Images of climate innovation
Construction products from mineralised CO2
Atmospheric carbon dioxide gas is ?used? by nature to weather rocks exposed at the surface of the Earth. Millions of tonnes are mineralised each year by weathering reactions that produce solid carbonate. Strategies, such as CO2 mineralisation, have potential to help mitigate Global warming by converting CO2 gas (otherwise emitted to atmosphere) into construction products [Hills et al., 2020]. Indeed, the Global CO2 Initiative believe there is potential to manage 3Gt of CO2 this way [GCI 2017].
By replicating weathering reactions in a managed process to selected rocks and/or solid wastes, the mineralisation of CO2 can be achieved in minutes. The challenge is how to do this in a cost-effective way to produce carbonates that are 'engineered' so they have potential to be used beneficially. In achieving this, the University of Greenwich team have developed an award-winning technology called Accelerated Carbonation Technology (ACT).
ACT is commercialised and available in fixed and mobile plants producing x100,000 t of construction products each year. A major step was to produce products that were 'fit for purpose', i.e., they met regulatory and construction materials standards. The approach taken was to use industrial solid residues as the medium to mineralise CO2, as these wastes tend to have a negative value, being normally disposed of in the environment.
A key part of the ACT process is the presentation of CO2 gas to waste, so the product is formed in minutes and is ready for use almost immediately. The CO2 is mineralised in meaningful quantities such as the 30% w/w (total weight) that can be incorporated in some industrial thermal residues. The Greenwich team are further developing ACT for use with biomass waste [Tripathi 2020] and are working closely with Carbon8 Systems [c8s.co.uk] in the deployment of the World's first mobile ACT plant in France [VICAT, 2021].
Entrant: Colin Hills , University of Greenwich
Copyright: Colin Hills
Links
https://www.globalco2initiative.org