The Potential of Energy

Energy is what lets us do work—lots of different kinds of work. Energy powers our cars, heats our homes, turns on lights and makes machines go. But where does energy come from?

Lots of different energy sources are used to power our world. When you turn on the lights, you’re using electricity. When we drive a car or a bus, we use gasoline. When we light a fire in a stove or fireplace, we use wood. Even when you eat food, you’re storing energy that you can use later to work or play.

Energy can never be destroyed, but it can be changed from one form to another. Stored energy is called potential energy—like the energy stored in a battery or that contained a gallon of oil. This stored energy can be converted to another form to do useful work:

• Burning the oil turns the potential energy stored in the oil into heat energy


• Heat energy is then used to raise the temperature of water enough to turn it into steam


• The potential energy in the steam is turned into kinetic energy when it spins a generator


• The generator turns the energy into electric current which is then transmitted over the wires to our homes

Most of the energy we use to power our world—homes, businesses, vehicles and cities—comes from energy sources that we extract from the ground by mining or drilling. These are what are knows as “fossil fuels” because they were formed by rock and soil pressing down on the remains of dead animals and plants over hundreds of millions of years. These sources—including oil, coal and natural gas—don’t get replaced. The more we use today, the less supply remains for the future.

Recently, more and more people are using renewable energy sources. These energy resources—such as solar energy and wind—will never run out.