Techno-Economic Assessment of the Integration of Direct Air Capture and the Production of Solar Fuels

Abstract

Non-abatable emissions are one of the decarbonization challenges that could be addressed with carbon-neutral fuels. One promising production pathway is the direct air capture (DAC) of carbon dioxide, followed by a solar thermochemical cycle and liquid fuel synthesis. In this study, we explore different combinations of these technologies to produce methanol from an economic perspective in order to determine the most efficient one. For this purpose, a model is built and simulated in Aspen Plus®, and a solar field is designed and sized with HFLCAL®. The inherent dynamics of solar irradiation were considered with the meteorological data from Meteonorm® at the chosen location (Riyadh, Saudi Arabia). Four different integration strategies are assessed by determining the minimum selling price of methanol for each technology combination. These values were compared against a baseline with no synergies between the DAC and the solar fuels production. The results show that the most economical methanol is produced with a central low-temperature DAC unit that consumes the low-quality waste heat of the downstream process. Additionally, it is determined with a sensitivity analysis that the optimal annual production of methanol is 11.8 kt/y for a solar field with a design thermal output of 280 MW.