Inefficient use of fuel, premature failure of diesel generators, and diesel generator maintenance are areas of concern in forward military operations.  One of the main reasons for these problems is the necessity to underutilize generators of fixed capacity.  This prevents the generators from operating in the optimum region of the engine performance map, which also leads to increased emissions and potentially results in a build-up of exhaust products (“wet-stacking”).  One approach to address these issues is to integrate the generator into a system where the generator can always operate near design output levels.  This can be accomplished by storing excess generator output, that is above the instantaneous load requirements, for later use.  Figure 1 shows a proposed system comprised of a generator, electrolyzer, fuel cell, and hydrogen storage vessel.

Figure 1, Silent Camp System and Methodology.

The type of system presented in Figure 1 could contribute to the future design of a “Silent Camp.”.  In this system, a diesel-fueled generator provides power to the load.  Excess output from the generator powers an electrolyzer, which dissociates water into hydrogen and oxygen.  The hydrogen is stored in a tank for later use in a fuel cell to provide silent power for night-time loads.  When the fuel cell is operating and powering the loads, the diesel generator can be shut down altogether.  This system offers several potential benefits:  it reduces maintenance of the diesel generator, enables forward military operations to silently power loads, lowers acoustic and thermal signatures, lessens environmental impact, may increase overall system efficiencies, and produces hydrogen in the battlefield to fuel hydrogen fuel cell vehicles and other hydrogen devices (e.g., computers, sensors).

The benefits of this Silent Camp electricity and hydrogen generation system vary greatly depending on the magnitude and shape of the load profile the system is serving.  In addition, the availability and efficiency of hydrogen conversion devices for powering automobiles and other devices significantly affects overall system efficiency.  Nonetheless, the generation of a valuable and transportable hydrogen fuel stream and its storage in relatively light-weight (low logistics burden) vessels may be significantly more attractive than using batteries or other energy storage devices in these types of power systems. Previous research has utilized typical base camp load profiles as inputs to simulate the potential efficiency gains and fuel savings of the Silent Camp system versus the base case.  This paper analyzes the sensitivity of the load profile and associated parameters, and the contribution of hydrogen end-use technologies to the efficiency and fuel usage of the system.

Keywords: Hydrogen, Generator, Fuel Cell, Electrolyzer, Silent Camp