ECO-CBET: GOALI: Autothermal Direct Air Capture (aDAC) for a Circular Carbon Economy

Northern Arizona University, Flagstaff AZ

Investigators

Abstract

Limiting the catastrophic effects of global warming from human-generated greenhouse gas emissions requires solutions that eliminate new emissions and remove those that cannot be avoided or were emitted in the past. This project focuses on Direct Air Capture (DAC) materials and processes that separate and concentrate carbon dioxide (CO2) from the air. The goal is to convert this major greenhouse gas into carbon neutral fuels/chemicals or permanently store it. Important early demonstration of DAC systems reveals the need for less energy intensive processes and less costly materials. This project explores a solid sorption-based separation using low-cost polymer-based hybrid sorbents that can release and concentrate captured CO2 using moisture and heat produced during water sorption. Further, these materials will integrate within a system designed to utilize low-grade water sources and renewable power. The process and material research will be co-designed with Indigenous communities in which the technology may be adopted to optimize net benefits such as purified water and renewable fuels or chemicals. This proposal aims to design novel CO2 capture sorbents which regenerate via an autothermal vacuum moisture swing (aVMS) integrated with downstream CO2 utilization. The heterogeneous sorption sites will balance heats of water adsorption with heats of CO2 desorption. The PIs hypothesize that heat of water sorption can be balanced to meet both the hydration and thermal loads of CO2 desorption, reducing external heat inputs to the overall DAC operation. To test this hypothesis, the team will combine approaches of sorbent material synthesis, material characterization, new unit operation and process models, and feed these into life cycle and technoeconomic analyses of revenue generating systems. The outcome of the proposed activities will be fundamental understanding of multi-component adsorption and how to tune the different strengths of water vapor and CO2 heat of sorption necessary for autothermal based separations. Integrating material and process design with community engagement that explores risks and benefits of different carbon removal and utilization configurations will enable socially responsible and impactful innovation. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.