Life Cycle Assessments and E85 Part II

Note: This is the second of a two-part series. Read Part I for an introduction to using life cycle analyses.

Part II: Ethanol's Greenhouse Gas Benefits
The GREET model, or Greenhouse gases, Regulated Emissions, and Energy use in Transportation model, was developed and originally released in 1996 by the Argonne National Laboratory. The GREET model is annually updated and refined to account for the latest technologies in transportation and fuel options. GREET is a type of life cycle assessment developed specifically for evaluating fuel and transportation impacts on the environment. According to GREET's authors at Argonne, this analytical tool can account for more than 85 different vehicle and fuel combinations, and can be used by fleet managers and researchers, as well as by auto and energy industries. It allows users to compare traditional forms of transportation and fuel to renewable forms and make the best decision based on calculated energy costs, emissions, and overall impact.

GREET includes 1,000 predefined pathways or "processes that represent the various stages in the production of the product. A process converts inputs into outputs, and emissions are generated by technologies used or by losses that occur within the process.” Needless to say, the number of vehicle-fuel combinations plus all the possible pathways results in very complex yet detailed assessments of energy use and emissions.

When you look at the nationwide averages in the model, we see that a regular E10 gasoline (i.e. regular 87 octane unleaded gasoline in all of Minnesota) produces 421 grams of greenhouse gases (GHG) for every mile traveled (grams per mi). Conversely, E85 produces 299 grams per mi of GHG. That’s nearly a 30% reduction when you choose to use E85. Remember, this already takes into account the change in fuel use rates between the fuels, land uses for crops, and likely any other factor you would want to consider—the entire life cycle. Bottom line: If you drive a flex fuel vehicle, and aren’t using E85 already, you can reduce your emissions starting with your very next fill-up!

Beyond this calculation from GREET, two additional items must be considered when comparing E85 GHG emissions to petroleum-based gasoline GHG emissions. First, the crops that are planted each year to produce E85 also help absorb carbon dioxide, a primary GHG, from the atmosphere. Petroleum gasoline, on the other hand, is only adding it to the atmosphere. Most of the carbon in E85 came out of the atmosphere to begin with, not from being locked away deep underground.

Secondly, Minnesota gets most of its petroleum by importing it from the Canadian Tar Sands, which means our gasoline is much more carbon intensive than the national average used in the calculation from GREET.

While today's focus was primarily on GHG emission reductions, there are far more pollutants coming from our tailpipes that we should consider when evaluating air quality. Visit the Air Quality section of to learn more, and continue to check this blog for additional evidence on the clean air benefits of ethanol.

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