As noted in Daily Kos,
[...] So I was really impressed to see that a collaboration among the ETH Zurich and a few other Eurpoean organizations actually built a plant that, in real sunlight, out in the field, converts carbon dioxide and water into aviation fuel. This is the first time anyone has ever actually done this for real. Check it out in the July 20 edition of the Cell Press journal Joule .
[...] At the center of this process is an inexpensive and durable catalyst called ceria, or cerium(IV) oxide.
If we heat ceria to a very high temperature (here they used 1,500°C), we can strip off some of its oxygen atoms. Its crystal structure won't change; we'll just have vacancies where the dislodged oxygen atoms were. Those oxygen atoms will form O2 gas up off the surface, so we can blow or vacuum that O2 away to keep it from re-reacting with the ceria.
So now, what we're left with is an angry material that really, really wants its oxygen atoms back. If we spray it with some water vapor, it'll rip O right off of H2O and give us H2 (hydrogen gas). Or, if we blow some CO2 over it, it'll likewise yank off an O and give us CO (carbon monoxide). These reactions are so vigorous that they actually produce a lot of heat, so it's best to let the stripped ceria cool down a bit before going to this step (that is, stop shining sunlight on it). When we're done, we have good old regular ceria back, and we can keep using it over and over again.
Because we can control how much H2O and CO2 we put in, we can make exactly the ratio of H2 and CO that we want. The H2-CO mixture we make is called synthesis gas, or syngas. Our H2 and CO are much more reactive than H2O and CO2, so now we're in really good shape to build some bigger molecules out of them.
We do that with the Fischer-Tropsch process, which is very well-established.
So how did their process actually perform in this version 1.0? Not bad at all. They converted 4% of the incident sunlight to syngas energy, and that was without a whole lot of improvements that even I can think of. Such as, they didn't try to recover any of the lost heat from cooling the ceria, and although they used porous ceria bricks, there are surely better arrangements to get more surface area than that.
They used 18.1 kg (39.8 lb) of ceria — hey, they must have paid forty bucks for that! — and had an average solar input of 42 kilowatts during the ceria heating step. So the radiation intensity into the reactor aperture was that of about 2,500 Suns! Their average product length was 18 carbons — a little bit more diesely than keroseney, but that's easy to fix. They don't need to be Fischer-Tropsch experts, because lots of other people are.
The sunlight-to-syngas efficiency will have to come up to 15% or 20% to make this economically viable, but this is not a bad debut at all. Look, someone has just built a plant that turns sunlight into aviation fuel, not in some business dev guy's fantasy or in a little beaker with custom-sculpted platinum filigree, but outside in the Sun with readily accessible components and materials, for the first time ever. A lot of people talk, but these scientists and engineers are delivering. Don't underestimate what they have just done.
Journal Reference:
Stefan Zoller, Erik Koepf, Dustin Nizamian, et al., A solar tower fuel plant for the thermochemical production of kerosene from H2O and CO2 [open], Joule, 2022. DOI: 10.1016/j.joule.2022.06.012
(Score: 2) by c0lo on Wednesday July 27 2022, @10:25AM (8 children)
Groan!
https://www.youtube.com/watch?v=aoFiw2jMy-0
(Score: 5, Insightful) by janrinok on Wednesday July 27 2022, @11:30AM (3 children)
(Score: 2) by c0lo on Wednesday July 27 2022, @01:29PM (2 children)
True, but at this efficiency, better use corn or sorghum [wikipedia.org] and convert the entire biomass to fuel.
Maybe they'll improve, I'll drink to that.
PS my "groan" meant "fuck, there's a heck of a way still to go".
https://www.youtube.com/watch?v=aoFiw2jMy-0
(Score: 4, Insightful) by DeathMonkey on Wednesday July 27 2022, @07:21PM (1 child)
Kind of ironic that the highest efficiency in the link you just posted is 4%.
(Score: 2) by c0lo on Wednesday July 27 2022, @11:31PM
4.5%
https://www.youtube.com/watch?v=aoFiw2jMy-0
(Score: 5, Insightful) by azAZp on Wednesday July 27 2022, @11:50AM (1 child)
The best solar panels today have ~23% efficiency. (reference https://www.cleanenergyreviews.info/blog/most-efficient-solar-panels) [cleanenergyreviews.info]
They've been at it for 60+ years.
4% for a working prototype is good enough. It's better than fusion anyway :)
(Score: 2) by DeathMonkey on Wednesday July 27 2022, @07:23PM
They have 0% efficiency at making Jet Fuel though!
(Score: 2) by rleigh on Wednesday July 27 2022, @05:15PM (1 child)
4% is good. It's way more efficient than photosynthesis, which is rate-limited by rubisco (https://en.wikipedia.org/wiki/RuBisCO)
(Score: 2) by c0lo on Wednesday July 27 2022, @06:31PM
I beg to disagree [wikipedia.org] - look at C4. With some photosynthesizing cyanobacteria expected to go above.
Even C3 can be pushed higher if fed with an atmosphere richer in CO2 or engineered for efficiency [wikipedia.org]
https://www.youtube.com/watch?v=aoFiw2jMy-0
(Score: 4, Interesting) by Rich on Wednesday July 27 2022, @01:16PM
1m^2 near the equator will roughly have 10kWh/d of sun energy, roughly equivalent to 1l of aviation fuel (~diesel). 5% of that would be 50ml/d output. Plaster a square km with that stuff and get 50000l of fuel per day, roughly 50 tons. An A380 has ~250 tons capacity, so you'd need 5 square kilometres of that stuff to top up an A380 once a day. Looks like a lot.
But put it into relation with the plane's price, about $500M. Our fuel plant has 5M square metres, so if you manage to plaster one at $100 at scale, the plane could be airborne sustainably at double its current price. Not too shabby. Of course this process will have efficiency losses everyhwere, but it's not out of the ballpark by magnitudes. Cheap mass tourism wouldn't work anymore, but anyone who really had to fly probably still could.
(Score: 3, Funny) by Tokolosh on Wednesday July 27 2022, @02:27PM
Easy Recipe for Rat Souffle
Make sure that the rat's squeals are not audible from the street, particularly in areas where the Anti-Souffle League and similar do-gooders are out to persecute the innocent pleasures of the table. Anyway, cut the rat down and lay it on the chopping-board. Raise the chopper high above your head, with the steel glinting in the setting sun, and then bring it down - wham! - with a vivid crunch - straight across the taut neck of the terrified rodent, and make it into a souffle.
-- Monty Python
(Score: 2) by SomeRandomGeek on Wednesday July 27 2022, @10:27PM
I will note that they turned the sunlight into heat, then turned the heat into kerosene. So, the sunlight is incidental to this process. It could be done with heat from a nuclear reaction, or geothermal heat, or waste heat from any number of processes. Or mix and match. An efficient way to turn heat into fuel is far more useful than an efficient way to turn light into fuel.