This seems like it would fail energetically; the amount of energy required to mine and transport a bunch of rock to a beach would surely exceed the amount of CO2 sequestered.
It seems like you didn't read the paper, or really anything on this.
But, to make it easy for you:
* 1 ton of Olivine will absorb 1.25 tons of CO2[1]
* Transportation cost is 161.8 grams of CO2 per ton mile[2]
* They are looking at mines within a 300km[1] (or ~190 miles) radius. That's a maximum transportation cost of ~31kg CO2. That's a rounding error.
* Mining cost for a ton of Olivine is ~$30/ton right now. Let's say it's all for hydrocarbon fuels, and they're cheap, so 30 gallons of fuel. Let's make it 50 gallons, because I'm lazy. A gallon of fuel produces 20 pounds of CO2[3], so 1000 pound of CO2. That's half a ton.
* Let's assume for reasons beyond our ken we'll spend another quarter ton of CO2 on this. Likely due to people arguing on the Internet.
That still leaves us with half a ton of CO2/ton of Olivine.
Maybe do at least back-of-napkin calculations before claiming things will certainly fail.
You're right, I didn't read enough or do enough back-of-the-napkin math. I read more; this seems plausible in life cycle terms, but now I have doubts about the economics. At $30/ton, 30Gtons becomes $900 billion a year. For comparison US discretionary spending is $1.4 trillion. It's not clear to me where this level of spending is going to come from (jewelry sales?), for an activity that has no useful economic output other than sequestering carbon. In addition I'm not sure that $30/ton is an accurate estimate of all of the capital outlays and so on required - entire industries have to be created to facilitate this process at scale. Much of this activity has to be done in decentralized fashion, i.e., it is not a single polity or entity that must partake in olivine mining to make this viable, which adds cost and political overhead.
I'm also not clear on what putting 30 gigatons of rock onto coastal sea shelves each year is going to do in terms of ecosystem impact, and how tolerant local polities will be of this. For example, Costa Rica gets something like 6% of its GDP from tourism, a lot of which is ecotourism; it seems unlikely they will be happy about a significant mining and rock-dumping operation taking over its beaches.
EDIT: Also, on the life cycle question, I'm unclear on how real the "1 ton for 1.25 tons of CO2" claim is - would a real beach weathering actually produce this much absorption per ton? Would it happen on a 1-year time scale so that we could actually offset this much every year? Uncertain; if you have citations demonstrating this please post them, if you're not above arguing on the Internet.
Mines or potential mining sites for extracting Olivine on this scale don't exist within short distances of these tropical beaches. Many of the beaches are on islands which are essentially coral heads above the water. Digging down to any deposits of other rock are going to require either significant effort in terms of dewatering, caissons, and equipment or else mining underwater.
This is a good idea that's probably not practical. It sounds ok if you accept that that much rock can be mined, processed, and moved within the constraints given, but they're probably not even close with these estimates.
On top of that, you're talking about completely changing the composition of the beaches in much of the tropics, displacing the existing beach materials and probably causing mass die-offs and disruption in the ecosystems attached to them.
Plus, you'll have to keep hauling sand. Beaches in active areas like the tropics aren't static. The sand migrates down them and out into the ocean. Sometimes islands like the Bahamas even have to dredge sand back out of the water to rebuild beaches.
Underwater sand isn't going to absorb much atmospheric CO2.
"The Life Cycle Analysis (LCA) of the release of CO2 from mining, milling, and transport of olivine creates an approximately 4-6% loss on CO2 removed. We will always work to minimize the transport distance from the source of olivine, and utilize low impact transit such as rail and boats. Further, many tons of olivine are already mined because the deposits are found above other valuable minerals, such as diamonds (found in a rock formation called Kimberlite). Utilizing these piles of waste rock, known in the industry as tailings piles, will allow us to harvest olivine without causing a significant CO2 output. Further, the dust from mining itself can contribute to the offset of the entire mine, as well as the very ground where the olivine is exposed. It starts weathering right away, and many ultramafic mineral mines, abandoned or active, eventually offset their own footprint and even go towards negative emissions. On of our olivine weathering rate sources is actually these tailings piles."
From the second item on their FAQ (https://projectvesta.org/frequently-asked-questions/):
> The Life Cycle Analysis (LCA) of the release of CO2 from mining, milling, and transport of olivine creates an approximately 4-6% loss on CO2 removed.
groby_b|6 years ago
But, to make it easy for you:
* 1 ton of Olivine will absorb 1.25 tons of CO2[1]
* Transportation cost is 161.8 grams of CO2 per ton mile[2]
* They are looking at mines within a 300km[1] (or ~190 miles) radius. That's a maximum transportation cost of ~31kg CO2. That's a rounding error.
* Mining cost for a ton of Olivine is ~$30/ton right now. Let's say it's all for hydrocarbon fuels, and they're cheap, so 30 gallons of fuel. Let's make it 50 gallons, because I'm lazy. A gallon of fuel produces 20 pounds of CO2[3], so 1000 pound of CO2. That's half a ton.
* Let's assume for reasons beyond our ken we'll spend another quarter ton of CO2 on this. Likely due to people arguing on the Internet.
That still leaves us with half a ton of CO2/ton of Olivine.
Maybe do at least back-of-napkin calculations before claiming things will certainly fail.
[1] https://projectvesta.org/ [2] http://business.edf.org/blog/2015/03/24/green-freight-math-h... [3] https://www.fueleconomy.gov/feg/contentIncludes/co2_inc.htm
astazangasta|6 years ago
I'm also not clear on what putting 30 gigatons of rock onto coastal sea shelves each year is going to do in terms of ecosystem impact, and how tolerant local polities will be of this. For example, Costa Rica gets something like 6% of its GDP from tourism, a lot of which is ecotourism; it seems unlikely they will be happy about a significant mining and rock-dumping operation taking over its beaches.
EDIT: Also, on the life cycle question, I'm unclear on how real the "1 ton for 1.25 tons of CO2" claim is - would a real beach weathering actually produce this much absorption per ton? Would it happen on a 1-year time scale so that we could actually offset this much every year? Uncertain; if you have citations demonstrating this please post them, if you're not above arguing on the Internet.
Accujack|6 years ago
This is a good idea that's probably not practical. It sounds ok if you accept that that much rock can be mined, processed, and moved within the constraints given, but they're probably not even close with these estimates.
On top of that, you're talking about completely changing the composition of the beaches in much of the tropics, displacing the existing beach materials and probably causing mass die-offs and disruption in the ecosystems attached to them.
Plus, you'll have to keep hauling sand. Beaches in active areas like the tropics aren't static. The sand migrates down them and out into the ocean. Sometimes islands like the Bahamas even have to dredge sand back out of the water to rebuild beaches.
Underwater sand isn't going to absorb much atmospheric CO2.
thesausageking|6 years ago
roonilwaslib|6 years ago
I'd still like to see the LCA.
thebluehawk|6 years ago