Solar jet fuel made out of thin air

[Recursion]

http://www.rsc.org/chemistryworld/2014/05/solar-jet-fuel-made-out-thin-air

The dream of producing hydrocarbon fuels from carbon dioxide and sunlight is one step closer thanks to chemists in Europe who have made jet fuel from scratch in a solar reactor for the first time. Although the chemists only produced enough kerosene to fill a glass jar, they believe a full-scale solar concentrator could produce 20,000 litres of jet fuel a day.

'This technology means we might one day produce cleaner and plentiful fuel for planes, cars and other forms of transport,' said Máire Geoghegan-Quinn, European commissioner for research, innovation and science. 'This could greatly increase energy security and turn one of the main greenhouse gases responsible for global warming into a useful resource.'

The idea of extracting carbon dioxide from the atmosphere and converting it into fuel is simple enough. At high temperatures carbon dioxide and water dissociate into hydrogen, carbon monoxide and oxygen. The hydrogen and carbon monoxide mixture, known as synthesis gas or ‘syngas’, can then be converted into liquid hydrocarbons such as petrol or kerosene via the well-established Fischer–Tropsch process, which was invented by the chemists Franz Fischer and Hans Tropsch in Germany in the mid 1920s.

Unfortunately, the idea has suffered from two problems. One is that the dissociation of carbon dioxide and water only takes place at very high temperatures, typically above 2200°C. But the other, more difficult, problem is that the syngas cannot be tackled by the Fischer–Tropsch process until all the oxygen is removed as it is dangerously explosive.

Before the furies start howling, this is not a claim of "free energy", but of a feasible way to convert solar energy to hydrocarbon form. Roughly, synthetic photosynthesis.

[okaawhatever]

1. Cool. nt

[emsimon33]

2. K&R

[TexasProgresive]

3. What caught my eye

a full-scale solar concentrator could produce 20,000 litres of jet fuel a day

20.000 liters comes to 5283 U.S. gallons of jet fuel. A Boeing 777 uses about 5 U.S. gallons per mile (1). So the "full scale concentrator" would fuel one plane for 1,060 miles. What would it cost to build plants to produce 60.5 million(2) gallons of jet fuel per day? I am not sure if this figure includes military use which includes tanks and other turbine driven vehicles.

(1) http://en.wikipedia.org/wiki/Boeing_777
(2) http://www.indexmundi.com/energy.aspx?country=us&product=jet-fuel&graph=consumption
1 barrel = 42 U.S. gallons

[stevenleser]

5. Seems like you would need 12,000 "full-scale solar concentrators"

That also assumes that the kind of fuel produced this way is as efficient as JP-7 or whatever other fuel is the currently used jet fuel.

Still, this is very tempting. That isn't a bad starting point. How many 'full scale' oil wells do we have now?

[Heidi]

4. Kick!

[hunter]

6. The U.S. Navy process seems more promising...

http://science.dodlive.mil/2014/04/11/energy-independence-creating-fuel-from-sea-water

It's proposed that such fuel would be made from sea water using nuclear power, thus allowing an aircraft carrier to fuel its own planes and support vessels. The process could also be adapted to solar energy.

But the problem is thermodynamic. Fossil fuels will always be less expensive to make, even using ghastly environmentally destructive fuels like coal, tar sands, or fracked gas and oil.

The only way to quit fossil fuels is to outlaw them and allow the market to fill the resulting vacuum with alternatives.

[Tom Rinaldo]

7. In a wild best case, could this help reduce global warming?

If somehow economy of scale some day made this a commercially viable way to produce vast quantities of fuel, does anyone have an informed opinion what impact extracting that much carbon dioxide would have on the atmosphere relative to climate change?

[FSogol]

8. Yes, it will help reduce global warming the same way unicorns do. n/t

[Tom Rinaldo]

9. Thanks for the snark. There's never enough to go around. n/t

[Igel]

10. Trivially.

Jet fuel isn't a huge component of carbon added to the atmosphere.

This removes carbon and then returns it. It's sort of like the role a mature forest plays in carbon sequestration--none at all. (Others will object. A mature forest has about as much loss of biomass through decomposition as production of new biomass. The arbon returned to the air is about as much as it removes through photosynthesis.)

It's not the removal of carbon that would matter; it's the lack of new carbon derived from fossil fuels that would matter.

[Tom Rinaldo]

11. Thanks

In saying "wild best case" I was wondering what could happen if auto fuel could be produced some day by this or a related process, not just jet fuel. But your answer was exactly what I was hoping someone might offer. In theory, at best, this might be a carbon neutral fuel source.

[muriel_volestrangler]

12. A way to get liquid fuel for air travel may remain important

since weight matters more when flying, compared to road travel. So a carbon-neutral way of synthesizing hydrocarbons, like this, may be useful.

If we produced calcium carbonate from seawater and atmospheric carbon dioxide, we'd have a stable solid we could deposit in ocean trenches to get recycled back into the mantle.

[Marrah_G]

13. Stargate Universe!

They would recharge by flying through suns

[eppur_se_muova]

14. To split hairs, this is thermochemical synthesis, even if it's solar thermal ...

I suspect there are much more efficient ways to do this -- it is inherent in the process that one is fighting thermodynamics by "unburning" hydrogen. Using solar thermal power to run a Stirling engine/generator and electrolyzing water would seem to be a better route to the same end -- H2 and O2 thus produced are normally kept separate anyway, so the separation problem is completely avoided. Just add CO2 (which, BTW, is so stupefyingly obvious to so many people that I don't understand how this research got funded in the first place).