http://www.marssociety.org/portal/TMS_Library/Frankie_2001
We have several times reported on NASA's current use of the Sabatier reaction aboard the International Space Station, to recycle the astronauts' exhaled Carbon Dioxide; and, of their planned use for it on the planet Mars, to manufacture Methane, for further processing into rocket fuel, from the primarily Carbon Dioxide Martian atmosphere.
Herein, they are seen to be taking that technology one step further, by adding a "dry reforming" process, very similar to, or nearly the same as, the "Tri-reforming" process described by Penn State University, wherein the Methane, produced via the Sabatier reaction from Carbon Dioxide, is reacted with even more Carbon Dioxide to synthesize higher hydrocarbons with even greater fuel potential.
Comment follows excerpts from:
"Dry Reforming: A Unique Flowsheet for Fuel Production on Mars
In: On to Mars, Colonizing a New World, edited by Zubrin, RM, and Crossman, F. Apogee Books.
Abstract: 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."
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The Abstract doesn't actually make it too clear, and might reflect limitations in the author's understanding; but, we assure you, the addition of a dry reformer onto a Sabatier reactor means that they intend to synthesize, via "dry reforming", a more complex hydrocarbon, with a much higher energy density than Methane, from the Methane produced, from Carbon Dioxide, by the Sabatier process.
And, the "dry reforming" of Methane is, again, accomplished by reacting it with even more Carbon Dioxide.
The author notes that such systems are "difficult to automate or control remotely". That's fine by us. Don't we have some bright folk in West Virginia, and in the rest of US Coal Country, who could benefit from, what should be, well-paying, hands-on jobs recycling power plant CO2 into liquid fuel?
Maybe they could even start wearing turbans and kaftans to work.
Moreover, the author notes that the addition of a dry reformer "increases the power requirements". That, too, would be okay. Coal-fired power plants generally have excess generating capacity, and that has inspired invention of several schemes to store excess power generated during off-peak demand for use during peak demand periods. And, liquid fuel synthesis has already, as we have documented and as we will further document, been suggested as one way to accomplish that.
But, those increased "power requirements", as has already been suggested, as we have reported, by Sandia National Laboratory in their plans for Carbon Dioxide recycling, could represent a genuine opportunity for the truly productive employment of environmental - i.e., wind, solar, hydro - energy.
In any case, if we can, through NASA, realistically contemplate the production, on Mars, of high-value fuels based on the recycling of Carbon Dioxide, why can we not do the same here, on Earth?