The word geothermal is derived from ‘geo‘, which relates to the Earth’s ground or land and ‘thermal‘ which relates to heat.
The radioactive decay of radioactive substances releases heat energy, which heats up the rocks underground.
How geothermal energy works:
1. Water is pumped underground
2. The water pumped down is heated by hot rocks underground
3. The heated water then turns to steam (water vapour), which rises to the surface.
4. The steam is used to turn a turbine
5. The turbine is connected to the generator, which will generate electricity.
Geothermal energy is a great alternative to burning fossil fuels because it does not involve burning fuels. This means that no CO2 is being released and there are no fuel costs. The hot water and steam can even be used to heat buildings.
The term biofuel combines ‘bio‘, relating to living things (primarily plants), and ‘fuel‘, which refers to a material burned to produce heat or power.
So to make biofuels:
1. The plants are grown
2. The plants are harvested
3. The plants are burned in power stations
When plants burn, they release carbon dioxide (CO2). However, this is not as harmful as it might seem because plants absorb CO2 through photosynthesis as they grow. This means that burning plants only releases the CO2 they previously absorbed, without adding extra CO2 to the atmosphere. Therefore, in theory, biofuels are carbon neutral.