Path to Low-Cost Direct Air Capture

Abstract

It is now accepted that gigatonnes of Carbon Dioxide Removal (CDR) from the atmosphere are needed to avoid the threat of catastrophic climate change. Direct Air Capture (DAC) is a promising scalable CDR with a relatively small environmental footprint. But questions about DAC cost and energy use remain that are delaying the needed DAC policy decisions to create a mobilization effort like was done in the Manhattan Project and to address the Covid crisis.  Global Thermostat (GT) has publicly claimed costs of under $50 per tonne for mature GT technology deployed at a climate-relevant scale1. Why this low DAC cost is achievable will be addressed by a simplified analysis of generic DAC costs and using that analysis combined with experimental data to evaluate GT's DAC technology. A detailed cost analysis of different approaches to DAC by the National Academy of Sciences (NAS) found an approach to DAC that had a learning cost limit as low as $25 per tonne GT's DAC technology will be shown in Appendix 1 to have the same performance characteristics of the lowest-cost DAC identified in the NAS study. Thus, like solar costs, DAC costs can be reduced by learning by doing, but in the case of DAC, only one order of magnitude in cost reduction is needed2.Therefore DAC technology can reach its low learning by doing cost limit  at a scale much smaller than necessary to address climate change. From a climate perspective, current DAC embodiments costs and scale have less relevance than their learning curve cost limit.  While GT’s technology has demonstrated the crucial performance parameters to achieve a low cost DAC, no inference should be drawn that other approaches cannot achieve low or lower cost, if they can demonstrate the crucial performance parameters. Continued R&D on those performance parameters is needed. In parallel the six orders of magnitude increase in DAC capacity needed in 20-30 years to minimize the risk of catastrophic climate change requires a global mobilization effort starting immediately. Any further delay will significantly increase the risk of exceeding global warming targets and associated climate impacts.

Keywords: direct air capture, climate change