Every year, America generates 1020 joules of energy (equivalent of 10 billion barrels of oil), mostly through chemical means like combustion, but only about 40 percent of it is actually used for work, the rest is lost through wasted heat. Physics Professor Bruce White and his team are discovering materials that capture that unused energy.
"Even if we're not very efficient at collecting that energy, it's still a lot of energy," he says. "If we only get 10 percent of it, that would still be a tremendous amount."
He's looking specifically at thermo-electric materials, which produce voltage when one part gets hot while another remains cold. They have been known about for at least 100 years, but most are remarkably inefficient, and the best ones are either 10 times more rare than platinum or they're toxic. So White and his team are trying to make their own.
They're working with silicon because it's abundant and has very efficient electrical properties, but it also conducts a lot of heat. However, computer simulations have shown that by randomly mixing atomic layers of silicon and a heavier substance like tin, thermal conductivity decreases by a factor of 10,000.
"Silicon goes from having an efficiency of close to zero, to something in the 10 to 20 percent range," he says. "And that's a really big deal."
The team has succeeded in making materials and increasing efficiency, but it hasn't been able to make any as efficient as simulations suggest. White thinks they've figured out why and the next round of experiments should help him understand if he's right.
Last Updated: 6/3/15