Benefits of the Space Program: Work On the SOFC to Reduce CO2 Using Electricity

[NNadir]

If you must know, I'm not really a "manned/womanned space flight" kind of guy. To me the trip to the moon in its time, 40 years ago, was worthwhile to some extent, although Mars Pathfinder probably demonstrates that robots could have done the same job better and cheaper in the case of returning rocks from the moon.

(For me, the chief benefit of the manned space program was not Aldrin's - and his successor's - missions - was the ability to service Hubble, Hubble being for me, the apogee of American Space Technology.)

Galileo, Cassini, Voyager, Pioneer, Messenger, Pathfinder...these are my kind of space missions.

Nevertheless, Buzz Aldrin has been making the rounds speaking wherever he can about the benefits of the American space program to American technology - I've seen him several times on CSPAN-3 and the Science Channel making his case - and he's an engaging and passionate speaker who argues from a different perspective of my own. He wants to go to Mars, all that kind of stuff, and he says - and makes a good case - that the benefits on Earth will justify it.

I want to acknowledge his argument, and not my own necessarily, by pointing to a paper in the recent literature in the journal Solid State Ionics.

The paper is entitled, "Carbon dioxide reduction on gadolinia-doped ceria cathodes." It is work of American scientists at NASA (Glenn Research Center in Ohio), Case Western Reserve University, and the University of Washington.

The abstract of the paper is here: http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TY4-4SRM829-1&_user=10&_coverDate=07%2F31%2F2008&_alid=1033998238&_rdoc=2&_fmt=high&_orig=search&_cdi=5608&_sort=r&_docanchor=&view=c&_ct=259&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=7998bef6555f04567700618df5635677">Solid State Ionics 179 (2008) 647–660

Although my own approach to carbon dioxide reduction is very different, for me the reduction of carbon dioxide electrolytically represents a kind of Holy Grail, since it will allow for the use of clean sources of energy like nuclear energy and the somewhat less desirable solar and wind power (the latter two being pretty much useless thus far on scale) to deal with the planet's massive dangerous fossil fuel waste situation.

Many researchers around the world are working on this problem, and this paper touches on the utility of this approach in the context of manned and womanned space flight.

Some excerpts:

NASA is beginning to plan manned and unmanned exploratory missions to return to the Moon and eventually to Mars, as part of the Exploration Vision directed by the President in January 2004 <1>. As NASA begins to develop these more detailed plans, it becomes clear the severe restrictions our present and near-term propulsion technologies impose on the mass and volume of unmanned or manned payloads that we can launch to our moon or a planet. For a mission to Mars, the natural resource most readily available is the atmosphere, which consists of roughly 95% carbon dioxide. This potential feedstock can be converted to oxygen for crew respiration and propellant for the return trip by reducing carbon dioxide via solid oxide electrolysis. There are also potential non-aerospace applications. Recently, combined carbon dioxide and water electrolysis has been proposed as a method of producing syngas <2,3> with the potential benefit of reducing carbon dioxide emissions from coal-fired electrical power plants, i.e. a possible alternative to carbon dioxide sequestration <4>.

Solid oxide electrolysis (SOE) of carbon dioxide was originally suggested as a technique for removing carbon dioxide from a spacecraft habitat <5,6> as early as the mid-1960's. In the late 1970's, it was first proposed as a way of generating oxygen <7,8> for a spacecraft on the Mars surface, a so-called In-Situ Resource Utilization (ISRU) technology. Richter <9> performed some initial experimental work on Pt/YSZ/Pt cells...

(YSZ is yttrium substituted zirconia.)

So here is Aldrin's case made in the introduction.

...Although the majority of carbon dioxide reduction work has been performed on porous Pt paste electrodes, more recent work has focused on alternative electrode materials. Lauvstad et al. <11> made polarization and impedance measurements on strontium ferrate...Most of the more recent work has focused on utilizing Ni on YSZ and/or Ni-YSZ cermets for carbon monoxide oxidation, following extensive work on Ni-YSZ cermets as the state-of the- art composite for solid oxide fuel cell anodes <12> utilizing hydrogen as a fuel...

In this work, the primary focus is to investigate another potential alternative electrode material for CO2 reduction,gadolinia-doped ceria (Ce_xGd_{1 − x}O_{2 − δ}), which will be referred to as GDC in this paper...

There is a very long technical description of the work in the paper, and then this note in the conclusion:

In this paper, initial AC impedance measurements for CO₂ reduction on a 40 mol% gadolinium-doped ceria electrode were presented. The impedance measurements at zero-bias voltage indicate this electrode has a lower electrode area-specific resistance (ASR) than for CO– O₂ exchange on Ni-YSZ and porous platinum electrodes in the literature...

...We caution that limited work has been performed on solid oxide electrode materials under these particular CO–CO2 conditions, as the primary research focus to date has been CO in mixtures of hydrogen and other hydrocarbons.

The bold is mine and is inserted for the same reason that I came down on the side of putting this post here rather than in the E&E forum - where it might have some additional relevance. I want to avoid the magical thinking that goes on with "my car is saved!!!!" kind of rhetoric over there that accompanies every single report of this type. (Thanks be to scientists who are cautionary in their work.)

Cerium and gadolinium are widely available elements right now, but it's not clear that there is enough of them to make a brazillion magic cars to save the bourgeois lifestyle in a painless way if only we have faith. There isn't.

However this is still interesting work, the kind of work that we should be funding, either as a means of running spacecraft or more earthly prospective.

[Cobalt-60]

1. Buzz invented the art of working in space

It was he that tossed a model spacecraft into the pool and
developed methods for men to work in space.
So he's first in the line of space mechanics leading to that Hubble job.
I'm a big fan of manned flight.
But it also makes sense to blaze the trail with robots.
That's what they did on the way to the moon.
It was Ranger, Lunar Orbiter, Surveyor, and then Apollo.