Fuel cells offer significant savings of loads, in weight and volume, compared to conventional power sources. For example, a 13 pack BA-5590 batteries weigh more than 29 lbs and cost $100 each. (Thirteen batteries are required to support a typical 72-hour deployment.) The US Army is evaluating the use of inexpensive, injection-molded fuel cell technology formed into the common BA-5590 form factor, to power SOF PRC-117 field radio, resulting in a weight saving of over 13 lbs and decrease its cost by at least 50%.
Other power sources are provided by Direct Methanol Micro Fuel Cell (DMFC), under development at MTI Micro. The company has already demonstrated the operation of its power system on 100% methanol fuel resulting in 0.9 watt hours of energy per cubic centimeters (cc) of fuel, extracting from methanol more than three times the energy of most current lithium ion batteries. The company is teaming with Harris RF Communications Division, to develop a fuel cell prototype that will replace standard batteries in Harris’ Falcon II portable, military radio. The MTI Micro-Harris prototype is currently producing a power output of 5 watts with a peak power of 25 watts and an energy content of greater than 50 watt hours. The fuel cell is designed to fit into a size and form of a standard BA-5590 battery, while generating twice the energy of the radio’s internal battery, and approaching the energy of the external rechargeable battery – the BB390.
DMFCC Introduces Methanol Fuel Cell Cartridges
Direct Methanol Fuel Cell Corporation (DMFCC), has completed product development of a first methanol fuel cell cartridge. The new cartridge was co-developed with and manufactured by DMFCC’s Korean partner, SMC Co., Ltd. Fuel cells offer longer operating time as compared to current lithium ion batteries. With the introduction of the new cartridges, fuel cells could be instantaneously recharged by replacing the disposable fuel cartridge.
These fuel cell powered devices are expected to be introduced into the marketplace by major electronic product manufacturers in 2007. One cartridge is expected to provide five to 10 hours of computer operation depending on the efficiency of the fuel cell. The DMFCC methanol cartridge holds 50 cubic centimeters of 100% methanol and is designed for a laptop computer and similar applications. Cell phones will require smaller cartridges, and other applications may require larger ones. DMFCC also plans to develop cartridges for other fuels such as formic acid or ethanol, as customers require.
DMFCC focuses on producing disposable fuel cartridges containing liquid fuels, such as methanol, to provide the energy source for laptop computers, cell phones and other portable electronic devices powered by direct methanol fuel cells.
Palm Power Application
Another use of DMFC studied by DARPA is Palm Power program. This future portable man-packed power unit could replace larger diesel generator sets that are currently towed on a trailer. Palm Power will utilize compact fuel cells and thermal to electric energy conversion technologies. Where applicable, these power sources are also providing co-generation (producing heating, hot water, or cooling, in addition to electricity). Fuel chemistries considered for the program are Direct methanol oxidation fuel cells (DMFCs). The Palm Power Program will produce a completely packaged 20-watt direct methanol fuel cell, that, combined with a battery, could yield a hybrid soldier power system with significantly longer endurance than a system using batteries alone. Typical consumers for such power cells are robots and autonomous ground vehicles, future soldier systems, micro-air vehicles etc. DARPA is expecting radically new approaches developed to meet the specific energy goals of the program, which is on the order of thousands of Whr/kg at the system level. Higher power levels envision other approaches, including planar solid oxide fuel cells (SOFC), thermo-photo-voltaics (TPV), alkali metal thermal to electric converters (AMTEC), and small turbine engines, that will operate in the 300- to 500-W range on approved military fuels.
Vehicular Power Cell
A different fuel cell technology is considered for an auxiliary power unit developed by Radian Inc. The system is planned for deployment on US army vehicles. The fuel cell consists of the Proton Exchange Membrane (PEM) technology, developed by Hydrogenics Corp. Since modern armored vehicles rely on the use of many electronic and electrical systems, even when positioned in stationary positions, the APU will offer adequate supply of electrical power, to operate digital equipment and extended silent watch requirements. As an alternative to the battery systems and diesel generator sets currently being used by the military, fuel cell power generation offers longer operation, zero emissions, improved cycle-life, low noise signature, reduced deterioration and improved cold weather performance. In Regenerative fuel cell technology the system’s electrolyser will recharge the hydrogen supply while the vehicle engine is operating, supplying the hydrogen storage subsystem with sufficient fuel to operate the fuel cell auxiliary power system for up to ten hours at the field destination with a load of 3 kW average, and peak demand of 5 kW.
Solid Oxide Fuel Cell Process (SOFC)
SOFC to Operate on Military JP8 Fuel – (January 16, 2006): Gas Technology Institute (GTI) has demonstrated operation of a high-power-density solid oxide fuel cell (SOFC) using standard military logistics fuel (JP8) containing 600 to 700 ppm of sulfur. This is an important milestone on the path to developing SOFC technology providing efficient, clean, and quiet power for military applications.
The process uses steam reforming process that prepares the gas for the SOFC stack, enabling effective thermal management which is key for the system’s efficiency. The JP8 fuel processor uses an advanced sulfur tolerant catalyst, novel JP8 burner, and radiant heat transfer system to convert JP8 military logistics fuel into hydrogen and other SOFC fuel gases. This JP8 fuel processor has operated stably for 600 hours of testing to date. The overall system is designed to capture and recycle water so that it can operate without an external water supply.
The planar SOFC stack was supplied by Versa Power Systems (VPS). It is built of twenty-one cell stack, producing about 800 watts from JP8 processing, with an impressive power level of 315 mW/cm2. The next generation demonstration system will use advanced SOFC stacks to achieve the 3 to 10 kW power goal – suitable to meet the military’s Mobile Electric Power (MEP) generation requirements.
The work is funded through the U.S. Department of Defense under the U.S. Army Engineer Research and Development Center’s Construction Engineering Research Laboratory (ERDC-CERL).
