Hold up a piece of charcoal, or, if possible, a piece of real coal. Coal is burned to heat homes and run electrical machinery. About 20 percent of the energy we use comes from coal. Other petroleum products similar to motor oil are burned to fuel motor vehicles and heat homes. About 45 percent of energy used comes from oil.
Natural gas is used to heat the homes of many people.
About 25 percent of the energy we use comes from natural gas. The fuel used in lighters is not the same as the natural gas used to heat homes, but the lighter can be used as an example. Most of the energy used by people today comes from these fossil fuels. But fossil fuels are limited in their supply, can pollute and are sometimes hard to find. The following energy sources not require the sun.