Accelerating Natural Processes to Capture Carbon

Dr James Rae and Dr Paul Webb

School of Earth and Environmental Sciences and School of Chemistry

The dissolution of carbon dioxide in seawater and its subsequent reaction with marine limestone removes carbon dioxide from the atmosphere and stores it in the ocean as bicarbonate. This process has repeatedly operated in Earth’s history, drawing down gigatonnes of carbon following large volcanic eruptions. Our research explores the potential of harnessing this natural process for the capture of anthropogenic carbon dioxide at the point of emission. This “Accelerated Weathering of Limestone” could be used to capture carbon dioxide from difficult to decarbonise energy and industry sources (e.g. cement production) or be paired with biomass power to provide a novel capacity for negative emissions.

This photograph, taken on the local East Neuk coastline, captures contrasts between sources and sinks of carbon dioxide. The dark layers in the background are carbon-rich mudstones and thin coals, some of the most carbon-rich rocks on the planet. Burning these converts the carbon directly into atmospheric carbon dioxide – it’s hard to imagine a more efficient way to elevate atmospheric carbon. However, the light-coloured limestone layers observed in the foreground, in which fossil corals are visible as small twig-like features, offer a possible solution. This rock is sufficiently reactive to dissolve in a stream of carbon dioxide gas, neutralising it in the process. Current work by Drs James Rae (Earth and Environmental Sciences) and Paul Webb (Chemistry) is investigating whether this “Accelerated Weathering of Limestone” can be deployed at the University’s biomass plant to provide a novel source of carbon capture and negative emissions.

Photographer: Olivia Booker