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US Navy Tries To Turn Seawater Into Jet Fuel
Hugh Pickens writes "New Scientist reports that, faced with global warming and potential oil shortages, the US Navy is experimenting with making jet fuel from seawater by processing seawater into unsaturated short-chain hydrocarbons that with further refining could be made into kerosene-based jet fuel. The process involves extracting carbon dioxide dissolved in the water and combining it with hydrogen — obtained by splitting water molecules using electricity — to make a hydrocarbon fuel, a variant of a chemical reaction called the Fischer-Tropsch process, which is used commercially to produce a gasoline-like hydrocarbon fuel from syngas, a mixture of carbon monoxide and hydrogen often derived from coal. The Navy team have been experimenting to find out how to steer the CO2-producing process away from producing unwanted methane by finding a different catalyst than the usual one based on cobalt. 'The idea of using CO2 as a carbon source is appealing,' says Philip Jessop, a chemist at Queen's University adding that to make a jet fuel that is properly 'green,' the energy-intensive electrolysis that produces the hydrogen will need to use a carbon-neutral energy source; and the complex multi-step process will always consume significantly more energy than the fuel it produces could yield. 'It's a lot more complicated than it at first looks.'"
But it's easy to put a nuclear reactor in a ship, and not so easy to put one in a fighter jet.
Brett
Nuclear powered aircraft carrier, so you've got a pretty good supply of energy there, being able to convert electricity into jet fuel would save them money and reduce the amount of fuel they have to carry (reducing the amount of flammable liquids held in a ship that might get hit by a missile), and could end the need to resupply fuel, all in all very sexy if you're going in to combat.
For the life of me I can't see how this will be cost effective or environmentally friendly.
I know sometime in the future there will be scarcity of oil, or peak oil (if we aren't there yet) but no-one seriously thinks that there will be so little fuel that a navy ship won't be supplied for many decades.
Oil will become relatively more scarce through time, but at some point I think it will cease being used in cars and turbines, and used only for niche machinery and for making plastics. By the time there is no oil left for navy ships, I am betting another fuel source will have come along.
Also, from TFA:
"CO2's abundance, combined with concerns about global warming, make it an attractive potential feedstock, Dorner says. Although the gas forms only a small proportion of air - around 0.04 per cent - ocean water contains about 140 times that concentration, he says."
Can someone smarter than me explain how it addresses concerns about global warming to get the highly CO2-concentrated sea water, convert it into fuel, that presumably is then sent via an exhaust stack into the air? Isn't it just like mining coal and sending it into the air, except this plan uses carbon in the oceans?
If the pattern goes 9am, 10am, 11am, why isn't noon 12am?
Methane is a good fuel in its own right. Using solar power this could be a good general source of transportable energy.
http://michaelsmith.id.au
Thermodynamically a huge waste.
This has got nothing to do with creating free energy, and it's got nothing to do with environmentalism. It's all about military strategy.
Your nuclear-powered carrier fleet is on patrol in a war zone. Resupply convoys are a risky business. How do you keep your planes in the air without a constant supply of jet fuel?
You make your own on board. Who cares if it's "thermodynamically a huge waste"? You've got a freaking NUCLEAR REACTOR. It's got plenty of energy to spare, all you gotta do is repackage that energy into a form that can be poured into an aircraft fuel tank.
Not only that, you could use nuclear power to perform the operation, making it a carbon-neutral way of producing and using oil. Heck, if this ever ended up being an economical way to produce chemicals for plastics, it would actually sequester carbon.
He who lights his taper at mine, receives light without darkening me.
Perhaps they plan to build carriers with larger reactors that have greater output than the needs of the ship itself, so that the excess output can be used to power a small on-board jet fuel production plant? In that scenario, who cares if the energy required outweighs the work done by the resulting fuel?
Not to mention the fact that it's a waste of perfectly good booze.
Hydrogen is a stupid fuel, except for fusion (and, maybe fuel cells).
Storage is a royal pain, since hydrogen molecules are very small and simply wander off from containers, surrounding them with a highly flammable gas. If pressurized and cooled to liquid, they wander off less, but you have added costs of weight to the vehicle and compression/cooling to the production side.
Per weight/volume, hydrogen generates relatively little power compared with hydrocarbon fuels . In general, the more carbon in the fuel molecules, the more energy available in combustion (you're not going to run high-performance aircraft on fuel cells). The C-C bonds are cheap to break compared to H-H bonds and C-O bonds provide decent return, so the net output is more. Diesel cars/trucks generate more useful power and better fuel efficiency than gasoline cars or hybrids. Similarly, there's a lot of energy in the long-chain molecules of kerosene/paraffin used as jet fuels.
I did always find it odd that people who didn't have sex were judged based on their sexual preference.
It's been a long time.