Ramasamy, Murugan ORCID: https://orcid.org/0000-0002-3023-9165, Amann, Thorben and Moosdorf, Nils ORCID: https://orcid.org/0000-0003-2822-8261 (2024) Regional potential of coastal ocean alkalinization with olivine within 100 years. Environmental Research Letters, 19 (6). 064030. DOI https://doi.org/10.1088/1748-9326/ad4664.

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Abstract

The spreading of crushed olivine-rich rocks in coastal seas to accelerate weathering reactions sequesters atmospheric CO2 and reduces atmospheric CO2 concentrations. Their weathering rates depend on different factors, including temperature and the reaction surface area. Therefore, this study investigates the variations in olivine-based enhanced weathering rates across 13 regional coasts worldwide. In addition, it assesses the CO2 sequestration within 100 years and evaluates the maximum net-sequestration potential based on varying environmental conditions. Simulations were conducted using the geochemical thermodynamic equilibrium modeling software PHREEQC. A sensitivity analysis was performed, exploring various combinations of influencing parameters, including grain size, seawater temperature, and chemistry. The findings reveal significant variation in CO2 sequestration, ranging from 0.13 to 0.94 metric tons (t) of CO2 per ton of distributed olivine-rich rocks over 100 years. Warmer coastal regions exhibit higher CO2 sequestration capacities than temperate regions, with a difference of 0.4 t CO2/t olivine distributed. Sensitivity analysis shows that smaller grain sizes (10 µm) exhibit higher net CO2 sequestration rates (0.87 t/t) in olivine-based enhanced weathering across all conditions, attributed to their larger reactive surface area. However, in warmer seawater temperatures, olivine with slightly larger grain sizes (50 and 100 µm) displays still larger net CO2 sequestration rates (0.97 and 0.92 t/t), optimizing the efficiency of CO2 sequestration while reducing grinding energy requirements. While relying on a simplified sensitivity analysis that does not capture the full complexity of real-world environmental dynamics, this study contributes to understanding the variability and optimization of enhanced weathering for CO2 sequestration, supporting its potential as a sustainable CO2 removal strategy.

Document Type:	Article
Programme Area:	PA2
Research affiliation:	Biogeochemistry and Geology > Submarine Groundwater Discharge
Refereed:	Yes
Open Access Journal?:	Yes
DOI:	https://doi.org/10.1088/1748-9326/ad4664
ISSN:	1748-9326
Date Deposited:	05 Jun 2024 17:12
Last Modified:	05 Jun 2024 17:12
URI:	http://cris.leibniz-zmt.de/id/eprint/5443

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