A Nifty Device Could One Day Turn Your Car's Exhaust Into Electricity

Gas-powered cars have been getting more and more efficient since they were first put to use more than 100 years ago. The most efficient engines out there can transfer 50 percent of the potential energy you put into the tank to the car's wheels, with the remaining 50 percent lost as heat. That could change, though, as a team of scientists has developed a new device that straps to your tailpipe and turns waste heat energy into sweet electrical power.

A team of researchers from the Department of Mechanical Engineering at Pennsylvania State University has created a nifty way of turning the heat lost at your tailpipe into electrical power, reports Futurism.

To do this, the team harnessed a principle that sees electrons move from the hotter part of a material to the colder part. As the electrons move along the temperature gradient, a current is generated that the team of scientists has then been able to harness:

In this case, the researchers say they used a semiconductor made of bismuth-telluride to facilitate this process. But the main challenge is maintaining that temperature difference. Without intervening, the cold part of the generator would start to heat up, too, and you'd lose the current.

Some solutions, as the researchers note, use water cooling. That introduces a lot of complications, though, and makes a device more complex and bulky. What they were going for was meant to be adaptable and practical.

So instead, they used a clever but relatively simple heatsink design using a cylinder with fin-like protrusions that wraps around a tailpipe, providing additional surface area to let off heat via forced convection — or in other words, moving, ambient air carrying away the heat. And in a fast vehicle, that comes naturally.

The scientists, led by Rabeya Bosry Smrit, have so far been able to generate around 40 watts of electricity from the tailpipe of a car, which is enough to power a light bulb. If strapped to the exhaust of something larger, like a helicopter engine, the device could generate three times as much power.

In their paper, the team said the technology was proving to be "particularly promising" when it comes to finding a way of improving "operational capabilities and endurance" of vehicles like cars, motorbikes and helicopters.

In the future, such energy harvesting tech could be integrated into cars to power some internal systems, or may be available as an add-on that you could one day fit to the aging gas car that you insist on driving everywhere. 

If you like interesting science that's finding new ways of cleaning up our planet, head here to find out how battery tech is advancing in electric cars or here to see how electricity was generated through fusion for the first time.