The potential of liquid hydrogen as a military aircraft fuel

As domestic petroleum supplies diminish and prices escalate, the U.S. Air Force will need to consider the implications of relying on primary energy resources other than petroleum for its aviation fuel needs. Our recent studies have examined various candidate synthetic fuels and the types of vehicles in which they might be employed. In this paper, we have emphasized those results which highlight the possible use of liquid hydrogen as a fuel for very large airplanes (with maximum gross weights in excess of one million pounds). Comparisons are provided of the life-cycle costs and life-cycle energy consumption for both synthetic jet-fuel and liquid hydrogen fueled airplanes. Both fuels are assumed to be synthesized from coal. In addition, the relative cost-effectiveness and energy-effectiveness of the two alternatives are presented for a variety of mission applications. These results suggest that a synthetic jet-fuel (similar to today's Jet-A or JP-4) derived from coal is more attractive than liquid hydrogen as a military aircraft fuel.