Scientists Invent Device That Straps to Any Car's Tailpipe, Transforming Exhaust Into Electricity

Pretty neat!

The combustion engines in gas-powered cars can produce a lot of power by burning dead dinosaurs, but they're surprisingly inefficient at it, with most of the energy they consume — an estimated three quarters of it — getting lost as heat off the engine and through the tailpipe.

That raises an obvious question: what if you could recover some of those wasted thermal emissions and put them to use, recapturing the lost power to greatly increase vehicles' efficiency?

It's an idea that scientists have long been chasing, with limited progress as far as practical implementations go in vehicles, in part due to cost-effectiveness challenges.

But now, a team of researchers say they've created a device that can do just that — turn exhaust heat into electricity — with a relatively simple design that can be added to an existing car's tailpipe, or even the exhaust vents of other vehicles like helicopters.

As detailed in a study published in the journal ACS Applied Materials & Interfaces, the prototype thermoelectric generator was able to produce a maximum power output of 40 Watts, which is enough to power a lightbulb — and that's just in their limited experiments so far.

Thermoelectric generators rely on temperature gradients to work. In essence, when one of these devices is placed near or on something producing waste heat, electrons are drawn from the hot side to the cold side, creating an electric current.

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.

When simulating high-speed environments, the researchers found that their thermoelectric system could produce up to 56 Watts of power when traveling at the speed of a car. And for helicopters, it was nearly thrice that: 146 Watts.

"These results could potentially pave the way toward the integration of TE devices into complex system designs for practical applications," the authors concluded.

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