Cost Analysis of Direct Air Capture and Sequestration Coupled to Low-Carbon Thermal Energy in the United States

Abstract

Negative emissions technologies will play an important role in preventing 2 °C warming by 2100. The next decade is critical for technological innovation and deployment to meet mid-century carbon removal goals of 10−20 GtCO 2 /yr. Direct air capture (DAC) is positioned to play a critical role in carbon removal, yet remains under paced in deployment efforts, mainly because of high costs. This study outlines a roadmap for DAC cost reductions through the exploitation of low-temperature heat, recent U.S. policy drivers, and logical, regional end-use opportunities in the United States. Specifically, two scenarios are identified that allow for the production of compressed high-purity CO 2 for costs ≤$300/tCO 2 , net delivered with an opportunity to scale to 19 MtCO 2 /yr. These scenarios use thermal energy from geothermal and nuclear power plants to produce steam and transport the purified CO 2 via trucks to the nearest opportunity for direct use or subsurface permanent storage. Although some utilization pathways result in the re-emission of CO 2 and cannot be considered true carbon removal, they would provide economic incentive to deploying DAC plants at scale by mid-century. In addition, the federal tax credit 45Q was applied for qualifying facilities (i.e., producing ≥100 ktCO 2 /yr).

Natural Gas vs. Electricity for Solvent-Based Direct Air Capture

“…Other capture systems, not studied here, use solid sorbents and thereby can use lower grade heat, ∼100 • C. This adds several options for alternative thermal energy sources, including solar thermal heat, geothermal heat, and the direct use of waste heat from a thermal power cycle. Similar analyses for solid sorbent-based DAC are underway elsewhere (National Academy of Sciences Engineering and Medicine, 2019;Lawrence Livermore National Laboratory, 2020;McQueen et al, 2020).…”

Carbon‐Neutral Pathways for the United States

“…Offsetting of small or widely dispersed CO 2 sources for which CCS or drop‐in fuels were not economic was done with negative emissions technologies (NETs), specifically bioenergy with CCS (BECCS) and DAC (Breyer et al, 2019; Clarke et al, 2014; Keith et al, 2018; McQueen et al, 2020; Sanz‐Perez et al, 2016). NETs were most economic when tightly coupled to the E&I system, where the captured carbon could be flexibly used for fuels and products (e.g., plastics) or sequestered as needed.…”

How (Carbon) Negative Is Direct Air Capture? Life Cycle Assessment of an Industrial Temperature-Vacuum Swing Adsorption Process

“…The most developed DAC concepts separate CO2 from the air by either ab-or adsorption. [28][29][30] DAC based on absorption typically uses aqueous hydroxy sorbents like alkali and alkali-earth hydroxides. In contrast, DAC based on adsorption can employ a wide range of solid sorbents.…”

“…40 Furthermore, sorbent regeneration requires high temperatures. 30,41 In contrast, DAC by adsorption can operate at low regeneration temperatures (< 100°C). 30,39,42,43 The first commercial DAC system employs solid adsorbents in cyclic temperature-vacuum swing adsorption.…”

“…30,41 In contrast, DAC by adsorption can operate at low regeneration temperatures (< 100°C). 30,39,42,43 The first commercial DAC system employs solid adsorbents in cyclic temperature-vacuum swing adsorption. [44][45][46] While DAC removes CO2 directly from the atmosphere, the potential climate benefits of DAC are partly offset by indirect environmental impacts due to the supply of energy and materials.…”