Solar panels are great at making electricity when the sun is shining, but we use electricity 24 hours a day, 365 days a year — even at night or when the sun is hidden behind thick, dark rain clouds. We can and do use batteries to store the energy from the sun, but there's another way to make electricity that's getting a lot of attention right now — fuel cells.

Fuel cells are basically hydrogen batteries. Instead of using chemicals and materials like those inside a "D" cell in your flashlight, fuel cells use hydrogen to make electricity. Fuel cells are very efficient, and they produce only water as a by-product, so they are friendly to the environment. In fact, fuel cells can be used almost anywhere, even at the most remote locations where power lines don't go or mounted on cars, trucks and buses to make low-emission vehicles. Fuel cells are expensive, but researchers and manufacturers are doing their best to bring down the costs now compared to costs of conventional power generation.

If you'd like to learn more about fuel cells from someone who is designing and building them, visit the Web site of German fuel cell maker Heliocentris GmbH or send an e-mail to Henrik Colell and Brian Cook, two guys working for Heliocentris who helped write this section.

If you'd like to get some hands-on experience with fuel cells, Heliocentris has created an educational kit with a fuel cell and experiments for the classroom. For more information on the kit, visit the Web site of U.S. distributor Frey Scientific or send an e-mail.

If you're in grade 8 or higher, learn more about fuel cells and our energy future .