Ozzie Zehner, visiting professor at UC-Berkely and author of the upcoming book Green Illusions (Lincoln and London: Bison Books, 2012), says all this CO2-as-a-fuel talk reminds him of the failed hydrogen dream of just a few years ago. That technology used excess solar wind power to create hydrogen to power cars. The only problem was in order to make that happen you needed to put more energy in to create hydrogen fuel than you got out of it. It’s like having a machine that creates $20 bills, but it costs $23 to create each one.
And Zehner says creating CO2 fuels is just as energy intensive. “The process can be used to store heat or electrical energy in a dispatchable liquid form for later use,” he says, “but CO2 is not a fuel on it’s own.” It must be refined into other things that can be used as fuels, like methane, which is the primary component of natural gas. And the problem, Zehner notes, is you need an endothermic reaction to make that happen. You need to provide a lot of heat and energy to get your resulting fuel, and you’ll get some, but not all, of that energy back. “Until they figure out how to change the laws of thermodynamics,” Zehner says, “we are stuck with what we have.”
And at the end of the day, it may be easier and cheaper to just extract and use existing natural gas resources. “We have a ton of methane now,” says Zehner. “Why pay to extract CO2 from the air and mix it with hydrogen and heat to create methane and water? No one does that.” And on the argument that the CO2 fuel is cleaner than fossil fuels, Zehner says by definition it’s not. “You need energy to either create the CO2 fuel or to reform it,” he says. “You might have to use nuclear power to get enough energy to convert CO2 into methane, so whether nuclear is cleaner than fossil fuels is is a political question.”
In the end, Zehner says we may just be trading one negative for another. “It isn’t acceptable for doctors to promote low-tar cigarettes,” he says. “Why should environmentalists promote alternatively fueled automobiles?”
That may make for a great sound bite, but the very real and lingering question is, in the case of the environment, is a “lower tar” alternative a viable solution? Let me know your thoughts in the comments below.