Fuel cell manufacturers and OEMs continue to benefit from an increased military emphasis on energy security and logistical efficiency associated with the complex and challenging operational conditions being encountered in remote wartime environments such as Afghanistan. Reducing the strategic and tactical vulnerabilities associated with powering military equipment and remote installations has emerged as a leading priority for U.S. military leadership.
Fuel cells complement this mission in many ways offering significantly longer runtimes and significant savings in terms of weight and volume when compared to conventional military power sources such as the BA-5590 batteries and diesel generators. Fuel cell generators also offer tactical advantages by achieving significant reductions in the amount of noise, heat, and emissions associated with conventional diesel generators.
At the same time, logistical concerns regarding fuel availability for fuel cells represents one of the key challenges facing the fuel cell industry. The U.S. Department of Defense currently lacks an effective distribution system for conventional fuel cell fuels such as methanol and propane. Instead, the DOD has emphasized the need for achieving fuel compatibility with specialty military fuels where distribution networks already exist.
These specialty fuels are prominent across a wide spread of military applications. For example, JP?8, a fuel that is similar to commercial diesel and aviation fuel, is considered the most prominent fuel on the battlefield powering everything from tactical generators and unmanned vehicles to the military’s mine resistant ambush protected (MRAP) vehicles, helicopters, and fighter aircraft.
The difficulties associated with engineering fuel cells that can run off these fuels are primarily associated with their high sulfur content. The sulfur content of these fuels is extremely high; up to around 3,000 ppmv S for jet fuels (JP-8, JP-5) and 10,000 ppmv S for naval distillate (NATO F-76). By comparison, commercial gasoline contains 30 ppmv S, while diesel power has around 15 ppmv.
The high sulfur content is poisonous to the reformer and electrode catalysts found in a fuel cell stack. Sulfur compounds in the liquid hydrocarbons must be subsequently reduced to less than 0.1 ppmw for polymer electrolyte membrane fuel cell (PEMFC) and at least less than 30 ppmw for the solid oxide fuel cell (SOFC).
According to Xialiang Ma, Altex Technologies Corporation, the development of new deep desulfurization processes for liquid hydrogen fuels has subsequently become one of the major challenges in developing the hydrocarbon processor for military fuel cell applications. As a result, the DOD has been supporting efforts to engineer hydrocarbon compatible fuel cell processors. For example:
– Adaptive Materials Inc., has been heavily involved in developing technologies that enable the use of JP-5 and JP-8 in fuel cells
– Ceramatec has also shown promising results with its GlidArc plasma reformer successfully reforming JP-8 at the 5kW-10kW scale
– In March 2011, Lockheed Martin and Technology Management Inc. (TMI) operated a fuel cell for 1,000 hours using JP-8
These developments suggest a positive outlook for the integration of fuel cells across a wide range of military power generation applications.
Article by Euan Sadden appearing courtesy the Matter Network.
