Hot water or steam from within the earth can be used to heat establishments, or to produce electricity. It is one source of renewable energy because, water can be replenished by the rain, and the heat itself flows consistently from within the earth's core.

Around 4,000 miles below the earth's surface, temperatures can reach levels hotter than the sun's surface. This is where geothermal energy is generated.

The planet is made up of several layers:

- The core consists of two parts: an inner solid iron core, and the outer core which is full of molten magma.

- The mantle, which is made up of rocks and magma.

- The outermost layer is the crust. The crust is composed of plates.

Magma can rise up toward the earth's surface, through the plates. As one goes deeper into the earth, the temperature of the rocks and water gets hotter.

Modern technology has made it possible to harness geothermal energy to generate electricity, or to produce heat for various purposes.

Within the United States, geothermal reservoirs are located in Hawaii, Alaska, and in some western states. On the sites of these reservoirs you can find geothermal power plants that use the steam rising from the reservoir, to power a generator, which in turn creates electricity.

There are other uses for this type of energy. Hot water can be used to directly heat a building, can be used in greenhouses, can help to dry crops, or can be used to pasteurize milk. These are just a few examples of how the heat itself can be used, aside from producing steam which generates electricity.

As of 2008, just 1% of the total energy used around the globe was produced by geothermal methods. Hopefully, in the near future, we will see an increase in the usage of this form of energy.

Not only is this a renewable energy source, but it is also clean. It doesn't emit harmful emissions. No fossil fuel is used. Rising oil prices are a non-issue, where geothermal energy is concerned.

The downside is that the temperature produced is much lower than that of most steam turbines. This means geothermal plants are less efficient in producing electricity, than conventional coal plants.

Another cause of worry for some is the environmental impact of some practices. Enhanced geothermal systems, for example, inject water into hot dry rock.

But the advantages of geothermal energy still overshadow the disadvantages, and the drawbacks themselves do not hinder its progress. It is simply a matter of continuing research and development, creating better ways to harness the earth's heat.