Variability Necessitates Reporting of LCA Results As a Range Instead of Point Values: MIT Study

Researchers from the Massachusetts Institute of Technology (MIT) report that in the Life Cycle Analysis (LCA) of biofuels, "changing key parameters can dramatically change the total greenhouse gas emissions from a given biofuel".

LCA is a tool that is commonly used for the assessment of net energy yields and greenhouse gas emissions of a particular biofuel, as it goes through cultivation, processing and eventual use (combustion) as a biofuel product. Their study showed that "variability in life cycle analysis (LCA) is inherent due to both inexact LCA procedures and variation of numerical inputs".

Using examples from the production of biofuels from 14 different feedstocks, they were able to show the magnitudes and types of variabilities in their corresponding LCA's. Sources of variability have been attributed to three categories: (1) pathway specific, (2) coproduct usage and (3) allocation/land use change. Subjective biases in the methodologies for coproduct usage and allocation, for example, are an important sources of variability. These can be minimized, according to the researchers, through the "application of a consistent analysis methodology across all fuel options". They also recommend that "LCA results should be presented as a range instead of a point value".

The full study is published in the Environmental Science and Technology journal (URL above).