Ethanol Fuels: E10 or E85 – Life Cycle Perspectives (5 pp)

Abstract

Goal and Scope

The environmental performance of two ethanol fuel applications (E10 and E85) is compared (E10 fuel: a mixture of 10% ethanol and 90% gasoline by volume, and E85 fuel: a mixture of 85% ethanol and 15% gasoline by volume).

Methods

Two types of functional units are considered here: An ethanol production-oriented perspective and a traveling distance-oriented perspective. The ethanol production-oriented functional unit perspective reflects the fact that the ethanol fuel supply (arable land or quantity of biomass used in ethanol fuel) is constrained, while the traveling distance-oriented functional unit implies that the ethanol fuel supply is unlimited.

Results and Discussion

In the ethanol production-oriented functional unit perspective, the E10 fuel application offers better environmental performance than the E85 fuel application in terms of natural resources used, nonrenewable energy and global warming. However, in the calculations based on the traveling distance perspective, the E85 fuel application provides less environmental impacts in crude oil consumption, nonrenewable energy and global warming than the E10 fuel application.

Conclusions and Outlook

The choice of functional units significantly affects the final results. Thus the functional unit in a descriptive LCA should reflect as nearly as possible the actual situation associated with a product system. Considering the current situation of constrained ethanol fuel supply, the E10 fuel application offers better environmental performance in natural resources used, nonrenewable energy and global warming unless the fuel economy of an E85 fueled vehicle is close to that of an E10 fueled vehicle.