If you’re the owner of a plug-in hybrid, you’re likely one of the many car drivers around the world who wanted to do their bit for the planet by owning a car that’s capable of zero tailpipe emissions travel for short distance trips but which can also provide longer-distance capabilities without the need to constantly find a charging station to plug-in at.
But that convenience also comes with a downside: even if you’re charging your car’s on-board battery pack from renewable sources of power such as solar power or wind, your car still has a carbon footprint associated with the miles it drives in range-extending mode.
Now a team of scientists at the University of Gloucester in the UK have developed an alternative designed to help alleviate plug-in hybrid owners of their guilty carbon footprints by replacing the internal combustion engine with a new breed of super-efficient nano thermopile that makes it possible to generate large amounts of electricity from any heat source, including compressed wood bricks.
“This is really a breakthrough for both static and mobile applications,” said Dr. Edward Foster, professor of applied engineering at the University of Gloucester. “Powered by responsibly-farmed and sourced wood stock, this could finally be a zero-carbon way of generating power when other renewable sources aren’t possible.”
Thermopiles are made up of lots of thermocouples — strips of two different metals joined together — connected end to end in parallel. When you heat one side of the a thermocouple and keep the other side cool, an electric current is induced in the circuit. Combine many thermocouples into a thermopile, and the amount of electricity you can generate is larger.
Traditionally, thermopiles have been used as temperature sensors in electronics applications, producing a potential difference — or voltage — across the hot and cold junctions proportional to the heat difference between them. And while it’s been possible to produce high-voltages with enough thermopiles, generating electricity in that way has been considered generally inefficient.
But now nanotechnology — in the form of nanostructured superlattice thin films — has made it possible for researchers to build a thermopile unit that can generate up to 20 kilowatts of electrical energy from the heat generated by a decent roaring fire.
As well as opening up possibilities for domestic applications by integrating the new nanothermopiles into the case of modern wood-burning and gas stoves, the researchers say they’ve found a way to provide power on the move thanks to a new super-compact, super-efficient stove.
Built with the latest carbon fiber technology — namely carbon-fiber reinforced carbon — the new RoamR stove is super lightweight, super-strong and extremely thermally efficient. It also happens to take up about the same space as the engine in your average plug-in hybrid.
Before a long trip, the driver must place three or four compressed wood bricks onto the RoamR‘s upper grate, then close and seal the burning chamber. On the road, the burner can be activated by the driver remotely and the fire ignited by careful introduction of pure oxygen from a small attached O2 tank on the side of the unit and then igniting it with a spark.
Burn rate is carefully controlled using automated air flow valves on the top and bottom of the unit, while any smoke is diverted underneath the car and out of the exhaust as it would be with a conventional gasoline-powered vehicle. The faster the air flow, the more quickly the wood burns, and the more power produced.
Still in its prototype phase, the RoamR will eventually be fitted to a BMW i3 EV and sent on a round-UK trip to prove its suitability as a range-extender for electric vehicles. Dr. Foster says the i3 was chosen as a test-platform vehicle because its range-extender variant — the BMW i3 REx — has a similarly-powerful gasoline range-extender to the RoamR‘s power output.
“With most gas stations selling compressed wood pellets or small logs, there’s no range anxiety or fear of running out of fuel,” he said. “And unlike an ICE our RoamR can work with almost any fuel source you can name, provided necessary modifications are carried out.
“It could even be used in developing nations or in locations where gasoline is difficult to source, opening up the possibility of carbon zero transportation for all,” he concluded.
We’ll keep track of this exciting if unusual new technology, and we’ll let you know if and when it makes it to mainstream production.
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