Techno-Economic Assessment of Direct Air Capture Integrated with Heating Tower Heat Pump

Direct Air Capture (DAC) technologies offer a promising means of mitigating climate change by removing CO2 from the atmosphere, but their widespread adoption has been hindered by high energy consumption and operational costs. To address this challenge, this study proposes an innovative approach that integrates DAC with an existing heating tower heat pump (HTHP), capitalizing on their structural and functional similarities. Structurally, both systems share key components, including fans, pumps, and towers. Functionally, while the HTHP absorbs heat from the ambient air, the DAC system captures atmospheric CO2, and both rely on regeneration processes to sustain operational efficiency. The integrated system uses a sodium carbonate (Na2CO3) solution to absorb both heat and CO2, enabling efficient integration of DAC and HTHP functions. Aspen Plus simulations show that the proposed system requires only 2.37 GJ/tCO2 for CO2 capture, representing a 73.1% reduction compared with a conventional DAC process (8.81 GJ/tCO2). The operating expenditure is correspondingly reduced to $39.5/tCO2, which is 68.4% lower than that of the conventional DAC system ($120/tCO2). If a carbon capture and direct utilization integrated technology is applied instead of conventional thermal desorption, the energy requirement can be further reduced to 0.5 GJ/tCO2. These findings demonstrate that integrating DAC with the HTHP system enables low-energy and low-cost carbon removal, offering a feasible and scalable pathway for large-scale CO2 capture.