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Comment on Capturing CO2 With Copper, Scientists Generate 'Green Methane'

Auzy@beehaw.org ⁨4⁩ ⁨months⁩ ago

Why can’t we use batteries? There’s no reason we can’t given all the battery chemistries available including chemistries which are still undiscovered.

As you said, it’s really just energy. And if this process is only 75% efficient, and then using it is 75%, it’s a waste of a huge amount of energy.

I’d we’re just going to burn it and put it back in the air, it’s not a solution at all… We’re just replacing one greenhouse gas with one that is just as bad

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Wanderer@lemm.ee ⁨4⁩ ⁨months⁩ ago
If you have excess oil you build a really cheap metal container to put it in. If you have extra energy to go into the battery to need to spend the full amount to make a new battery to store it.

It’s fixed cost vs marginal cost. Marginal cost of oil storage is pretty low

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- Auzy@beehaw.org ⁨4⁩ ⁨months⁩ ago
  Yes… Sure, its cheap to set up…
  
  Great at periods when you have lots of extra solar/renewables.
  
  But… if the efficiency is low, a potentially worse solution for the rest of the year (like Winter), because any excess you can generate, will mostly be lost.
  
  Furthermore, you’ll need a way to convert it back into electricity. In the future, they’re aiming for 60% efficiency for Gas Power Plants… energy.gov/…/how-gas-turbine-power-plants-work . At the moment apparently its much less
  
  So 60% * 0.85 = 50% efficiency… AND THAT IS OPTIMISTIC AND DETERMINANT ON FUTURE TECH!
  
  So you lose half of the power you store. Which means you’re replacing the money you spend on batteries… on more power generation anyway…
  
  They definitely have some utility when there is insufficient battery as a final backup. They may also be useful in applications which don’t use power too and in some utilities which use the gas directly. It also is still centralised power generation, so rural areas will still be unreliable…
  
  But, I’d prefer they deploy Vanadium Redox Flow batteries instead as they’re 75-90% efficient.
  
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  - Five@slrpnk.net ⁨4⁩ ⁨months⁩ ago
    That’s correct. Electro-chemical storage is not limited by the Carnot efficiency limit like combustion engines are. Conversion losses should be a huge factor in choosing energy storage.
    
    The fertilizer that’s propping up our unsustainable factory farming is created using the Faber process that turns methane and nitrogen into ammonia. Food prices are lower because methane is cheap as a byproduct of oil refining. It might be cool to instead take carbon out of the atmosphere and then convert it into fertilizer to grow plants that remove even more carbon from the air.
    
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Tobberone@lemm.ee ⁨4⁩ ⁨months⁩ ago
You said it yourself. Still undiscovered. The technology we have today can’t be used to save more than a day or so of electricity. We need to handle months. Finding more energy dense ways of doing it is crucial.

And even if we burn it and put it back in the air, it is still positive, because we won’t have added more from oil. And if we get enough of the stuff we can let the trees grow, which would be a carbon sink.

Step 1: stop using oil. If we use the methane as is, we’ve accomplished this step. Step 2: scrub carbon from atmosphere. Upping the game and replacing wood for heating would let the trees scrub the atmosphere, creating carbon sinks Step 3: accelerate. Can processed methsne be stored in energy dense compounds? Like oil was?

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- Auzy@beehaw.org ⁨4⁩ ⁨months⁩ ago
  That makes no sense…
  
  Australia keeps less than 21 days of petrol of all types. Why would we need to store months? This seems like one of those silly arguments where it’s assumed incorrectly that the sun stops shining and the wind stops blowing (which only happens in limited locations).
  
  And when I say including undiscovered, I mean its only getting better. For grid energy storage, energy density isn’t an issue. Energy density is ONLY an issue for transportation and phones. We just need to scale up the technology now, and thats already rapidly happening.
  
  This entire thing comes down to efficiency at the end of the day. The efficiency of the conversion here is 85%, and you still need to convert it back into energy (which is hugely inefficient). Even if converting it back to energy is 75% efficient (it’s likely not), that’s only 64% efficient.
  
  Batteries are 94%. Even Vanadium Redox Flow is 75-90%. There’s plenty of low density low cost efficient batteries (especially now Sodium batteries are available)
  
  Also…
  
  “If we use methane as is, we’ve accomplished this” - You can’t just swap current products with methane… Even if you did, petrol engines are totally inefficient. We’re likely talking not even talking 50% efficient
  
  “Replacing wood for heating”. We already HAVE a solution for heating. Burning methane is less than 100% efficient max. Heat pumps are already at 500% efficiency and the efficiency is growing.
  
  Why would you want to store it like oil? It’s incredibly toxic… And, burning it is inefficient.
  
  This has it’s applications, but its likely more competing with Hydrogen, NOT batteries. Also, this is still a research paper, not a commercial product. By the time it’s commercial, batteries might be 50% cheaper again…
  
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  - Tobberone@lemm.ee ⁨4⁩ ⁨months⁩ ago
    Oh, you are aussie:) i should have guessed by your username.
    
    Ok, for starters, where I live that big yellow thing stops shining. Practically (for electricity production anyways) for almost 6 months of the year and almost totally for 3. And even with heat pumps we still use several MWh of electricity every year to heat our homes. A battery park can keep a city running for 1h. Even those planned in NSW (BESS is it?) would struggle to keep things running for mire than a day. To be clear:
    
    We need more energy storage than can be provided by electric batteries, than can be bought at battery prices and in scales larger than can be produced with any technology current or in the overseeable future. And we needed it yesterday. Any form of low cost, stable, easy to store solution we can use is a huge step forward. Solar is great! But we need the electricity when the sun doesn’t shine. Heat pumps are awesome! But their awesomness is needed when the sun doesn’t shine so much. That is why we need more energy storage solutions.
    
    Summertime there are almost limitless electricity available, but that energy needs to be stored somehow. And with limitless (in practice) efficiency isn’t an issue. Even storing 1% is better than 0%. Regardless of efficiency.
    
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