Fossil fuels are energy sources that come directly from nature. First, the sun's radiant energy is stored as chemical energy in plants by photosynthesis. When the plants die, they start decaying. After many years, the plants are turned into fossil fuels. The fossil fuels are mainly coal and oil, but if the decaying plants are exposed to heat and pressure, they turn into natural gas. We mine coal from the ground. We also pump oil out of the ground using machines (pictured left). Then we turn much of that oil into gasoline so we can run our cars. We put the coal in furnaces inside power plants. Then we burn the coal to heat water and produce steam. The steam turns turbines which creates electricity. Natural gas is transported by pipeline to some power plants where we convert it to electricity as well. The energy in fossil fuels is potential because it is stored. It is nonrenewable because fossil fuels don't form fast enough to match the speed of fossil fuel consumption. Fossil fuels are good because you can find them almost anywhere. However, they pollute the environment by producing carbon dioxide, which contributes to global warming. Extracting them from the ground is also dangerous because there could be leaks, cave-ins, or fires. They also are nonrenewable, so we need to be able to manage our consumption very carefully.
This is an example of a transformation with fossil fuels. First, the tree (chemical energy) decays over many years and eventually turns into coal. Next, the coal is extracted and burned. The fire heats up water, which turns it into steam (thermal energy). Then, the steam turns a turbine to create electricity (mechanical energy). The electricity goes through power lines (electrical energy) and it comes to our houses, where we can use it for a variety of electrical appliances such as a hair dryer (thermal energy).