This is a topic that was discussed on the blog last year, but the article I read on popsci.com that was posted last month talked about solutions to the problems with the Air Force’s plan to change the type of jet fuel their planes use. The motivation for the shift is due to many factors. The Air Force currently uses more fuel than all other branches of the military combined, making up 10% of the total domestic aviation market, which comes out to the small sum of $5.6 billion. A lot of that fuel is imported from other countries and that also makes the military uncomfortable. So their idea is to use more of our available domestic resources, which would be petroleum, natural gas, or coal. Since we are the 'Saudi Arabia of coal', coal seems to be a good option. They want to dig more coal mines and build coal-to-liquid (CTL) plants, a plan which is meeting a lot of opposition from people who believe we need to find an alternative to dirty coal. However, this could help with job creation and decreasing dependency on foreign oil. To create the fuel, the coal is steamed, creating gas which is then exposed to catalysts to liquefy it.
The Air Force is pursuing their plan to fuel the entire fleet with a 50/50 blend of this synthetic fuel from coal and regular jet fuel by 2016. Thus far they have certified the B-52 and C-17 to use the alternative fuel and testing has already begun for the B-1 Bomber, F-15, F-22, and KC-135. The goal is to complete the testing and certification for all aircrafts by 2011.
Supporters spin the criticism of coal by saying that burning CTL is cleaner than regular jet fuel because particulate emissions, SO2, and NOX are eliminated during the gasification process. However, the proponents leave out the fact that twice the amount of CO2 is produced during coal mining and burning. That isn’t allowed by Section 526 of the 2007 energy bill which forbids the US government from spending taxpayers money on fuels that don’t produce “ lifecycle greenhouse gas emissions” that are “less than or equal to such emissions from the equivalent conventional fuel produced from conventional petroleum sources.”
So to get around Section 526 they have to deal with the extra CO2. Here are some solutions: recycle the CO2 to produce more fuel, use it to grow oil-producing algae, or convert it to other gases that would be useful in the industrial sector. However, the technology isn’t ready for those three. Enhanced oil recovery could be pursued, but it has its own set of problems. Carbon capture and storage (injecting CO2 into underground formations) could also be another option but at this point it is quite expensive. According to the article, even Vaclav Smil says that “sequestering 10% of the world’s 2005 CO2 production would require more plants and pipelines than are used in the entire worldwide business of crude-oil extraction.” Hmmm, that seems like a big hurdle.
Obviously low carbon fuels would be better options than coal-to-liquid or petroleum fuels, but they aren’t ready yet so the dilemma is this: foreign oil or domestic coal-based fuel that’s dirtier? I wonder what Steven Chu thinks…