This paper presents results from research conducted to provide a high level techno-economic and performance assessments of various emerging technologies for capturing CO2 from the air, directly and indirectly, on a life-cycle basis. The technologies assessed include 'artificial trees', the soda lime process, augmented ocean disposal, biochar and bio-energy with carbon capture and storage. These technologies are subjected to quantitative and qualitative analyses, based on the most recent peer reviewed data in the literature, to identify their potential performance as well as the technical and non-technical barriers to their adoption and scale up. Key findings for each technology are presented which seek to highlight the state of technological development and research needs, the anticipated life cycle capture cost in $/tCO(2) based on their potential to deliver a 0.1 ppm CO2 reduction per annum, policy requirements for scale up and, in light of these findings, the likely role that they will play in addressing climate change and broader environmental issues in the medium to long term. The key finding from the work is that the degree of scale-up required for negative emissions technologies to have a material impact on atmospheric emissions (i.e. at a ppm level) is probably unrealistic in less than 20 years. Therefore, emissions prevention efforts should remain the main focus in addressing climate change and the likely role for negative emissions technologies will be in augmenting a suite of mitigation measures targeting economically or practically difficult emissions. (C) 2012 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.