Join us for a Lunch & Learn with Geneva Kirk Drayson as she discusses her research on site selection framework for carbon-neutral alkalinity production for open-ocean carbon dioxide removal.
Lunch is provided.
Presentation Details
Site selection framework for carbon-neutral alkalinity production for open-ocean carbon dioxide removal.
Geneva Kirk Drayson, James Franke, Manon Duret, David Keith.
Abstract: Open ocean alkalinity enhancement (O-OAE) is a promising carbon dioxide removal strategy with the potential to remove multiple gigatons of CO2 per year at low costs and with minor environmental impacts. O-OAE requires the production of carbon-neutral alkalinity, achieved via the calcination of sedimentary rocks (e.g. limestone and dolomite) powered by renewable energy. The primary drivers when identifying optimal sites for carbon-neutral alkalinity production at scale are proximity to sedimentary rock deposits, geological CO2 storage, cost-effective renewable energy, and the ‘efficiency’ of the adjacent ocean (CO2 removed per unit of alkalinity added). We introduce a robust framework to highlight optimal sites for carbon‑neutral alkalinity production plants for O-OAE by analyzing the strongest combinations of the aforementioned factors. By limiting fixed cost inputs and relying on tunable weights, the model remains robust to shifts in construction and technology costs across time, location, and scale. For each sedimentary deposit, the ideal plant location is determined by optimizing by (i) optimizing the transport network to the mine, coast and CO2 storage to minimize total distance while (ii) avoiding unsuitable land and populated areas, and (iii) by positioning the plant where combined renewable energy generation capacity (wind and solar) is strongest thereby ensuring continuous, year round power. All parameters are then normalized and weighed with coefficients to yield a “score” for each candidate site. We applied this framework to an inventory of over 8,000 feasible sedimentary deposits worldwide, with scores ranging from 0.04–1 (median 0.52), with the top quartile exhibiting combined capacity factors > 0.69 and total transport distances < 55 km. We estimate that the best sites may be 12-26 times more efficient (in 2024 USD) per ton of CO2 removed than proposed and currently operational alkalinity production sites. Sobol sensitivity analysis of the weighted coefficients attributes 62 % of ranking variance to renewable‑energy coefficients and 38 % to transport multipliers, while ± 20 % perturbations in coefficients alter top‑quartile rank order by less than 15 %, and the top-scoring 50 sites by less than 3%, demonstrating robustness of the optimal sites to cost‑scaling uncertainties.
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