Avista PEM Takes Modular Approach Fuel Cells
By Ann Chambers,
Avista Laboratories Inc. has announced a manufacturing prototype and plans to commercialize it for commercial and industrial applications. The Avista Labs PEM generator has a compact, modular and scalable architecture. It is intended to be a source of primary or back up power for the industrial process, commercial and residential markets. The generator will be available for testing by its initial customers beginning in May.
The manufacturing prototype is about the size of a small air conditioning system, consisting of a 720 W subrack with a dozen 60 W power modules and weighing approximately 94 pounds. The unit is scalable to match specific load characteristics. The design overcomes the disadvantages of costly designs based on stacked graphite plates by using low cost materials, minimal support systems, a highly modular design and a unique approach to water management. The unit operates at ambient pressure and is self humidified.
The power modules, about the size of VCR cassettes, are continually monitored for moisture, temperature and performance by an embedded control system. Users can see the performance of each module through a lighted display on the front of the unit. If a cartridge needs attention, it can be removed and serviced without taking the unit off-line.
The only moving part in the module is a high-efficiency fan. The fuel cell operates at 60 to 80 C. The unit offers a three minute startup time, compared with the one hour startup time of some other PEM fuel cells.
Kim Zentz, Avista Labs president, said her company is working to increase the power of the modules from 60 W to 200 W and to reduce the profile of the unit. Avista has received an award from the U.S. Department of Commerce to aid in this effort.
The units can be connected in series or parallel. They operate on hydrogen, which can be reformed from a variety of sources, including methane, propane, methanol, ammonia, ethanol, diesel, gasoline, and jet fuel. The hydrogen must contain 10 ppm or less of CO. Compressed, industrial-grade hydrogen from cylinders is suitable, and four 261-foot cylinders of compressed hydrogen will power a PEM generator at a full power output for 55 hours. Overall electrical efficiencies typically range between 45 percent and 50 percent depending on the load. Air-to-heat exchangers can be used to recover waste heat, bringing total thermal efficiencies to more than 75 percent.
For more information on the research and development status of a variety of fuel cell technologies, see “Fuel Cells Demonstrate Commercial Potential,” in this issue. p
The Avista Labs PEM generator has a 720 W subrack with a dozen 60 W power modules and weighs 94 pounds.