The prospects of massively scalable nuclear-powered direct air capture as a climate solution

• A large overshoot in greenhouse gas emissions relative to official targets is likely. • Thus, negative emissions technologies are needed in the second half of the century. • Nuclear can supply direct air capture (DAC) technologies with heat and power. • A large nuclear-DAC fleet can be constructed in the cheapest locations worldwide. • The resulting cost of avoided CO 2 is estimated as 101.6 (71.3–153.9) $/ton. Direct air capture (DAC) has recently emerged as a promising and scalable solution for removing accumulated CO 2 in the atmosphere to mitigate global warming. Because DAC needs to capture CO 2 from highly diluted levels in the air, it has considerably higher energy demands than conventional CO 2 capture from concentrated industrial sources, making cheap input energy essential. The present study proposes that DAC facilities be powered by dedicated large-scale nuclear power plants designed to deliver the optimal heat/electricity ratio to a DAC unit serving as the condenser in the Rankine power cycle. Such plants are unbound by proximity requirements to CO 2 point sources or electricity demand centres and can be built where nuclear reactors are cheapest to construct, strongly improving the business case. A bottom-up techno-economic assessment and uncertainty quantification study for the year 2050 showed median and 90 % confidence intervals of the levelized cost of removed CO 2 to be 101.6 (71.3–153.9) $/ton when conventional nuclear reactor technology is used. An advanced configuration employing emerging high-temperature nuclear reactor technology to generate excess electricity for co-production of green methanol was slightly more expensive with a larger uncertainty range: 108.0 (68.8–176.1) $/ton. Despite the uncertainty in the assessment, the calculated CO 2 removal costs are attractive compared to projected CO 2 prices in climate change mitigation scenarios targeting substantial emissions reductions by mid-century. However, several non-economic challenges were identified and further work on these topics is recommended to clarify the long-term potential of nuclear-DAC technology as a leading climate change solution.