| Title | 50kW Solar Tower Produces Jet Fuel in the Field | |
| Date | Wednesday July 27 2022, @06:06AM | |
| Author | janrinok | |
| Topic | ||
| from the dept. | ||
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
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printed from SoylentNews, 50kW Solar Tower Produces Jet Fuel in the Field on 2024-05-12 12:49:14