Graphene turns heat into electricity

Graphene was first isolated at the University of Manchester in 2004 by Sir Andre Geim and Sir Kostya Novoselov. In 2010, they were awarded the Nobel Prize for Physics for their discovery. Graphene’s most unique property is that it is only 1 atom thick, making it the first 2-dimensional material. Today, the university remains the home of graphene research, with over 40 industrial partners working on graphene-related projects.

Recently, its scientists, working with European Thermodynamics Ltd, created low-cost thermoelectric materials that could be used to capture heat from automobiles and convert it into electricity. That electricity can then be used to recharge the batteries in hybrid, plug-in hybrid, and electric cars to give them more range.

The team—led by Prof Ian Kinloch, Prof Robert Freer, and Yue Lin—added a small amount of graphene to strontium titanium oxide. The resulting composite was able to convert heat that would otherwise be wasted into an electric current over a broad temperature range, beginning at room temperature. Previously, thermoelectric materials only functioned at extremely high temperatures around 700 degrees Celsius.

“Our findings show that by introducing a small amount of graphene to the base material can reduce the thermal operating window to room temperature which offers a huge range of potential for applications,” says Prof Freer. “The new material will convert 3-5% of the heat into electricity. That is not much but, given that the average vehicle loses roughly 70% of the energy supplied to it by its fuel to waste heat and friction, recovering even a small percentage of this with thermoelectric technology would be worthwhile.”

The numbers get a bit confusing, but if a conventional internal combustion engine only converts 30% of its fuel into forward motion, recapturing just 3% of its wasted heat could translate into a 10% improvement in fuel economy. Car manufacturers today would be thrilled to make their cars 10% more fuel efficient as they struggle to comply with tough new regulations set to begin shortly in the US and Europe.

The quest to improve fuel efficiency while retaining performance is of enormous interest to car manufacturers. Not only could graphene boost fuel economy, it could also improve safety when used as a composite material in the chassis to reduce overall vehicle weight.

Recapturing waste energy for tomorrow’s cars has led to proposals for tires that produce a small electrical voltage while driving as well as shock absorbers that do the same thing. Range is the new “Holy Grail” for makers of cars with batteries. Anything that helps add range to tomorrow’s cars will be gladly exploited by the auto industry.

Watch this helpful if somewhat light hearted video to learn more about graphene.

Photo: University of Manchester