Green energy from greenhouse gases: A novel paradigm in mitigating global warmingPublished on February 16th, 2009 | By: firstname.lastname@example.org
(the following is a guest post from Abdul-Majeed Azad, associate professor, chemical engineering, University of Toledo)
As we know, the ultimate chemical fate of the conventional fossil fuel combustion is always CO2 and H2O, two well-known greenhouse gases responsible for contributing considerably to the global warming. In 2007 the global level of CO2 was 30 billion metric ton and is projected to be 43 billion metric ton by 2030. The United States contributes the largest amount – 22.2% – of global CO2 emissions.
What if we could convert CO2 into carbon monoxide (CO), water into H2 and a mixture of CO2+H2O (the ultimate product of complete combustion of hydrocarbon-based fossil fuels, including biofuels) into syngas (CO+H2), respectively? Syngas is a valuable precursor for the well-known Fischer-Tropsch process perfected by Germans during WW II to make synthetic fuels since Germany had coal but no oil reserves. All these streams (CO, H2 and CO+H2) are also ideal fuels for solid oxide fuel cells. Hence, essentially the waste products of combustion could become a fuel source and can be recycled. Alternatively, if desired, CO could be converted into H2 via catalytic water-gas-shift reaction that then could become feed for proton exchange membrane fuel cells.
We have developed an inexpensive heterogeneous ceramic catalyst that we experimentally found capable of converting CO2 and H2O into CO and H2, respectively, on a 1:1 molar basis, under mild temperature and atmospheric pressure. These streams when fed into an intermediate temperature SOFC at 650°C create an open circuit voltage, quite comparable to that of the same SOFC run with pure H2.
The technology is also of relevance to NASA’s in-situ resource utilization program for MARS exploration since Martian atmosphere is ~ 96% CO2. NASA might be interested in looking at our technology for creating CO from Martian CO2 and, use it either as such or after water-gas-shift reaction to generate hydrogen as fuel for a SOFC stack. In the Martian context, to make the process truly self-sustained one could use solar concentrators to generate enough heat to raise the temperature to cause the desired conversion (CO2 to CO to H2). Thus, the fuel can be generated (and used) during daytime and stored and utilized to run fuel cells in the night hours.
It is predicted that global clean energy markets are going to quadruple in the next decade from $55.4 billion in revenue in 2006 to more than $226.5 billion by 2016. The approximate market size of this greenhouse gas mitigation is over $1 billion. The technology and the product are potentially of interest to energy producers and suppliers, utility chains, SOFC manufacturers and users, organic synthesis companies and Mars human exploration missions. The United States Department of Defense uses logistic fuels for its operations and could employ the greenhouse gas-fueled SOFC technology for many military field operations, including mobile forward base units, auxiliary field hospitals, field command posts, operational forays, and unmanned aerial vehicles. NASA is also currently looking at non-petroleum-based jet fuels in the pursuit of alternative fuels that can power commercial jets and address rising oil costs. A greenhouse gas-derived F-T fuel could respond to that quest.
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