GEOTHERMAL ENERGY

It gets hotter and hotter as you go down towards the centre of the earth. This heat is geothermal energy. In some places the temperature increases as much as 40°C per kilometre, and this is a very good 'heat gradient. A normal heat gradient is 25°C per kilometre. Often if you make a deep hole in the ground, you will find hot water deep underground. For example, engineers drilled for hot water in Southampton, England. At 1500 metres they found water at 60°C. There is enough hot water there to heat a thousand houses for thirty or forty years. In some places you do not have to drill to obtain geothermal energy. This is because hot water and steam are already coming out of the ground. The most famous examples of this are in California (USA), New Zealand, Italy and Iceland. In these places the water and steam are very hot. It is hot enough to heat most of the capital of Iceland, Reykjavik, or to drive, i.e. provide the power to work, electric generators in California.

There is not always hot water deep down, but there is often very hot dry rock. Of course, we want to use this heat, but can we get it out? In Los Alamos, USA, scientists are trying to do this. They are drilling down to the hot rock. Then they are going to break the hot rock. They will then send cold water down to the bottom, and il will get hot there. This hot water will return to the top through another hole. The hot water will be useful for making electricity or heating houses.Geothermal energy will never be an important source of energy. But there are many places where it can be very useful.