New technology hopes to turn excess heat into electricity

by Antonio Pasolini on November 20, 2009

Source: MIT News Office

Source: MIT News Office

Did you know that more than half of the energy consumed worldwide is wasted, mainly as excess heat?

A new technology being developed at MIT is hoping to harvest all this waste-energy and convert it into electricity more efficiently than existing devices. If successful, the technology could lead to cellphones with double the talk time, laptop computers that can operate twice as long before needing to be plugged in, or even power plants that put out more electricity for a given amount of fuel.

Current devices only achieve one-tenth of the Carnot Limit, a 19th century formula for determining the maximum efficiency that any device can achieve in converting heat into work, says Peter Hagelstein, associate professor of electrical engineering. In experiments involving a different new technology, thermal diodes, Hagelstein worked with Yan Kucherov, a consultant for the Naval Research Laboratory, and coworkers to demonstrate efficiency as high as 40 percent of the Carnot Limit. The calculations show that this new kind of system could ultimately reach as much as 90 percent of that ceiling.

Hagelstein says that with present systems it’s possible to efficiently convert heat into electricity, but with very little power. It’s also possible to get plenty of electrical power from a less efficient, and therefore larger and more expensive system. “It’s a tradeoff. You either get high efficiency or high throughput,” says Hagelstein. But the team found that using their new system, it would be possible to get both at once, he says.

Now, the million dollar question: are we going to see this happen any time soon? The type of chip on which the new technology depends (called quantum dot devices) is currently being developed but years away from commercial availability. So, no, not any time soon, but it would be nice if this technology reached the general public as, alongside switching over to clean energy, we need to solve the waste energy problem.

Source: MIT News Office

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