R&D Status of RFC Technology for SPF Airship in Japan

Abstract

The first phase R&D program of the regenerative fuel cell (RFC) technology for the unmanned solar-powered stratospheric platform (SPF) airship of Japan Aerospace Exploration Agency (JAXA) has been conducted during 1998 and 2009. The SPF airship has an important role on provision of a new infrastructure for telecommunication services and the earth observations. For this high altitude and long-term station keeping (long endurance) airship realization, a combined power technology of solar cells (SC) and RFC is viewed as one of the most important technical challenges which shall be solved on a R&D road to the SPF airship feasibility in near future. The design targets for “solar-RFC” power technology demonstration have been definitely specified through ground-based research tasks after the SPF airship feasibility study in 1998. The ground test RFC model of 1KW output was developed in 2001, and the RFC technology was evaluated to provide more detailed data in closed-circuit RFC operations. And the on-board type RFC model of 3KW maximum output was developed in 2004 and the performance, cycle operations and environment (low temperature, low frequency motion, attitudes and low pressure) testing of this model had been conducted during 2005 and 2008. Based on these testing results, the on-board solar-RFC system was evaluated to achieve the energy density of 450 Wh/kg for 30KW output system after several key technologies for the system weight reduction were developed. Summarized herein are technical achievements available to date from these solar-RFC research activities in JAXA and IHI Aerospace (IA), and our future R&D planning is also described. The RFC technology is an attractive energy storage device, so this will be expected to be utilized in many aerospace systems.