But you can’t grow trees everywhere. These folks estimate the increased carbon sequestration capacity of CONUS forestlands to be <200 MMT CO2 per year: https://www.pnas.org/content/117/40/24649#ref-15
To put that in context, US emissions in 2019 were ~6 GT CO2 eq.
He is talking about the possibility of using asteroid material to fertilize the oceans, which certainly has its own issues, but he goes into the numbers on what it would take.
There’s a longer one and a shorter one. I watched the longer one, don’t know if he goes into as much detail on the numbers on the shorter one.
Anyway, the quantities needed to fertilize the oceans enough to offset our CO2 emissions, assuming that there is enough dead zone to be fertilized in this way, is pretty immense.
It may be a part of the solution, but what we really need to do is to stop putting all the CO2 into the atmosphere in the first place.
You seem to be reading things into the OP’s hypothetical that weren’t stated. It didn’t ask about “practical” or “reverse climate change” (or “in a useful amount of time” or “for a useful amount of time”.) All it asks is “can it be done?”
There is a possible fairly recent precedent For noticably reducing atmospheric CO2 and global temperature through reforestation.
That’s valid criticism. And I agree, its in the same category as Cold Fusion. Yes it can be done, but not not at a scale useful for our society. You can invest billions of dollars into it, just like cold fusion OR look at other solutions.
Thats historical record. With the current crisis in water, the west coast is in 20 year drought and the Colorado is under crisis, reforestation will be extremely difficult in most places in the world. The next wars will be for water - and I am not sure if we can divert it for “reforestation”.
All planting trees does is shift the equilibrium point.
Take an aspen tree - 12" in diamter and 50’ tall and a spread of 20’ Lets just save a cylinder 30cm with height 10m - volume winds up being 2.8 m3. I’ve seen cites where 1m3 is 1 metric ton of CO2.
So per tree we can store 2.8 tons of CO2 over the course of 30 years. And we get 1 tree for every 34m2.
To remove 1000 MT of CO2 would need to plant a square 110km pre side and wait 30 years and the US emits 5000 MT each year.
So trees are neat, very cool and helpful but not putting the damn stuff in the air in the first place has the bigger bang for the buck.
You know this already but for the benefit of others, a headache with FT is the broad product distribution, e.g. (random GIS):
The reaction itself scales down just fine (I’ve seen it), but the separation to get jet fuel out of that waxy mess does not.
I’m less familiar with MTG. The methanol itself (or DME) shouldn’t be a problem. IIRC Mobil was targeting shorter products for passenger vehicle fuels. And I don’t know much about Topsøe’s improvements (TIGAS) other than that it’s a thing.
Again, the OP didn’t ask about price and didn’t ask about timeline and didn’t ask about it being helpful to humans. Do what the colonists did in the 1500’s–depopulate a continent and let the whole thing return to forest. Or depopulate all the continents. Plenty of surface area.
If the question is “can it be done?”, we have the geologic record that of course it can and has occurred multiple times over the last several hundred million years. OP answered conclusively.
But that’s awfully reductive. It’s only becomes interesting if we are asking if it can be achieved on a planetary scale by human beings and/or on a human timescale. Otherwise, the answer is again reductive - wait several million years. It’ll happen one way or another naturally after human beings aren’t a factor anymore.
I disagree. Not Cold Fusion. That is a red herring. It’s the other fusion you mean.
And to the OP: scrub carbon from the atmosphere on a planetary scale? Yes, it happens all the time. By weathering of rocks containing calcium (limestone and other calcareous rocks like aragonite, calcite, vaterite, chalk, marble…), which happens on a grand scale in mountains like the Himalayas, the Dolomites and the Rocky Mountains where those rocks are exposed through erosion. Glaciers increase the contact surface a lot (alas, glaciers are in retreat almost everywhere). And in the sea, where dissolved CO2 is eating away the shells of those animals, corals, shells and whatnot, the result is a decrease in CO2 by creating calcium carbonate (CaCO3), which in turn creates CO2 back when it reacts with an acid. It is unfortunately not enough to reverse the increase caused by burning fuels, but when we stop burning them it should eventually reverse the trend.
In a couple of million years.
The answer to the OP is yes. The technology is know as Carbon Removal. I’m citing the same Iceland Direct Air Capture facility as Senegoid, although I read a different source.
That Climeworks facility will remove 4000 metric tones of CO2 from the air annually. It has 8 “air collection containers”, each the size of a shipping container, plus a processing building. Global CO2 emissions in 2019 were 38.0 gigatons of CO2.
So that’s 76 million “air collection containers”. I don’t know how many ACC’s a processing building could handle, and I wasn’t able to find information on an ACC’s electricity requirements. But presumably they’d be driven by solar power or wind power. So that’s several million processing buildings, windmills and solar panel hectares required. Costing that would be an exercise in futility, but it would surely cost several trillion dollars. The thing is, a several trillion dollar project on a global scale is achievable - if there’s global buy-in. Getting that bit after the if accomplished is an implementation feature, not a design feature, so I’m going to leave it others to work out.
The other thing is that all that electricity that we’re hypothetically generating for Direct Air Capture - that isn’t the best use of that electricity. Building continental power grids, and replacing all fossil fuel electrical generation with zero emission electrical generation would be much more effective. So would replacing petroleum powered cars with electric cars. There’s a long list of things that zero emission electrical power is better suited to than Direct Air Capture, or other Carbon Removal technologies. It may have a place in a future overall net-zero carbon scheme to offset necessary carbon-emitting processes - fertilizer production is one area that comes to mind. But it will never be a case of status quo, except we’re removing all the CO2 from the atmosphere to achieve net-zero emissions.
The plant will capture 4,000 tons of CO₂ a year, making it the largest direct-air capture facility in the world. But that only makes up for the annual emissions of about 250 U.S. residents. It’s also a long way from the company’s original goal of capturing 1% of annual global CO₂ emissions — more than 300 million tons — by 2025. The company is now targeting 500,000 tons by the end of the decade.
500,000 tons of CO2 removed represents the carbon footprint of 31,250 US residents (by the estimate above; I actually make the average carbon footprint to be an average of 13.44 tonCO2/person in 2018 figures, so around 37,200 US residents). So increasing the capacity by four orders of magnitude over their end of decade projection should just about cover the United States, which of course is a large emitter per capita but only accounts for about 15% of CO2 emissions worldwide, so add another order of magnitude. That is, of course, assuming that it can actually meet the capture target of “4,000 tons of CO₂ a year”; meeting advertised capture targets has been a technical challenge that other CCS systems have thus far struggled and generally failed to accomplish.
The short version: Turning carbon dioxide into anything else costs energy, more energy than you got by burning the fossil fuels that produced the carbon dioxide. So if you’re powering your sequestration plant using existing power sources, you’re losing. You can, instead, power your sequestration plant with green sources like wind or solar, but if you have those green sources, you’re better off using them to replace fossil fuel plants. Turning atmospheric carbon dioxide into something else would only make sense after you’ve already shut down almost all of the fossil-fuel consumption.
Alternately, you can leave the carbon dioxide as it is, but try to bury it. This is made extremely difficult by the fact that it’s a gas, with very high volume (much, much greater than the volume of coal or oil that produced it).
Right; the energy or monetary cost to do something with it is important. Carbon Engineering estimated 8.8 GJ of natural gas (yes, burning NG to run their direct air capture) or 5.35 GJ NG + 366 kWhr of electricity per ton CO2 captured to deliver a 15 MPa stream. Not to stick it underground or use it for chemical energy storage.
Right, and even conventional controlled “hot” fusion has more than just a scalability problem; no controlled fusion reactor to date has actually produced more energy than the energy required to produce the reaction. So even that technically can’t really be done yet, even on a small scale. The first fusion reactor that may produce net energy is the international ITER collaboration, which hopes to have an initial demonstration at the end of 2025 (so realistically, maybe 2026).
The science doesn’t agree with you. The overwhelming human contribution to climate change is the burning of fossil fuels. Deforestation can be unhelpful but is not a major factor, and in fact, depending on the intended purpose of the deforested land, land use changes can actually increase surface albedo and constitute a negative feedback (i.e.- a small cooling effect) – especially in winter where you may get lots of snow cover on cleared land. In any case, the main point here is that burning fossil fuels for transportation, electricity, and industry is by far the leading source of atmospheric CO2 and other GHGs.
