Small fuel cells storage

The advantages of small fuel cells often depend on the method used for the supply of fuel. Currently small fuel cell systems predominantly use some form of hydrogen storage. It is anticipated, however, that in the future, small systems will also utilize proeessed forms of common fuels (e.g., methanol, natural gas, and liquefied petroleum gas) as weU as unprocessed methanol. 

Natural Gas. Small fuel cell systems that are stationary and have ready access to a natural gas pipeline will predominantly take advantage of the natural gas availability (just as in the case of a larger stationary fuel cell). The principal constituent of natural gas is generally methane, CH4. The cost per unit energy for natural gas is the most attractive, and compactness is presumably not a major issue. Since its storage characteristics are not attractive and its processing system is no more favorable than that of LPG, these are likely to be the only circumstances under which natural gas would be utilized in small fuel cells. 

Defining hydrogen fuel quality specifications is a high priority for the Roadmap. Such specifications must be quantified at the vehicle-station interface and must consider how the presence of small amounts of contaminants affects the performance and durability of fuel cell and balance of plant material compatibility of onboard and stationary hydrogen storage systems and the operation and maintenance of hydrogen production, purification, and delivery systems. Most importantly, fuel quality specification must consider... 

Fuel cell APUs will likely have to operate on gasoline, and for trucks preferably on diesel fuel, in order to match the infrastructure available, and preferably to be able to share on-board storage tanks with the main engine. The small amount of fuel involved in fueling APUs would likely not justify the establishment of a specialized infrastructure (e g. a hydrogen infrastructure) for APUs alone. Similarly, fuel cell APUs should be water self-sufficient, as the need to carry water for the APU would be a major inconvenience to the operator, and would require additional space and associated equipment. 

Figure 25. (A) Comparison of the energy storage capability of fuel cells and batteries. Only after several refueling operations are fuel cells more efficient energy storage devices on a Wh/L and Wh/kg basis. (B) Fuel cells have a set volume and weight for the fuel cell stack and peripherals to supply the reactants to the stack. The small incremental fuel volume to continue operation supplying energy makes them more efficient for longer operations.

German fuel cell and hydrogen storage industry is the market leader in Europe with a number of small and large companies. 

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