Opportunities for Geologic Carbon Sequestration in Washington State

Abstract

Washington State has a goal to reach net-zero greenhouse gas emissions by 2050. To achieve this goal, active sequestration of carbon dioxide will be required. This report reviews processes of geologic carbon sequestration and how they could be applied in Washington, including: sequestration in saline aquifers within sedimentary basins; in situ carbon remineralization in mafic and ultramafic rocks; surficial enhanced weathering of crushed rock distributed over cropland; and enhancing the aforementioned methods by incorporating seawater and other advances. The geology of Washington offers abundant opportunities for all of these approaches, with a total capacity equivalent to centuries of the State’s current carbon dioxide emissions. While in situ remineralization in ultramafic rock, surficial enhanced weathering, and enhancements using seawater are not mature technologies, carbon sequestration in saline aquifers and in situ basalt remineralization are already proven viable. These two approaches could play an important role in meeting Washington’s net-zero emissions target, in a portfolio of approaches that also includes emissions reductions.