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A preliminary assessment for the Empire State Electric Energy Research Corporation indicated that power system networks might be better optimized if dispersed storage devices, located close to urban areas, were available. However, some capacity would be required which could operate not only as stored energy peak-shaving devices, but, which can be counted upon to operate as firm capacity in either the peak-shaving or continuous intermediate generation duty region of the load curve depending on system conditions. It was felt that this would provide the flexibility needed for more efficient utilization of existing capital intensive generation and transmission facilities. This paper presents the results of a comprehensive analysis for "Dual Mode" operation of fuel cells as an intermediate load generation device using coal derived or distillate fuels during certain periods and as peak-shaving units in conjunction with electrolyzers at other times. In the latter case, hydrogen generated by the electrolyzer was assumed to be injected into the natural gas network during off-peak electric demand periods. During peak electric demand periods an equivalent amount of BTU's would be removed from the gas network for conversion to electricity. Based on the referenced expansion plan for the New York Power Pool (NYPP), it is shown that fuel cell capacity in combination with electrolyzers could generate net annual savings to NYPP member companies totalling $131 million (1974 dollars), including a reduction in fuel oil consumption of 30 million barrels annually by 1989. This assumes a NYPP reference generation system mix containing 3000MW of pumped storage hydro and the expansion plan with fuel cells to contain 1800MW of fuel cells instead of an equivalent amount of planned conventional fossil units. Other power system benefits due to fuel cell performance characteristics, both static and dynamic are analyzed. The importance of the type of converter interface selected and the corresponding system benefits are analyzed. The system benefits that can be derived from a force-commutated dc converter interface apply equally well to a dispersed dc battery storage source.