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power generation for high-altitude airships Sang Choi An advanced thermoelectric generator outstrips photovoltaic cells in converting solar energy to electric power, and this lightweight system could power many high-flying vehicles. A high-altitude airship (HAA)—essentially a lighter-than-air craft that can travel at roughly 20km above the earth’s surface— could be used for many applications including atmospheric or military surveillance. Takeoffs, landings, and maneuvering, however, will require a light and efficient source of power. Nonetheless, stringent weight limitations, which are needed to allow high-altitude flight for long periods, do not permit the use of onboard fuel storage for power generation. Solar energy could be used instead. For this reason, the HAA requires lightweigh