What is a fossil fuel??

Fossil fuel is the most widely used fuel in the world, represents depleted non-renewable energy sources, and including three sources:
– Coal
– Crude Oil
– Natural gas
Fossil fuels have been formed with specific stocks in the earth during millions of years ago, and cannot be restored in a short period of time.
When extracted from the ground and burned with oxygen in the air, it produces the heat used in all areas.
Fossil sources, currently constitutes 87% of the energy needs in the world and is expected to become 80% in 2030 due to the steady increase in using hydropower, solar and wind energy.