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And to quantify this a bit more, current costs for direct air extraction and sequestration of CO2 are about $6/gallon of gas. Climeworks is charging early custo
by epistasis 5y ago
And to quantify this a bit more, current costs for direct air extraction and sequestration of CO2 are about $6/gallon of gas. Climeworks is charging early customers $600/ton of CO2 [1], and about 100 gallons of gas convert to a ton of CO2.
This sort of direct air capture will be absolutely necessary in the second half of this century for all of our current oaths to keep warming to 1.5C, according to the IPCC SR1.5 report. And though many parts of the supply chain of CO2 direct air capture might get cheaper with time, the actual sequestration part might get harder and more expensive with time.
Chevron had promised to capture only a small amount of CO2 as part of a LNG project in Australia, but is facing massive fines because they didn't understand the geology enough to actually sequester CO2.
So while I'm fairly confident that we could eventually get the tech for CO2 capture down to maybe $1/gallon of gas, the actual sequestration is only going to get more difficult with time.
Every gallon of gas burned today makes 20 pounds of CO2 that will need to be removed in the future we are burdening future generations with an incredibly difficult debt that we don't yet know how to pay down.
[1] https://www.theverge.com/2021/9/9/22663597/largest-direct-air-capture-plant-c02-climeworks-iceland https://www.theverge.com/2021/9/9/22663597/largest-direct-ai...
- dmitrygr 5y ago> 100 gallons of gas convert to a ton of CO2 Gasoline is about 87% carbon and 13% hydrogen by weight. And its density is around 700 kg/m^3. 100 gallons is 378.5 liters, which is 265.0 kg. That is 230.5 kg of carbon. C is 12.011 per atom, O is 15.999, thus that converts to 844.6kg, not a ton. Rounding up by >15% to make numbers more impressive is not nice when we are taking science
- epistasis 5y agoA gallon of gas converts to 20 pounds of CO2, and there are 2000 pounds in a US ton. My first web search hit, just to make sure my memory was not faulty, was this explanation: https://climatekids.nasa.gov/review/carbon/gasoline.html https://climatekids.nasa.gov/review/carbon/gasoline.html Using imperial units is always unfortunate, but when dealing with the typical unit of gasoline in the US, it's inevitable. Not sure where you are getting your numbers, perhaps you're using a UK gallon or something?
- dmitrygr 5y agoI gave all my numbers making it trivial to check that I am using the us gallon and. Perhaps a site for kids that you cited isn’t using more than one sig fig?
- epistasis 5y agoThe kids site is far more correct than yours, and consistently uses two significant figures in its calculations. See, for example, the US federally accepted value of 19.59 pounds or 8.887 kg CO2/gallon burned: https://www.epa.gov/energy/greenhouse-gases-equivalencies-calculator-calculations-and-references https://www.epa.gov/energy/greenhouse-gases-equivalencies-ca... Your error appears to be using a single significant figure for the density of gasoline, at 700. Other sources place it from 711 to 749 kg/m3. Hopefully you will reconsider my comment being "not nice," since you started with one sig fig and ended with four, and then did not consider the two different meanings of ton. And on top of this all, this ignores all the upstream emissions to generate the gasoline, which is greater than the 15% which you said was "not nice."
- dmitrygr 5y ago378.5 * 749/1000 * .87 * (15.999 * 2 + 12.011) / 12.011 = 903.7 still well short of a ton
- epistasis 5y agoYou seem to be accepting that I was able to find your error on the single significant figure. However, I already told you that I was using a US ton, 2000 pounds, 907kg: https://duckduckgo.com/?q=1+ton+in+kg https://duckduckgo.com/?q=1+ton+in+kg Additionally, you are not including the 3-6 pounds per gallon in upstream emissions for gasoline. Let's recall that this all started from the phrase "about 100 gallons of gas convert to a ton of CO2" and that when you quotes, you omitted the "about" so that you could try to make your incorrect quibble relevant. So at this point I would like to call this a very "not nice scientifically" departure from anything relevant, but I'm all ears if you were going somewhere interesting with this.
- lostlogin 5y agoWhen I search I get a variety of answers, with the bulk being around the same or lower CO2 emissions than your calculation. Why does it the answer vary? Does it change depending on the grade of the fuel?
- epistasis 5y agoI have not found a single page with estimates as low as dmitrygr’s 18.6 pounds per gallon. The numbers from the top hits ina web search for me: 19.64 - http://www.patagoniaalliance.org/wp-content/uploads/2014/08/How-much-carbon-dioxide-is-produced-by-burning-gasoline-and-diesel-fuel-FAQ-U.S.-Energy-Information-Administration-EIA.pdf http://www.patagoniaalliance.org/wp-content/uploads/2014/08/... 20 - https://climatekids.nasa.gov/review/carbon/gasoline.html https://climatekids.nasa.gov/review/carbon/gasoline.html 20 - https://www.fueleconomy.gov/feg/contentincludes/co2_inc.htm https://www.fueleconomy.gov/feg/contentincludes/co2_inc.htm 19.6 (converted from grams) - https://www.epa.gov/energy/greenhouse-gases-equivalencies-calculator-calculations-and-references https://www.epa.gov/energy/greenhouse-gases-equivalencies-ca... “Just over 19” - https://epicenergyblog.com/2013/05/24/how-many-pounds-of-carbon-dioxide-co2-does-a-gallon-of-gasoline-produce/ https://epicenergyblog.com/2013/05/24/how-many-pounds-of-car... The next hit isn’t about CO2 from burning Gas, but about the upstream emissions that go into producing gasoline, which it pegs at 3.3 to 6.7 per gallon - https://www.sierraclub.org/sierra/ask-mr-green/hey-mr-green-how-much-co2-generated-producing-and-transporting-gallon-gas https://www.sierraclub.org/sierra/ask-mr-green/hey-mr-green-... What sort of estimates are you getting?
- dragonwriter 5y ago> Why does it the answer vary? Does it change depending on the grade of the fuel? Yes, “gasoline” is a family of related fuels of different densities and compositions, and it will also vary based on assumptions about how it is burned. Incomplete combustion will result in more “dirty” pollution and less CO2.
- dragonwriter 5y ago> Gasoline is about 87% carbon and 13% hydrogen by weight. And its density is around 700 kg/m^3. That density seems to be on the low end; different formulations have different densities, and the sources I’ve found give somewhat different ranges, but the ranges given typically seems to be about 750±35 kg/m³.
- tombert 5y agoI'm not 100% sure why you're downvoted, but I don't think we disagree with anything. As I said on my previous post, I was just making up the numbers, and so if it costs $6/gallon-o-gas for CO2 extraction, then my previous point is even more accurate (though I might not have said it very clearly).
- epistasis 5y agoYes, I totally agree with you, did not mean to come across as contradictory in any way. I do not fear being downvotes at all on this topic. If I'm not getting downvoted by the few persistent anti-climate-change voters here, then IMHO I am not pushing forward the truth enough! People, even here, have a lot more to realize about the technological, economic, and political implications of the transition that we must go through in the coming decades.
- Karrot_Kream 5y agoHave to say, I've fenced off about nuclear with you before, but thanks for always being up-front about your calculations and really pushing the conversation forward here.
- specialist 5y agoYes and: IIRC 1 ppm of CO2 is ~1 gigaton of carbon. Roughly the weight of Mt Everest. We're adding ~26 Everests annually.
- pfdietz 5y agoMt. Everest has a mass of about 6 trillion tonnes.
- specialist 5y agoUgh. Stupid brain. Trying to get sense of the challenge, I worked some numbers to try visualizing how much carbon we're talking about. I'll refind my notes or recreate. Thanks.
- soperj 5y ago1 ppm of C02 ~ 2.13 gigatons of carbon, which is ~ 7.8 gigatons of CO2. (1) We add about 43 gigatons of CO2 to the atmosphere per year 55% of which is absorbed by natural sinks. We're definitely not adding 26 ppm of C02 to the atmosphere each year. 1.https://skepticalscience.com/print.php?r=45 https://skepticalscience.com/print.php?r=45
- PeterisP 5y agoHey, I've always had a question which perhaps you can answer. In essence, we're still burning lots and lots of carbon just to extract energy. Thermodynamics says to reverse the process and get carbon from CO2 we need to put all that energy back, with a hefty bonus due to inefficiencies. So how can it be feasible to afford enough energy to "unburn" a century's worth of burnt carbon if we can't even get enough energy to avoid burning new carbon in the first place? Like, our energy generation might double in a few decades, but this "unburning" would require so much spare energy that it doesn't seem likely to achieve as soon as the second half of this century.
- tombert 5y agoI could be wrong, but I think what you're referring to would be to convert it back to raw carbon. I believe that "carbon capture" would be literally taking out the raw CO2 and leaving it as-is, presumably holding it underground or something, which I don't think would take nearly that much energy.
- PeterisP 5y agoThe physics of storing equivalent weights of gas versus solids - the volume and/or pressure containment required - make it quite impractical to store meaningful amounts (on the scale of billions of tons) of it as gas; the fact that CO2 is just 28% carbon and 72% oxygen is comparably a lesser issue but doesn't help as well. Perhaps you can avoid "unburning" it by some other chemical process (which is why I was asking this) but simply pumping the CO2 somewhere does not seem a reasonable option, the only place on Earth that can easily hold that much of CO2 gas is the general atmosphere where it already resides.
- epistasis 5y agoI agree that sequestering co2 gas is a losing game, and that's why I think all the fossil fuel companies' plans for CCS are pure bunk. Climeworks' proposal to pump it into basalt caverns, where it chemically reacts and becomes solid, is one way around that. Carbon Engineering is doing gas to liquids, and claims that they need ~2.25 kWh of electricity to convert atmospheric CO2 to 1 kWh worth of liquid hydrocarbons. We will see. We will need gigatons/year of sequestration in 2050. It's going to require a ton of innovation to get there.
- brutusborn 5y agoDo you have any more information on the Chevron carbon capture failure? As far as I understand it, the failure had nothing to do with Geology.