Most of the energy we use today comes from fossil fuels-coal, oil, and natural gas. These are fuels that are being consumed more rapidly than they are being replaced. That means that someday we could run out of these fuels.

Renewable energy comes from energy sources that are constantly being replaced and are usually less polluting than energy from fossil fuels. Examples of renewable energy include solar, wind, geothermal, biomass and hydro.

Solar energy comes from the sun. It is used to heat homes and water in more than 200,000 houses in the United States today. It can also be made directly into electricity using photovoltaic (PV) cells. PV cells make electricity without moving, making noise, or polluting. We most often see these in calculators and watches.

Wind is used to generate electricity. The windmills built long ago had many blades, but today's wind turbines usually have just two or three blades that turn when the wind blows. These blades can be up to 82 feet long! They have wind farms where large groups of wind turbines are connected to electric utility power lines and provide electricity to many people.

Biomass energy comes from plants and trees. Wood is the largest source of biomass energy. We also use corn, sugarcane wastes, and other farming byproducts to produce biomass energy. It can be used in three ways: burned to produce heat and electricity, changed to a gas-like fuel, or changed to a liquid fuel. This liquid fuel is very important for transportation because nearly one-third of our nation's energy is now used for transportation. Energy produced by biomass could someday supply much of the fuel for our cars, trucks, buses, airplanes, and trains. This is very important because nearly one-third of our nation's energy is now used for transportation.

There are other sources of renewable energy including trash, water, and geothermal. One day much of the energy you use may come from renewable sources. As scientists find better ways to develop renewable energy, we may no longer have to depend upon fossil fuel energy. This will help us keep our environment cleaner.

Renewable Energy—A Wave of the Future

Main Idea

1. this story explains
____	sources of renewable energy.
____	that solar energy comes from the sun.
____	biomass is liquid fuel.

 
Sequencing

2. Number the events below in the order that they are discussed.
____	Trash is a source of renewable energy.
____	Fossil fuels are being consumed more rapidly than they are being produced.
____	Energy is the capacity to do work.
____	Wind turbines can be up to 82 feet long.
____	Renewable energy is constantly being replaced.