Removing atmospheric CO2 by spreading surplus concrete on farmland

The process is being tested in the agricultural heart of the US

Spotted: Enhanced weathering is a process in which carbon dioxide in the air reacts with fine rock particles spread over an area of land or sea. The technique accelerates natural chemical weathering processes and locks away CO2 by converting it into stable bicarbonate ions, which can be stored in the ocean for more than 80,000 years(if the process takes place on land, the bicarbonate makes its way into waterways that eventually wash it to the sea). The process has attracted the interest of scientists, and now Irish startup Silicate is conducting an important trial of the technology on farmland in the US corn belt.

The source of the rock particles influences the overall impact of enhanced weathering techniques and using waste materials removes the need for extractive and environmentally damaging mining. Silicate has therefore turned to surplus concrete, having developed a method of altering returned milled concrete to unlock its full carbon-capturing capabilities. Around 10 per cent of all the ready-mixed concrete produced in the US is returned to suppliers, so the startup’s process is a good use of a common waste material.

Silicate has conducted promising trials in Ireland, but the latest trial – which is being conducted on 50 hectares of land in Buckingham, Illinois – is testing how the concrete material performs in the soil conditions of the American Midwest. Enhanced weathering offers co-benefits for farmland such as increased soil health and crop productivity, so its application in one of the world’s most important agricultural regions could have benefits beyond capturing carbon. A successful result would also pave the way for the rapid scale-up of the process through collaboration with farmers and companies across the Midwest.

Other enhanced weathering innovations spotted by Springwise include the use of mine waste for the purpose in Brazil, and a study conducted by the University of Sheffield.

Written By: Matthew Hempstead