A techno-economic and environmental evaluation of the integration of direct air capture with hydrogen derivatives production

Abstract

Carbon-neutral fuels are key to decarbonizing hard-to-abate sectors. Solar redox cycles can produce them by creating oxygen vacancies in a metal oxide capable of splitting water and CO2. The resulting synthesis gas can be processed into a liquid fuel like methanol. To close the carbon cycle, feedstock CO2 can be captured from the atmosphere with direct air capture (DAC), but the synergies between synthetic fuel production and DAC are largely unexplored. In this work, four integration strategies between DAC and solar redox cycles are proposed. Each of them is modeled with Aspen Plus and HFLCAL and compared with a techno-economic and a cradle-togate life cycle assessment. The optimal configuration, with a levelized cost of 7.9 ± 0.4 USD2022/kgMethanol and a climate change impact of − 450 ± 30 g CO2e/kgMethanol, uses solid DAC powered by waste heat. Therefore, the study recommends the integration of DAC in the production of synthetic fuels.