r/science • u/Wagamaga • Feb 13 '25

Chemistry Researchers have developed a reactor that pulls carbon dioxide directly from the air and converts it into sustainable fuel, using sunlight as the power source

https://www.cam.ac.uk/research/news/solar-powered-device-captures-carbon-dioxide-from-air-to-make-sustainable-fuel
4.3k Upvotes

97% Upvoted

255 comments sorted by

View all comments

1.5k

u/MrSpotgold Feb 13 '25

It's almost as if they invented a tree!

340

u/T_M_name Feb 13 '25

Well, I've actually seen one of such prototypes. Was a lot more complex and more expensive than a tree.

131

u/SyrioForel Feb 13 '25

Was it about as efficient as a single tree, too? Or maybe even two trees?

156

u/glibsonoran Feb 13 '25

Scientists have made more efficient versions of photosyntesis, typically by modifying a molecule used in natural photosyntesis: RuBisCo that tends to be very inefficient because it tends to bind to Oxygen instead of CO2. Also they've created pigments that absorb a broader spectrum of light than chlorophyll. And some entirely synthetic photosynthesis processes are even more efficient.

  • Natural Photosynthesis ~4 - 6% efficient
  • Engineered Photosynthesis (modified bacteria and algae) 10 - 15% efficent
  • Artificial Photosynthesis (Artificial leaves, Photocatalysts) 20 -25% efficent
  • Hybrid Bio-synthetic (Bacteria and Nanomaterials) 15 - 20% efficient

24

u/somaganjika Feb 13 '25

AI teach us to make better photosynthesis using chemicals from Walmart

28

u/DerivingDelusions Feb 14 '25

I would like to point out that photosynthesis chooses to ignore most wavelengths of light because it doesn’t need that much energy and if it tried it would cook itself

24

u/pittaxx Feb 14 '25

There's very little "choice" in the matter. Evolution found something that works, and that's it.

Different wavelengths would mean not using chlorophyll, which would mean reinventing the entire photosynthesis, and evolution really does not like reinventing things.

Not cooking itself is a separate thing - plants radiate extra energy as heat to avoid getting burned, which is additional efficiently penalty.

6

u/DerivingDelusions Feb 14 '25 edited Feb 14 '25

Well they could’ve used other pigments to capture light but those wavelengths are preferred to limit ROS production to a manageable level. (And some things do just look at like some algae) So you don’t really need to reinvent photosynthesis because that whole thing is kinda independent of the type of pigment used. It just matters how fast it can reasonably use energy before radicals kill it.

On a side note, another cool thing plants can do to not cook themselves is increase their stomatal conductance. But they don’t like to do that all the time because now they’re losing water (unless it’s plentiful). It’s quite literally like they’re sweating.

They can also increase intracellular proline concentrations to resist stress but it doesn’t feel as cool (unless you use ninhydrin to make it have funny red color)

4

u/pittaxx Feb 14 '25

Yes, other viable pigments exist. I meant reinventing from the perspective of the organism not in general.

As in, the pigment is one of the foundational blocks that is picked before the organism goes multicellular. Given the prevalence of it, it clearly gave some big advantages in the early development stages. A billion+ years and countless development stages later, that point is rather moot, as swapping a pigment would require rebuilding most of the organism starting from the photosynthesis (hence reinventing).

And yes, you can definitely find a lot of cool things in nature.

2

u/Xylenqc Feb 15 '25

He explained the pigment is just one the building block, it can be swapped as long as a similar reaction still takes places. Another comment pointed out that scientist have produced a better pigment, if they can do it in less than a couple years, evolution would have stumbled across it a long time ago. Maybe plants just don't need that much energy, and maybe some already use different pigment. I wouldn't be surprised if some algae had a blue absorbing pigment for deeper water.

1

u/Cheesemasterer Feb 15 '25

Wrong. Evolution f-ing loves to reinvent crab

1

u/pittaxx Feb 15 '25

Yes, convergent evolution is a glorious thing.

I meant more in a sense of swapping out a trait for an alternative version on an existing complex organism.

In a more general sense, multiple variants of photosynthesis evolved separately and coexist now. It's just that one of them is way more common than all the others combined.

0

u/SuperGameTheory Feb 14 '25

Evolution didn't find anything. You're anthropomorphizing it. Out of continued random variation, the photosynthesis that know is what's continued to be left over when other variations are unsustainable.

1

u/mayorofdumb Feb 14 '25

Is it meth-powered?

1

u/salebleue Feb 15 '25

Depends on what you’re measuring efficiency by. To a plant its pretty efficient for its needs because it recognizes its necessities and non necessities

0

u/[deleted] Feb 13 '25

[removed] — view removed comment

21

u/glibsonoran Feb 13 '25

It's a sugar, not Rubidium: ribulose-1,5-bisphosphate carboxylase/oxygenase

1

u/tanghan Feb 14 '25

That could be useful to grow plants on mars which gets much less sunlight.

Here on earth maybe we should be careful so the modified plant doesn't out compete everything else

1

u/glibsonoran Feb 14 '25

It's useful here. All plants don't live in unfettered direct sunlight, often plants grow in canopy forests where lower level plants struggle to get enough light. Also, while the typical Calvin cycle can't really use much more light absorption than chlorophyll provides, modifications to that process (e.g. to RuBisCO and other components) can increase efficiency and output where plants can use the additional energy.

2

u/tanghan Feb 14 '25

I'm sure the plants would do great on earth, I just think they might work too good for the ecosystem in general

12

u/froschkonig Feb 14 '25

The problem is when that tree dies, the rotting process will release that stored CO2, ultimately making it a net zero in the long term. Having machines like this could help tip the balance on the net zero.

3

u/Skatterbrayne Feb 14 '25

If this process creates "sustainable fuel", you can bet that will get burned, so it's net zero too.

What we need to do is sequester carbon to take it out of the cycle. Basically bury trees or the "fuel" created in this process.

2

u/MannToots Feb 15 '25

It doesn't release it all. Some does stay locked in the soil as the tree has its carbon integrated my insects,  bacteria,  and fungus.  

17

u/[deleted] Feb 13 '25

[removed] — view removed comment

47

u/SyrioForel Feb 13 '25

For technological innovations that are realistically impossible to scale quickly enough to avoid or delay planetary catastrophe, it’s important to point this out so that people get out of this wrongheaded mindset that we can stay on course because some magic technology will come and save us.

-21

u/Recent_Night_3482 Feb 13 '25

Artificial intelligence is pivotal in accelerating the development of new technologies. Relying solely on non-technological solutions to address humanity’s challenges is likely ineffective.

25

u/SyrioForel Feb 13 '25

AL hallucinations and AI slop are not going to save you.

The issue is not a lack of technology, it’s the fact that industries will continue destroying the planet as long as governments continue to allow it.

This is not a question of scientific innovation, it’s a question of social policy. We are well past the point where any technology can realistically prevent or reverse the destruction of this planet. Time has already run out. We are about a century too late to try to stop this through technology.

-13

u/Recent_Night_3482 Feb 13 '25

You make it sound like AI hallucinations and slop are all we’ll ever get, but we’re in the infant stages of AI. Just like every technology before it, it will evolve and become more effective. At the end of the day, saving the environment will be the most profitable path forward. Whether it’s reversing damage or just keeping us alive in whatever world we create, technology will be the only way through. If we really are past the tipping point, then adaptation is all that’s left. Get ready for your great-great-grandkids to grow up in biodomes.

3

u/gearnut Feb 13 '25

AI is currently nowhere close to justifying its power usage which unfortunately is only going to grow. The nuclear industry is happily jumping into bed with data center clients due to ready availability of funds, but each plant built to power data centers is going to encourage more power usage for AI and won't be available to help decarbonise existing power supply needs.

4

u/Duckel Feb 13 '25

In 20 years AI won't have any innovation on its wiki page.

1

u/James_Vaga_Bond Feb 14 '25

As our technology has advanced, our impact on the environment has increased. Even advances in energy efficiency have been offset by increased consumption. The problem in the first place is the overuse of technology, not a deficiency of it.

3

u/Solrokr Feb 13 '25

I mean, horsepower is kind of outdated at this point. Maybe tree-power is the better alternative.

32

u/toothofjustice Feb 13 '25

Honestly I doubt it was more complex than a fully functioning biological system.

22

u/irisheye37 Feb 13 '25

More complex, probably not. Infinitely higher maintenance requirements? Undoubtedly

5

u/[deleted] Feb 14 '25

More ugly than a tree? You bet your eyes it is.

26

u/Threlyn Feb 13 '25

By complex, they were obviously referring to human implementation. Trees are complex, but planting a seed for a tree is simpler than the artificial tree from a human labor/innovation/implementation standpoint.

90

u/OnlyOneChainz Feb 13 '25

The difference is that you can place this machine anywhere there is sun. To offset the yearly human carbon emissions you'd need to roughly double the forested area of the world. It's just not an realistic option, you'd have to convert massive amounts of farmlands to forest. Theoretically, you could pop this thing down in the desert where no tree would ever grow.

96

u/D-F-B-81 Feb 13 '25

Rooftops of our big city buildings, to suck put as much from the areas that produce the most emissions would be a great place to put them.

And you already have knowledgeable maintenance crews that keep the other rooftop equipment in working order, so this could be a legitimate partial solution.

I hate how people often reject an idea because it doesn't solve the whole equation. These can play a significant role, along with other options in reducing carbon emissions.

7

u/beigechrist Feb 13 '25

This is a good thought, and who knows, maybe a lot of them could help offset the heat sink that cities have in summers.

6

u/noggin-scratcher Feb 14 '25

I would expect that "heat island" effect to be because of the materials used in city construction absorbing/retaining more heat, rather than because of any difference in local CO2 concentration.

0

u/beigechrist Feb 14 '25

It is. I’m just thinking aloud about any smaller effect by the device. Cheers

-2

u/alimanski Feb 13 '25

Unfortunately, the sheer weight of the ground and water needed for the tree makes it not feasible on many rooftops. It means the roof needs to be much stronger, meaning the entire building needs to support it, more concrete and steel, more energy and emissions, more maintenance, more costs...

13

u/Naritai Feb 14 '25

Yes, so let's put in these machines instead

19

u/TheColdWind Feb 13 '25

Check out the Sahel project in Africa. It didn’t work exactly as planned, but did work in very unexpected ways. Smithsonian magazine has an excellent article on it. It basically began as a 10 mile wide, 4300 mile long desert barrier, but wound up being a native land use project that turned vast swaths of African deserts green and allowed for more productive land use by native peoples. It was all done on a shoestring budget with local labor. Very interesting to learn about.

9

u/OnlyOneChainz Feb 13 '25

Yes I know, planting trees in the Sahel is extremely important and a fascinating project. The Chinese government did a similar thing, partly to stop sandstorms from the western deserts to reach the bigger cities to the East. (Chinese green wall). Forests do not only store carbon but have a wide array of benefits, if done correctly (focusing mainly on diverse, native species; proper management techniques etc.)

Agroforestry is another option to possible increase carbon storage in farming areas.

Planting forests can absolutely be part of the solution.

7

u/SirPseudonymous Feb 14 '25

The Chinese government did a similar thing

That project is actually ongoing. It was set up to be this huge 50 year long reforestation campaign and it's still nowhere near complete, although it's been moving faster than originally projected.

The only real problem is that while in some places it's been way more successful than expected and the forest gets wider every year, in other places it's basically just fighting to stand still and replanting the same stretches every year. Fortunately the whole project is also one big research testing ground to identify problems like that and find workable solutions to them, so hopefully they find some way around that.

There are some worries about the ground water cycle in some areas, too, with the trees sequestering water that would have otherwise gone into aquifers and losing enough of it to evaporation that it's gradually depleting said aquifers. But that's a comparatively small price to pay to stop the expansion of the desert.

4

u/TheColdWind Feb 13 '25

Was the Chinese project in the Gobi?

5

u/OnlyOneChainz Feb 13 '25

Yup. They had some initial troubles because they only used one specific poplar clone and some bug found that poplar quite delicious and had a feast but since then they have vastly ramped up the diversity and planted area and I think it has been quite the success.

1

u/TheColdWind Feb 13 '25

Even a dead tree becomes a biodiversity hotspot I think, attracts birds, they drop nutrients, attract insects, etc. I’m going to look into the project later. Tks

2

u/OnlyOneChainz Feb 13 '25

Yes, dead wood is awesome from an ecological standpoint but for carbon storage or wind protection it's obviously not ideal.

1

u/TheColdWind Feb 13 '25

Sure, of course, it’s on its way back to the atmosphere at that point.

11

u/lurkerer Feb 14 '25

We could easily reduce the amount of farmland we use by a huge amount:

In the hypothetical scenario in which the entire world adopted a vegan diet the researchers estimate that our total agricultural land use would shrink from 4.1 billion hectares to 1 billion hectares. A reduction of 75%. That’s equal to an area the size of North America and Brazil combined.

Vegan world -> Less pasture land and arable crop land needed.

Potential benefits:

Restoring ecosystems on just 15 percent of the world’s current farmland could spare 60 percent of the species expected to go extinct while simultaneously sequestering 299 gigatonnes of CO2 — nearly a third of the total atmospheric carbon increase since the Industrial Revolution, a new study has found.

A massive answer staring us in the face, and yet... But hey, people don't want to go vegan. Consider that it would take all of half a year for R&D into lab-grown meat to scale if real meat wasn't allowed. The change to diets would be temporary in exchange for saving the world.

38

u/Zvenigora Feb 13 '25

 Now you just need to make about a trillion of them, and then keep them all maintained and in working order.

40

u/Kain222 Feb 13 '25

I mean, with Climate Change, you can't let perfect be the enemy of good.

Sure, this thing won't slow stuff down on its own, but we should take every single win we can get.

16

u/OnlyOneChainz Feb 13 '25

It depends, since it's technology it could possibly made way more efficient than a tree. I agree this is probably not going to happen though.

16

u/[deleted] Feb 13 '25

[removed] — view removed comment

9

u/twystoffer Feb 13 '25

Given the flow rate and efficiency, more like 100+ trees.

However, this particular experiment was only designed to test the feasibility of solar powered carbon exchange using this particular method.

With some slight tweaks and maybe an introduction of another power source (wind or tidal), you could potentially ramp that up even further.

The biggest issue is that it creates syngas, which breaks down into CO and H if not used, and CO2 if it IS used.

But...

Considering that syngas is a precursor to fertilizer, it might be worth it...

6

u/-Ch4s3- Feb 13 '25

Carbon neutral synthetic gas seems pretty great if it’s commercially viable. If you’re just cycling CO2 out of the air, through combustion, and back into the air then you could replace a lot of things that still couldn’t be battery powered. Synthetic gas for marine fuel could be a huge benefit to overall carbon reduction insofar as it would cut a lot of net emissions.

2

u/twystoffer Feb 13 '25

That's exactly what ethanol is. We have an pretty decent abundance of carbon neutral fuels, but not nearly enough carbon extraction.

2

u/-Ch4s3- Feb 14 '25

Corn ethanol is not in any way carbon neutral. I think something like 40 gallons of diesel go into 1 gallon of corn ethanol production.

-6

u/JBstard Feb 13 '25

I don't think you're going to beat mother nature in efficiency stakes

7

u/Hei2 Feb 13 '25

Mother nature doesn't really care about efficiency; it cares about what works. There are plenty of examples of inefficient design in biology (think the recurrent laryngeal nerve in giraffes, or the optic disc in human eyes).

11

u/irisheye37 Feb 13 '25

Nature has far more variables than the efficiency of a single task.

4

u/Fr00stee Feb 13 '25 edited Feb 13 '25

since corporations only do things if they can make money, some chemical/oil corp would love to be able to put these things everywhere and keep using the output to power gas engines. The only feasible way I see to get these corps to do something that would fix the planet.

2

u/KnottShore Feb 13 '25

The probable case for a chemical/oil corp is to buy an exclusive license and kill the technology.

2

u/Fr00stee Feb 13 '25

there researchers can just patent it then give the ability to use it for free

2

u/bielgio Feb 13 '25

Won't get funding or subsides required

Pay attention, we either have a monopoly or the government to have innovation at scale, right now the richest country in the world has no government

1

u/Fr00stee Feb 13 '25

this is from the UK so idk

1

u/Naritai Feb 14 '25

sure it will, we don't need this kind of doomerism

1

u/klingma Feb 14 '25

Okay? What's the problem though? 

Our issue is that climate change is causing havoc across the Earth and if we can't motivate people to do something about it out of the goodness of their hearts but we can with money, we still accomplish the same end goal, right? 

We don't criticize dogs who follow commands because they want a treat, why would we criticize someone who wants to do something about climate change but also make money? In scenario one the dog sits and in scenario two we get progress fighting climate change. 

0

u/Fr00stee Feb 14 '25 edited Feb 14 '25

there is no problem? I was just saying that it might be a viable solution since companies don't really want to do anything about climate change using current technologies

-2

u/Opie67 Feb 13 '25

Why is it the people that panic and cry about climate change the most are viciously against any real potential solutions

1

u/ThrowbackPie Feb 14 '25

We aren't. But we are very frustrated that our solution is to keep destroying the natural world and replacing it with machines.

2

u/eagee Feb 13 '25

Um, have you never been to the mojave and sonoran deserts? There's a lotta space there with endless supplies of sunshine.

3

u/polypolip Feb 13 '25

You could turn most of the farmlands into forests if humanity stopped breeding cows.

1

u/Naritai Feb 14 '25

Any plan that involves "If everyone would just..." is a stupid plan

4

u/noggin-scratcher Feb 14 '25

If you need 100% participation then sure, such plans are implausible.

But often a statistic like "if everyone would X, then Y" remains true of "if 10% of people would X, then 10% of Y" and the stronger statement is an illustration of the upper limit of potential.

1

u/AlkaliPineapple Feb 14 '25

Or we could just... Strike the source and lower carbon emissions? I have no doubt that the production of these things would release more carbon dioxide than it absorbs

16

u/FreshlyHawkedLooge Feb 13 '25

This viewpoint is often used as a funny "gotcha", but the real problem is that fossil fuels have disrupted the carbon cycle and planting trees everywhere only temporarily traps carbon.

Carbon needs to be more permanently sequestered and removed from the atmosphere to ultimately return carbon dioxide levels to appropriate levels. Trees capture carbon but release it back when they die.

This technology is important and it's not solving the problem it seems you seem to think it is. "Hur dur trees go brrrr" is oversimplifying the problem.

7

u/neizan Feb 14 '25

A new forest is a permanent reservoir of carbon. As one tree dies another takes its place. Of course a mature forest is in equilibrium, but while a forest is growing it is a carbon sink. 

4

u/ThrowbackPie Feb 14 '25

Isn't it still a sink as carbon is slowly stored in soil? Or is my understanding of oil outdated.

4

u/FreshlyHawkedLooge Feb 14 '25

The key is in the rate, though I believe mature forests are net neutral. The sinks, buried organic material that is effectively removed from the carbon cycle, are at a lower rate than the oil, natural gas, and coal we're unearthing.

https://ocean.si.edu/conservation/gulf-oil-spill/what-are-fossil-fuels

Before the industrial revolution, coal, gas, and oil deposits were largely untouched and Earth's surface was covered in whatever growth it could maintain, generally speaking. Covering the Earth back in whatever growth can be maintained still doesn't account for all of the carbon we dug up.

Ergo, trees cannot rescue us... we need to remove carbon from the carbon cycle by artifical or heavily expedited natural processes or suffer the green house effects of daid carbon.

https://earthobservatory.nasa.gov/features/CarbonCycle

1

u/neizan Feb 14 '25

I am not an expert!

But, my understanding is that on some time scale the forest will reach equilibrium. Peat bogs can accumulate carbon long term, but I think that growing forests eventually reach a steady state maximum for carbon storage including in the soil and understory - I think that carbon can leach away via biological processes and via water erosion.

2

u/Kazruw Feb 14 '25

There is also the question of what is some with the trees. If they’re for example used to build houses then the carbon continues to be trapped long term and the more trees you grow the more carbon is captured.

1

u/neizan Feb 14 '25

Yep, that's true on some sort of timescale. Wood used as timber has a lifetime of decades, I'd say. Definitely long enough to be useful as a reservoir of carbon.

2

u/Kazruw Feb 14 '25

If we are looking past useful use cases for wood then one could just simply bury it in sufficiently stable conditions underground.

3

u/BananaUniverse Feb 13 '25

What about algae? It can spread out over a wide surface area and capture light better than leaves can.

1

u/isamura Feb 13 '25

They’ve monetized trees, again!

-7

u/LakeSun Feb 13 '25

No...what happens after you burn this new fuel...CO2.

21

u/ennuiui Feb 13 '25

The means that the fuel source is carbon neutral since the whole process adds as much carbon as it removes. That is certainly much better than the use of fossil fuels.

-4

u/LakeSun Feb 14 '25

It's carbon neutral but we need carbon Negative.

3

u/jdmetz Feb 14 '25

Don't burn some of the fuel you produce? Refill abandoned oil with it or something.

Carbon dioxide is about as low energy as you can get, so any way we take carbon out of the atmosphere (other than just concentrating CO2) is going to result in something higher energy that could be considered a "fuel" if we choose to burn it.

0

u/ExpeditingPermits Feb 14 '25

Yea, but how profitable are trees? Unfortunately, they are not.