Its an interesting thought. The Chinese are particularly sensitive to the idea of famine. But why would the US want to take away disposable income from the Chinese/Russians? they are already being squeezed on energy and materials like everyone else.
Its also unclear as to where the export earnings are going to come from since the grain is to be consumed as biofuel in the US. More likely the US will have to start importing ethanol from where it is produced more efficiently (eg Brazil).
Efficiently distributing ethanol requires infrastructure which has yet to be built (an article in this weeks Economist on this) - so they will have to commit to this fuel. The US may have advantages in the production of other fuels also e.g. coal and gas to liquid, electricity. I know the Air Force is looking at flying planes on a coal based fuel, but interesting that there is not a big subsidy program behind it, and none whatsoever behind electricity.
