While electric vehicle sales are slowly taking off around the world, the majority of cars on the roads still run on gasoline. And those gas-powered cars are extremely inefficient. Their engines only use a quarter of the fuel’s energy to turn the wheels, with the rest wasted as heat and released via an exhaust pipe.
Researchers have now created a device that could recover some of that wasted heat. Attached to a car’s exhaust pipe, the device—called a thermoelectric generator—could convert the heat into electricity and put it to use in the vehicle, making the car more fuel-efficient.
Thermoelectric generators are not new. They’ve been around for decades, in fact. These devices rely on a temperature gradient across so-called thermoelectric materials to generate electricity. But TEGs so far are efficient. They also require a water-cooling system to maintain the temperature differential between the hot and cold side. This adds bulk and complexity, making TEGs not very practical for use in vehicles.
Researchers at Pennsylvania State University have come up with a more portable, practical design for a TEG, which they describe in the journal ACS Applied Materials & Interfaces. Their design is a cylindrical device with fin-like protrusions that wraps around a car’s tailpipe.
The finned design makes it easier to dissipate heat into air. This keeps the tailpipe side of the TEG module hot and the opposite air-facing side cool, providing the temperature differential needed for electricity production. The prototype produced a maximum output of 40 Watts, enough for low-power applications such as phone-charging.
In a fast-moving vehicle, the cooling efficiency improves further. Simulations of the device on a car driving at high speed produced up to 56 Watts of power. And for helicopters, it produced 146 Watts.
Source: Rabeya Bosry Smriti et al. Thermoelectric Energy Harvesting for Exhaust Waste Heat Recovery: A System Design. ACS Applied Materials & Interfaces, 2025
Image by Andreas Lischka from Pixabay
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