The current Oxygen Generating Assembly (OGA) on the International Space Station (ISS) utilizes a large variety of custom components including a cathode feed electrolyzer, rotary separator, containment dome and use of dual seals to mitigate the risk of hydrogen leakage. While this system has operated for decades on station, the heavy use of custom-made components makes it prohibitively expensive for future commercial aerospace applications. This paper describes the next generation (NextGen) OGA system utilizing commercially available hardware. Major changes to the system architecture include the switch from a cathode feed electrolyzer to an anode feed. While this presents challenges by adding an additional phase separator effective in micro-gravity, recent investment in electrolyzer technology for supporting clean energy applications has caused a surge in commercially available stacks with proven reliability. These stacks are almost exclusively anode feed, sparking an interest in re-examining an anode feed based OGA. Despite the need for an additional separator, recent advancements in separation technology help to mitigate the risk and cost, with inexpensive commercial separators offering potential alternatives to custom rotary separators. In addition to switching to anode feed, the NextGen system examines an alternative hydrogen safety approach which eliminates the use of a dome and dual seals, replacing them with a ventilation and monitoring strategy and drawing on lessons learned from years of operating the OGA system on ISS.
Myles et al. (Sun,) studied this question.