Energy Resources & Energy Generation (Cambridge (CIE) IGCSE Environmental Management): Revision Note

Renewable & non-renewable energy

Renewable (non-finite) energy resources

• Renewable resources—energy sources that can be replenished naturally in a relatively short time

  • They are non-finite, meaning they will not run out on a human timescale

• Examples of renewable energy sources:

  • Biofuels—fuels made from living or recently living material, such as crops or waste

    • Includes bioethanol, biogas, biomass, and wood

  • Geothermal power: uses heat from rocks deep underground

  • Hydroelectric power: uses moving water from rivers or dams

  • Tidal power: uses the rise and fall of sea levels

  • Wave power: uses the movement of waves at the ocean surface

  • Solar power: uses energy from sunlight

  • Wind power: uses moving air to turn turbines

Non-renewable (finite) energy resources

• Non-renewable resources—energy sources that exist in limited amounts and cannot be replaced quickly

  • They are finite, meaning once used, they will eventually run out

• Examples of non-renewable energy sources:

  • Fossil fuels—coal, oil, and natural gas formed from ancient organisms

  • Nuclear power—produced by splitting uranium atoms to release heat energy

Generation of electricity by renewable energy sources

Biofuels (bioethanol, biomass, biogas, wood)

• Biomass—plant or animal material burned as fuel

  • Burned in a boiler to heat water

  • Water turns into steam, which spins turbines

  • Turbines turn generators to produce electricity

• Biogas—gas (mainly methane) from rotting organic waste

  • Collected and burned in a power station

  • Heat is used to make steam that drives turbines and generators

• Bioethanol—alcohol fuel made by fermenting crops such as sugarcane or maize

  • Burned in power stations or engines to provide heat or movement

  • Can be used to turn generators and make electricity

• Wood—logs or wood pellets burned as fuel

  • Heat from burning wood boils water

  • Steam turns turbines connected to generators

Geothermal power

• Cold water is pumped down into hot rocks underground

• Rocks heat the water so it turns into steam

• Steam rises and turns turbines at the surface

• Turbines drive generators to produce electricity

Hydro-electric power

• A dam is built across a river to form a reservoir

• Water is released from the reservoir and flows through pipes

• Fast-moving water turns turbines at the base of the dam

• Turbines spin generators to produce electricity

Tidal power

• A barrage is built across an estuary or bay

• As the tide rises and falls, water flows through turbines

• Moving water spins the turbines

• Turbines turn generators to produce electricity

Wave power

• Floating devices or wave machines are placed on the sea surface

• Waves move the devices up and down

• This motion drives pistons or turbines inside the device

• Turbines turn generators to produce electricity

Solar power

• Solar panels (photovoltaic cells) are placed on roofs or in solar farms

  • Photovoltaic (PV) cells—panels that change light energy directly into electrical energy

  • Sunlight hits the cells and electrons move, creating an electric current

• Solar thermal systems can also be used

  • Mirrors focus sunlight onto water-filled pipes or a central water tank

  • Water is heated to make steam

  • Steam turns turbines and generators

Wind power

• Wind turbines have large blades mounted on a tall tower

• Wind pushes the blades, making them spin

• The blades turn a shaft connected to a generator

• The generator produces electricity as the shaft spins

• Wind turbines can be located on-shore (on land) or off-shore (in the sea)

Generation of electricity by non-renewable energy sources

Fossil fuels (coal, oil, natural gas)

• Fossil fuels are burned in a furnace in the power station

• Heat from burning fuel boils water in pipes or a boiler

• Water turns into high-pressure steam

• Steam is directed onto turbine blades, making the turbines spin

• Turbines drive generators, which produce electricity

• Steam is cooled back into water and reused in a closed loop

Nuclear power (uranium)

• Uranium fuel rods are placed in a nuclear reactor

  • Nuclear fission occurs

  • Uranium atoms split, releasing large amounts of heat

• Heat from the reactor core is used to heat water

• Water turns into steam in a separate loop

• Steam spins turbines, which then turn generators

• Electricity is carried away by power lines to homes and industries