Design and fabrication of a system to capture ambient CO2

Abstract

Introduction:In the coming decades, addressing climate change necessitates substantial Carbon dioxide (CO₂) emission reductions. Carbon capture and storage are vital for achieving these goals. Beyond industrial emissions, Direct Air Capture (DAC) extracts CO₂ from the atmosphere, complementing point source capture and enabling the reduction of atmospheric CO₂ concentrations. Our research confirms the thermodynamic feasibility of DAC with Potassium hydroxide (KOH) solution, taking into account energy and performance considerations.
Materials and methods: To assess DAC's potential, we built a 1.2 m contactor prototype measuring CO₂ absorption from the air. Operating at 100 pa with an air speed of 1.75 m/s in a cross-flow regime, we used KOH and NaOH solutions as capture mediums, implementing duty cycles for absorbent pumping and exhaust fan operation.
Results: Our findings revealed that transitioning to intermittent operation can dramatically reduce overall energy costs by 70%. We explored various absorbent concentrations for both KOH and NaOH solutions, examining their impact. Operating temperatures ranged from 14°C to 33°C, providing insights into temperature's pivotal role in DAC performance.
Conclusion: This study showcases the viability of DAC with a KOH solution, particularly highlighting the significant energy savings achieved through intermittent operation. These findings emphasise DAC's role as a vital tool in our collective efforts to combat climate change.