We know that geothermal energy is a renewable form of energy that can be extracted from certain places on the earth.
The difference in temperature between the surface and the region slightly inside the earth is already being utilized in various homes for heating/cooling, as the need maybe. Have a look at this video, to get an understanding of this residential geothermal application. It's high time we start using such systems to generate energy. I will write about this in detail later.
On a larger scale, geothermal energy is extracted from hot springs and molten liquid like lava. But these things depend on locating geo-thermal power stations in the place where hot springs/lava is located. Often, that is a difficult proposition.
A company called as Altarock Energy has developed a patent-pending technology that enables it to extract heat from any place on the earth, by drilling into the earth at a certain depth. As you might know, the earth gets hotter as we go deeper and combined with other proprietary methods, this company is able to inject cold water into deep fissures and extract hot water out of it, which is then used to generate energy.
Have a look at the following video to get a better understanding of this technology -
