Recycling Heat Just Got Way Cooler

Image courtesy Hinode JAXA/NASA

Fight disinformation: Sign up for the free Mother Jones Daily newsletter and follow the news that matters.


We waste 60 percent of all the energy we produce burning fuels and in power plants—most lost as excess heat. If we could harvest that waste heat we could use a lot less electricity.

Now a paper in the current Journal of Applied Physics suggests a new way to recycle waste heat. The process might, for instance, double the run time of cellphones and laptop computers and increase output in power plants.

Here’s the current conundrum. Existing solid-state technologies that convert heat into electricity are inefficient. Existing systems that efficiently convert heat into electricity produce very little power. Your choice: high efficiency or high throughput, but not both.

On top of all that, theory predicts that energy conversion can never exceed a specific value, the Carnot Limit. Even so, modern commercial thermoelectric devices only achieve about one-tenth of the Carnot Limit.

So how to do it better?

The MIT experiments involve a different technology—thermal diodes—which suggest future efficiencies as high as 40 percent of the Carnot Limit and ultimately perhaps 90 percent.

Here’s what the researchers did:

  • They started from scratch rather than trying to fix existing devices.
  • They carried out their analyses using a supersimple system that generated power with a single quantum-dot device—a kind of semiconductor confining electrical charges very tightly in all three dimensions.

Add to their efforts the results of another MIT paper showing an intermediate step towards achieving heat transfer at a rate orders of magnitude higher than predicted by theory.

The end result: heat converted into harnessable electricity at a rate promising enough that a new company, MTPV Corp (Micron-gap Thermal Photo-Voltaics), is already working on the development of a new technology based on the work described in this paper.

Co-author Peter Hagelstein tells MIT that when work began on the project in 2002 such heat-recycling devices “clearly could not be built. We started this as purely a theoretical exercise.” Developments since then have brought theory much closer to reality.

I suppose someone’s going to get filthy rich and powerful making a cleaner-powered world… Conundrum: Part 2?
 

TIME IS RUNNING OUT!

We have an ambitious $350,000 online fundraising goal this month and it's truly crunch time: About 15 percent of our yearly online giving usually comes in during the final week of the year, and in "No Cute Headlines or Manipulative BS," we explain why we simply can't afford to come up short right now.

The bottom line: Corporations and powerful people with deep pockets will never sustain the type of journalism Mother Jones exists to do. And advertising or profit-driven ownership groups will never make time-intensive, in-depth reporting viable.

That's why donations big and small make up 74 percent of our budget this year. There is no backup to keep us going, no alternate revenue source, no secret benefactor. If readers don’t donate, we won’t be here. It's that simple.

And if you can help us out with a donation right now, all online gifts will be matched thanks to an incredibly generous matching gift pledge.

payment methods

TIME IS RUNNING OUT!

We have an ambitious $350,000 online fundraising goal this month and it's truly crunch time: About 15 percent of our yearly online giving usually comes in during the final week of the year, and in "No Cute Headlines or Manipulative BS," we explain why we simply can't afford to come up short right now.

The bottom line: Corporations and powerful people with deep pockets will never sustain the type of journalism Mother Jones exists to do. And advertising or profit-driven ownership groups will never make time-intensive, in-depth reporting viable.

That's why donations big and small make up 74 percent of our budget this year. There is no backup to keep us going, no alternate revenue source, no secret benefactor. If readers don’t donate, we won’t be here. It's that simple.

And if you can help us out with a donation right now, all online gifts will be matched thanks to an incredibly generous matching gift pledge.

payment methods

We Recommend

Latest

Sign up for our free newsletter

Subscribe to the Mother Jones Daily to have our top stories delivered directly to your inbox.

Get our award-winning magazine

Save big on a full year of investigations, ideas, and insights.

Subscribe

Support our journalism

Help Mother Jones' reporters dig deep with a tax-deductible donation.

Donate