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The impact of direct air carbon capture on climate change

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Re: The impact of direct air carbon capture on climate change

#41

Post by zmmmmm »

scarygliders wrote: post #35
pipermerriam wrote: post #29

Earlier quoted context omitted.

Can you provide anything beyond conjecture that there is any merit to what you've stated? My understanding is that the effects of CO2 as a greenhouse gas are pretty well understood at this point.

I can only ask that you read some Stuff From The Other Side Of The Argument... http://www.drroyspencer.com/ is a good start on that. I'm already being downvoted on here - proof that there are a substantial number of HN users who have Made Up Their Minds on this, and simply do not want to even consider that they have been bamboozled by various interested parties. I realise that no one likes to either admit they've bee…

Hint: capitalizing things and tossing about assertions about behavior of HN readers the way you do significantly undermines your credibility. If you really want to advance the argument you are making in good faith, you need to adjust your approach.

Re: The impact of direct air carbon capture on climate change

#42

Post by spodek »

Not a word about the most effective, cheapest strategy: reduce emissions?

Most Americans could reduce their emissions by 75% while improving their standard of living by buying less junk, wearing a sweater in the winter, eating more healthy, and other low hanging fruit that will make them more active, healthy, connected to their communities, etc.

Reduce consumption by half. There, I just saved us $300 million.

How is reduction not our top priority and activity??

Re: The impact of direct air carbon capture on climate change

#43

Post by relieferator »

kijin wrote: post #38
Robotbeat wrote: post #23

Earlier quoted context omitted.

Not objectively true, as plants and even rocks grab CO2 out of the air pretty efficiently. From a thermodynamics standpoint, you can burn fossil fuels at 50-70% efficient (50% is not uncommon), and the actual theoretical lower bound of CO2 direct air capture is ~20 kJ/mol,[0] or about 1.7MJ/kg of elemental carbon, compared to 33MJ/kg for burning elemental carbon (same as high grade coal). (Burning methane is even bet…

> Burning methane is even better Actually, burning is probably the best way to deal with any excess methane. Methane has a significantly higher warming potential than CO2 does. So if there's any methane we're venting into the atmosphere, we should burn it to convert it into CO2. Bonus points if you can use the generated energy to capture the CO2 as well.

From what I can recall, landfills produce more methane than any other process. How about we build a carbon capture next to every landfill, divert the methane and burn it to run the DAC?

Re: The impact of direct air carbon capture on climate change

#44

Post by tekstar »

btilly wrote: post #20

I would have liked to see https://projectvesta.org/ commented on in the article. They claim to be able to sequester carbon by scattering olivine rock in an active and warm coast. The cost of the rock is $25/ton now, with the prospect of $10/ton in the future. Plus whatever it costs to break it up and scatter it. That makes it at an interesting price point if it works as advertised. Even more interesting to me is that…

I believe this type of project is referred to as geo-engineering, which is a bit more controversial as it's typically assumed that the side effects are somewhat unknown.

Re: The impact of direct air carbon capture on climate change

#45

Post by cagenut »

I really like the way the author tries to ballpark orders of magnitude and compare against known-budgetary-things for frames of reference. That said, talk of 10/tonne is pure fantasy, the real band is between 100 and 1000, so the analysis here is a full decimal place naive (of course, IMHO).

Just to contribute, another americanized version of the numbers: $100/tonne of a carbon tax works out to about $0.87 per gallon of gasoline. So if you assume carbon engineerings pilot plant estimates turn out to be right but on the high-end, at $232/tonne that's an almost perfect $2/gallon.

Which raises an interesting point to ponder... if anyone were capable of extracting carbon from the atmosphere at under $200/tonne... then all the oil companies would almost instantly switch to only building those plants. Why fight for drilling rights and production share agreement terms when air is everywhere.

Re: The impact of direct air carbon capture on climate change

#47

Post by SystemOut »

relieferator wrote: post #43
kijin wrote: post #38

Earlier quoted context omitted.

> Burning methane is even better Actually, burning is probably the best way to deal with any excess methane. Methane has a significantly higher warming potential than CO2 does. So if there's any methane we're venting into the atmosphere, we should burn it to convert it into CO2. Bonus points if you can use the generated energy to capture the CO2 as well.

From what I can recall, landfills produce more methane than any other process. How about we build a carbon capture next to every landfill, divert the methane and burn it to run the DAC?

Landfills do collect and burn methane. Those pipe like structures you see sticking out of a completed landfill are part of the process.

https://archive.epa.gov/climatechange/kids/solutions/technol...

Re: The impact of direct air carbon capture on climate change

#50

Post by gwbas1c »

_rpd wrote: post #11
jarvist wrote: post #6

I'm not sure if this article hammers home the key point: extracting carbon from the air always takes more energy that was gained by burning the fossil fuel to make that carbon. This is inevitable due to the entropy cost of de-mixing CO2 from the air, and from the limited efficiencies of thermal power generation (~33-40% for a coal power plant, perhaps 20% in an internal combustion engine), and limited efficiency of t…

> it only makes sense to spend energy on sucking CO2 out of the atmosphere, once you've already de-carbonised everything which you possibly can. Except possibly when energy prices are negative due to wind and solar intermittency - although that is also a signal that you need more storage in the grid, additional storage may not be economic for some reason.

Honestly, I suspect that long-term storage will be inefficient for a long time.

For example, batteries exceed 90% efficiency for storage, but they are only cost effective for day-to-day storage. (Charge when the sun is out, discharge at night.)

In contrast, charge during long summer days, and discharge during shorter winter days will probably be lower efficiency at first. For example, generating hydrogen by electrolysis is about 75% efficient (https://en.wikipedia.org/wiki/Hydrogen_production#Electrolys...), and then pressurizing it will also consume energy.

This means it may be more cost efficient to extract CO2 from the atmosphere as "storage" and then burn natural gas... At least until we find a better way to store energy than hydrogen!

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