Mar 11, 2009
“Nothing beats finding vast lakes of oil for the pumping, or vast deposits of coal for the digging; thanks mother nature!” proclaimed Craig Grimes of Penn State University in an emailed response to my skeptical question regarding his work on catalysts that can convert the greenhouse gas carbon dioxide into a fuel, methane.
I report on his fascinating work in the March issue of Intute Spotlight. The process involves using solar power to chemically reduce carbon dioxide back to a combustible hydrocarbon. Grimes suggests that a flow system employed on fossil fuel burning power station chimney stacks could scrub out the carbon dioxide before it enters the atmosphere and provide us with a viable additional energy source.
Playing devil’s advocate, my skepticism was regarding the energy required to produce the catalysts, which are composed of relatively rare minerals, to build and maintain the plant and to decommission it at end-of-life. There are also the costs of actually trapping the carbon dioxide and then transporting the methane produced to sites where it is needed. Moreover, burning that methane then releases the carbon dioxide elsewhere, so it’s not a quick fix.
Grimes retorts that, “The idea is we better start figuring out how to not put carbon dioxide into the atmosphere, and begin to anticipate that our vast lakes of oil and vast deposits of coal are finite. Solar energy is not finite, at least in any conventional sense, but it is diffuse. There are lots of pitfalls with renewable energy sources, which is why coal and oil are cheaper to buy and use,” he told me. “Yes, you have to make the materials, install them, etc. All of that takes time, energy and money. However, outside of praying for a miracle, i.e. Having a faith-based energy policy, we would be well put to start trying to come up with an alternative to coal and oil.”
I also asked Grimes whether the same system might be used to process carbon dioxide sequestered from the atmosphere directly. “Yes, carbon dioxide that is to be ‘buried’ could instead be used as feedstock for the process, so its win win,” he told me. “The idea is not to burn the methane venting it back in to the atmosphere. You burn, collect, recycle, burn, collect, recycle…”
My Intute Spotlight column has an entirely environmental theme this month. Alongside my report on Grimes’ carbon conversion catalysts, we have a write-up on the recent modelling of Antarctic cooling 35 million years ago and a report on new materials that can efficiently extract hydrogen gas from mixtures and so might fuel a future hydrogen economy.
Oomman K. Varghese, Maggie Paulose, Thomas J. LaTempa, Craig A. Grimes (2009). High-Rate Solar Photocatalytic Conversion of CO2 and Water Vapor to Hydrocarbon Fuels Nano Letters, 9 (2), 731-737 DOI: 10.1021/nl803258p