Over long periods of time and under immense pressure from the earth, these bacterially active fossil beds formed pools of oil under the earth's surface. From oil, we have learned how to extract gasoline which can be burned to release energy. However, once a fossil fuel is burned, it is gone and cannot be reused or recycled. About half of all the oil produced in the world is made into fuels to power our cars, trucks, airplanes and boats. Some oil is also used to generate electricity.
Oil is so easy to use in so many different ways, that people still depend on it a lot.
There are other problems caused by moving oil from where it is found to where we use it. About half of the oil in the world is moved in huge tanker ships. Accidents sometimes happen, spilling oil into the ocean, which kills fish eggs and tiny ocean creatures that other water animals feed on. When there is an oil spill, birds and other ocean animals get oil in their fur and feathers which is impossible for them to get out. Oil that is transported by pipeline over land does less damage, but the pipelines take up space in one big long path across the countryside.