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>All you need is napkin maths. We gain energy by turning carbon into carbon dioxide. Now, we need the same energy to reverse it, but with a loss factor. All th
by gruez 2y ago
>All you need is napkin maths. We gain energy by turning carbon into carbon dioxide. Now, we need the same energy to reverse it, but with a loss factor.
All the serious proposals for carbon capture involve use cases where it's unfeasible to swap in photovoltaics or whatever. For instance, fertilizer production, cement production, and air transport.
- Earw0rm 2y agoThe first two examples are feasible, the last not so much. You need extra energy to power the CCS, and to store the captured CO2. That's not practical on any airliner. One kilo of jet fuel produces about 3.5x its weight in CO2. The solution to aviation is "fly less", also "don't air-ship fresh produce which can be moved by sea or road" (and if it can't, don't ship it). Sorry gents, those Kenyan roses for Valentines are over. Get your loved one some tulips instead.
- gruez 2y ago>You need extra energy to power the CCS, and to store the captured CO2. >That's not practical on any airliner. One kilo of jet fuel produces about 3.5x its weight in CO2. Carbon capture includes direct air capture, which doesn't come with any weight constraints. >The solution to aviation is "fly less", also "don't air-ship fresh produce which can be moved by sea or road" (and if it can't, don't ship it). Any solution that's predicated on "do it less" is going to be DOA politically. The options available voters aren't "electric planes" or "don't fly", they're "do something" or "do nothing". Telling people they're going to have to make upfront sacrifices for vague future benefits is going to be a losing proposition politically. Any solution to climate change is going to have to come from technological advances, not getting people to consume less. US emissions per capita has dropped more than 25% since 1990[1]. That's not because people ate 25% less meat or drove 25% less. [1] https://en.wikipedia.org/wiki/Greenhouse_gas_emissions_by_the_United_States https://en.wikipedia.org/wiki/Greenhouse_gas_emissions_by_th...
- Earw0rm 2y agoHow much does diffuse DAC cost? Add the price of that on a flight ticket (which we ultimately have to anyway) and we'd be helping address the problem already, before the tech is even deployed. And the next 35 years - to 2060 - have to be a much steeper reduction than 25%, or the 35 years after that will, one way or another, represent a _forceful_ reduction of a lot more than 25%. Finally is that 25% on a production or consumption basis? Offshoring and deindustrialisation are not trends that are likely to continue, again more for political reasons than anything else.
- gruez 2y ago>How much does diffuse DAC cost? >Add the price of that on a flight ticket (which we ultimately have to anyway) and we'd be helping address the problem already, before the tech is even deployed. It's $1000/ton today, which works out to a 70% price increase for a new york to london flight. I disagree that would "address the problem already, before the tech is even deployed", because zero chance anyone would vote for it in the first place. That's where technological advancement comes in. Startups claim they can hit $250-$350/ton by 2030[1], which is a much more manageable 21% increase. >Finally is that 25% on a production or consumption basis? Offshoring and deindustrialisation are not trends that are likely to continue, again more for political reasons than anything else. It's around 17% on a trade basis[2], but the point stands. Americans haven't eaten 17% less meat, drove 17% less, or bought 17% less stuff. [1] https://en.wikipedia.org/wiki/Climeworks https://en.wikipedia.org/wiki/Climeworks [2] https://ourworldindata.org/consumption-based-co2 https://ourworldindata.org/consumption-based-co2
- Ntrails 2y agoIt remains infuriating to be repeatedly lied to by politicians who say they can "hit net zero" etc without any lifestyle changes. It is utter nonsense and simply ensures every conversation on the topic is grounded largely in fantasy. There are hard choices to be made and we insist on letting people pretend otherwise. It's infuriating
- gbear605 2y ago
- Thorrez 2y agoI don't think the idea is to have the capturing machinery on the plane itself. The idea is to have capture machinery on the ground, offsetting the carbon released by the plane.
- Earw0rm 2y agoThat's right, but then you have to capture it from atmospheric concentrations (430ppm) rather than directly from a waste gas stream at a much higher concentration. It can be done but the economics don't look good right now. Possible very cheap solar energy in desert regions can change that a bit. Australia have been trying but they didn't get very far with it yet, granted there is still room for solar to get cheaper again.
- wongarsu 2y agoLuckily CO2 is fairly fungible. Instead of the airplane capturing its own CO2 we can just capture 3.5t CO2 on the ground for every ton of jet fuel fueled into an airplane.
- ZeroGravitas 2y agoIf the entire world's electric supply isn't decarbonised at that point then that money would be better spent on deploying renewables somewhere without a 100% clean grid as the article says or electrifying heat or industry. That has issues with proving the deployment actually displaces carbon but carbon capture has similar issues proving that the carbon is actually permanently removed.
- jfengel 2y agoThat's the thing. All of these mitigations are meaningless if we still have vast industries predicated on burning fossil carbon. And once we've eliminated the burning of fossil carbon, the mitigations are unnecessary. Nature will gradually find an equilibrium, and anything we do to speed it up (even removing carbon) is as likely to cause harm as good. Maybe there is a future where we have so much extra renewables that we can think about trying to undo what we've done. But any effort spent on it now feels like an attempt to decrease the need to eliminate fossil fuels as fast as possible.
- JumpCrisscross 2y ago> we can just capture 3.5t CO2 on the ground for every ton of jet fuel fueled into an airplane Entropy makes one of these much easier. For planes, synthetic jet fuel is the answer. The sign we’re taking jet emissions seriously will be when someone drops the flygskam and hydrogen shtick and passes a synthetic-fuel mandate on private jets. (Less than 3x the cost in America [1].) [1] https://www.reuters.com/sustainability/us-sustainable-aviation-fuel-production-target-faces-cost-margin-challenges-2023-11-01/ https://www.reuters.com/sustainability/us-sustainable-aviati...
- slashdev 2y agoAir transport is one of those things that would better offset with carbon capture - maybe even by making synthetic jet fuel, then it's carbon neutral - but very expensive. But really it doesn't matter. Air transport is 2.5% of global CO2. If we solved every other problem first, we could keep pumping oil for airplanes for centuries. Take the engineer's mindset, reach the low-hanging fruit first. Replace coal with nuclear and natural gas, then start replacing natural gas. Cars don't need to run on gasoline anymore, BEVs are a superior technology. The market is doing its work to decarbonize that all by itself. Slowly at first, and then all at once. If you're middle-aged today, you'll likely live to see the end of gasoline cars. We can speed things along by removing subsidies on fossil fuels or offsetting them with green incentives.
- fxtentacle 2y agoThe reason why nobody is replacing coal with nuclear is that the former is cheap and the latter is expensive. And at the moment, higher energy prices are a very though sell, politically, even if everyone agrees that we don't want to leave scorched earth for our kids.
- ViewTrick1002 2y agoOr just skip the nuclear power step and go directly to renewables with storage since it is vastly cheaper and the deployment time is counted in months rather than decades.
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- mapt 2y agoAviation fuel has a trivial replacement in renewable biofuels, and three nontrivial replacements in liquid hydrogen combustion, liquid hydrogen fuel cells, and for short flights in battery power.
- gruez 2y ago>trivial replacement in renewable biofuels That's basically direct air capture with extra steps. All the carbon in those biofuels is coming from somewhere (the air).
- cyberax 2y agoYeah, but you basically are using self-replicating solar-powered machinery (aka "plants") to capture it.
- rtpg 2y agoMaybe I'm just stupid but if all the planes in the world used biofuels, wouldn't that mean that flying is net-zero carbon (at least as it comes to fuel consumption)? Like you do your flying, release CO2, but that CO2 gets captured again... I mean that doesn't sound bad, right? It's not going to reduce the level of CO2 in the air right now, but it would stop further increases... which, mathematically, seems to be the same thing as if we kept the status quo and did something else to reduce CO2 output? What am I missing?
- mapt 2y agoYeah. Except it isn't so unbelievably terrible on both capex and opex as mechanical DAC.
- Qwertious 2y agoBiofuels as in from farming? Modern farming just turns oil into crops, so turning the crops back into oil is a non-solution. The only viable current biofuels work by turn leftover waste matter into fuel - in other words, recycling. Also, any farming done for primary energy is farming not done for food.
- pfdietz 2y agoFertilizer production is dominated (in energy terms) by nitrogen fertilizer, and that's made with hydrogen. Hydrogen would come from electrolysis, and driving that with PV is very likely to be feasible, especially with cheap Chinese electrolysers.
- fch42 2y agoWhile Ammonia generation "involves just nitrogen and hydrogen", the crux is that it requires high temperature. Haber-Bosch doesn't do at ambient - something like 800°C IIRC. And the heating for such is done by burning something (coal decades ago, gas now). For many "ordinary" chemicals, the so-called process temperature is the challenge with carbon-free. Not dissimilar from steel or aluminium making (melt the ore first before reducing it).
- pfdietz 2y agoHaber-Bosch operates at 350-550 C. The energy needed is in compressing the gases, and (at lower pressure) refrigeration to separate ammonia. These are work inputs, and all can be provided by PV generated electricity. At pressure, the ammonia production reaction is exothermic, so ammonia production is a source of heat, not a consumer of heat.
- pfdietz 2y agoIn more detail: https://www.c-thru.org/wp-content/uploads/2022/12/Ammonia-Technical-Brief-June2022.pdf https://www.c-thru.org/wp-content/uploads/2022/12/Ammonia-Te... "Generally, in the ammonia synthesis loop there is no need for an external heat source because the ammonia synthesis reaction is exothermic. The produced heat from the reaction is a high-valued source which can be recovered to satisfy the temperature requirements of the converter feed-stream and to generate high pressure steam for use in other plant processes. In modern plants, the compressors of the synthesis loop (the syngas/recycle compressors as well as the ammonia refrigeration compressor) are usually centrifugal ones driven by steam turbines which work with the produced steam from the recovered waste heat available within the plant (European Fertilizer Manufacturers’ Association (EFMA), 2000). Overall, electricity consumption values of ~0.32 to ~0.64 kWh/kg-NH3 have been reported in literature for the synthesis loop, depending on the variations in the syngas production pressure, synthesis loop pressure and compression efficiencies (X. Liu et al., 2020)." Note that the figure given there is an order of magnitude less than the electrical energy needed to make the necessary hydrogen by electrolysis.