In a potentially controversial move, US military tech chiefs have decided to investigate the idea of using mobile nuclear reactors to provide power and synthetic jet fuel at forward bases overseas.

In a request for information issued yesterday, Pentagon scientists say they would like to hear proposals for "deployable nuclear reactor technologies for the generation of electrical power and military logistic fuels (JP-8) in forward land based and maritime military operations".

JP-8 is standard US forces jet fuel, regarded as relatively easy to synthesise from commonly available ingredients compared to the other main military fuel, diesel.

Boffins at the US Naval Research Laboratory have already developed processes by which it would be possible to make JP-8 using carbon dioxide and hydrogen extracted from sea water. The process would require a lot of energy, but in a US naval context this might not be a problem: American aircraft carriers have powerful nuclear reactors to drive their propulsion and catapults, which would have plenty of surplus grunt whenever full-speed launch operations weren't in progress.

This would be well worth doing, as the onboard supply of jet fuel is the main limiting factor on how long a nuclear carrier can keep operating its planes: the reactor's uranium lasts for years.

At the moment, the naval boffins' process produces large amounts of methane as a byproduct. Methane is a potentially useful fuel, but probably not in a military context; however, it could simply be dumped into the atmosphere, or more likely burned off in a flare stack for environmental* and safety reasons.

So the "maritime military operations" part of the plan is quite sensible. But what about "forward land based" reactors?

Well, from the point of view of a military supply officer, the idea could be an attractive one. At the moment, a military base in Afghanistan is likely to be powered by generators running on diesel. Its planes and helicopters will be burning through huge amounts of JP-8.

All this fuel has to be brought in by road convoys, along dangerous routes plagued by ambushes and bombings. It would be great if instead of diesel generators, the base's electricity came from a reactor that wouldn't need refuelling for years on end - probably not until after the war was over, in fact. It would be even greater if the reactor could also top up the base's supplies of JP-8 for its thirsty choppers and planes.

The problem here, though, is one of getting hold of the necessary hydrogen and carbon feedstocks with which to synthesise the jet juice. There's no limitless supply of seawater here.

Hydrogen could still be obtained from river or lake water, by using reactor power to crack it using electrolysis. Getting hold of the necessary carbon could be difficult, however, as huge - probably prohibitive - amounts of water would need to be processed to extract useful amounts of CO 2 .

The Pentagon RFI has this to say:

Technical approaches to fuel production should accommodate a broad range of hydrogen and carbon feedstocks (water/seawater, biomass, waste materials, etc). Concepts that involve carbon capture or sequestration should be well justified in terms of technical feasibility given known carbon concentrations in the proposed carrier stream.