In the natural world, rocks such as basalt absorb CO2 as part of the continuous process of erosion over millions of years.

This weathering process can be accelerated by crushing rocks to increase the reactive surface area and allow more CO2 to be absorbed. This is known as Enhanced Rock Weathering.

Spreading crushed basalt over farmland helps absorb and store carbon. It can also improve soil health and increase crop yields, leading to a reduction in the use of fertilisers and pesticides. The dissolved CO2 is eventually washed away into rivers and oceans where it is stored for hundreds of thousands of years.

Some crushed basalt is available as a by-product from quarries. Mining and crushing basalt specially would require more energy and potentially more emissions.

The Enhanced Rock Weathering Demonstrator is investigating the use of crushed basalt obtained from by-products of mineral extraction in agriculture, quantifying carbon removal and impacts on soil health and food production.