Energetic and Life Cycle Assessment of Direct Air Capture: A Review

Abstract

Recent prospective climate scenarios start to embrace direct air capture (DAC) technologies to achieve climate goals, although the realistic application of DAC systems remains controversial, particularly with regard to their energy consumption and overall environmental concerns. In this paper, the energetic and life cycle analysis studies are systematically reviewed for typical DAC technologies. Existing energetic analysis approaches are identified and analyzed through key features and the methodological choices for each LCA step are discussed in detail. Although the inconsistencies in the contexts and assumptions of these studies would not allow a direct comparison of results, it is observed that DAC could achieve negative emissions for all technology families, from a life cycle perspective. Nevertheless, the carbon removal efficiency of typical systems demonstrates significant variation from lower than 10 % to over 95 %, which is dominated by the types of energy source and the amount of energy consumption. To improve the understanding of the realistic potential of DAC, it is recommended to develop a standard energetic and life cycle assessment framework with the further effort to deal with the multifunctional, scale-up and cost issues for emerging DAC technologies, while dynamic LCAs are needed to explore the effect of time variation parameters.