Natural hot springs have been enjoyed by people for hundreds of years. ©Getty Images

Natural hot springs have been enjoyed by people for hundreds of years. ©Getty Images

'Geo' means 'earth' and 'thermal' means 'heat', so geothermal energy is heat found inside the earth.

We know that deep inside the Earth it is extremely hot because we see the lava and hot steam that come out of volcanoes and geysers, and we see places that have natural hot mud or water springs.

The top three metres of the Earth keep a constant temperature.

Humans have enjoyed bathing in hot springs for thousands of years.

Using geothermal energy

We can use geothermal energy in our buildings as hot water and heating. It is renewable energy and can heat a home in winter and remove summer heat from the building and transfer it into the ground.

From deeper in the Earth, geothermal water can be piped into homes and offices for heating.  In some places, such as Iceland, geothermal hot water is piped under roads and footpaths to melt the ice and snow in winter.

We can also use geothermal energy to make electricity by drilling about one and a half kilometre or more to tap underground steam or hot water storages, and use it to drive turbines that generate electricity. This is done in different ways:

Jet of steam, Bolivia ©Getty Images

Jet of steam, Bolivia ©Getty Images

  • the oldest is the dry steam method that uses steam found in deep cracks in the rocks to drive turbines;

  • the flash method moves extremely high pressure water into low pressure water that is cooler, and this creates steam that drives the turbines;

  • the binary method passes very hot water through another liquid that has a lower boiling point than water, causing that liquid to become steam that drives the turbines.

A geyser of hot water and steam. ©Getty Images

A geyser of hot water and steam. ©Getty Images

 

The advantages of geothermal energy

The advantages of geothermal energy is that no fossil fuels such as coal or oil need to be burned, so no harmful substances affect the air, and it is less expensive.

Geothermal energy is constant... it is always available. However, the heat insome places may eventually cool down.

There is some concern that some tapping of geothermal energy may release a gas called hydrogen sulfide, which smells like rotten eggs.

This technology is still developing and being investigated, so at the moment only a small part of the world's electricity is made this way. Some countries produce more geothermal electricity than others...for example, Iceland has about 25 active volcanoes and many hot springs and geysers, and so geothermal energy is used to heat many of its buildings and swimming pools.

Read more here and watch a video

http://science.howstuffworks.com/environmental/energy/geothermal-energy.htm

Read about geothermal energy in Australia

http://futuresparks.org.au/inspiration/all-about-energy/geothermal-energy.aspx

In Japan, even monkeys living in the mountains thaw off in hot springs. ©Getty Images

In Japan, even monkeys living in the mountains thaw off in hot springs. ©Getty Images