Research project uses alcohol-based fuel cells to extend range of e-cars

May 28, 2013 // By Christoph Hammerschmidt
With a novel energy storage technique, researchers of the Berlin Technical University will improve the driving range of electrically driven cars: They use ethanol - but instead of filling it into the tank, they plan to build an ethanol-based fuel cell.

Fuel cells are not new as an energy source in the automotive industry. Actually, several carmakers including Daimler and Opel (General Motors) are in the prototype phase for a potential roll-out of serial-built fuel-cell powered e-cars later in this decade. Their common denominator is a hydrogen fuel cell whose electric power could directly drive an electric car.

The approach of the Berlin research group headed by professor Peter Strasser is different. While it basically is possible to build fuel cells based on alcohol instead of hydrogen, alcohol-based fuel cells feature a significantly lower energy density than their hydrogen counterparts. Nevertheless, alcohol fuel cells could offer significant benefits over hydrogen cells. The reason is that storing the very energy-rich hydrogen in high-pressure tanks as well as the process of refuelling requires strict safety measures. Since this tank frequently takes place under the passenger compartment, fuel cell vehicles face safety concerns in the public.

Strasser's approach is different. Ethanol (a.k.a. alcohol) can be filled into a simple tank much like gasoline. Due to the lower energy content of alcohol compared to hydrogen however, the energy generated by such a fuel cell is not sufficient to directly supply an electric car - at least for the time being. For this reason, Strasser plans to use the electric energy to continuously charge lithium-ion batteries, the standard energy storage solution for today's electric cars. This method would increase the driving range of an e-car from some 120 km to a value comparable to conventional gasoline-driven cars of several hundred kilometres - much like the range extender engine provided in a number of concepts.

Besides the safety advantages, the hydrogen approach offers several other benefits over existing approaches. Ethanol is cheap and easily available. Some of today's gasoline types such as E10 already contain 10% ethanol anyway. This alcohol needs to be separated from traces of moisture - a very costly and energy-consuming process. The alcohol