[moffkalast]

Ah yeah right of course, it's something like Na+ Cl- H2O --> O2 NaOH Cl2 (sorry chemists, I know your eyes are probably bleeding)

But if they manage to get H2 from it then the sodium, oxygen, and chlorine have to bind into something else than usual I guess.

[LarsAlereon]

There is a proposed method to sequester carbon and reduce ocean acidification by doing this process, extracting the Hydrogen and Chlorine (or hydrochloric acid) for industrial purposes, and releasing the sodium hydroxide to absorb dissolved CO2 (carbonic acid) into sodium carbonate.

[philipkglass]

You're probably thinking of this paper from 2007:

"Electrochemical Acceleration of Chemical Weathering as an Energetically Feasible Approach to Mitigating Anthropogenic Climate Change"

https://pubs.acs.org/doi/10.1021/es0701816

It was mind blowing for me at the time! Subsequent approaches to accelerated silicate weathering like Project Vesta dropped the chemical component and just used mechanical crushing of rocks to accelerate weathering. The all-mechanical approach is less complicated and energy intensive.

[LarsAlereon]

If you're extracting chlorine to react it with rock it probably makes more sense to just react the rock directly. But if you can use the chlorine industrially it makes more sense not to involve the mining and transport of rock. There's currently a significant industry of chlorine and HCl production that isn't linked to a carbon sequestration process that we can supplant.

[pfdietz]

One could also release the chlorine into the atmosphere to destroy atmospheric methane. Elemental chlorine in sunlight is rapidly (within minutes) broken down into chlorine atoms. These atoms, being free radicals, efficiently extract hydrogen from methane molecules, starting a chain of reactions that converts the remaining fragment to CO2 and water.

You'd need a hell of a lot of chlorine to compensate for current methane injection, though.

[arbitrandomuser]

No , cholrine radicals will also deplete ozone layer , Besides I don't think releasing highly reactive gases at any concentration into the atmosphere is a good idea, there can be other effects we haven't studied well enough.

[pfdietz]

They wouldn't make it to the ozone layer, if released in sunlight.

[pmontra]

If you could release it close to methane concentrations. Otherwise it's going to react with anything close to it. Soil, lungs, vegetation, etc.

[pfdietz]

Methane is present throughout the troposphere -- it has an atmospheric lifetime of something over a decade and becomes well mixed. You'd want to release the chlorine in a sufficiently dilute and dispersed form that it didn't overwhelm the methane in the air it which it was released.

[tinglymintyfrsh]

Needs massive energy input which would come from where? Also, massive amounts of toxic chemicals. Use biology to solve climate change by growing biomass (bio CCS) in the form of kelp, diatoms, and other high growth life (maybe GMO) to sink to the bottom of the ocean.

[LarsAlereon]

Nuclear plants can provide plenty of excess electricity as well as heat for thermal desalination.

[tinglymintyfrsh]

Sounds like wishful thinking/hand-waving. Plus, the risks of and limitations of nuclear energy.

Biological processes are far more efficient at fixing carbon into biomass and using unlimited free solar energy. Bio CCS.

[rootusrootus]

> But if they manage to get H2 from it then the sodium, oxygen, and chlorine have to bind into something else than usual I guess.

It's the same electrolysis process used today in swimming pools to generate chlorine. The hydrogen evaporates, the chlorine ends up in the water, and the chemical reaction ends up producing the same salt it started with. You don't have to add salt[0] and the chlorine pretty quickly evaporates and breaks down in sunlight if you don't put cyanuric acid in the water to bind it.

Mostly it could be ignored, though if the chlorine level got high enough it would kill the organic things.

[0] except for losses due to other reasons than chlorine generation