Sweden’s KTH The Royal Institute of Technology researchers are using thermoelectric generation to save vehicles hundreds of liters of fuel and reduce their carbon emissions by as much as 1,000 tons per year.

Working with automotive manufacturer Scania, the researchers from Sweden’s KTH Royal Institute of Technology have been testing semi trucks equipped with a system that converts exhaust heat into power – through a process called thermoelectric generation (TEG). The voltage produced by the system can help power the truck and reduce the strain on the engine, explains researcher Arash Risseh.

The TEG system operates on the principle of the thermoelectric effect, by which differences in temperature heat is converted into voltage – a phenomenon discovered in 1821 by German physicist Thomas Johann Seebeck, and often referred to as the “Seebeck effect.”

Researcher Arash Risseh explained, “Most fuel energy is not used to drive a truck forward. Some 30 percent of this unused energy is lost as heat from the exhaust pipes.”

A truck that generates 440kW would see about 132kW of energy disappear in the form of heat coming out of the exhaust pipes, he said. “That’s enough to power a typical passenger vehicle.”

Capturing this excess energy takes a load off the truck’s generator, and in turn, the engine, Risseh said. That means better fuel efficiency and lower emissions.

The Seebeck effect requires a temperature differential – cool on one end of the circuit and hot on the other, which means a truck must rely on a coolant in order to stimulate the voltage. Cooling the circuit is easier with natural alternatives, such as seawater for a ship’s engines. Ships also make good candidates for TEG because their buoyancy offsets the constraints of weight and volume that road vehicles face, Risseh said.

TEG is also regarded as a potential energy saver in data centers that are located in cold climates. Near the Arctic circle in northern Sweden, a data center that uses 1 Terawatt hour per year could potentially recover 1 Gigawatt per year – a savings of some €100,000, he said.

Whatever Risseh is up to working with Scania, the partnership points up some serious commercial attention. Over in Europe, where fuel taxes are from an American point of view outrageously high, there is more economic room for the capital costs of energy recovery. But a foothold into a market for capturing the energy going out the exhaust pipe would be a step into going to scale, a move that would start the drive to lower costs.

Congratulations to the Swedish team. TEG has gotten a wee bit off the ground.


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