When he isn't studying, rehearsing on his cello, speaking in his native German, volunteering at the local library or training for the Baltimore marathon, David Linus Hamann is trying to figure out a way to more efficiently convert the sun's solar energy into electricity that can power our household appliances.

Even by the impractically busy standards of today's college-bound teen, that's an impressive use of downtime.

Impressive, too, are the other competitors in the Siemens Foundation's annual competition in math, science and technology. This weekend, 16 high school students from New York, New Jersey and Massachusetts convened at Carnegie Mellon University for one of the competition's regional final events, using Friday to set up and explaining their research to judges Saturday.

Mr. Hamann, a senior at Yorktown High School in New York, explained that he has been investigating ways to minimize battery usage in the delivery of solar power. One way to do that is to program nonpersonal appliances that use electricity cyclically -- such as refrigerators and water heaters -- to tap into the grid only when solar power is at its peak availability.

How to know when it's available? Mr. Hamann, along with his project mentor, built a camera and a computer program that could take photos of the sky and predict, three minutes into the future, whether the sun would be "available" or obscured by clouds.

Why work so hard to eliminate the batteries?

"Batteries have a lot of problems," chief among them cost, he said during his 12-minute presentation, which was then followed by a Q and A with competition judges. "It's better to use energy the instant it is created" rather than store it in a battery.

While Mr. Hamann was working on the electrical side of America's energy consumption problem, twins Shweta and Shilpa Iyer -- of Comsewogue High School on Long Island in New York -- have been working on a way to reduce our dependence on gasoline and petroleum-based fuels by making hydrogen fuel cells more commercially practical.

One reason hydrogen isn't yet practical is because the water electrolysis process that creates hydrogen fuels relies on a platinum electrode catalyst. The Iyer twins, who have been working on their project since June, have found a way to use soybeans to turn the mineral element Molybdenum into an inexpensive catalyst that resembles noble metals, which are precious -- and more expensive.

"It's an extremely viable option," Shweta Iyer said. So viable, they believe, that they've already applied for a patent and submitted a paper to a science journal. Their research was inspired, they said, by a recent trip to India, where the crowded cities are choked by vehicle emissions and where residents face daily power outages.

"Our lives have been pretty much consumed by this" project, Shilpa Iyer said, so much so that the two seniors have yet to make any college visits this year. (The twins are sure, however, that they want to go to different universities.)

Siemens calls the award the "highest science honor awarded to American high school students." These projects -- akin to graduate- or Ph.D.-level research -- are being developed by some of America's brightest young science minds and have "implications for the way we live our lives," said Jeniffer Harper-Taylor, president of the Siemens Foundation, the philanthropic arm of Siemens AG, the German industrial conglomerate with Pittsburgh operations.

The two winners (one individual, and one team) from the CMU finals, announced Saturday evening, were Jiayi Peng of Chappaqua, N.Y. -- for her biophysics project on brain signals -- and the team of Jeremy Appelbaum of Woodmere, N.Y. and William Gil and Allen Shin of Valley Stream, N.Y. -- for their research on the tumor-suppressing protein COP-1.

They will advance to the finals in Washington, D.C., for a chance to compete for a $100,000 scholarship.