Using copper to convert CO₂ to methane
phys.org
phys.org
> Carbon dioxide offers a unique opportunity as a feedstock for energy production through electrocatalysis. Methane production holds promise for its widespread applications and market demand. However, commercial viability faces challenges of low selectivity, current density, and high applied potential. Efforts to improve methane selectivity while suppressing multi-carbon products, e.g., ethylene, often involve lower alkalinity electrolytes. However, it reduces current density due to increased ohmic resistance without significant gains in the reaction yield. This study utilizes quantum mechanics computations to design a nano-cluster copper catalyst that redirects the reaction pathway from ethylene towards methane, even under alkaline conditions. We achieved a Faradaic efficiency (FE) of 85 %, a current density of 1.5 A/cm2, and stability of over 10 hours solely by controlling particle size in copper catalysts. This work paves the way to overcoming current limitations in electrocatalytic methane production and holds broader implications for advancing sustainable CO2 utilization in energy systems.
Also of interest - could this electrochemical setup be run in reverse, as a methane fuel cell? That I'm aware of, 85% efficiency would be far better than the current state of the art there.
AFAIK, ceramic membranes work perfectly well as exchange elements for hydrocarbon-oxygen fuel cells; but I have no idea why they aren't being used everywhere. It used to be mostly due to longevity issues, but I haven't kept up.
Also, Faradaic efficiency is not the total efficiency. For a fuel cell it would automatically be close to 100% anyway, while total efficiency is normally much lower.
Especially if said contaminants include stuff like H2C2. That can be rather explosive. And might accumulate somewhere in the plumbing, unsuspected until ...
Ethylene, on the other hand, is a chemical feedstock used for many products. There's been a longstanding effort to upgrade methane to ethylene because the latter is so much more valuable.
For on-site "methane battery" uses, it's probably fine if your methane is fairly contaminated with a known-when-you-designed-the-system mess of somewhat-higher hydrocarbons.
But from a quick search, gas and power utilities seem very much concerned with higher hydrocarbons in their methane. And "higher" = "worse". Which makes sense. Those would alter the proper fuel/air ratios, and probably impact emissions. And they do not want liquid hydrocarbons to condense inside their high-pressure gas lines in cold weather, then cause "water hammer" damage to equipment.
Is there demand for methane? Why are there so many methane flares at oil wells in Texas, then?
At the rate solar, wind, and batteries are coming along, carbon capture is a waste of time and resources. Price alone is going to eliminate most demand for carbon based fuels. This is happening much faster than expected. See last week's Economist.
From what I know it is just cheaper to flare natural gas that occurs as byproduct of oil production than to deal with it otherwise.
In general, starting from methane you can then work your way up to all sorts of various hydrocarbons like gasoline or jet fuel.
Methane is also the propellant of SpaceX's Starship. If they launch as frequently as they want to launch, Elon will likely invest in local zero-carbon production of methane using techniques like the OP.
Flaring is more cost effective at current prices
- Methane is 28x more potent as a greenhouse gas than CO2 is. I'm rusty on my chemistry but it seems like CH4 + 2 O2 => CO2 + 2 H2O, so by flaring it you're getting a 28x reduction in GHG potential even though it looks bad seeing it burning like that.
- The infrastructure isn't in place to harvest, liquify, and transport methane from oil fields. Oil itself is relatively easy to transport away from oil fields to refineries, while natural gas needs near-site processing to turn it into a liquid and keep it compressed. You also would need to build out (smaller) pipelines to transport it from the oil field to the existing natural gas handling infrastructure which may not be nearby.
It's one of those things where it's basically free coming out of the well but a big investment would be required to capture it and, assuming you're going to be pulling the oil out anyway, burning it is better for the environment than just venting it.
Edit: I do recall recently reading about some tech though where they were going to start using it on-site for fuel for equipment. I think it was for on-site generators instead of using electricity from the grid, but I don't have a link handy.
https://www.crusoe.ai/blog/turning-waste-into-power-crusoes-...
"Copper nanoclusters: Selective CO2 to methane conversion beyond 1 A/cm²" (2024) https://www.sciencedirect.com/science/article/pii/S092633732...
Additionally, I recently discovered a company Valar Atomics who are working on small scale nuclear reactors to produce methane from h2o and co2 using this method.
- Valar Atomics announcement https://x.com/isaiah_p_taylor/status/1720418162985054350?s=4...
The idea is not new, but it is not bad https://en.m.wikipedia.org/wiki/Power-to-gas
- creating H2 from H2O - concentrating CO2 from either the atmosphere or the waste products of an industrial process such as cement production - creating CH4 from the H2 and the CO2. AKA Sabatier.
This paper uses H2 as an input, so is only talking about the last step. A cheaper/better Sabatier is nice, but AFAICT it's the least expensive step of the three.
How can that be surprising for “a new catalyst for converting carbon dioxide (CO2) into methane”? Are there any catalysts where their effectiveness doesn’t increase with surface area?
Also, if they make them tiny (“we used copper catalysts with different sizes, from small ones with only 19 atoms to larger ones with 1000 atoms”), how do you make sure you don’t pump out the catalyst with the methane? A filter?
How expensive is this process?
Is it feasible to scale this?
Are other catalysts better than this one at producing methane from CO2?
The current synthesis process starts with oil. I imagine through hydrogenation.
The idea here is producing methane as a battery. A solarfarm would be upgraded to a power plant that generates electricity all day. That's it
That's it, but that would be incredibly valuable, as the big downside of solar is that it only works during the day, and only really works for the peak part of the day, maybe 6-8 hours depending on where you are.
The question will be is this process to store solar energy as methane cheaper (bottom line, i.e. accounting for losses in turning it back into electricity later) than storing it in batteries.
Germany needs about 300GW in winter once it switches to electric heating and EVs. In winter, renewables regularly drop to about 10% of their average production for weeks at a time. So Germany will need to import about 250GW of power from its neighbors. That also need power for their own use.
This is just not feasible.
So the plan right now is to replace the coal generation with natural gas generation, and color the pipes in green paint. Oh, and make the companies to pinky-promise that they are "hydrogen ready".
A kilogramme of hydrogen - the unit most often used – has an energy value of about 33.3 kWh.[1] So a tonne of hydrogen delivers about 33 MWh and a million tonnes about 33 terawatt hours (TWh). To provide a sense of scale, the UK uses about 300 TWh of electricity a year.
It takes a good while to build out the physical infrastructure to deliver green hydrogen equivilants:
Green hydrogen is made from renewable energy, producing zero pollution – its only by-product is steam. FFI’s ambition is to grow its green hydrogen production to 15 million tonnes of green hydrogen per year by 2030, accelerating to 50 million tonnes per year in the next decade thereafter.
The person doing this isn't in the "pinky promise" game, they built out a penny stock company from 2c a share to ~$28 a share over two decades to capture a large chunk of a billion tonne per annum raw iron ore market.
Yeah, swindling governments is a profitable business.
“So the plan right now is to replace the coal generation with natural gas generation, and color the pipes in green paint.” - eh no. This is not “the plan” although getting rid of all coal is part of the plan.
It is: https://www.reuters.com/business/energy/germany-agrees-subsi...
> The ministry said hydrogen transition plans should be drawn up by 2032 to enable the plants to be fully switched to hydrogen between 2035 and 2040.
> "Germany last year agreed with the European Commission to tender 8.8 GW of new hydrogen plants, and up to another 15 GW that will run initially on natural gas before being connected to the hydrogen grid by 2035 at the latest, but Berlin and Brussels have disagreed on how the gas plants would be subsidised."
So basically, Germany is _paying_ companies somewhere around $20B to build new gas power plants and make _plans_ to switch to hydrogen by 2032. The switch itself can go into 2040-s.
Realistically, long-term hydrogen storage is the only technology that is even remotely feasible. There are several demonstrator projects ongoing right now. I'm personally not too optimistic about them.
Not to say that there are no grounds for criticizing German policy but most of the criticism seems to be politically motivated rather than based on specific failures of the policy.
Secondly, why hydrogen? It's a potent greenhouse gas - GWP100 of 12 or 13 times that of CO2. Yes it's less potent than methane but it's far "leakier" and more difficult to contain than methane as well as being more dangerous and difficult to handle. It cannot be combusted in air (most are suggesting mixing it with methane) in a domestic setting because of the 10 times as much NOx caused by the higher burning temperature. While all the infrastructure for methane/natural gas already exists including long term (seasonal) storage facilities, I see no compelling reason to spend 100s of billions to build all this new infrastructure to use a different warming gas for energy storage and transport.
To be honest it's a minor issue in the grand scheme of things - keeping natural gas around to cover the last 10% of electricity generation is no big deal as the world rushes to electrify the other activities which currently release large amounts of CO2. The focus should be on getting to that 80-90% carbon-free electricity and the electrification of as much as is possible of pollution sources like domestic heating/cooking, transport and heavy industry.
Sure. The good old coal power plants and natgas turbines are extremely reliable and capable.
As for Germany being an exporter, Sweden and Norway both have recently declined to expand their interconnects with Germany. They don't want their local markets to be swamped by cheap low-quality power during the summer, and then squeezed during the winter when German renewables are greatly diminished.
> Not to say that there are no grounds for criticizing German policy but most of the criticism seems to be politically motivated rather than based on specific failures of the policy.
The specific failure of the policy is simple. Germany's power is DIRTY. And it's not getting any better.
> Secondly, why hydrogen?
Because there are no alternatives. Power-to-methane is going to be about 3-4 times more expensive than pure hydrogen. And again, this is not my personal preference, but the official policy of the German state.
> To be honest it's a minor issue in the grand scheme of things - keeping natural gas around to cover the last 10% of electricity
It won't be 10%, more likely 30% once Germany switches to electric heating and EVs. This switch right now is being held back by horribly high energy cost.
Elections carrying electricity do not have the quality of being “cheap” or “low quality”. If you’re convinced that there is some measurable difference between an electron produced by a hydro-power turbine and one from a coal plant, then I don’t think we have any basis for further discussion.
Sorry. Just reporting the news: https://www.reuters.com/business/energy/swedish-government-s...
> Elections carrying electricity do not have the quality of being “cheap” or “low quality”.
They do. Because electrons, that are forced to move by the wind, cease moving when there's no wind. And this happens for weeks at a time in winter in Germany.
There's a fix for that: capacity markets. In essence, if you can guarantee that your source of electrons will always be available, you get paid for that. Europe has pledged to "do something" about that EU-wide by 2028.
Here's the article: https://industrydecarbonization.com/news/is-there-a-place-fo...
I had posted it on HN, but didn't get upvoted.
> For companies seeking to use e-methane, it usually means their technology and production processes don't have to change. They are merely buying e-methane that has already been subsidized elsewhere.
I feel like things like e-methane are attractive when you're thinking like an MBA where your first instinct is to preserve the value you of your capital assets and suppress competition.
Good: Pretend we can use e-methane to fuel our existing Direct reduced iron (DRI) plants. Advantage you kick the can down the road and when it fails you're either already gone or can blame the government for interfering.
Bad: Admit direct electrolytic reduction processes will obsolete all your equipment. Disadvantage watch the market price in the future value of your company.
Liquified natural gas might still have few decades for certain industries, but with electrification underway for pretty much everything all these processes seem pointless.
Sure you could capture CO2 from a plant, liquify, ship to where sun shines, convert to CNG, then ship back. Or you could just build power lines.
If this finding is worth it, strap the machine doing it onto a car with methane motor (already exists) and you'll have an Perpetuum mobile.
It is directly addressed.
Excess solar power pulls excess co2 from atmosphere, and puts it into methane, which is stored.
It can then be sequestered (carbon captured), or burned (carbon neutral energy storage).
So its not a game changer, its barely even relevant to the CO2 levels. Might have some applications but its not the solution it is presented as (Like the previous "solutions" that cropped up every other week on HN and are now long forgotten).