This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Life cycle assessment is used to quantify the environmental impact of products and services and forms an important basis for political decisions. However, the necessary data is always difficult to capture completely.
A study by the Paul Scherrer Institute PSI now shows that four established hybrid methods can be reduced to just two: a first step towards open-source software that could enable such analyses even without in-depth mathematical knowledge. Anyone wanting to know how environmentally friendly a car, a piece of cheese or a wind turbine is has to rely on life cycle assessment (LCA). This method captures the upstream supply chain of a product or service.
"Life cycle assessment is ultimately a mathematical method: It is only as good as the data it is based on," says Michael Weinold, who now works at ETH Zurich. He carried out the research at PSI's Laboratory for Energy Systems Analysis. The problem: Conventional life cycle assessments cannot capture all processes that contribute to a product's environmental impact.
Where the boundary lines are drawn is decided by those who create the life cycle assessment. Weinold closely examined methods that can close these gaps using data from the global economy. In doing so, he encountered another problem: several methods exist for such "hybrid" life cycle assessments, and the differences between them had not yet been clearly defined.
Together with Guillaume Majeau-Bettez, a professor at the CIRAIG Life Cycle Assessment Research Center in Canada, Weinold investigated the various methods. In two studies published in the Journal of Industrial Ecology, the researchers demonstrate that four established hybrid methods can be mathematically reduced to just two. They also provide recommendations on which method should be used and when.
A life cycle assessment is supposed to capture data from a product's entire life cycle—a process chain that includes not only manufacturing but also raw materials, energy supply, transportation and many other activities. For example, when it comes to gasoline for a car, it's not just the combustion that matters, but also the origin of the fuel. "For crude oil, this chain usually ends where the oil is extracted," says Weinold.
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