By Carey King
The Journal of Industrial Ecology has a special issue on Meta-Analysis of Life Cycle Assessments (LCAs) freely available online.
There are several articles discussing what we can and cannot learn from making and comparing as many LCAs as possible. One of the introductory articles is: What Can Meta-Analyses Tell Us About the Reliability of Life Cycle Assessment for Decision Support? (Miguel Brandão, Garvin Heath and Joyce Cooper).
The authors explain how the amount of literature about life cycle assessment has grown at a “dauntingly rapid rate” over the last decade. Indeed, in some cases LCAs have been published on the same or very similar technologies or products, leading to hundreds of articles.
“One result is the impression among decision makers that LCAs are inconclusive, owing to perceived and real variability in published estimates of life cycle impacts,” write Brandão, Heath, and Cooper. They say that despite the policy need for more conclusive assessments, only modest attempts have been made to synthesize previous research. “A significant
challenge … are differences in characteristics of the considered technologies and inconsistencies in methodological choices (e.g. system boundaries, coproduct allocation, and impact assessment methods) among the studies that hamper easy comparisons and related decision support.”
There is, however, an emerging trend of meta-analysis of a set of results from LCAs, which “has the potential to clarify the impacts of a particular technology, process, product, or material and produce more robust and policy-relevant results”. Brandão, Heath, and Cooper define meta-analysis in this context as “an analysis of a set of published LCA results to estimate a single or multiple impacts for a single technology or a technology category, either in a statistical sense (e.g. following the practice in the biomedical sciences) or by quantitative adjustment of the underlying studies to make them more methodologically consistent.”
Most of the studies focus on greenhouse gas emissions, and this shows the need for more research into other metrics of LCA such as full energy accounting for net energy analysis. Other metrics such as land and water needs are more difficult to compare across many studies of energy systems in different parts of the world.
Here I simply list links to some of the studies for those who might want to go straight to looking at specific energy technologies (although the special issue also has an article on computers and biobased materials):
Coal power: here.
Electric power systems with carbon capture and storage.
And one study of GHG for concentrating solar power from both trough and power tower designs.