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Direct air capture: our technology to capture CO₂

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Re: Direct air capture: our technology to capture CO₂

#51

Post by i2cmaster »

mchannon wrote: post #46
i2cmaster wrote: post #16

I don't see how these are improvements over algae bioreactors. Capturing the CO2 without reducing it will lead to less oxygen in the atmosphere as well. Also at least with bioreactors you get useful products/energy. This just generates more waste products and consumes energy.

Removing ALL the CO2 in the atmosphere would be 1-2% the partial pressure of O2 in the atmosphere (barometric pressure where you live swings more than that). Of all the concerns, this one’s low on the list.

The justification for these things is that the oxygen is being converted to CO2 faster than CO2 is being reduced back to oxygen. So if you capture CO2 at a high rate eventually this would lead to you capturing all of the oxygen.

Re: Direct air capture: our technology to capture CO₂

#52

Post by jlund-molfese »

gus_massa wrote: post #45
fwlr wrote: post #22

Their subscription page is currently offering a rate of about $1.35 USD per kg of CO2 removed, and they promise to complete your order within 6 years. It’s nice to have some hard numbers on end-stage or “gold standard” CO2 offset (no doubt there are cheaper carbon credit options but this directly solves the hardest problem, CO2 that’s diffused into the atmosphere.

For comparison, 1 gallon of gasoline release 9kg of CO2, so it's $0.15 USD more per gallon to be carbon neutral. I think that number is too low to be real.

Wouldn’t you multiply rather than divide, to get +$12.15/gallon?

Re: Direct air capture: our technology to capture CO₂

#53

Post by DannyBee »

kuprel wrote: post #40
Mizza wrote: post #18

Earlier quoted context omitted.

For context, 4000 tons of CO2 is roughly the emissions of a full 777 flying from San Francisco to London and back twice.

The entire aviation industry emitted 619 million tons of CO2 in 2019 [1]. So about 155 thousand of these plants would be needed just to offset air travel [1] https://www.iea.org/reports/aviation

I mean, that's not a lot compared to trees. There are >3 trillion trees in the world.

Re: Direct air capture: our technology to capture CO₂

#54

Post by mabbo »

lom wrote: post #25

The article says that the plant can remove 4000 tons of co2 per year. If you look up what’s the equivalent of that, just under 900 average vehicles less on the road per year. Or the equivalent co2 savings of building one wind turbine to replace polluting forms of energy production. What a joke.

Both techs are important. We need to reduce our production of greenhouse gasses, but that only gets us to break even. We then need to quickly undo the damage we caused, which needs tech like this.

But you're right: first we need to prioritize reducing our carbon output.

Re: Direct air capture: our technology to capture CO₂

#55

Post by mchannon »

thx-2718 wrote: post #3

"Our plants require less land than other techniques. E.g., on a land area of 0.42 acres, our Orca plant can remove 4,000 tons of CO₂ from the air every year, which is almost 1,000 times more effective than trees. The same land would host around 220 trees with an estimated capacity of 22kg each" How much land, in solar panels for example, is required to power this? Also what's the carbon waste that this generates? Is…

1000 kWh/ton (found it on google):

166 kW/ton in a sunny place:

1000 square meters/ton in a sunny place:

4 million square meters = ~1000 acres of PV to power. One unit.

Yeah, that’s going to happen. /s “We’re too ashamed of our energy requirements to post them on our page and are well aware they’re dooming this technology until cold fusion comes out” is what I read between the lines on their fluff page.

Re: Direct air capture: our technology to capture CO₂

#56

Post by A1kmm »

pilaf wrote: post #33
Mizza wrote: post #18

Earlier quoted context omitted.

For context, 4000 tons of CO2 is roughly the emissions of a full 777 flying from San Francisco to London and back twice.

That doesn't sound right, 4000 tons is more than 10 times the maximum takeoff weight of a 777.

I tried calculating it two ways to see.

Firstly, based off two full fuel tanks for a 777. Apparently a 777-200 has a 117350 L fuel tank, and the density of jet fuel is approximately 800 g / L.

The emitted carbon dioxide combines oxygen from the air with carbon from the jet fuel. Apparently the average chain length is 12, so it would be C_12H_10 for a straight hydrocarbon.

Factoring in the molecular masses, the amount of CO2 from two full tanks would be: (12 * 12.011 + 212.01115.999) / (1.0080 * 10 + 12 * 12.011) * 117350 * 800 * 2/ 1E6 = 643 tonnes.

Now, they might not use the full tank. Another estimate is that long haul flights use about 0.1 g / passenger / km. Apparently it is 4308 km in a straight line from SF to London, and a 777 seats about 350 people depending on the configuration, so multiplying by 2 for a return trip comes out at 302 tonnes of CO2 (that's probably an underestimate since it is a straight line).

So I think 4000 tonnes is an overestimate (and they said tons, which is even more than a metric tonne, at 4480), but the emissions of such a flight is still significant (and the global warming impact is higher because combustion also disperses water, which also has a warming effect at that altitude).

Re: Direct air capture: our technology to capture CO₂

#57

Post by Tuxer »

mabbo wrote: post #50
alhw wrote: post #43

Earlier quoted context omitted.

Jet fuel is comprised mostly of hydrocarbons with 8 to 16 C atoms, and a large fraction of these hydrocarbons are straight-chain alkanes. Combustion of dodecane (a C12 straight-chain alkane) makes 12 CO2 molecules. A 747 jet consumes about 4 L of jet fuel per second when in flight. Based on the density and molecular weight of dodecane and the stoichiometry of its combustion reaction, you'd arrive at something like 0.…

Ah, so you're saying (if I'm reading this correctly) that the plane only carries the carbon portion of the CO2, and the oxygen comes from the air itself. That's how it's emitting more CO2 then it's fuel mass. Is that right?

Correct. Fuel is around 16/36th of the CO2 mass it emit when being burnt. A 777 carries around 120 tons of fuel for a SF/LON flight, so that's around 300 tons of emissions per flight.

Re: Direct air capture: our technology to capture CO₂

#58

Post by gus_massa »

jlund-molfese wrote: post #52
gus_massa wrote: post #45

Earlier quoted context omitted.

For comparison, 1 gallon of gasoline release 9kg of CO2, so it's $0.15 USD more per gallon to be carbon neutral. I think that number is too low to be real.

Wouldn’t you multiply rather than divide, to get +$12.15/gallon?

Yes, obviously! My bad. I must don't make math in the morning. Thanks for the correction.

Re: Direct air capture: our technology to capture CO₂

#59

Post by shafyy »

Climate scientist David Ho has a good thread on CDR: https://mastodon.world/@davidho/109511745525784891

It's hard for people to visualize removing tons or billions of tons of #carbon #dioxide (CO₂). I propose we talked about CO₂ #removal (CDR) like a #time #machine (e.g., this machine will take us back 5 minutes). For example:

Q: How far back in time does planting 100 million #trees take us?

A: If one mature tree takes up an average of 25 kg of CO₂ per year, then 100 million trees will take up 2.5 MtCO₂. That's a time machine that takes us back 33 minutes and 6 seconds in a year. It's not a lot.

The bottom line being: 99.999% of today's efforts need to focus on cutting emissions. This is like if you want to lose weight: It won't help you if you keep eating 5k kcalories a day and work out for 2 hours a day. Cut the intake, and then do some workout for the rest.

Re: Direct air capture: our technology to capture CO₂

#60

Post by jvanderbot »

My friend runs this amazing ASCII website which also happens to be the news feed for their Carbon-capture-to-fuel devices.

Like top comment suggests, it doesn't make sense to just capture, you have to get off carbon positive processes entirely.

This company aims to do both, effectively.

https://terraformindustries.com/

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