Fuel Cell Demonstration Project

This demonstration project has focussed on the investigation of fuel cells as a potential technology for stand-alone power systems for remote areas. Fuel cell technology could be used in a remote area power system in two possible ways. In the first option, the fuel cell would replace the internal combustion generator (diesel, petrol or other) with the fuel being delivered to, and stored, on site. Given that this fuel would not be hydrogen, it would then need to be reformed (via a reformer) prior to use by the fuel cell, as shown in the following diagram.

The second option would involve generating the fuel (hydrogen) on site using a renewable energy source. The excess power from the RE source would be used to produce hydrogen, with the most likely method being the electrolysis of water (via an electrolyser). This hydrogen would then require storage, with the most feasible methods being either in a pressurised vessel or within a solid compound such as a metal hydride or carbon nanostructure. The former method would require either a high pressure electrolyser or a compressor to compress the hydrogen to pressures suitable for storage.

This RISE project sourced two small scale (<5kW) fuel cell systems and implemented them into a dedicated test facility. The systems utilised competing fuel cell technologies (PEM and Alkaline) and the differences in their performance characteristics were evaluated. The following list of key findings provides an indication of the advantages and disadvantages of fuel cells as potential technology for remote stand-alone power systems.

Advantages:

• Fuel cell system efficiencies were higher than existing internal combustion generators (ICGs) and hence may offer a better alternative to these technologies
• Fuel cells have a fast electrical response and are well suited to remote stand alone power systems loading
• Fuel cells operate near their high efficiency point during remote stand alone power systems type loads
• Fuel cells maintain a high efficiency under highly variable loading
• Fuel cell systems can potentially be used for combined heat and power, i.e. will also supply the household's heating requirements

Disadvantages:

• Hydrogen fuel cell stand-alone power systems are currently uneconomical when compared to ICGs and renewable systems
• Fuel cell systems currently lack robustness
• Hydrogen fuel cell efficiency is lower than for battery stand-alone systems
• Hydrogen storage is difficult and costly
• Emerging alternative technologies may offer better alternatives to hydrogen fuel cells for stand-alone power systems

This is a current RISE project which is in the final stages. Published versions of these results and the associated data will be available in October 2006.

Fuel Cell Test Facility

The fuel cell testing facility is used to conduct performance testing on fuel cell systems. This facility is also used to display the fuel cell technologies. The testing comprises of short and medium term fuel cell operation (less than 8 hours) supplying a user programmed load profile. The testing facility also has the potential to test fuel cells in a micro DC grid application where the system can be run in tandem with a wind turbine or other source. The facility can potentially test any stand alone hydrogen fuel cell system of up to 5kW in net output. The system was initially built to demonstrate a 5kW alkaline fuel cell (AFC) system, but it was then adapted for flexible testing of other fuel cell systems. So far the system has been used to test and demonstrate a 5kW Proton Exchange Membrane (PEM) fuel cell and a 1.2kW Alkaline Fuel Cell (AFC). This test facility was based around the requirements of testing such systems found in ASTM standards documents. For further information concerning testing fuel cells contact Nigel Wilmot.

The chart below depicts the normalised steady state efficiencies for the two fuel cells mentioned above.

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