They propose mining and transporting 11 cubic kilometers* of olivine per year, at $10 per ton when scaled up, which comes out to $365 billion per year assuming that’s metric tonnes. Might or might not be considered “reasonably cheaply” depending on what you think of the alternatives.
*they also mention 7 cubic miles, which would be almost a trillion dollars per year, but this would be a lot more than would be needed to offset world carbon emissions if their claim of 1.25 to 1 ratio of CO2 to olivine is correct—so I think that’s a misconversion from the 11 cubic km figure rather than the other way around.
For some further perspective, $10 per ton at 1.25 times removal of CO2 would be $8 per ton of CO2. So, we could theoretically pay for it with a relatively affordable $8 per ton global carbon tax if that could somehow be made to work politically.
They propose mining and transporting 11 cubic kilometers* of olivine per year, at $10 per ton when scaled up, which comes out to $365 billion per year assuming that’s metric tonnes. Might or might not be considered “reasonably cheaply” depending on what you think of the alternatives.
*they also mention 7 cubic miles, which would be almost a trillion dollars per year, but this would be a lot more than would be needed to offset world carbon emissions if their claim of 1.25 to 1 ratio of CO2 to olivine is correct—so I think that’s a misconversion from the 11 cubic km figure rather than the other way around.
For some further perspective, $10 per ton at 1.25 times removal of CO2 would be $8 per ton of CO2. So, we could theoretically pay for it with a relatively affordable $8 per ton global carbon tax if that could somehow be made to work politically.