Techno-economic Assessment for Bio-accelerated Weathering for Carbon Sequestration

Abstract

Significant efforts are required to remove CO₂ from the atmosphere to mitigate the worst effects of climate change. While several methods for CO₂ capture and storage have been proposed, weathering of silicate-rich rocks—which releases divalent cations like magnesium and iron for subsequent carbonation—has the highest potential removal capacity. However, natural weathering and carbonation rates are far too slow to prevent significant atmospheric warming. Bio-accelerated weathering aims to use microorganisms to accelerate these processes, but while it has been explored in laboratories, its economic viability at large scale remains unknown. Here we calculate the costs and revenues of bio-accelerated weathering of ultramafic mine tailings by the mineral-dissolving microbe Gluconobacter oxydans. Without tax credits and with unfavorable feedstock market prices, the cost for capturing and storing one tonne of CO₂ through bio-accelerated weathering could be as high as $3,465. However, under favorable feedstock pricing, tax credits, and revenue from co-leached metals, a profit of $3 per tonne of CO₂ captured and stored could be obtained. This study identifies microbial feedstock costs as the major cost driver, suggesting that process optimization, alternative feedstock development, and genetic engineering are the efforts most likely to maximize economic viability. Our results suggest that bio-accelerated weathering warrants further exploration as a climate change mitigation strategy.