Global carbon management using air capture and geosequestration at remote locations

Abstract:

CO₂ emissions need not only stop; according the IPCC, emissions need to turn negative. This requires means to remove CO₂ from air and store it safely and permanently. We outline a combination of secure geosequestration and direct capture of CO₂ from ambient air to create negative emissions at remote locations. Operation at remote sites avoids many difficulties associated with capture at the source, where space for added equipment is limited, good storage sites are in short supply, and proximity to private property engenders resistance.

Large Igneous Provinces have been tested as secure CO₂ reservoirs. CO₂ and water react with reservoir rock to form stable carbonates, permanently sequestering the carbon. Outfitting reservoirs in large igneous provinces far from human habitation with ambient air capture systems creates large CO₂ sequestration sites. Their remoteness offers advantages in environmental security and public acceptance and, thus, can smooth the path toward CO₂ stabilization.

Direct capture of CO₂ from ambient air appears energetically and economically viable and could be scaled up quickly. Thermodynamic energy requirements are very small and a number of approaches have shown to be energy efficient in practice. Sorbent technologies include supported organoamines, alkaline brines, and quaternary ammonium based ion-exchange resins. To demonstrate that the stated goals of low cost and low energy consumption can be reached at scale, public research and demonstration projects are essential.

We suggest co-locating air capture and geosequestration at sites where renewable energy resources can power both activities. Ready renewable energy would also allow for the co-production of synthetic fuels. Possible locations with large wind and basalt resources include Iceland and Greenland, the north-western United States, the Kerguelen plateau, Siberia and Morocco. Capture and sequestration in these reservoirs could recover all of the emissions of the 20th century and still contribute to a carbon neutral economy throughout the 21^st century. Mobilizing industrial infrastructure to these areas poses a challenge. However, the urgency of the climate problem requires immediate action, with economic incentives and commitments to site evaluation and engineering development.