Other Sources

There are other ways of making generators turn around.

Wind turbines The kinetic energy of the wind turns the turbine which turns the generator	Waves and Tides The energy in moving water turns turbines	Hydroelectric Build a dam in a river then let the water fall through turbines

The three examples above are renewable. We will never run out of wind or moving water.

Geothermal Energy
There are parts of the world where the Earth's crust is quite thin. Because of this the rocks underground, close to the surface, are very hot. If we pump cold water underground it comes back up hot. Sometimes hot enough to be used to make electricity. The rocks wont stay hot forever. Eventually the plant will have to move somewhere else.

Solar Energy
Solar cells produce electricity directly. Sunlight energy falls on them and they convert this into electricity. To make a lot of electricity you'd need a lot of cells and a lot of sunlight. It does have the advantage of being renewable.