Completely Passive Capture of Carbon Dioxide from Air Using Solar Energy

In addition to reducing greenhouse gas emissions, it is now imperative that we implement direct air capture (DAC) of CO₂ from the atmosphere at a scale of hundreds of giga metric tons before the year 2100 to avoid catastrophic climate change. Development of a viable DAC technology is still limited by the high cost and high energy consumption that result from a low adsorbent capture capacity, requirements for expensive, cumbersome infrastructure, and widespread societal acceptance challenges. In this work, we aim to address all three of these challenges and have designed and demonstrated a completely passive DAC device with a projected net CO₂ capture cost as low as 80 $ t_CO2^–1, lower than the ‘Carbon Negative Shot’ 2030 goal (100 $ t_CO2^–1) and potentially profitable at 100 $ t_CO2^–1 with the 45Q carbon tax credit. Our DAC device captures CO₂ passively at night and desorbs CO₂ passively during the day. It uses solar energy as the sole energy source with minimum maintenance requirements. The modular design and passive operation of the system should enable deployment across broad geographic regions far from infrastructure centers, thereby enabling a distributed, self-powered solution to the problem of removing dilute CO₂ from the atmosphere. It further combines low-cost solar-thermal and low-risk photovoltaic technologies, facilitating installation at different scales in any corner of the world with abundant solar resources.