Sunday, March 2, 2008

Turning Carbon Dioxide into Gasoline?

There was an article on the New York Times about two scientists from the Los Alamos National Laboratory that are proposing to turn carbon dioxide into usable petroleum products such as gas, methanol and jet fuel. And they have named it Green Freedom. The idea is to capture the carbon dioxide from the air using a liquid solution of potassium carbonate, then separating the carbon dioxide out and through chemical reactions, viola! methanol, gasoline and jet fuel. This concept would thus create a closed cycle of carbon use. So far, they have not built a small prototype, they only have a detailed plan. But the article states that there is one small issue to deal with. This process will need a lot of energy. The concept sounds very interesting, but it is unknown whether it is economically and environmentally viable.

There are many factors that need to be addressed. Here are some I can come up with:

First, the issue of high energy requirements. There has not been any word on exactly how much energy will be needed. But there needs to be a study that focuses the issue of energy in versus energy out. If you look at the concept of the hydrogen economy and possibly corn-based ethanol, both require a great deal of energy and it is uncertain whether there will be a net gain. Especially concerning with hydrogen production such as hydrolysis.

Second, assuming that all fuels will be synthetically produced using this process, closing the carbon cycle by eliminating fossil fuel sources still means there is still a great deal of green house gases in the atmosphere, which will still aid in global climate change.

Thirdly, this concept will address fuels from the transport sector. Stationary sources such as large coal-fire power plants will be emitting carbon dioxide.

Obviously, this idea , if possible, will not be the silver bullet. Concerning the issue of energy requirements, the proposal includes the use of a dedicated nuclear power plant to provide the necessary energy. The scientists claim that the project would be economically viable if gas hits $4.60 a gallon. The price would then fall slowly due to economies of scale. The scientists claim that the technology exists and plan to pursue a pilot project within the next year. It will be interesting whether or not this technology will be viable and it should be pursued further but with a critical eye.

1 comment:

Candide said...

I spent a year doing research on the bioelectrocatalysis of carbon dioxide to methanol -- using enzymes to assist in the reduction of CO2 to a liquid fuel. A couple of points that came up from your interesting post.

1. This process is a net energy loss, by the second law of thermodynamics. That is why a nuclear plant would be necessary to generate the requisite energy.

2. The technology for converting CO2 to methanol is essentially akin to running a fuel cell backwards, and still has all sorts of efficiency hurdles to overcome before it could be tested at a pilot plant scale. The article didn't discuss how they might do it, but we were attempting it with enzymes because inorganic catalysts were not very effective.

3. When I was working on this topic, the idea was to use CO2 emissions from coal plants, because you would need a large, steady stream to make enough liquid fuel to put a dent in our oil consumption. As you pointed out, if the fuel is then burned in a car CO2 emissions would still be a problem. Reading the article, it seems like they would be extracting carbon dioxide from standard air, which is an interesting difference that seems much less practical.

4. With the number of technological hurdles still remaining, I am amazed that they have a estimate of the price of gas ($4.60) necessary for this process to be economical. Ultimately, I imagine it could be a lot more, or it could be less once the kinks are worked out. I think they are probably speculating on this price.

All in all, very interesting. Thanks for the post with the link to the article.