What the Heck is Geothermal Energy?

I read an article named "What the Heck is Geothermal Energy?" from the website about protecting our environment. Actually, I didn't hear what Geothermal Energy it is. I think it is very unfamiliar energy source. The Geothermal Energy is an alternative energy source likewise solar, wind, and biofuels. However, you guys only hear about solar, wind, and biofuels.

What the heck it is? You can watch a video about Geothermal Energy when you click link which I mentioned above. Geothermal Energy has many uses. For example, many farmers have used this energy to hear their greenhouse. Some countries especially Italy and Hungary have been using Geothermal Energy for a very long time.

Geothermal Energy is very simple formation. The electricity that comes from heating water, and from using that hot water. Heating water can make very high temperatures and steam, which work in many ways.

I think that alternative energy sources are very useful instead of other energy sources. It is because it makes less pollution. We should develop more alternative energy sources.