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Entropy? Never heard of it. (lemmy.dbzer0.com)

submitted 3 days ago* (last edited 3 days ago) by [email protected] to c/[email protected]

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[–] cynar 109 points 3 days ago (32 children)

Just checked the numbers, for those interested.

A gas power plant produces around. 200-300kWh per tonne of CO2.

Capture costs 300-900kWh per tonne captured.

So this is basically non viable using fossil fuel as the power. If you aren't, then storage of that power is likely a lot better.

It's also worth noting that it is still CO2 gas. Long term containment of a gas is far harder than a liquid or solid.

[–] [email protected] 34 points 3 days ago (16 children)

Who says you power that thing with fossil fuels? The real way to do that is via giant nuclear reactors or reactor complexes.

Fission power can be made cheaper per MW by just making the reactors bigger. Economies of scale, the square cube law and all that. The problem with doing this in the commercial power sector is that line losses kill you on distribution. There just aren't enough customers within a reasonable distance to make monster 10 GW or 100 GW reactors viable, regardless of how cheap they might make energy.

But DACC is one of the few applications this might not be a problem for. Just build your monster reactors right next door to your monster DACC plants.

[–] cynar 14 points 3 days ago (2 children)

There are 3 use cases I've seen.

Making fossil fuel power stations "clean".
CO2 recovery for long term storage.
CO2 for industrial use.

It's no good for the first, due to energy consumption. This is the main use I've seen it talked up for, as something that can be retrofitted to power plants.

It's poor for the second, since the result is a gas (hard to store long term). We would want it as a solid or liquid product, which this doesn't do.

The last has limited requirements. We only need so much CO2.

The only large scale use case I can see for this is as part of a carbon capture system. Capture and then react to solidify the carbon. However, plants are already extremely good at this, and can do it directly from atmospheric air, using sunlight.

[–] [email protected] 1 points 1 day ago (1 children)

It's poor for the second, since the result is a gas (hard to store long term). We would want it as a solid or liquid product, which this doesn't do.

Why wouldn't the device include or feed a compressor to liquidize the CO2? It takes just a little over 5 atm of pressure which is trivial.

[–] cynar 1 points 1 day ago

You also need to sustain 5 atm, with no leaks for years. Where is it being stored, and who's paying for the maintenance? All it would take would be a bit of civil unrest, or corruption, and the work could be undone in mass.

[–] [email protected] 1 points 2 days ago

The only DAC variant i could see working out is if it takes the CO2 from high-concentrated sources (such as portland cement factories) and transforms it into something practical, like liquid fuel or methane.

It could be leading to cheaper methane than from biological sources, because technological processes can have higher efficiency, and therefore lower prices.

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