Aviation industry’s quest for a sustainable fuel: considerations of scale and modal opportunity carbon benefit

Abstract

Aviation biofuels require higher processing energy inputs than fuels derived from the same feedstocks used for land-based transport. This article investigates the tradeoffs in the decisions of feedstock and processing by introducing the opportunity carbon benefit metric for the resulting transportation service across modes. We evaluated combinations of feedstocks, processing methods, and transport system use between aviation and surface modes (i.e., pathways) for fuel yields, as well as the process energy and greenhouse gas emissions of several feedstocks to determine their opportunity carbon benefit. In the current conditions, gasification for electricity generation to power electric vehicles would lead to the highest transportation services. Taking into account process energy and the limited number of electric vehicles, diesel and ethanol pathways maintain a lead. Contrary to their relatively high transportation service yields, biomass-to-electricity conversion pathways fail to generate the opportunity carbon benefits of biomass-to-liquid pathways. Biomass-to-liquid pathways vary little, with the jet pathway having a slight disadvantage over the diesel option owing to its higher process energy needs. On the feedstock side, the marginal land feedstocks, such as salicornia and switchgrass, have the advantage over the process energy and cultivation energy inputs, despite their relatively lower per hectare yields.

Acknowledgements

The authors are grateful to two anonymous reviewers for their suggestions and diligent comments that have significantly improved the quality of the article. In writing the revised version of the article we have benefited from discussions with Dr James Hileman and Russell Stratton and their critical reading has helped in clarifying some of the original assumptions.

Financial disclosure

The Masdar Institute is currently working on research related to Integrated Seawater Agriculture Systems and the potential use of halophytes as biofuels. The authors are actively involved in this academic research effort. The authors do not work, consult for, or own stock in companies that are commercially active in the biofuels sector.

The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.