Carbon Capture and Storage works! If you have just exactly the right location. With just exactly the right kind of rock. That is just exactly porous enough. And is just exactly the right temperature. And if you have 10 times as much fresh, clean water for every ton of carbon. But otherwise it works!

Enhanced rock weathering is a non starter as it just becomes absurdly infeasible to scale up. That particular project has always seemed like a sketchy money making scheme to me too... partly because the founder also set up a company selling pills that he claims makes you smarter or something. The Project Vesta site has a lot of stuff wildly over estimating the potential of the project whilst leaving out all of the drawbacks... and then tries to sell you some shitty necklace for $25.

Before they set up this project a very similar idea had been floated of scattering basalt on farmland around the world to sequester carbon dioxide. However the most optimistic estimate was that to capture 5Gt of CO2 annually they would need to mine, powder, transport and spread 15Gt of rock every year or two across pretty much every bit of farmland in the world. Incidentally this would make it the world's second largest resource industry after water, supplanting concrete which is currently second at something like 10Gt a year and is a big source of CO2 emissions.

The emissions from such an industry would heavily eat into how much impact it has and 5Gt was the most optimistic scenario. Other estimates suggested maybe 1-2Gt a year. Some suggested the emissions could exceed that which it hopes to capture.

Their site has essentially copied this idea (in fact I think some of the papers they are quoting are that one, absent the discussion about it being infeasible). Their 'how it works' section goes on and on about the cost and how cheap it would be to do but never mentions the CO2 cost of doing it. For instance how it casually mentions '3000 megacarriers' like it's nothing.

  • 1.2 gigatons (gt) of olivine is 3000 megacarrier loads of 400,000 metric tons of olivine.
  • Based on a model for a 5,000 tonnes per day mine in the USA, the cost of mining and crushing volcanic rock is $7.32 / metric ton.
  • For transport, we would use self-unloading megacarriers that can each hold 200,000 tons of olivine.
  • Loading and unloading of mega carrier takes (4-5 days)*2 = 10 days
  • Speed 15.4 knots (28.5 km/h; 17.7 mph) = 650 km/day
  • Travel Outbound/Inbound (~ 2000 km)*2 = 4000 km = 6 days
  • Cost of 200,000 ton megacarrier daily operations = ~$40,000/day
  • Loading, travel to location, unloading, and travel back = 16 days (although can be less with partial unloading while traveling)
  • 16 days x $40,000 = $640,000
  • $640,000 operational cost of loading+dumping+travel/200,000 tons per boat = $3.20 cost to distribute each ton
  • $3.20 (distribution cost) + $7.32 mining cost = $10.62 / ton of olivine to reach weathering destination in ocean
  • $10.62/1.25 (1.25 tons of CO2 removed for each 1 ton of olivine weathered)

  • =~$8.50 per ton of CO2 removed from atmopshere and ocean

https://projectvesta.org/plan/

So first off its unclear how many ships they're actually talking about here as it says 3000 megacarriers of 400,000 tons one minute and then that megacarriers can hold 200,000 the next. Most importantly though for such a detailed breakdown of the cost it never once mentions the undoubtedly huge emissions that these 3000 or 6000 ships will have in their half month mission to dump rock... let alone the emissions from mining it in the first place.

The kind of ships it is talking about here are the biggest bulk carriers around.

http://bulkcarrierguide.com/size-range.html

It says it would take 3000 loads like it is nothing but there aren't actually that many of these ships which are that big. Definitely less than a thousand, if that, as it seems the bulk of the carrier fleet is smaller ships. The number that can self unload in the manner required is fewer still so that is a really high number of boatloads. Also it seems likely that they did mean 200,000 and just pulled the 400,000 figure off Wikipedia for some reason as it quotes capacities of up to that figure, though those are the extreme few and not the shops they would be using. 1.2Gt in 200k tonne increments is 6000 loads so why they mentioned 3000 I don't know.

A bit of googling and digging through boring pdfs suggests emissions of 5 grams of co2 per tonne per kilometre for these large ships. So that's one tonne per kilometre and it's citing 4000 kilometres of travel so just for the outbound travel of 2000km whilst fully loaded it would be 2000 tonnes per load. 6000 journeys would be 12 million tonnes of CO2. This is without factoring in the emissions of the empty ship returning back or the 10 days spent loading and unloading during which engines will still be running to power cranes or conveyors and to move the ship up and down the beach to unload. So you can probably at least double that figure if not more. That's without even trying to work out the emissions from mining it, powdering it and transporting it by road to the ships which I expect would be the bulk of the emissions. Their 1.5Gt captured per 1.2Gt of rock figure seems very optimistic anyway but factoring in emissions is going to take a chunk off that number, which they neglect to bother talking about at all.

Even without worrying about emissions though the project just doesn't scale. Let's say they somehow acquired 100 of these 200,000 tonne capacity ships, a not insignificant portion of the fleet which is usually busy transporting oil, resources, food or chemicals and isn't conceivably going to stop any time soon. But in any case... that would be 60 journeys per ship and at 16 days per journey, back to back without any downtime that's 960 days. 2.6 years. Just to dump enough rock to supposedly sequester 1.5Gt. So before they'd even finished we'd have released another 100Gt into the environment (of which about half is absorbed naturally). They're never going to make a dent in the >1000Gt of CO2 above the 1850 baseline that is currently in the atmosphere and causing all the problems.

Factoring in the cost, emissions, time and sheer scale of it this project is never going to be remotely feasible or make any significant difference.

/r/collapse Thread Parent