Potential of offshore wind energy for direct air capture

The world is setting aggressive targets for climate change mitigation and most pathway models require negative emission technologies (NETs) to meet these targets. Direct air capture (DAC) is a promising NET that captures carbon dioxide (CO₂) from the atmospheric air; however, indirect and embodied emissions to power and build DAC systems must be considered when exploring NET options. Wind energy has experienced rapid cost reductions in the past few years and experts predict a significant continued decline in offshore wind energy costs. Here, we develop a conceptual design and conduct an energy assessment of two dominating DAC designs to show the potential of offshore wind to meet the DAC energy demand for two different scenarios capturing 3.3 GtCO₂/y (10%) and 11 GtCO₂/y (33.3%) of current global CO₂ emissions covering a range of estimates for future NETs required to meet net-zero goals. Energy assessment showed that the estimated energy requirement for the Carbon Engineering based design is higher as compared with Climeworks based design owing to the high temperature (900°C) requirement in the calcination step required for the desorption of CO₂. However, conceptual design revealed that area requirements for DAC configurations are much less for Carbon Engineering based design comparatively. Employing offshore wind energy can eliminate indirect emissions associated with meeting DAC energy demands, facilitative modular NET deployment globally, be positioned geographically to avoid competition with grid decarbonization and take advantage of otherwise stranded offshore wind resources. Large-scale offshore wind energy integrated DAC systems, therefore, deserve development efforts and deployment alongside other mitigation and NET options.