Negative emissions technologies or techniques (NETs) are means of accelerating the removal of greenhouse gases from the atmosphere.
mclaren environmental has undertaken a wide-ranging review and asesessment of NETS, examining the technological readiness, capacity, costs and side-effects of more than 30 potential techniques, including biochar, direct air capture, ocean calcination and tree burial. We believe this to be the most comprehensive assessment undertaken so far.
The research concludes that NETs will be needed to avoid too great a risk of dangerous climate change, that the global capacity of NETs is limited (especially by the availability of geological storage for carbon dioxide, and the sustainable supply of biomass), that the costs of NETs will typically be much higher than those of mitigation, and that much development effort is needed to bring NETs to scale.
The report argues that development of NETs should be actively pursued as a supplement to mitigation. It identifies the techniques which appear to offer most promise. Recognising the serious moral hazard involved, it also makes recommendations for reducing that risk.
The full report 'First Stop Digging' is available as a PDF through the links below, as is a summary of the assessment spreadsheet.
The research was undertaken in parallel with the compilation of a short report on the same topic for Friends of the Earth (England, Wales and Northern Ireland), which can be found at http://www.foe.co.uk/resource/reports/negatonnes.pdf.
The research has been presented at the Lund Conference on Earth Systems Governance (April 2012) with a focus on governance implications, and at the Third Trans-disciplinary Summer School on Climate Engineering in Oxford (August 2012) - with a focus on considerations of justice. The papers and presentation slides from each event can be downloaded below.
Nov 2012 update: A further version of the research has now been published in a special issue of the journal Process Safety and Environmental Protection dedicated to negative emissions technologies. The online version is available at http://dx.doi.org/10.1016/j.psep.2012.10.005