One of the projects here at the Intel International Science & Engineering Fair that caught the attention of the staff back in the office was "the air battery."� What was it, our technology editor wanted to know? So I went up to Joseph Christopher Church, a high school sophomore in Washington, DC, and asked him. Church had built something he called an air battery out of a small tank of compressed air and a tiny turbine. The idea was to show that he could unleash the energy stored in compressed air to power the turbine, which would then"�use the energy to recompress the air. It's not as far-fetched as it sounds, actually: Some scientists have proposed storing solar power as compressed air in underground caverns, then tapping it at night. By the time I visited his booth, the air tank was empty, so Church used a bicycle pump to show me how the battery created voltage. [Text continues after the photos] Church acknowledges that it's just a proof of principle, and that the efficiency wasn't as high as he'd need to make the concept into reality. But when he had a full air canister, the battery did provide enough juice to power his Walkman " yes, this kid born in the mid-90s still has a Walkman " and he hopes to improve it in a number of ways. If it pans out, chemical batteries could lose some of their market share. "Air is completely non-toxic and there's an endless supply,"� he says. "You can't beat that."� -- Edited by Ivan Oransky at 05/15/2008 2:35 PM