Perspective by Professor Bruce Dale, Michigan State University
I have worked for over 30 years to develop cellulosic biofuels, so I am not particularly interested in corn ethanol. I am, however, very interested in using life cycle analysis (LCA) to show how the environmental performance of biofuels can be improved. Thus a recent life cycle study on corn ethanol plants caught my eye.
Plants built since 2004 reduce ethanol’s life cycle greenhouse gas (GHG) emissions by 50-60% compared to gasoline. These plants represent about 75% of current ethanol capacity and stand in stark contrast to older ethanol plants that achieved only about 20% GHG reductions.
The paper was published in the Journal of Industrial Ecology, one of the two “gold standard” journals for LCA research. The study is meticulous and detailed, and uses the most recent data available from real corn dry mills. While it represents a sort of “best case” set of scenarios for newer plants, it does show what is possible with corn ethanol.
Innovation and technological improvement (e.g., thermo-compressors for heat reuse, raw starch hydrolysis, collocating with animal feeding operations) dramatically improve the GHG emissions of these plants versus those built prior to 2004. Over time, the best case ought to become the norm. This study provides guidance to help make that can happen—which is precisely the purpose of LCA.
A recent blog criticized the paper for dealing only with direct GHG emissions, not those from so-called indirect land use change (ILUC) analysis. This criticism is uninformed.
The logic behind ILUC is that increased demand for corn for ethanol will lead, through increased prices, to more crops being planted elsewhere. The planting of these crops may cause land clearing and subsequent GHG release. Note that these hypothetical crops are not part of the actual biofuel life cycle. They are part of the life cycle of other products. ILUC theory proposes that these crops become part of the biofuel life cycle.
Why all this emphasis on LCA? Because the Energy Independence and Security Act of 2007 requires the use of life cycle methods to determine the GHG performance of renewable fuels. If LCA is to help us improve biofuel performance, we must use it within its limits. LCA has strict standards regarding technical issues such as system boundaries and allocation. ILUC simply does not meet these standards; it goes well beyond the limits of LCA. Whatever else ILUC may be, it is not life cycle analysis.
Bruce E. Dale, Ph. D.
Distinguished University Professor
Dept. of Chemical Engineering & Materials Science
Rm. 3247 Engineering Building
Michigan State University
East Lansing, MI 48824