Dirk Pässler (carbon-drawdown.de) did some back-of-the-napkin calculations for their experiments (enhanced weathering of basalt dust on cropland):
> In the end we calculated the actual emissions to be 44,6 tons CO₂, due to the fact that we drove more truck kilometers than we had planned. This is less than 10% of 1217 t basalt’s CDR potential of 509 t CO₂. In summary: The mining and transport emissions are one order of magnitude smaller than the CDR effect, even with 300-500 km transport distances. This will only get better in the future with more green energy, electric trucks and optimized logistics.
>If rock powder was produced exclusively for ERW applications, a proportional share of the scope 1-3 emissions of the mining facility will be attributed by the methodology.
They purposely ignore what could be the most carbon intensive step in their process. But it's good they considered all other steps and gave an estimate of them.
> In the end we calculated the actual emissions to be 44,6 tons CO₂, due to the fact that we drove more truck kilometers than we had planned. This is less than 10% of 1217 t basalt’s CDR potential of 509 t CO₂. In summary: The mining and transport emissions are one order of magnitude smaller than the CDR effect, even with 300-500 km transport distances. This will only get better in the future with more green energy, electric trucks and optimized logistics.
https://www.carbon-drawdown.de/blog/2022-12-14-how-cdr-with-...