Energy life-cycle assessment of soybean biodiesel

A. Pradhan, D. S. Shrestha, A. McAloon, W. Yee, M. Haas, J. A. Duffield, H. Shapouri

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review


The first comprehensive life-cycle inventory (LCI) for biodiesel produced in the United States from soybean oil was completed by Sheehan et al. in 1998. The purpose of the study was to conduct a life-cycle assessment (LCA) to quantify and compare the environmental and energy flows associated both with biodiesel and petroleum-based diesel. One of the most often cited results from Sheehan et al. is that the fossil energy ratio of biodiesel is equal to 3.2. In other words, biodiesel yields 3.2 units of energy for every unit of fossil energy consumed over its life- cycle. By contrast, it was found that petroleum diesel’s life cycle yielded only about 0.84 units of energy per unit of fossil energy consumed. The purpose of the following analysis is to update the energy life cycle of the model to determine if any significant changes in the original inventory have occurred since the model was first developed 10 years ago. The LCI of biodiesel in this analysis includes four subsystems: feedstock production, feedstock transportation, soybean processing with biodiesel conversion, and product distribution. All significant sources of energy are included in the inventory, such as the liquid fuel and electricity used to directly power equipment in the system. The energy requirements to produce materials that are made from energy resources, such as fertilizers, pesticides, and other petrochemicals, are also included in the inventory. The soybean crushing model in this analysis uses the hexane extraction method to extract oil from soybean seed, and transesterification is used to convert soybean oil into biodiesel. Oil extraction and transesterification result in the production of two important coproducts, soybean meal and crude glycerin, respectively. A massbased allocation method is used to account for the energy associated with the soybean meal and crude glycerin.

Original languageEnglish
Title of host publicationBiofuel Lifecycle Issues and Research
PublisherNova Science Publishers, Inc.
Number of pages1
ISBN (Electronic)9781536114416
ISBN (Print)9781617286575
Publication statusPublished - 1 Jan 2010
Externally publishedYes

ASJC Scopus subject areas

  • General Engineering
  • General Energy


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