Natural gas and oil are all fossil fuels. Fossil fuels give us energy and come from things that we’re once living. They were formed millions of years ago. Fossil fuels are a very good source of energy. Many things depend on it such as cars, homes and businesses.

Oil can be burned to release energy. Many people use oil to heat their homes. It could also be used in gasoline and kerosene. Oil was made many years ago when the Earth was covered with seas. Many plants and animals died, were washed into the seas and became part of the sediment. Scientists believe that oil formed from these decayed plants and animals, and then became trapped in rocks.

Natural gas is formed in a similar way. Bacteria began to decompose plants and animals that were mixed in the sediment. It created methane gas as a waste product. Methane is one natural gas that we use for energy.

To get oil and natural gas, wells are drilled into the Earth, and the materials are pumped out. It is expensive to produce natural gas and causes pollution. It is also nonrenewable and will not last forever.

Oil and natural gas is _________ for the environment.