Quantifying Carbon Dioxide Removal using Pore Water Data from Enhanced Rock Weathering Field Trials in Scotland

Enhanced rock weathering (ERW) has emerged as a promising carbon dioxide removal (CDR) strategy, with tens of dedicated EW commercial entities having been set up in the last three years. UNDO is one of these, with commercial operations across the Northern United Kingdom and Eastern Canada.

Commercial entities selling CDR, like UNDO, are required to measure, verify and report how much CO2 has been removed at regular time intervals. However, different methods of CDR quantification are likely to produce different numbers, depending on where the measurement has taken place (e.g., soil-based measurement vs a pore-water sample). 

We propose an approach that uses pore water concentrations in conjunction with climate data to more robustly estimate CDR per unit area of land, as new pore water data is generated. This approach allows us to estimate the amount of charge-balanced bicarbonate/carbonate ions that are transported past a certain depth point. 

Furthermore, our method is compared against other indicators of weathering processes, such as exchangeable cations and carbonate precipitation. For these calculations and comparisons, we will use data from a field trial that has been running for 2 years.