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Silicate: Storing Carbon for 100,000 Years

Silicate is the first company in the world to utilize returned concrete to remove CO2 from the atmosphere. The startup based in Ireland is on a mission to durably and safely remove 1 billion tonnes of carbon dioxide from the atmosphere by 2040 through enhanced weathering.

Motivated by the urgency of our changing climate and the desire to not stand by, but to take action, Maurice Bryson of Silicate and Professor Frank McDermott of University College Dublin decided to employ their collective experience in geochemistry, agriculture and carbon finance to deliver a robust, science-based, and permanent carbon removal solution to help maintain a habitable planet. Convinced that enhanced weathering has the highest chance of delivering megatonne- and eventually gigatonne-carbon removal volumes and thus contributing substantially to achieving the level of carbon removal the Intergovernmental Panel on Climate Change calls for, the two scientists developed a novel CDR approach, utilizing a previously untapped material:

“We take returned concrete - this is concrete that has gone to a building site and was surplus to requirements - and turn it into a carbon removal solution through processing the material and working with farmers to apply it to their fields,” says Maurice, founder of Silicate. “We believe that returned concrete can be an affordable, rapidly scalable, and durable carbon removal solution, that has, until now, not been harnessed. We see massive potential in this material and are working to demonstrate this through our field- and lab-based trials.”

Silicate’s unique approach, which most recently gained wide-spread attention by being selected as finalist for the 2022 “Irish Times Innovation award”, utilizes surplus construction materials rather than mined rocks to make use of a natural process: the weathering of minerals. Every year, basalt, olivine, and other mafic and ultramafic rocks and minerals weather naturally; they react with carbonic acid to form bicarbonate and calcite - a natural process that removes CO2 from the atmosphere and turns it into rock.

“Our material can play the exact same role, but it can do it in about 1/20th the time of basalt”, says Maurice.

The process uses the silicate-carbonate cycle to durably and safely remove excess CO2 from the atmosphere. Silicate mineralizes carbon by using the geochemical reactivity of an alkaline construction material to sequester shallow-soil CO2 as soluble groundwater bicarbonate, that will ultimately precipitate solid calcium carbonate (limestone) in the ocean. The material not only removes carbon from the atmosphere, storing it in an inert state for millennia, but can also help to reduce ocean acidification. The startup partners with farmers to help them farm more sustainably, replacing agricultural lime as a soil pH amendment. This, in turn, can have co-benefits to the crops where it is applied, such as boosting root health and enhancing the impact of fertilizers, as well as potentially avoiding CO2 emissions generated by the application of lime.

But with enhanced weathering, one challenge prevails: the process of rock weathering and precipitation into dissolved inorganic carbon is well characterized and studied, but challenges remain to measure this carbon removal process in the field. Consensus has not yet been reached on a method for reliably measuring and verifying the amount of carbon captured through enhanced weathering.

Within Catalyst, Silicate is optimistic, it will be able to address this challenge and contribute to the establishing of a joint standard:

“Robust in-situ measurements of carbon removal rates are essential for any enhanced weathering carbon removal solution – aligning processes across different material types and between companies and academia is, to us, the most important way that Catalyst can help us to grow our solution.”, says Maurice. “We feel that models will be an essential tool in scaling enhanced weathering, but ground-truthing and validating them with regular in-situ measurements will be vital. The best models will be able to assimilate data through time to ensure accuracy. By working with Catalyst, we will create a scientifically robust enhanced weathering standard that ERW companies and our customers can have confidence in.”

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