Submitted to: Current Opinion in Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2012
Publication Date: 3/22/2013
Citation: Borak, B., Ort, D.R., Burbaum, J.J. 2013. Energy and carbon accounting to compare bioenergy crops. Current Opinion in Biotechnology. 24(3):369-375. Interpretive Summary: In liquid fuels, the enormous barriers that face plausible substitute sources are derived from two factors: the lowest-cost economics of commodities and the logistics of implementation of new technologies at immense scale. These barriers make the development of alternatives to petroleum one of the most challenging problems faced by human society. In theory, strategies that produce renewable biofuels both at low cost (relative to increasingly scarce petroleum) and at large scale will help lead to a cleaner, more sustainable future. However, to compare the utility of potential future biofuels a large hurdle is to develop objective measures, which provide a quantitative and robust evaluation of the alternatives. A system for the evaluation of new bioenergy crops that combines both energy and carbon accounting is proposed.
Technical Abstract: To compare the utility of current and future biofuels and biofuel feedstocks in an objective manner can be extremely challenging. This challenge exists because agricultural data are inherently variable, experimental techniques are cropdependent,and the literatures usually report relative, rather than absolute, values. Here, we discuss the ‘PETRO approach’,a systematic approach to evaluate new crops. This approach accounts for not only the capture of solar energy but also the capture of atmospheric carbon (as CO2) to generate a final carbon-based liquid fuel product. The energy yield, per unit area, of biofuel crops grown in different climate zones can thus be benchmarked and quantitatively compared in terms of both carbon gain and solar energy conversion efficiency.