US Navy Tries To Turn Seawater Into Jet Fuel 402
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.'"
Re:But the beauty is (Score:4, Interesting)
Plus low carbon energy isn't that much of a fools dream...
I mean there are some really great designs for wave power floating around right now (yes, pun intended). Plus wind has some potential.
But even if we fed all the countries of the world on carbon free electricity and all had electric cars, we'd still need planes and jet engines in particular.
We could potentially build an electric jet engine-replacement (giant air compressor?), but until batteries become a lot lighter that would obviously be very counter-productive.
Re:Cost effective? (Score:5, Interesting)
oceans absorb CO2
CO2 + H20 H2CO3
H2CO3 ==> HC03- + H+ with a pKa of 3.6
This means that we will eventually turn the oceans into Coca Cola. Not too good for the flora and fauna, I can imagine. There's a practical limit to the CO2 that the oceans can absorb.
Of course if we could create some sort of genetically engineered algae that happened to produce carbonic anhydrase, you'd be able to degas huge amounts of ocean water just by pouring it into your algae tank...
Re:Trying to avoid Methane? (Score:5, Interesting)
Re:But the beauty is (Score:4, Interesting)
Weight itself isn't the issue, it's energy density and max instantaneous energy output.
Even if you could make a 1,000,000 amp-hour battery, it's useless if it's internal serial resistance is too high to provide the amperage needed. Conversely, a low ESR capacitor can deliver quite a punch, but not for long enough to drive a jet across the country.
A gazillion dollars a year are spent on developing new battery technologies. One day they might rival the density of gasoline but I'm not holding my breath any time soon.
Re:Makes sense (Score:4, Interesting)
Well if countries that do not like the US decide to embargo oil to the US
and or supply lines are cut, then you have the choice of syngas or no gas.
That is likely the reason they are considering this because if things
continue to degrade with Israel and Iran, and the war in Afghanistan
and Pakistan is going poorly.
If things go VERY wrong, then we could find ourselves with an oil embargo
like we ran into in 1973.
http://en.wikipedia.org/wiki/1973_oil_crisis [wikipedia.org]
The odds this will happen is high if several of the foreign powers
consolidate power due to some event.
Re:But the beauty is (Score:3, Interesting)
Much less than what happened on 11/9, without the jet-fuel there would be no powerful steel-melting furnace. We might still need to demolish the building to clear the nuclear waste, but it could be done controlled after the everyone was evacuated. New Yorkers in general might become a little weirder and more radioactive, but I don't think anyone would notice.
60% of a nuclear reactor is "waste" heat (Score:5, Interesting)
So it may actually be more efficient thermodynamically.
Energy intensive industry and wind power (Score:4, Interesting)
Wind power has lots of advantages, but one major drawback - it is intermittent. If you have an industry which is very energy intensive but has low capital cost, this presents an opportunity: build your plant, and run it only when the wind is blowing and power is very cheap. This works especially well if your product is easily storable.
This process is clearly energy intensive and produces an easily storable product - whether it has the required low capital cost is much less clear. (Although the interest of the navy suggests they're wanting to use aircraft carrier nuclear power, but once developed it could find wind-powered civilian use.)
Water desalination and aluminium smelting might also qualify (I don't know the capital costs of these). Recharging electric cars certainly does (given that you're buying the car anyhow), except that you have a very limited storage capacity.
Despite not being low capital, data centres are even starting to go this way, being built with the intention of only running them when electricity is cheap (or less is required for air conditioning.) In this case the product is extremely transportable rather than easily storable.
Re:Or... (Score:4, Interesting)
Actually, we CAN run planes on booze. It's just not very good for the fuel system, and it costs an arm and a leg. Otherwise, jet turbines can burn pretty much anything.
Re:Energy intensive industry and wind power (Score:4, Interesting)
The navy has to worry about delivery costs and operational advantages. Don't make the mistake of equating military feasibility with civilian cost-efficiency. After all, for civilian use a nuclear bomb would be a very costly and inefficient way of clearing a large chunk of land, whereas for the military it's quite effective.
Re:Makes sense (Score:4, Interesting)
Re:But the beauty is (Score:1, Interesting)
Actually, I would say the main difference is that gasoline has little inherent energy. It however has a lot energy when combine with oxygen. Most batteries need to carry all of there reactants with them. This makes gasoline very light and compact because you don't need to carry the oxygen with you as long as your in the atmosphere. I don't think that batteries that don't absorb air are going to ever beat the energy density of fuels(Anything that burns) in applications that can breathe air in the next hundred years. Also the fact the you can release the chemical byproducts of the reactions safely into the air makes them lighter. This is what people don't get about fuels they are incomplete with the free air, I wonder what the energy density of gasoline plus the oxygen needed to burn it is vs a battery. Also since airplanes do not stop and go like cars do there is little to be gained from having way to convert braking back into usable energy.
Re:But the beauty is (Score:3, Interesting)
Lets just fill our tanks with antiprotons and let them consume the engines...
Re:Or... (Score:4, Interesting)
Why not nuclear power? They can use nuclear power on an aircraft carrier to power the conversion at minimal cost and zero extra emissions.
Taking this one step further, and with some creativity develop a nicely controlled natural uranium-deuterium based fission reaction that could produce sufficient power to run a jet at minimal risks.
Re:Or... (Score:5, Interesting)
Re:But the beauty is (Score:3, Interesting)
The cool thing about electric cars is that they are so much more efficient that you don't need batteries that are as energy dense as gasoline. The tesla roadster has a range of 240miles with a battery pack that holds 53kWh. A gallon of gas has the energy equivelent of about 35kWh. So a tesla can go 240 miles on only 1.5 gallons of gas. This is because the battery and motor are so much more efficient than an internal combustion engine which wastes most of the gasoline energy as heat.
So in order to build awesome electric cars we either need batteries that can be recharged a little more quickly or batteries that can store a energy a little more densely, but we don't need energy storage as dense as gasoline for electric cars to work well.