A new conceptual flowsheet is presented for Martian in situ fuel production. The dry reforming flowsheet incorporates the well-known Sabatier-Electrolysis process with a carbon dioxide/methane reforming step to consume some of the Sabatier methane. By varying the ratio of effluent to reformed methane, any desired methane/oxygen ratio can be produced by the dry reforming process. Such a machine will enable utilization of all imported hydrogen into an optimal methane/oxygen fuel mixture, with copious quantities of surplus oxygen produced for crew consumables.

The reforming process is highly endothermic and requires temperatures above 650 centigrade on precious metal catalysts. Appropriate feed/effluent heat exchange reduces the reformer power requirements, but an increased oxygen/methane ratio increases the power requirements. In addition, the complexity introduced by the reformer and its interactions with the Sabatier system make the system relatively difficult to automate or control remotely. The energy usage and complexity imply that a dry reforming process will not be useful in the early stages of Mars exploration. However, the increased material usage efficiency and oxygen generation capability of the dry reforming technique will make it an attractive technology to consider for second generation ISRU systems. In addition, the potential ease of retrofitting Sabatier/Electrolysis units with a dry reformer provide an important advantage for early adoption of the technology. Minor preinvestment in the Sabatier system - essentially just provision for interconnections - will allow the addition of a reformer, thus extending the useful lifetime of the Sabatier system, instead of replacing early Sabatier systems with entirely new second generation systems. Thus, dry reforming will be an important technology to allow cost effective expansion of early Martian exploration and base building efforts.

Utilizing Martian Resources