Energy resources are divided into two groups. Renewable energy is an energy resource that we can use over and over again while non-renewable, is an energy resource that gets used up and cannot be replenished in a short period of time. Renewable energy resources include solar energy, wind energy, geothermal energy from inside the Earth, biomass from plants, and hydropower from water stores in reservoirs and oceans in the form of waves.
However, we get most of our energy from non-renewable energy resources, which include crude oil, natural gas and coal. They are called fossil fuels because they are formed over millions of years from the remains of dead plants and animals by the action of heat from the Earth's core and pressure from the rock and soil. Fossil fuels are continually produced by decaying plant and animal matter, but the rate of their production is extrmely slow, very much slower than the rate at which we use them.
