Indirect carbon emis sions of enhanced weathering in Malaysia

Enhanced weathering (EW) of rocks and minerals can be used as a carbon dioxide removal (CDR) technique. EW relies on accelerated geochemical reactions between carbonic acid in rainwater and slightly alkaline minerals to permanently sequester carbon atoms as bicarbonate ions in runoff water. The material needs to be crushed to a fine powder to increase reactive surface area and then spread on land at a rate calibrated to match local weather and soil conditions. However, large-scale EW with virgin material will entail an increase in the outputs and carbon footprints of different economic sectors to support the CDR system. Input-output analysis is used to model such indirect effects when basalt EW is used in all of Malaysia’s oil palm plantations to cut greenhouse gas emissions. Results at fixed electricity carbon intensity show that about half of the direct CDR will be offset by incremental carbon footprints from the mining, electricity generation, and transportation sectors due to the requirements of EW operations; total greenhouse gas emissions are reduced by up to 11.0% to 213.7 Mt CO₂e/y. Cutting the carbon intensity of electricity supply in half allows emissions to be reduced further to 126.9 Mt CO₂e/y. The scenario analyses demonstrate the synergy between renewable energy deployment and EW implementation, supporting Malaysia’s developing carbon management policy landscape.