind and tidal power for predictability.
- Why are several resources used together?
