Select your localized edition:

Close ×

More Ways to Connect

Discover one of our 28 local entrepreneurial communities »

Be the first to know as we launch in new countries and markets around the globe.

Interested in bringing MIT Technology Review to your local market?

MIT Technology ReviewMIT Technology Review - logo

 

Unsupported browser: Your browser does not meet modern web standards. See how it scores »

Researchers at MIT are developing new technology for converting heat into light and then into electricity that could eventually save fuel in vehicles by replacing less-efficient alternators and allowing electrical systems to run without the engine idling.

The technology, called thermophotovoltaics, uses gasoline to heat a light-emitting material, in this case tungsten. A photovoltaic cell then converts the light into electricity. The idea has been around since the 1960s, says John Kassakian, MIT electrical engineering and computer science professor. But until now, the light emitters for the photovoltaics produced inefficient and very costly systems. Improvements in the materials used in these latest devices – possible in part because researchers can modify the material structure at the nanoscale – are now making much more efficient systems, Kassakian says.

According to Kassakian, the system could potentially be a more efficient way to power electrical systems in a vehicle than the current alternator-based one, which wastes energy in two stages: the internal combustion engine converts only about 30 percent of the energy in fuel into movement, and then the alternator is only 50 percent efficient in converting the mechanical energy into electricity. He says a small prototype thermophotovoltaics device that could confirm the system’s improved efficiency might be ready in a year.

The researchers modified the surface structure of the light emitter, etching into it nano-sized pits to tune the wavelengths of light emitted to precisely those a photovoltaic cell can convert most efficiently into electricity. They further refined the device with the use of filters that allow the desired wavelengths of light to pass through to the photovoltaic cells, but reflect other wavelengths back to the light emitter. The reflected light carries energy that helps keep the emitter hot, reducing the amount of fuel needed.

In addition to replacing the alternator with a thermophotovoltaic module, says Kassakian, the technology could be part of an air-conditioning system for vehicles that doesn’t require a compressor. Because this would significantly decrease the load on an engine, it could make it possible to turn off the engine when the vehicle stops in traffic and easily restart it. Today’s hybrids use this technique to save gas, but require large batteries to provide electricity for the radio and lights, and to restart the engine, and they have to turn the engine back on when the battery charge runs out. In the new MIT system, these batteries wouldn’t be necessary.

34 comments. Share your thoughts »

Tagged: Energy

Reprints and Permissions | Send feedback to the editor

From the Archives

Close

Introducing MIT Technology Review Insider.

Already a Magazine subscriber?

You're automatically an Insider. It's easy to activate or upgrade your account.

Activate Your Account

Become an Insider

It's the new way to subscribe. Get even more of the tech news, research, and discoveries you crave.

Sign Up

Learn More

Find out why MIT Technology Review Insider is for you and explore your options.

Show Me
×

A Place of Inspiration

Understand the technologies that are changing business and driving the new global economy.

September 23-25, 2014
Register »