CO2 plus H2O solar kerosene?

[Moontanman]

I'm not quite sure what to make of this, my "it seems too good to be true" alarm keeps going off but if it's real I see no reason why individuals couldn't make their own kerosene at home...

 

http://interestingengineering.com/water-carbon-dioxide-solar-power-solar-jet-fuel/

[Essay]

"The Solar-Jet fuel project demonstrated an innovative process technology using simulated, concentrated sunlight to convert carbon dioxide and water to a so-called synthesis gas (syngas). The syngas, a mixture of hydrogen and carbon monoxide, is finally converted into kerosene by using the well established and commercial Fischer-Tropsch process. - See more at: http://interestingengineering.com/water-carbon-dioxide-solar-power-solar-jet-fuel/#sthash.MiTtjTTi.dpuf

 

Sure, by "using simulated, concentrated sunlight," anything should be possible, chemically. I don't know if they are using a laser to dissociate CO2, to create the syngas, but the trick is getting the syngas. Once they get that step, then traditional methods can take over for producing diesel or kerosene.

 

Syngas is the gas produced during "biochar" creation, through "reductive" pyrolysis. On an industrial scale, syngas can be a byproduct of biochar production. The syngas can then be processed to create liquid fuels. But on a small scale, the syngas is usually recycled to drive the firing process of biochar production.

 

The use of a "purge gas" is also similar to the reductive pyrolysis process, as the need to limit oxygen is critical for making syngas. Essentially, the two processes are the same, except these folks are taking CO2 directly from the air; whereas with biochar production, biomass is the source of carbon (as a source, extraced from the air, of "concentrated CO2"). Ultimately, through some process, the carbon-bearing molecules must be dissociated, so that CO is produced. Then synthetic processes can be used to build up a liquid fuel. It seems as if getting enough CO2 concentrated to run the process would be the hardest part; but maybe it could be used to clean CO2 from the exhaust of a coal-fired power plant.

 

Why don't they just use waste biomass for the carbon source, instead of trying to get enough CO2 out of the air? Are they trying to run the CO2 "collector" as the actual jet engine itself?

~

[John Cuthber]

Well, it could just be a lousy illustration, but they seem to be showing a mixture of hydrogen CO and oxygen coming out of the converter.

The clear implication is that the converter is very hot- that's what solar concentrators do.

The problem is that a hot mixture of CO, H2 and O2 will, of course, catch fire.

 

I'm not buying shares in this idea any time soon.

[Essay]

Well, it could just be a lousy illustration, but they seem to be showing a mixture of hydrogen CO and oxygen coming out of the converter.

The clear implication is that the converter is very hot- that's what solar concentrators do.

The problem is that a hot mixture of CO, H2 and O2 will, of course, catch fire.

...so maybe it is designed to be a "self feeding" jet engine, rather than just a producer of jet engine fuel, for future consumption.

 

That would need to collect enough CO2 to produce litres/second, and also be lightweight enough to not ruin fuel efficiency....

...doesn't sound like a sound or likely balance to achieve.

~

[Endy0816]

Basically just using the gas as a battery. Not a bad idea, depending the use you are putting it to.

 

Not sure which reaction they're using but there is quite a bit you can do with Ceria as a catalyst.

[Unity+]

I'm not quite sure what to make of this, my "it seems too good to be true" alarm keeps going off but if it's real I see no reason why individuals couldn't make their own kerosene at home...

 

http://interestingengineering.com/water-carbon-dioxide-solar-power-solar-jet-fuel/

Kerosene:

 

 

And the chemical formula presents as:

 

[math]26H_{2}O+12CO_{2}+catalyst=C_{12}H_{26}[/math](needs correcting?).

 

So, I think it is possible.

Edited May 7, 2014 by Unity+

[Sensei]

...so maybe it is designed to be a "self feeding" jet engine, rather than just a producer of jet engine fuel, for future consumption.

 

There is "just" 0.035% of CO₂ in the air.

 

To create just 1 cm^3 of Kerosene there would be needed to process (with 100% efficiency) 3656 Liters of air.

You can't do it during flight.

 

Boeing 747 burns ~4000 cm^3 (4 L) of fuel per second.

Edited May 7, 2014 by Sensei

[Acme]

...

Why don't they just use waste biomass for the carbon source, instead of trying to get enough CO2 out of the air? Are they trying to run the CO2 "collector" as the actual jet engine itself?

~

I see nothing in the article to suggest the collector is meant for use as an aircraft engine. As Sensei showed, it's impractical anyway.

 

I'd say the reason they don't just use biomass is that it must be transported for one, and as you point out, using biomass requires a fuel source whether it makes its own or otherwise. So with this new technology the big deals are no transporting the carbon source and using solar energy to power the process. I did some small scale experimenting a few years ago using a solar trough reflector to make biochar and while I didn't reach a sufficient temp in the receiver, a larger reflector would solve that. Not sure if a trough reflector is adaptable to this new technology or not.

 

PS Essay, do you know if anyone is doing solar pyrolysis of biomass?

[Essay]

I see nothing in the article to suggest the collector is meant for use as an aircraft engine. As Sensei showed, it's impractical anyway.

 

I'd say the reason they don't just use biomass is that it must be transported for one, and as you point out, using biomass requires a fuel source whether it makes its own or otherwise. So with this new technology the big deals are no transporting the carbon source and using solar energy to power the process. I did some small scale experimenting a few years ago using a solar trough reflector to make biochar and while I didn't reach a sufficient temp in the receiver, a larger reflector would solve that. Not sure if a trough reflector is adaptable to this new technology or not.

 

PS Essay, do you know if anyone is doing solar pyrolysis of biomass?

It was the picture, rather than the article, that made me wonder if maybe they were thinking along the line of a real-time collector/jet engine.

 

But no, I don't think there are any (solar-heated biochar) production facilities; only propane or self-fired. The nearest, would be facilities that use concentrated solar to fully convert biomass into oxidized product, almost like incineration. They use temps that are over 2000 degrees, I think; but don't know if they are still up-n-running. There was one in Denver a few years ago.

 

To do it right, they would need to select a more specific, lower temperature; and it would probably be different for each type of biomass, so that would complicate things lots. Plus, as you mention, the various costs of transport and processing the biomass makes it more complicated (expensive) too. If the price points and credits were structured differently, then maybe it could be more feasible. Thanks!

~