(i) an overview and classification of DACCS systems, (ii) an overview and harmonization of technical and economic performance of DAC technologies, based on publicly available data, (iii) a comprehensive list of technical and infrastructure-based obstacles to scaling DACCS systems, and (iv) a list of priority initiatives, including a roadmap to 2050, for unlocking research, development, demonstration and deployment (RDD&D) of DACCS. In (iv), we define priority initiatives as RDD&D activities necessary to overcome identified obstacles.