New inexpensive iron catalyst converts CO2 to methane.

July 23, 2017 8:54 PM

Visible-light-driven methane formation from CO2 with a molecular iron catalyst Doesn't seem like the efficiency is enough yet but seems promising.
posted by aleph (14 comments total)

How's it smell?
posted by Abehammerb Lincoln at 8:57 PM on July 23, 2017

Methane is actually pretty much odorless. You're thinking of other chemicals present in some of the best-known methane sources - hydrogen sulfide, methanethiol, dimethylsulfide and other volatile sulfur compounds are all pretty odoriferous.

(I tend to think that biological methanogenesis is a way cooler way to go from carbon dioxide to methane, but I admit that as a biochemist, I'm professionally biased towards the use of biological systems to do weird chemistry under relatively mild conditions.)
posted by ubersturm at 9:15 PM on July 23, 2017 [1 favorite]

So let me get this straight: we've figured out a process that will, with very low efficiency, convert CO2, a mild greenhouse gas, into methane, a much more potent greenhouse gas.

This is really cool development, but the opening sentence of that abstract is creepily tone deaf.
posted by phooky at 9:31 PM on July 23, 2017 [15 favorites]

So how does this method of converting CO₂ to methane compare to, say, a pasture?
posted by Sys Rq at 9:39 PM on July 23, 2017 [3 favorites]

Is this a device to create Methane to burn, and then reconvert the CO2 back to Methane to burn again? Will it be a closed loop of some sort where the sun and a catalyst does the recombining?
posted by Oyéah at 9:45 PM on July 23, 2017 [1 favorite]

Collection is a significant obstacle to pastoral sourced methane.
posted by wierdo at 9:46 PM on July 23, 2017 [2 favorites]

A real shame, given all the pews.
posted by dsword at 10:15 PM on July 23, 2017 [6 favorites]

Is this a device to create Methane to burn, and then reconvert the CO2 back to Methane to burn again? Will it be a closed loop of some sort where the sun and a catalyst does the recombining?

That'd be the approach. CO2 capture is plausible at the point of concentrated emissions, so if you could put one on a methane plant you could reduce emissions and methane consumption significantly (say, 80%.)

The appeal of these mitigation approaches is you can ramp down CO2 emissions at existing plants and 'retire' emissions far faster than any feasible timeline that imagines replacing all fossil fuel production. A lot would have to come together just right for the economics to work out that way in practice.
posted by mark k at 10:47 PM on July 23, 2017 [1 favorite]

Collection is a significant obstacle to pastoral sourced methane.

Not if methane-burning drones are deployed to position collection umbrellas over the hoofed mobile pastoral methane emitters.

And another tier of drones collecting the CO2 emissions of the first layer of drones.
posted by Laotic at 12:32 AM on July 24, 2017 [1 favorite]

>>>Methane is actually pretty much odorless.
Aha !! a plumber friend who works at our town sewerage works says it stinks when you burn it.
A quick google search didn't tell me what it does smell like when burnt. CH4
posted by Narrative_Historian at 1:19 AM on July 24, 2017 [1 favorite]

The comment about making a more potent green house gas is an issue, sure.

But what about the "loose" Hydrogen? Large scale Hydrogen gas production runs the risk of H2 leaks and the H2 interacting with the O3 in the upper atmosphere. The abstract doesn't point out if the process uses H2 gas or gets the H from water.
posted by rough ashlar at 2:04 AM on July 24, 2017

Will it be a closed loop of some sort where the sun and a catalyst does the recombining?

Unfortunately, as disclosed this is not a closed loop, but requires a constantly renewed electron source (triethylamine, or TEA). The use of iron as the primary metal center for the catalyst (cheap, abundant, and non-toxic) and ambient pressure and temperature are quite promising, but this still requires expensive fuels and iridium to proceed, not to mention accounting for the fact that you're turning one greenhouse gas (CO2) into a much more potent greenhouse gas (CH4).
posted by Existential Dread at 8:47 AM on July 24, 2017 [1 favorite]

So let me get this straight: we've figured out a process that will, with very low efficiency, convert CO2, a mild greenhouse gas, into methane, a much more potent greenhouse gas.

But that's also how it works for some biofuels generated via Bio-energy with carbon capture and storage BECCS. Simply capturing carbon from the air and sequestering it is not economically viable, so you do something like capture it from the air via plants and turn it into fuel that can be sold for energy, with intent to capture the resulting CO2 captured for storage. Yes, methane is a more potent greenhouse gas, but where do our supplies for natural gas power plants currently come from? Fossil fuel extraction. Fracking in particular has made natural gas pretty cheap. This technology is one that cuts out growing plants. Biofuels pose their own problems when the plants are from sources worse for emissions (I think fermentation of seaweed for methane will be best for this, but I'm not an expert).

You still need to sequester the CO2 from burning the fuel to make it CO2 negative. Otherwise it's just carbon neutral (that's good too) assuming all inputs are renewable on the balance. So just a tool in a set of tools for fighting emissions. We need all of them. IPCC's best case scenarios for staying under 2 degrees Celsius by 2100 require carbon sequestration of some level by the latter half of the century. So we need all the low cost ways to pull and use CO2 from the air as we can. Basic research like this is required. We are past the point where zero to low carbon emissions will keep us from dangerous global warming.
posted by Mister Cheese at 9:24 AM on July 24, 2017

Collection is a significant obstacle to pastoral sourced methane.

Or you can just feed them a little seaweed.
posted by CosmicRayCharles at 9:44 AM on July 24, 2017