Carbon: no silver bullet.

Abstract

On behalf of the European Academies Science Advisory Council (EASAC)—established by the national science academies in Europe to advise EU policy-makers on the science underpinning key decisions—we would like to respond to S. M. Benson's Editorial, “Negative-emissions insurance” (27 June, p. [1431][1]). EASAC has recently completed two studies on carbon capture and storage (CCS) ([ 1 ][2]) and on biofuels in Europe ([ 2 ][3]). The studies broadly support Benson's view that bioenergy with CCS might make a useful contribution to climate change mitigation in Europe, but their overall conclusion is that it is likely to be modest. As Benson recognizes, CCS is expensive. Costs are likely to be higher for biomass CCS than for CCS associated with large fossil-fuel–based plants, as the biomass CCS will be smaller scale and often remote from CO2 transport and storage facilities. The EASAC study concluded that there is rather limited scope to bring costs down. Confidence in the long-term integrity of CO2 storage will build slowly, given the need to monitor geological processes over long periods of time. This will slow the rate of the rollout of CCS in Europe. Furthermore, only limited indigenous biomass resources in Europe can sustainably be harvested for energy uses without deleterious impacts on the environment and food production. The research, development, and demonstration of relevant technologies to promote biomass-based CCS should be actively pursued, but it is no silver bullet. 1. [↵][4] Carbon capture and storage in Europe, EASAC Policy Report 20 (May 2013); [www.easac.eu/fileadmin/Reports/Easac\_13\_CCS\_Web\_Complete.pdf][5]. 2. [↵][6] The current status of biofuels in the European Union, their environmental impacts and future prospects, EASAC Policy Report 19 (December 2012); [www.easac.eu/fileadmin/PDF\_s/reports\_statements/Easac\_12\_Biofuels_Complete.pdf][7]. [1]: /lookup/doi/10.1126/science.1257423 [2]: #ref-1 [3]: #ref-2 [4]: #xref-ref-1-1 View reference 1 in text [5]: http://www.easac.eu/fileadmin/Reports/Easac_13_CCS_Web_Complete.pdf [6]: #xref-ref-2-1 View reference 2 in text [7]: http://www.easac.eu/fileadmin/PDF_s/reports_statements/Easac_12_Biofuels_Complete.pdf