Lessons for scaling direct air capture from the history of ammonia synthesis

Abstract

High-temperature direct air capture (DAC)—a technology which uses liquid solvents to capture carbon dioxide from the atmosphere—has made rapid technological progress and is on the verge of full commercialization. The feasibility of upscaling liquid DAC quickly enough pace to reach gigaton-scale by mid-century, however, and depends on complex social and economic factors in addition to purely technical ones. We assess the feasibility of rapid liquid DAC growth using ammonia synthesis as an historical analogue. Ammonia synthesis is a chemical technology with many similarities to liquid DAC. Ammonia synthesis plants were deployed rapidly during the twentieth century. We answer three questions. Firstly: what is the fastest historically-precedented rate of deployment for this kind of technology? Secondly: what factors might influence whether liquid DAC can reach these rates of deployment, given the technical, social, and economic differences between it and ammonia synthesis? Third: what can be done to accelerate the deployment of liquid DAC? The precedent of ammonia synthesis shows that very rapid deployment rates are possible for liquid DAC, enabling a total global capacity of around 1 GT of CO2 per year by mid-century are possible. However, ammonia synthesis only reached these compound annual growth rates due to aggressive state and industrial support, which was in turn only available due to the critical value of nitrogen as an economic and strategic resource. For liquid DAC to reach comparable rates of deployment, political and economic incentive structures will have to change significantly.