Robotic 'trees' can turn CO2 into concrete • Hacker News Board

Re: Robotic 'trees' can turn CO2 into concrete

#91

Post by throwaway5752 » Tue, Sep 11, 2018, 4:36 PM UTC

08-15 wrote: post #86

throwaway5752 wrote: post #62

Earlier quoted context omitted.

If only they had a soft cap and let people trade credits to try to keep emissions under that cap to incentivize sequestration and efficiency innovations.

You know what's the problem with that idea? There are no "sequestration and efficiency innovations". Sequestration doesn't work and takes too much energy, and efficiency cannot be improved much thanks to thermodynamics. Besides, if the IPCC is correct about how bad CO2 is, the only sensible cap for emissions is zero. You don't get there with tiny improvements in efficiency.

I'm sarcastically saying that we had proposals for a cap and trade system that would have mitigated it but it was destroyed for political reasons.

Re: Robotic 'trees' can turn CO2 into concrete

#92

Post by hinkley » Tue, Sep 11, 2018, 4:36 PM UTC

daveFNbuck wrote: post #81

throwaway5752 wrote: post #64

Seriously, everyone suggestions a crackpot idea for sequestering carbon should do the basic arithmetic for how much annual human emissions are (40 billion metric tons). I like https://blogs.scientificamerican.com/life-unbounded/the-craz... for the perspective it offers: current human CO2 emissions are equivalent to the entire continent of Africa being covered in coniferous forest and burning to the ground in forest f…

Concrete production accounts for about 5% of CO2 emissions, so this does reduce emissions.

And turning a source into a sink is better than stopping. Assuming that this process takes more energy than the current process, you could still be looking at a target of, say, 8% reduction of anthropogenic carbon.

Re: Robotic 'trees' can turn CO2 into concrete

#93

Post by OnlyRepliesToBS » Tue, Sep 11, 2018, 4:43 PM UTC

wow, that website layout is terrible

Re: Robotic 'trees' can turn CO2 into concrete

#94

Post by papeda » Tue, Sep 11, 2018, 4:53 PM UTC

Gustomaximus wrote: post #29

dithering wrote: post #20

Earlier quoted context omitted.

There's got to be something that grows faster, and is easier to sequestrate, than trees. Bamboo, maybe? Seaweed? Algae? Dry it off in salt pans and dump it in the deep, cold ocean? That's just dumping more carbon into one of our natural sinks, I think, rather than trying to create a new artificial sink. Even just using it as fertilizer has got to be an improvement over using inorganic fertilizers.

Iron fertilization https://en.wikipedia.org/wiki/Iron_fertilization

Cool idea, I'd never heard of this. TL-DR is that there are huge portions of the ocean that are nutrient-rich but have little life, and one hypothesis is that iron is the limiting factor here. Since various phytoplankton need iron to survive, why not dump iron in these places, watch the phytoplankton now thrive, and enjoy their carbon sequestration?

The answer seems to be "well, we don't really know what the effect would be". Some algae blooms are not good (red tide), deliberately altering an ecosystem is generally dangerous, it's not clear whether the positive local effect on carbon has some side effect elsewhere (maybe we're just moving phytoplankton around the ocean). Even doing experiments on this is difficult (the world's oceans are weirdly regulated), and current financial incentives don't make it all that enticing either.

But a cool idea.

Re: Robotic 'trees' can turn CO2 into concrete

#95

Post by hanoz » Tue, Sep 11, 2018, 5:13 PM UTC

tlb wrote: post #68

arlindohall wrote: post #50

I have a hard time taking an article seriously who uses an image of water vapor coming off nuclear cooling towers as an example of carbon emissions from energy production.

Those sort of cooling towers aren't just for nuclear power. They're the most efficient way of cooling anything, unless you're next to a river. Judging from the railway and storage around it, I think that's a coal plant.

Indeed it appears to be Drax coal-fired power station in Yorkshire (https://en.wikipedia.org/wiki/Drax_power_station), Britian's largest emitter of carbon dioxide.

Re: Robotic 'trees' can turn CO2 into concrete

#96

Post by teraflop » Tue, Sep 11, 2018, 5:46 PM UTC

ksdale wrote: post #80

OscarCunningham wrote: post #76

Earlier quoted context omitted.

How is that possible? Surely the volume of fossil fuels being burnt isn't remotely comprable to the volume of that forest.

I don't know if the math is correct, but oil and coal are far more energy dense than wood which may account for the discrepancy.

I think the math is somewhat wrong. The original source link for that "4.81 metric tons per acre" number is broken, but it appears to be talking about tons of carbon, not CO2 (which is roughly 27% carbon by mass). The article underestimates the amount of CO2 released by forest fires by roughly a factor of 4, and therefore overestimates the required land area by the same factor.

It's still a pretty staggeringly huge amount of land, though.

Re: Robotic 'trees' can turn CO2 into concrete

#97

Post by stephengillie » Tue, Sep 11, 2018, 5:51 PM UTC

Grow these on top of hills and mountains, then use the tech from the other thread[∆] to lower the blocks and generate electricity too.

[∆]https://news.ycombinator.com/item?id=17958700

Re: Robotic 'trees' can turn CO2 into concrete

#98

Post by ph0rque » Tue, Sep 11, 2018, 6:00 PM UTC

6nf wrote: post #2

Every time one of these articles come up I wonder about the price per tonne of CO2 removed by simply growing wood and not burning it. I'm not really sure what that price is, but it seems to be around $20-$40 per tonne? Does anyone have a more accurate number?

~$6 per (short) ton ($0.10 per tree planted, which removes ~34 lbs of carbon per year). More here: http://shindyapin.tumblr.com/post/141034501197/climate-chang...

Re: Robotic 'trees' can turn CO2 into concrete

#99

Post by roryisok » Tue, Sep 11, 2018, 6:07 PM UTC

throwaway5752 wrote: post #64

Seriously, everyone suggestions a crackpot idea for sequestering carbon should do the basic arithmetic for how much annual human emissions are (40 billion metric tons). I like https://blogs.scientificamerican.com/life-unbounded/the-craz... for the perspective it offers: current human CO2 emissions are equivalent to the entire continent of Africa being covered in coniferous forest and burning to the ground in forest f…

Reduced emissions are not enough. Even if we got to zero emissions worldwide in the next 20 years (impossible), the excess carbon in the atmosphere already needs to be dealt with. There are greenhouses gases coming from the permafrost. The forest carbon sinks we depend on are being reduced every year by logging and wildfires. The ocean is heating up and probably becoming less effective as a carbon sink. Basically, not only are we putting out more carbon per year, we're also removing less of it. We need more crackpot schemes, and we need them yesterday. Not instead of emission reduction but in conjunction with it

Re: Robotic 'trees' can turn CO2 into concrete

#100

Post by aeternus » Tue, Sep 11, 2018, 6:30 PM UTC

leoedin wrote: post #47

dTal wrote: post #32

Earlier quoted context omitted.

Additionally, if you permanently dedicate 1 acre of land to growing trees, then an acre of trees' worth of wood is permanently captured - though the individual trees may die and rot, more will take their place.

The only problem is that we don't have nearly enough space for that. An acre of trees stores ~393 tonnes of carbon dioxide permanently (in Vermont anyway, other areas probably vary a lot) [1] Humans generate ~40 Gtonnes of CO2 a year. That means we need to be adding ~100 million acres of trees every year to capture that. There's currently 4 billion hectares of forest cover - that's around 10 billion acres. If we repl…

There is a lot more area in the ocean and seaweed grows very quickly. Perhaps we could even accelerate the sequestration by building large seaweed farms over the deep ocean, then sinking the seaweed once it grows large enough, & repeat.