Distributed direct air capture by carbon nanofiber air filters

Abstract

The rising atmospheric CO₂ concentration is one of the biggest challenges human civilization faces. Direct air capture (DAC) that removes CO₂ from the atmosphere provides great potential in carbon neutralization. However, the massive land use and capital investment of centralized DAC plants and the energy-intensive process of adsorbent regeneration limit its wide employment. We develop a distributed carbon nanofiber (CNF)–based DAC air filter capable of adsorbing CO₂ downstream in ventilation systems. The DAC air filter not only has the potential to remove 596 MtCO₂ year⁻¹ globally but can also decrease energy consumption in existing building systems. The CNF-based adsorbent has a capacity of 4 mmol/g and can be regenerated via solar thermal or electrothermal methods with low carbon footprints. Through life cycle assessment, the CNF air filter shows a carbon removal efficiency of 92.1% from cradle to grave. Additionally, techno-economic analysis estimates a cost of $209 to 668 in capturing and storing 1 tonne of CO₂ from direct air.