Addressing solar power curtailment by integrating flexible direct air capture

Direct air capture (DAC) is one of the principal negative emission technologies for addressing climate change, but its deployment is hindered by the high cost and substantial energy consumption. Only being powered by low-cost renewable energy, DAC can maximize its negative emission potential, in return, DAC can help the decarbonization of the power sector. Due to the intermittency of renewable energy, effectively integrating renewable energy with DAC currently remains a significant challenge. To address this research gap, this study focuses on exploring flexible operation strategies of the adsorbent based DAC system, coupling them with an actual photovoltaic (PV) power station, and making DAC systems participate in minute-level dispatch. The adsorbent based DAC system adopts a modular design, allowing each unit to operate as an independent load, not requiring continuous operation and enabling interruption between cycles or processes. Additionally, the adsorption process is curtailable and extendable to dynamically adjust the time of activating desorption. The flexible operational combination allows the DAC to better match the fluctuation of PV. Based on actual data and time-of-use pricing, this paper conducts a comparative techno-economic analysis of DAC and battery energy storage (BES) systems. The results indicate that deploying flexible DAC is the most cost-effective among different given scenarios. Deploying 46,800 DAC units primarily powered by solar curtailment can achieve the lowest cost of $30,000/MW-year for the selected 1000 MW PV power station, along with an 80 % curtailment consumption rate and annual 634,000 tons CO₂ captured. Before 2030, coupling DAC with PV can effectively address the curtailment issues and assist with peak shaving. As carbon prices gradually rise and adsorbent costs decrease, by 2040, DAC will release its negative emission potential, playing a crucial role in achieving net zero or even negative carbon emissions.