Geothermal energy is a kind of power than makes use of the earth’s heat. In some areas of the world geothermal energy has been used for thousands of years. The earth’s core is very hot. It has a temperature so hot that it can melt rock. In areas with lots of volcanoes molten rock can be found very close to the surface.
For this reason geothermal power stations can be found in Italy, New Zealand, Iceland, Japan, the Philippines and the United States. These are all areas that contain volcanic rock. The intense heat from the rocks is used to generate energy and electricity and sometimes also for heating. But how does geothermal energy work?
Under the ground hot rock can be found. These rocks heat water to produce steam. By drilling holes down into the hot rock the steam is released. The steam can be purified and used to power turbines which in turn drive electric generators. Water may be pumped into the area of hot rock or natural groundwater may be used to produce the required geothermal energy.
To achieve this the water is pumped down an “injection well”. Then it filters through the cracks in the rocks where they are at a high temperature. The water then returns via the “recovery well” under pressure. As it arrives at the surface it forms steam which is then purified for use as geothermal energy.
The extent to which geothermal energy is useful depends on how hot the water gets. This is influenced by the heat of the rocks and the amount of water pumped into the area. If the rocks are not hot enough or cool down naturally this presents a problem for geothermal power stations.
Geothermal energy has several advantages and disadvantages. One main advantage is that producing it does not pollute the environment or add to the levels of greenhouse gases in the atmosphere. Such power stations use little space so there is little impact on the land and ecology. Geothermal power stations do not require any fuel to run. Once the plant is built the energy is nearly free.
The disadvantages of geothermal energy are that there are not that many areas in the world where a power station can be built. To do so you require a specific type of hot rock. It also needs to be at the right depth for drilling purposes. The type of rock above the site needs to be easily penetrable. Such power stations may also run out of heat for decades. Sometimes toxic gases and minerals force their way to the surface.
Where geothermal energy is used it has proven to be a useful and cheap alternative for fossil fuels. Iceland is almost entirely powered but geothermal energy. However, clearly, it is not going to be the solution for countries that have no volcanic rock to drill. Such areas of the world are going to have to find alternative ways to create clean, renewable energy resources for residential and industrial use.