Case Studies - Energy & Environment

As part of our fuel cell development programme we have designed and built a portable fuel cell device to provide power for mobile electronic systems. The unit is based around a proton exchange membrane fuel cell (PEMFC) designed in-house specifically for portable electronics. Capable of providing up to one amp per square centimetre its power is on a par with the leading ambient air operated cells and has been designed for commercial manufacture.

The application requiring power in this instance was the FIST C4I Research Set. This is a portable system that enables high-speed communication and data exchange across a battlefield. The system contains a large collection of electronic devices that process information, display maps, communicate with GPS satellites and send data via various radio links. The power source for this equipment had to be man portable, rugged and operate for long periods. It also needed to provide instant start-up power and stabilised dual voltage outputs. The power required was a continuous fifty watts.

With a view to future manufacture we designed a simple PEM fuel cell which can be made almost entirely from plastic and is simple to assemble. After some development we achieved very high current densities for ambient air breathing fuel cells (> 1 Amp/cm2). Using this single cell prototype we built a 30-cell stack which gave 50 watts continuous power and was capable of 100 watts output for short periods.

For ease of use we incorporated a series of system integration measures. The system is required to provide immediate power so we combined batteries with the fuel cell to enable instant power availability while the fuel cells started. We have been developing this type of hybrid power supply for some years and so we developed a programmable control system that automatically starts, runs and shuts down the fuel cell as required. This control system would also be able to recharge the batteries from the fuel cell.

Finally, we designed an enclosure to package the system so that it could be used with the full FIST system. The fuel cell is supplied with hydrogen from a commercial metal hydride storage system designed for a high rate of hydrogen release.

Future development will further miniaturise components and increase the range of power outputs to suit alternative applications. We are currently scoping a 25 watt version and the feasibility of adapting the cells for kilowatt sized systems.