The system is fuelled with denatured bioethanol, and one potential application is as a power supply for medical equipment in developing and threshold countries.
The core piece of the system to be presented at the Hannover Messe trade fair in April is a commercial proton exchange membrane (PEM) fuel cell with an electric power output of 300 W.
“If fuel cells are to achieve long periods of operation, then it is best if they are combined directly with a reformer. In this case, the use of hydrogen storage, be it either metal hydride storage or pressurised gas cylinders, is neither economical nor practical,” says Dr Thomas Aicher, Head of the group Hydrogen Production at Fraunhofer ISE.
The reformer fuel cell systems combine the high energy storage density of the fuel with the high power density of the fuel cell. A further advantage is that with the integration of a reformer, commercially available fuels like bioethanol, propane or petrol can be used.
The ethanol reformer fuel cell system developed at Fraunhofer ISE can be used outdoors and operates at ambient temperatures ranging from -10 to +40 °C.
The system including the tank has a total volume of 200 l and a weighs 30 kg, respectively. It consists of four modules (fuel cell, reformer with gas purification, electronics and tank). The main system functions are carried out by:
- A low-temperature PEM fuel cell from the company Schunk. This was optimised for operation with a reformate gas (product gas of the reformer);
- A reformer with gas purification. The latter reduces the amount of carbon monoxide in the reformate gas to a level that is suitable for the following PEM fuel cell;
- A tail gas combustor in which the offgas from the anode is oxidized and provides the heat needed for evaporation and overheating the feed streams (ethanol, water and air).
The development of the reformer fuel cell system is supported by the Federal German Ministry for Economics and Technology BMWi.