There is more carbon dioxide (CO2) in the atmosphere these days than ever before in human history, and while it would be marvelous to use these carbon atoms for something more useful, capturing CO2 directly from the air isn’t that easy. After capturing it would also be great if you could do something more with it than stuff it into a big hole. Something like producing syngas (CO + H2) for example, as demonstrated by researchers at the University of Cambridge.
Among the improvements claimed in the paper as published in Nature Energy for this direct air capture and utilization (DACCU) approach are that it does not require pure CO2 feedstock, but will adsorb it directly from the air passing over a bed of solid silica-amine. After adsorption, the CO2 can be released again by exposure to concentrated light. Following this the conversion to syngas is accomplished by passing it over a second bed consisting of silica/alumina-titania-cobalt bis(terpyridine), that acts as a photocatalyst.
The envisioned usage scenario would be CO2 adsorption during the night, with concentrated solar power releasing it the day with subsequent production of syngas. Inlet air would be passed only over the adsorption section before switching the inlet off during the syngas generating phase. As a lab proof-of-concept it seems to work well, with outlet air stripped from virtually all CO2 and very high conversion ratio from CO2 to syngas.
Syngas has historically been used as a replacement for gasoline, but is also used as a source of hydrogen (e.g. steam reformation (SMR) of natural gas) where it’s used for reduction of iron ore, as well as the production of methanol as a precursor to many industrial processes. Whether this DACCU approach provides a viable alternative to SMR and other existing technologies will become clear once this technology moves from the lab into the real world.
Thanks to [Dan] for the tip.
Seems like a very long way to go before a concept like this can be engineered and scaled to something of practical value but I do like the approach conceptually. Though I’m not convinced the solar energy input focus one very stage is worth the effort as that means it would be taking up space that could be photovoltatic – while efficiency should drop in terms of solar energy captured to end product for this generator taking solar PV to provide electric heating to the level required to me at least simplifies the problems of regulating the temperature, and the electric generated doesn’t have to go to this process all the time – flexibility is good.
The basic process has been around for some time, and it’s now getting market ready.
For example, Porsche is starting up synthetic fuel production from wind power in Chile.
https://techcrunch.com/2022/12/20/porsche-pumps-first-synthetic-fuel-as-chilean-plant-finally-starts-producing/
” Porsche’s next target is 55 million liters per year within the next three years. At that volume, Porsche’s Michael Steiner says the production cost will drop to roughly $2 per liter.”
We’re getting there.
That is working on a different methodology at most if not every single stage and has different chemical outputs as well no? Not entirely sure what Porsche is doing but I thought it was electrolytic cracking of water into hydrogen with the end goal being methanol…
I’m not saying carbon capture fuels can never be made, though the wisdom of creating them looks suspect so far as that promise is being used as an excuse to turn more carbon safely in the ground into air polution, and the economic model seems somewhat dubious as well. All I’m saying this process looks like it is a long way from being practical and scalable.
Also, there’s no lack of space for installing solar collectors. Thermal solar collectors are much more efficient at collecting solar energy as well, so you need fewer of them.
The problem is we need to be more intelligent about where we put the solar collectors, rooftops are fine until they need repairing or cleaning, so how about over the top of carparks, that way your car is coller when you get in it and the solar collectors can be washed by someone with a scaffold or a short pole.
I don’t get the cleaning problem. One rain keeps them clean enough most of the time. Two you can climb up there and clean them. Three why not drones carrying pressure washer at appropriate pressure to clean them safely, I’ve seen videos of this.
Rain really doesn’t keep them properly clean even in places like the UK where it rains often. I’d suggest rain is actually about as likely to make them dirtier bringing more of the sticky diesel soot type stuff that doesn’t easily wash off too them than it is to help.
I clean ours with a window cleaning mop on a long stick for the hard to reach ones about 2 maybe 3 times a year and it always on the first swipe saturates the mop with black gunge, even if its been raining all week before hand. Pressure washing the easier ones does work, but actually not that well either and a big drone carrying the pressure washer doesn’t seem like a great idea to me – pretty expensive and noisy bit of kit that upon making one tiny mistake is probably breaking the stuff its trying to clean. I’ve seen the method done very successfully against flat smooth vertical walls of glass though, so I don’t discount it.
And that is flat solar PV, heat capture with the reflector behind it and glass tube in the middle you can’t so easily push a mop over.
Its not just about the space its about the process, your solar collector is doing nothing at all when the reagents are spent, which with this setup so far anyway seems likely to happen pretty quickly really in each day/night cycle – so if 90% of your day is spent collecting heat you aren’t using…
Then when the goal is to get specific chemical reactions going you want to control the environment for the desired reaction and when you can’t be sure what the weather will be doing actually keeping it regulated in the right bounds is an added challenge, that many days may not be possible with outside energy supply anyway…
I’m not saying it can’t be done, this concept does look really interesting and is well worth further research, but a setup like this where the energy comes form the sun directly for so many steps doesn’t look ready for a real world prototype deployment let alone larger scale.
CO above a certain concentration is Immediately Dangerous to Life and Health. Worse, at lower concentrations it can ‘silently’ asphyxiate. Past a certain point all the oxygen in the world won’t help you until you can be thrown into a hyperbaric chamber, because CO latches so tightly onto hemoglobin.
Making a CO into a fuel is beyond stupid. This wouldn’t even be appropriate in industrial settings – the safety precautions needed would make it too cumbersome.
Internal combustion is dead. It’s wildly inefficient and stuff like this doesn’t help – it only distracts. All our resources should be going into solar, wind, tidal, hydro, energy storage, and electric vehicle tech. China is already doing this.
I don’t think anybody is suggesting syngas should be shipped around and used directly as fuel the way propane etc is, as that would be pretty insane. But it is a very good precursor for synthesis of other hydrocarbons, and to my understanding not uncommon as feed stock in other industrial processes either.
Dangerous when handled without enough care isn’t a good reason to ignore anything useful, its only when something is dangerous to the point it can never even in well controlled settings be used safely that argument can fly..
I also don’t entirely agree ICE is dead, yet anyway, though I am all for investing in the technologies of less ecological vandalism that might just keep this little blue dot habitable. ICE right now is like the steam locomotives that kept the railway running for many decades after the writing was on the wall and it is obvious the future will be diesel and electrification. It is that long established and reliable technology with all the infrastructure already in place that makes it practical to keep using no matter the limitations for now. And much like steam it probably will retain a niche or two where it is just the only sensible option for a very long time after its phased out of general use. For instance military fuels, as you can’t go nuclear even if you really really wanted to practically in the smaller vehicles, can’t go all electric and have everyone forever looking for a working grid hookup to sit at for the next 10 hours, and its wildly impractical to have a battery exchange mechanism and waste logistics effort shipping giant depleted batteries back for recharging. And you can’t stockpile electric for future need in the same way either. The best chemicals for use in fuel cells that could run your electric powertrain are even trickier to handle than the petrols, so technically possible to stockpile, but…
Also China is also going in for building many more Coal plants too, and much of the research and resources poured into the renewables is just mass producing often to lower quality something developed elsewhere (not saying there is no genuine inovation but lots of this ‘green’ tech boom there is simply willingness and the economical benefits and capacity to scale hugely. They are just as backwards and bonkers in their own ways.
I remember reading about this process 10-15 years ago. At the time they were achieving 60% efficiency from direct air capture to methane synthesis. Now they’re commercializing the process:
https://www.umsicht.fraunhofer.de/en/press-media/press-releases/2024/direct-air-capture-electrolysis.html
The entropy of DAC can be used to compute a minimum energy requirement per mass of carbon captured.
A first calculation would be the steady state to capture the ‘fresh’ carbon, that is CO2 that has just been produced. That would keep atmospheric CO2 levels where they are when such a system (capable of handling worldwide emissions) begins operating. DAC would also require the energy to move all that air past the capturing surface – in addition to the entropy multiplied by the absolute temperature.
DAC is just a way to pretend to act, saying ‘I don’t want to cut my emissions’.
There are other such schemes. Planting trees, for example, would require about 20 – 30 years to begin capturing that amount. As we have learned with all pollution, the most effective answer is Source Control, which means cutting emissions.
Dissolve it in cold water and have yourself a bubbly drink. If you’re feeling the need for something a bit more fancy, add a teaspoon of electrolytes for your very own sparkling mineral water.
Yay! Now I don’t have to drive a Tesla!
“There is more carbon dioxide (CO2) in the atmosphere these days than ever before in human history”
Citation please.
As Carl Sagan said, “extraordinary claims require extraordinary evidence.” Can you really, seriously claim that you know how much carbon dioxide has been in the atmosphere for the entire time that humans have been on the face of the earth? Really, like 300,000 years? Or maybe you have a different of “ever before”, like maybe in the last 50 years? I guess to most people, history begins the day they were born.
My point is that if you want to be taken seriously, you shouldn’t start your article with a patently absurd statement.
Here’s one:
https://www.science.org/doi/10.1126/science.adi5177
It’s only an extraordinary claim if you not been listening to climate researchers for the past few decades.
He didn’t say that. He said (and you already quoted) “in human history”. That’s a much shorter time.