The core element of the Fraunhofer ISE system is a commercial PEM fuel cell with an electric power output of 300 W. The reformer is fueled with denatured bioethanol, which is inexpensive, non-toxic and available worldwide.
The ethanol reformer-fuel cell system developed at Fraunhofer ISE can be used outdoors, and operates at ambient temperatures ranging from –10°C to 40°C. A buffer battery is used during the startup phase, when hydrogen is not yet flowing to the fuel cell. Including the tank it has a total volume of 200 liters and weighs 30 kg. It consists of four modules: the fuel cell, reformer with gas purification, electronics, and storage tank.
The main unit functions are carried out by:
- A low-temperature PEM fuel cell from German-based Schunk. This is optimized for operation with reformate.
- A reformer with gas purification. The latter reduces the amount of CO in the reformate to a level suitable for the following PEM fuel cell.
- A tail-gas combustor, in which the off-gas from the anode is oxidized and provides the heat needed for evaporation and overheating the feed streams (ethanol, water and air).
No further heat integration is used in the reformer, to maintain a simple architecture and achieve controllability of the entire power plant. The modules are stacked on top of each other within a housing mounted on wheels for easy transport.