» This Story:Read +| Comments
KidsPost

Explaining alternative energy sources to kids

Wind turbines in La Muela, Spain, are used as an alternative energy source in that country.
Wind turbines in La Muela, Spain, are used as an alternative energy source in that country. (Xabier Mikel Laburu/bloomberg News)
Discussion Policy
Comments that include profanity or personal attacks or other inappropriate comments or material will be removed from the site. Additionally, entries that are unsigned or contain "signatures" by someone other than the actual author will be removed. Finally, we will take steps to block users who violate any of our posting standards, terms of use or privacy policies or any other policies governing this site. Please review the full rules governing commentaries and discussions. You are fully responsible for the content that you post.
Washington Post Staff Writer
Tuesday, February 9, 2010

Most of the energy we use in this country comes from sources far beneath the Earth's surface called fossil fuels. Petroleum (which is used to make oil and gasoline), natural gas and coal formed deep underground over hundreds of millions of years. These deposits were created as once-living plants and animals decomposed under high pressure and heat.

This Story

Humans have created sophisticated ways to get these fuels out of the earth, and they now account for more than 80 percent of all the energy Americans use to heat our homes, cook food and drive our cars.

But someday, these deposits of fossil fuels will run out. So experts want to come up with alternative sources of energy that are "renewable," which means they won't run out. Here are a couple of interesting renewable energy sources that have been growing quickly.

Wind power: Do you remember seeing old grain windmills on a field trip or in storybooks? They used the wind to move giant blades, and as they turned, huge gears inside the windmill operated grain-crushing machinery. Modern windmills, called wind turbines, are used to generate electricity.

Rather than turning grain machinery, the gears attached to a wind turbine's rotors move wires inside a magnetic field, which causes an electric charge to form in the wire. Constant movement of these wires creates an electric current that can be used to power homes and businesses.

Companies are now building huge wind farms, but they can be placed only in areas that are consistently windy. Wind power now accounts for 1.5 percent of all electricity used around the world, and many more wind farms are planned.

Garbage fuel: Most of the trash we throw out ends up in landfills -- huge, rotting piles of garbage. As this waste rots over time, it lets off a gas called methane, which is the main ingredient in natural gas. Companies are building plants that capture the methane from garbage dumps and use it to manufacture natural gas.

When chilled to extremely low temperatures, natural gas turns into liquid, which takes up far less space and is easier to move around. In California, the trash collecting company Waste Management has built the largest plant in the world for turning methane from landfills into liquid natural gas. That fuel is then used to power hundreds of the company's garbage trucks.

There's another benefit to this technology: Methane contributes to global warming, so this process keeps it from seeping into the atmosphere from the garbage dump. There are more than 500 landfills in the nation trying to recycle waste into energy. It's expensive to do, but experts say it will become cheaper as more companies do it and the technology improves.



» This Story:Read +| Comments
© 2010 The Washington Post Company