Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

We need to take CO2 out of the sky – an overview of climate tech

orbuch.com

Post reply on HN
Print view View original

41–50 of 267 posts

Re: We need to take CO2 out of the sky – an overview of climate tech

#41

Post by orbuch »

ComputerGuru wrote: post #28

What the article leaves to the conclusion is what needs to be stated up front and center: it's virtually impossible to do this efficiently, cheaply, or effectively because there's so little CO2 in the air, meaning a) adding even a little bit more greatly affects the CO2 levels b) with a global ppm of ~400, it basically means that you need to filter 2500 molecules of air to get a single molecule of CO2, and that's ass…

(I wrote the post) This is good feedback that this is buried in the appendix -- I pulled that section up and made it inline with the flow of the post. Does that help?

Re: We need to take CO2 out of the sky – an overview of climate tech

#42

Post by avmich »

scythe wrote: post #32
symplee wrote: post #4

I empathize with people who are trying to help by reducing their footprint. Though I fear it'll all be in vain when a machine is invented that can suck a lifetime's worth of frugality out of the air in a fraction of a second.

There is a non-negotiable entropy cost associated with removing CO2 from the atmosphere: you need to either pump it, so P0 = 0.0004 atm; if P1 = 5 atm (liquid CO2) then E = M R T ln(5 / 0.0004) / 44 => E/M = about 500 J/kg, or you need to absorb it chemically, which requires a chemical with a vapor pressure of CO2 I expect that we will eventually develop technology for CO2 extraction, but it's not going to be easy or…

How did you calculate 500 J/kg? If you spend energy to pressurize gas, you can get it back when restoring the original pressure, right?

Re: We need to take CO2 out of the sky – an overview of climate tech

#43

Post by lopmotr »

roel_v wrote: post #14
symplee wrote: post #4

I empathize with people who are trying to help by reducing their footprint. Though I fear it'll all be in vain when a machine is invented that can suck a lifetime's worth of frugality out of the air in a fraction of a second.

The article links to a website where you can calculate your footprint, and buy offsets in various programs to negate that footprint (projectwren.com). It would cost me USD 17 / month to offset my (larger than average for my country) footprint. Why do I even bother with my reusable coffee cup and paper straws for that kind of money? I just don't understand. If an extra charge of $10 / month for everyone in Europe woul…

Reusable cups and paper straws aren't for climate change. They're for the quite unreasonable landfill scare. The people who subscribe to that belief have no idea beyond "plastic = bad" and "landfills = bad". Sometimes they try to link it to climate change for added credibilty though.

Re: We need to take CO2 out of the sky – an overview of climate tech

#44

Post by nullc »

sliken wrote: post #30
nullc wrote: post #19

Earlier quoted context omitted.

If you do the math, this essentially doesn't work out. :( Trees are far too slow, even if you have a good way to lock up the carbon once the trees capture it. For an intuitive understanding, consider: Our surplus of CO2 comes (mostly) from burning fossil fuel that took millions of years for the original plant life to accumulate.

Yes, but forests capture carbon quickly until the average age of the trees starts increasing. So zero to 50 years is good, but after that things really slow down. The amount of wood becomes relatively constant. So slowly, very slowly leaves fall/get eaten by bugs, break down, and get absorbed by new trees. But there is a net gain, just a very slow one. Then things like continents collide, mountain ranges come and go,…

Consider the scale of what you're describing now: cutting down and burying all trees on earth every 30 years.

We could certainly _burn_ all of them every 30 years, but that wouldn't help. The figure you need is the marginal capture after the emissions from the process.

Wikipedia says our current emissions from fossil fules and cement production is estimated at 10GtC (not absurd compared to your numbers, since you count only crude oil).

So restating, if somehow without adding any new carbon buried _all_ the vegetation on earth every 30 years, we'd remove 21 GtC per year or a net reduction of 11. To get back to pre-industrial levels it would still take 34 years even ignoring the >1000 GtC currently in the ocean surface that would come out of solution and fight the reduction. (I have no idea how to setup the diff eqs for solving for the ocean contributions...)

The fact that an emission free removal and replacement of all vegetation of earth would still take a long time is basically my point around "planting trees" not being a sufficient plan. :)

Not that planting trees is bad, but solving this is going to take some mixture of reduction and magic (presumably both the political and technological kind).

Re: We need to take CO2 out of the sky – an overview of climate tech

#45

Post by threeseed »

privateSFacct wrote: post #37
ComputerGuru wrote: post #28

What the article leaves to the conclusion is what needs to be stated up front and center: it's virtually impossible to do this efficiently, cheaply, or effectively because there's so little CO2 in the air, meaning a) adding even a little bit more greatly affects the CO2 levels b) with a global ppm of ~400, it basically means that you need to filter 2500 molecules of air to get a single molecule of CO2, and that's ass…

It only has to do it cheaply now because there is NO COST to putting CO2 into the air. Why are people surprised that if something is free (pumping CO2 into air) demand for it is high? You are telling me that doing a charge of let's say $10 - $100/ton of CO2 wouldn't have a DRAMATIC impact on emissions? Is $10 - $100/ton too little for a supposed climate emergency? There is so much funding and lawmaking and finger poi…

You mean a Carbon Tax ?

The tax that applies to every single business, every single product, every single process, everything. The one that causes every single vested interest to come out of the woodwork and join together to make it politically toxic.

We tried this in Australia. It has killed every government that even dared to discuss it. And politically it is utterly impossible to defend e.g. "Carbon tax that raises power prices for pensioners".

Re: We need to take CO2 out of the sky – an overview of climate tech

#46

Post by quixoticelixer- »

threeseed wrote: post #45
privateSFacct wrote: post #37

Earlier quoted context omitted.

It only has to do it cheaply now because there is NO COST to putting CO2 into the air. Why are people surprised that if something is free (pumping CO2 into air) demand for it is high? You are telling me that doing a charge of let's say $10 - $100/ton of CO2 wouldn't have a DRAMATIC impact on emissions? Is $10 - $100/ton too little for a supposed climate emergency? There is so much funding and lawmaking and finger poi…

You mean a Carbon Tax ? The tax that applies to every single business, every single product, every single process, everything. The one that causes every single vested interest to come out of the woodwork and join together to make it politically toxic. We tried this in Australia. It has killed every government that even dared to discuss it. And politically it is utterly impossible to defend e.g. "Carbon tax that raise…

Except many countries have carbon tax

Re: We need to take CO2 out of the sky – an overview of climate tech

#48

Post by wwweston »

lopmotr wrote: post #43
roel_v wrote: post #14

Earlier quoted context omitted.

The article links to a website where you can calculate your footprint, and buy offsets in various programs to negate that footprint (projectwren.com). It would cost me USD 17 / month to offset my (larger than average for my country) footprint. Why do I even bother with my reusable coffee cup and paper straws for that kind of money? I just don't understand. If an extra charge of $10 / month for everyone in Europe woul…

Reusable cups and paper straws aren't for climate change. They're for the quite unreasonable landfill scare. The people who subscribe to that belief have no idea beyond "plastic = bad" and "landfills = bad". Sometimes they try to link it to climate change for added credibilty though.

> The people who subscribe to that belief have no idea beyond "plastic = bad"

So... you're saying that there's not an accumulation of plastic waste / microplastics in the environment, or that we know any impacts or benign or negligible?

Good news if true, would like to know what position there's the most credible evidence for.

> and "landfills = bad".

I'm a fan of consumer goods, so naturally it's convenient for me if landfills == good, but I also tend to wonder (a) exactly how effectively they isolate waste issues from, say, groundwater or other environmental circulation and (b) if there might be some volume threshold past which landfills aren't an adequate solution for addressing waste streams.

Re: We need to take CO2 out of the sky – an overview of climate tech

#49

Post by quixoticelixer- »

willj wrote: post #12
pstrateman wrote: post #5

1. Plant trees 2. Cut down trees 3. Sink trees to the bottom of a great lake

Trees take about 10 years[1] to reach their peak CO2 consumption. That’s a long time to wait. Also, trees and other plants seem to be decreasing in how much carbon they are absorbing, compared to what they did a decade ago. [2] [1] http://urbanforestrynetwork.org/benefits/air%20quality.htm [2] https://cosmosmagazine.com/climate/trees-and-plants-reached-...

Not really, this is going to be a problem for a while

Re: We need to take CO2 out of the sky – an overview of climate tech

#50

Post by avmich »

orbuch wrote: post #41
ComputerGuru wrote: post #28

What the article leaves to the conclusion is what needs to be stated up front and center: it's virtually impossible to do this efficiently, cheaply, or effectively because there's so little CO2 in the air, meaning a) adding even a little bit more greatly affects the CO2 levels b) with a global ppm of ~400, it basically means that you need to filter 2500 molecules of air to get a single molecule of CO2, and that's ass…

(I wrote the post) This is good feedback that this is buried in the appendix -- I pulled that section up and made it inline with the flow of the post. Does that help?

Section "How to take CO2 out of the sky"

> Briefly: there are plant-based, mineral-based, and chemical options.

Where are cryocooling-based options?

Post reply on HN