The self-taught ChemE in me worries a little about any process that makes a solid product since that product could plate out inside the machine and clog it up, but maybe that's not really a problem here.
I don’t understand how HN works I guess; I submitted this exact article 24 hours ago, yet the hivemind has yet to call this a dupe. Not complaining, just truly don’t get it. When I submit a dupe it tells me?
I think in HN terms "dupe" means this story was on front page for some time and got some discussion, just a previous submission with few upvotes and no comments doesn't count as a dupe if it's clear it hardly can get on front page now (older than n hours).
Totally misleading and editorialized title!
No.
The reactor CONSUMES energy. Pyrolysis is endothermic bro. They're running a furnace at 1300°C. That heat comes from somewhere. The reactor produces hydrogen, which is an energy CARRIER, not a source. And the energy content of the hydrogen output is less than the methane input plus the heat dumped in. This is thermodynamics. You don't get to call an energy-losing conversion process "producing energy."
Let's look at the numbers. The energy to split one mole of CH4 (i.e. 16 grams) into C and 2H2 is 74.6 kJ. If you burn that carbon you get 393.5 kJ and if you burn the hydrogen you get 483.6 kJ [1].
> And the energy content of the hydrogen output is less than the methane input plus the heat dumped in. This is thermodynamics.
You are right, but you forgot something. You are not creating the methane. You are extracting it from the ground. The energy content of the hydrogen is only 60% of the energy content of the methane you use to get it, and if you account for the energy to split the CH4, you are left with only 50% of the original energy of the methane. But then you get hydrogen that can generate emissions-free electricity. It's a good trade off.
Math seems wrong "The team found that the loop design would convert 75% of the gas entering the system into useful resources, producing carbon nanotubes and hydrogen in a 3:1 mass ratio. In other words, for every 4 kilograms of methane the system successfully converts into useful resources, it makes 3 kilograms of nanotubes and 1 kilogram of hydrogen."
The 75% and the 3:1 ratio are not related. Methane has the formula CH4, so for 12 grams of carbon you have 4 grams of hydrogen. If you successfully break down the molecule CH4 you get a carbon-hydrogen ratio of 3:1. Now, let's say you start with 5.33 kg of methane. Only 75% gets converted, so that's 4 kg. Of that, you get 3 kg of carbon and 1 kg of hydrogen.
Calling H2 clean energy is dumb. We currently use millions of tonnes of H2 every year, almost all of that being significantly more carbon intensive. Until that stuff has been replaced, using new H2 for “energy” is wasteful, stupid, or predatory delay.
Wasting it as a “clean” fuel is not clean though. There are emissions at: 1) production, 2) usage, and 3) the averted emissions due to this being used.
As a fuel, the alternatives are electricity for land and biofuels for land and sea.
But as a chemical feedstock the alternator is dirtier hydrogen.
So wasting this as a fuel means that you aren’t replacing dirty hydrogen with it, but rather cleaner electricity.
When carbon byproducts are produced from these kinds of reactions, are they "pure" carbon, or will there be residues from the impurities in the methane?
The reason I ask is I wonder if the carbon could be used as a soil amendment to help replenish top soils in agriculture, or as a growing medium generally. But this would only be conceivable if it's just carbon.
ScholarlyArticle: "Production of hydrogen and carbon nanotubes from methane using a multi-pass floating catalyst chemical vapour deposition reactor with process gas recycling" (2025)
https://www.nature.com/articles/s41560-025-01925-3
It has nothing to do with clean energy, other than the downstream effects of cheap CNTs should the process be refined enough to scale and commercialize. The hydrogen is recycled in the process. The primary thing that it produces are CNT aerogels. However according to the paper catalyst efficiency is shit. Says less than 0.1% of catalyst particles actually grew CNTs. No wonder CNTs are currently ≥$200/kg. Needs improvement by either dramatically increasing catalyst efficiency or finding dirt cheap iron/sulfur sources.
Carbon fouling is also a major block to scale. 15-20% of carbon deposits as soot on reactor walls. At a 1MW scale thats 15-30 kg/h of crud degrading the catalytic heat transfer. Continuous cleaning or scheduled downtime would drive OPEX out of possible realities.
Hot hydrogen loops are a son-of-a-bitch and equal continuous embrittlement of pipes, valves, pumps. Seals that work at temperature. H2 Leak detection. Some real heavyweight process safety engineering here.
The reactor chemistry is solved. The paper proves it works.
The scale-up is where clean-tech startups go to burn money and die.
Would an electrochemical plasma process that takes graphene filters caked in CO2 (for e.g CNT production) be more useful?
Aluminum red mud is 40% iron.
Is hydrogen useful for plasma enhanced CVD?
Are there electrical plasma improvements to CVD specifically for CNT carbon nanotube production?
What optimizations of CVD produce nonmetallic aligned carbon nanotubes (with band gaps useful for semiconductor production for FET field-effect transistors, and integrated optical components)?
From gemini3pro, for human consideration;
> [ PECVD: Plasma-enhanced CVD] allows VA-CNT synthesis at temperatures as low as 450–650°C
> High-flux hydrogen (H_2) carrier gas is used in floating-catalyst CVD (FCCVD) to reduce the number of nuclei, favoring isolated semiconducting nanotubes over bundled metallic ones.
> Electric Field Alignment: PECVD uses the built-in electric field of the plasma sheath to guide nanotubes into vertical or horizontal alignment as they grow.
> [ Kite growth CVD with nonmetallic seeds like nanodiamond grow in tip-growth mode ]
Which would be useful for FET in Carbon-based chips
Couldn't hydrogen (cold) plasma clean a CVD reaction chamber?
There will be more atomic C in the upper layers of the Earth if you dig deep and pump out natural gas.
How long will the C atoms in those "stable product" stay there?
Burning wood is clean energy: it does not increase the number of atomic C in the upper layers. Natural gas is not, unless you find a way to store those C.
That sounds perfect. Except natural gas is a hydrocarbon, isn't it? Which means the processing is dirty at source? This idea of natural gas as a clean energy is rather the same as clean coal. In other words it's greenwashing.
This also produces carbon nanotubes, which they claim can be used in construction.
Given that construction currently uses a huge amount of concrete, and given that concrete emits huge amounts of CO2[1], if this could partially replace concrete in construction, it might actually be clean. At least compared to what we're doing now.
I doubt foundations are going to be made out of carbon nanotubes, but they might be useful for the structure (columns, beams, etc.).
The problems with natural gas are definitely not confined to combustion. Methane leakage is a huge problem.
That and if you just encourage more exploration, and it's cheaper to just burn the stuff anyways, guess what happens in the price conscious free market?
Wrong. First of all only 25% of the natural gas inserted into the reactor are converted (with the rest presumably resulting in emissions) and natural gas also produces emissions during exploration and exploitation
A big research area, see "Turquoise Hydrogen"
https://www.aga.org/its-time-to-pay-attention-to-turquoise-h...
in contrast to "Grey Hydrogen" [1] made by steam reforming
https://en.wikipedia.org/wiki/Steam_reforming
The self-taught ChemE in me worries a little about any process that makes a solid product since that product could plate out inside the machine and clog it up, but maybe that's not really a problem here.
[1] "Blue" if you capture the CO2
I don’t understand how HN works I guess; I submitted this exact article 24 hours ago, yet the hivemind has yet to call this a dupe. Not complaining, just truly don’t get it. When I submit a dupe it tells me?
Things take longer this time of year, and fake internet points never matter anyway.
I think in HN terms "dupe" means this story was on front page for some time and got some discussion, just a previous submission with few upvotes and no comments doesn't count as a dupe if it's clear it hardly can get on front page now (older than n hours).
Could be the time of day?
dupe: https://news.ycombinator.com/item?id=46368776
It didn't show any matching posts when I shared the URL.
ENH: HN: search for matching articles on debounced update to the submit URL field
Totally misleading and editorialized title! No. The reactor CONSUMES energy. Pyrolysis is endothermic bro. They're running a furnace at 1300°C. That heat comes from somewhere. The reactor produces hydrogen, which is an energy CARRIER, not a source. And the energy content of the hydrogen output is less than the methane input plus the heat dumped in. This is thermodynamics. You don't get to call an energy-losing conversion process "producing energy."
Let's look at the numbers. The energy to split one mole of CH4 (i.e. 16 grams) into C and 2H2 is 74.6 kJ. If you burn that carbon you get 393.5 kJ and if you burn the hydrogen you get 483.6 kJ [1].
> And the energy content of the hydrogen output is less than the methane input plus the heat dumped in. This is thermodynamics.
You are right, but you forgot something. You are not creating the methane. You are extracting it from the ground. The energy content of the hydrogen is only 60% of the energy content of the methane you use to get it, and if you account for the energy to split the CH4, you are left with only 50% of the original energy of the methane. But then you get hydrogen that can generate emissions-free electricity. It's a good trade off.
[1] https://en.wikipedia.org/wiki/Standard_enthalpy_of_formation...
Sure but if you attached a hydrogen burner would it be net positive?
Then wouldn’t you have a cleaner energy system then burning the methane directly?
Math seems wrong "The team found that the loop design would convert 75% of the gas entering the system into useful resources, producing carbon nanotubes and hydrogen in a 3:1 mass ratio. In other words, for every 4 kilograms of methane the system successfully converts into useful resources, it makes 3 kilograms of nanotubes and 1 kilogram of hydrogen."
The 75% and the 3:1 ratio are not related. Methane has the formula CH4, so for 12 grams of carbon you have 4 grams of hydrogen. If you successfully break down the molecule CH4 you get a carbon-hydrogen ratio of 3:1. Now, let's say you start with 5.33 kg of methane. Only 75% gets converted, so that's 4 kg. Of that, you get 3 kg of carbon and 1 kg of hydrogen.
(I had to reread that paragraph a couple times too)
Are the max yield and the yield efficiency numbers mixed up?
Calling H2 clean energy is dumb. We currently use millions of tonnes of H2 every year, almost all of that being significantly more carbon intensive. Until that stuff has been replaced, using new H2 for “energy” is wasteful, stupid, or predatory delay.
That.. is the whole point of the reactor? It produces clean H2 to make it worthwhile as a clean fuel.
Currently H2 is clean only at the usage stage, not at the production stage. Just like electricity for EVs in Germany :)
Wasting it as a “clean” fuel is not clean though. There are emissions at: 1) production, 2) usage, and 3) the averted emissions due to this being used.
As a fuel, the alternatives are electricity for land and biofuels for land and sea.
But as a chemical feedstock the alternator is dirtier hydrogen.
So wasting this as a fuel means that you aren’t replacing dirty hydrogen with it, but rather cleaner electricity.
At least electricity is easier to transfer and use than H2 which is brittle pain all the way. Methane is more useful as a fuel.
When carbon byproducts are produced from these kinds of reactions, are they "pure" carbon, or will there be residues from the impurities in the methane?
The reason I ask is I wonder if the carbon could be used as a soil amendment to help replenish top soils in agriculture, or as a growing medium generally. But this would only be conceivable if it's just carbon.
It extremely depends on the exact reactions. I'm not a chemist but AFAIK carbon nanotube production doesn't like taking in non-carbon atoms.
Things like crystallization reactions will produce very pure products, some other reactions will absorb more contaminants.
almost certain to be uneconomical.
ScholarlyArticle: "Production of hydrogen and carbon nanotubes from methane using a multi-pass floating catalyst chemical vapour deposition reactor with process gas recycling" (2025) https://www.nature.com/articles/s41560-025-01925-3
Oh come on. Produces 'clean energy' from natural gas? Yeah of course.
It has nothing to do with clean energy, other than the downstream effects of cheap CNTs should the process be refined enough to scale and commercialize. The hydrogen is recycled in the process. The primary thing that it produces are CNT aerogels. However according to the paper catalyst efficiency is shit. Says less than 0.1% of catalyst particles actually grew CNTs. No wonder CNTs are currently ≥$200/kg. Needs improvement by either dramatically increasing catalyst efficiency or finding dirt cheap iron/sulfur sources.
Carbon fouling is also a major block to scale. 15-20% of carbon deposits as soot on reactor walls. At a 1MW scale thats 15-30 kg/h of crud degrading the catalytic heat transfer. Continuous cleaning or scheduled downtime would drive OPEX out of possible realities.
Hot hydrogen loops are a son-of-a-bitch and equal continuous embrittlement of pipes, valves, pumps. Seals that work at temperature. H2 Leak detection. Some real heavyweight process safety engineering here.
The reactor chemistry is solved. The paper proves it works.
The scale-up is where clean-tech startups go to burn money and die.
Would an electrochemical plasma process that takes graphene filters caked in CO2 (for e.g CNT production) be more useful?
Aluminum red mud is 40% iron.
Is hydrogen useful for plasma enhanced CVD?
Are there electrical plasma improvements to CVD specifically for CNT carbon nanotube production?
What optimizations of CVD produce nonmetallic aligned carbon nanotubes (with band gaps useful for semiconductor production for FET field-effect transistors, and integrated optical components)?
From gemini3pro, for human consideration;
> [ PECVD: Plasma-enhanced CVD] allows VA-CNT synthesis at temperatures as low as 450–650°C
> High-flux hydrogen (H_2) carrier gas is used in floating-catalyst CVD (FCCVD) to reduce the number of nuclei, favoring isolated semiconducting nanotubes over bundled metallic ones.
> Electric Field Alignment: PECVD uses the built-in electric field of the plasma sheath to guide nanotubes into vertical or horizontal alignment as they grow.
> [ Kite growth CVD with nonmetallic seeds like nanodiamond grow in tip-growth mode ]
Which would be useful for FET in Carbon-based chips
Couldn't hydrogen (cold) plasma clean a CVD reaction chamber?
I'm a hardline no-fossi-fuels ever kind of guy and yes, this is clean energy.
If you collect the pollutants before emitting them and turn them into stable products, you aren't polluting.
Ergo, clean.
There will be more atomic C in the upper layers of the Earth if you dig deep and pump out natural gas.
How long will the C atoms in those "stable product" stay there?
Burning wood is clean energy: it does not increase the number of atomic C in the upper layers. Natural gas is not, unless you find a way to store those C.
Charcoal is stable for hundreds of years in the upper layers of the soil
Resource extraction is pretty much never a clean process. That gas came from somewhere.
That sounds perfect. Except natural gas is a hydrocarbon, isn't it? Which means the processing is dirty at source? This idea of natural gas as a clean energy is rather the same as clean coal. In other words it's greenwashing.
This also produces carbon nanotubes, which they claim can be used in construction.
Given that construction currently uses a huge amount of concrete, and given that concrete emits huge amounts of CO2[1], if this could partially replace concrete in construction, it might actually be clean. At least compared to what we're doing now.
I doubt foundations are going to be made out of carbon nanotubes, but they might be useful for the structure (columns, beams, etc.).
---
[1] "4-8% of total global CO2" according to https://en.wikipedia.org/wiki/Environmental_impact_of_concre...
> Except natural gas is a hydrocarbon, isn't it?
Why is that disqualifying?
The problem is combustion’s emission of sequestered carbon. If you don’t have that you don’t have this problem.
The problems with natural gas are definitely not confined to combustion. Methane leakage is a huge problem.
That and if you just encourage more exploration, and it's cheaper to just burn the stuff anyways, guess what happens in the price conscious free market?
Nice job conveniently ignoring the dirty processing problem.
> ignoring the dirty processing problem
You concluded it’s processed dirtily at the source based on that premise (“which means”). If you’re independently asserting that, you’d have a point.
Not sure what's wrong here. They said clean, not renewable right?
It's clean, but it's still non-renewable. Oil companies have to keep finding ways to greenwash themselves.
Yes, did you read it? Hydrogen and solid carbon, so the result is no greenhouse gas emissions.
Wrong. First of all only 25% of the natural gas inserted into the reactor are converted (with the rest presumably resulting in emissions) and natural gas also produces emissions during exploration and exploitation