Carbon capture and utilisation (CCU) uses captured CO2 to make useful substances or products with an economic value. However, as an non-reactive (inert) molecule, CO2 has limited use on its own and cannot be used to produce energy. Generally speaking, a lot of energy is needed to convert CO2 into useful products, which can also lead to more or fewer CO2 emissions, depending on where the energy comes from.
Several technologies are currently in use or being developed, including those to make plastics, concrete, chemical reactants and synthetic fuels. In order for CCU processes and products to have a climate benefit in line with the Paris Agreement and be climate neutral, two aspects need to be considered.
Firstly, the carbon footprint of the required electricity needs to be zero so CCU should only be run with climate-neutral energy sources. Secondly, it is important that CO2 is kept away from the atmosphere for as long as possible, if the CO2 cannot be circulated. If the final product re-emits CO2 at “end of life” (e.g. plastics, fuels), then the the CO2 must be captured from the air through biogenic processes or direct air capture. In this case, the carbon moves in a circle to ensure the CCU chain approximates carbon neutrality.
While climate-neutral CCU processes cannot lock away the volumes associated with large-scale geological CO2 storage, it can form part of a low-carbon economy by reducing the carbon footprint for products. Decoupled from the climate discussion, CO2 represents a new carbon source for the process industries that can substitute fossil carbon.