Geothermal energy heating a hot spring in New Zealand.Geothermal energy can mean different things for different people. There are two main forms of geothermal energy with the first deriving directly from the heat of the earth's core whilst the second derives from solar energy that has been absorbed by the first few feet of the earth and is sometimes referred to as "ground source heat". This article helps to explain what geothermal energy is and the difference between its two main forms.

The main form of geothermal energy is energy that derives from the core of the earth. The earth's core temperature is believed to be anywhere between 6000°C and 6500°C based on new research that came to light in 2013. Previously, the earth's core was widely believed to be somewhere around 5000°C. This intense heat is absorbed by the different layers of the earth, helping to heat our planet.

This geothermal energy can be used to generate geothermal power and is the source of our hot springs, volcanos and geysers.

So What Is Ground Source Heat?

Ground source heat is slightly different to the main form of geothermal energy in that it only applies to the first few meters of the earth beneath our feet.

Although ground source heat is still classed as geothermal energy as it is heat that is stored within the earth, the source of this heat isn't actually the earth's core. The main contributor of ground source heat is the solar radiation the earth receives from the sun. Depending on your location, the sun often shines down on the earth and during this process, solar energy is absorbed and stored by the first few feet of the earth.

Once this energy is stored in the earth, it can be tapped into by a ground source heat pump that utilises a network of pipes buried under the earth with water flowing through them. Cold water is fed through one end of the piping system and once it reaches the end, is often several degrees warmer than the temperature of the cold water. This can then be used with a geothermal heat pump in order to provide a more efficient and environmentally friendly method of generating hot water.