How mine pit lakes could help to tackle climate change

This low-cost method turns old mine infrastructure into a powerful carbon sink

Spotted: When mines are closed, the massive open pits will gradually fill up with groundwater, rain, and water run-off from the land’s surface to create mine pit lakes. The water in these lakes is mostly low-quality, contaminated, and acidic, meaning they have limited beneficial uses. But what if they could be used to capture carbon?

In a low-cost, low-energy process, US company Aquarry adds alkalinity to mine pit lakes to help them capture and store CO2 over the long term. The ocean is the world’s biggest carbon sink, and many scientists have already suggested the possibility of speeding up natural ocean alkalinity enhancement. IN this process, alkaline molecules produced through the gradual weathering of rocks react with CO2 in the ocean to create stable forms of carbon to accelerate the removal of atmospheric CO2.

However, because the ocean is a massive and complex ecosystem, it’s difficult to know the impact of rapidly speeding up alkalinisation, and whether this would harm marine life as an unintended consequence. Pit lakes, by contrast, are more closed systems, making it safer to explore and measure what the company refers to as ‘ocean-less alkalinity enhancement’. In fact, because they were former mines, raising the pH of pit lakes can help to remediate them and boost water quality.

Recently, Aquarry was selected as one of 13 carbon dioxide removal (CDR) projects impact giving platform Milkywire intends to support this year with a pre-purchase as part of its Climate Transformation Fund.

Springwise has spotted other carbon capture methods, including turning marine emissions into pebbles and transforming CO2 into sustainable chemicals.

Written By: Matilda Cox