Ambient weathering of magnesium oxide for CO2 removal from air

Noah McQueen; Peter Kelemen; Greg Dipple; Phil Renforth; Jennifer Wilcox

doi:10.1038/s41467-020-16510-3

Ambient weathering of magnesium oxide for CO₂ removal from air

Nat Commun. 2020 Jul 3;11(1):3299. doi: 10.1038/s41467-020-16510-3.

Authors

Noah McQueen¹, Peter Kelemen², Greg Dipple³, Phil Renforth⁴, Jennifer Wilcox⁵

Affiliations

¹ Department of Chemical Engineering, Clean Energy Conversions Lab, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA, 01609, USA.
² Department of Earth & Environmental Sciences, Lamont-Doherty Earth Observatory, Columbia University, 91 Rte 9W, Palisades, NY, 10964, USA.
³ Department of Earth, Ocean, and Atmospheric Sciences, Bradshaw Research Initiative for Minerals and Mining, University of British Columbia, 2020-2207 Main Mall, Vancouver, BC, V6T 1Z4, Canada.
⁴ Research Centre for Carbon Solutions, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
⁵ Department of Chemical Engineering, Clean Energy Conversions Lab, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA, 01609, USA. jlwilcox@wpi.edu.

Abstract

To avoid dangerous climate change, new technologies must remove billions of tonnes of CO₂ from the atmosphere every year by mid-century. Here we detail a land-based enhanced weathering cycle utilizing magnesite (MgCO₃) feedstock to repeatedly capture CO₂ from the atmosphere. In this process, MgCO₃ is calcined, producing caustic magnesia (MgO) and high-purity CO₂. This MgO is spread over land to carbonate for a year by reacting with atmospheric CO₂. The carbonate minerals are then recollected and re-calcined. The reproduced MgO is spread over land to carbonate again. We show this process could cost approximately $46-159 tCO₂^-1 net removed from the atmosphere, considering grid and solar electricity without post-processing costs. This technology may achieve lower costs than projections for more extensively engineered Direct Air Capture methods. It has the scalable potential to remove at least 2-3 GtCO₂ year^-1, and may make a meaningful contribution to mitigating climate change.