Earlier this month, Robert Rapier put up a piece about a US Air Force report to Congress criticizing the US Navy's biofuels research program (part of the "Great Green Fleet" program, a play on Teddy Roosevelt's Great White Fleet). The Oil Drum picked it up, and one of the comments there caught my attention. Basically, the comment was a short summary of all the reasons that biofuels are a waste of scarce resources: the fuel costs too much, the energy-return on energy-invested (EROEI) is terrible, and so on. This post is about why those objections are largely immaterial if your perspective is that of the US military.
Any logistics analyst  taking a long-term look at fuel supplies wants options. After all, petroleum-based liquid fuels have significant risks associated with them. There are a variety of alternate  sources possible: coal-to-liquids, gas-to-liquids, and biofuels are three of the most obvious. The first two of those are relatively well understood, particularly compared to biofuels. In part, that's because of the wide range of biofuel approaches that are possible. These include gasification or other rendering of plant and animal mass; algae; and a wide range of fermentation approaches. Even more exotic techniques are theoretically possible. One such scheme would use excess electric power generated by the reactor in newer aircraft carriers to combine sea water and carbon dioxide extracted from air to produce diesel fuel and JP8. None of the research projects may pan out, in which case coal- or gas-to-liquids is the fallback position. The goal is to get those 300,000 barrels per day reliably, with cost and EROEI as secondary considerations -- because the current mission can't be executed without that many barrels.
2020 is a relatively short-term target, though. In the longer term, it seems unlikely that the mission will survive various trends. By 2035, say, it seems more likely to me that the US will be getting by on six million barrels per day of liquid fuel than that we will still be able to get our hands on the current 18 million barrels. If true, it is probably that the military will have to take comparable cuts in its supplies. The most probable outcome of the experiment in Iraq/Afghanistan is that a trillion dollars accomplished very little, and as a result the American public will be reluctant to engage in such adventures for a long time. US infrastructure is falling apart at an increasing pace; yet another reason for the public to be increasingly reluctant to spend money abroad rather than at home.
My predictions? Biofuels or not, in 25 years the US military will be much smaller and have a much smaller mission than it has today. No other global power will have arisen to fill the gap. Security will be much more a regional thing.
 "Amateurs talk about tactics, but professionals study logistics," is probably the pithiest quote on the subject, but it's an old concept. Quotes for the Air Force Logistician (PDF) attributes Alexander the Great with "My logisticians are a humorless lot . . . they
know if my campaign fails, they are the first ones I will slay."
 The goal for the Great Green Fleet program is to get 50% of liquid fuels from alternate sources by 2020. Not renewable sources, alternate. Despite nice words about other objectives, this is about fuel security.