Critical aspects in the life cycle assessment (LCA) of bio-based materials – Reviewing methodologies and deriving recommendations

Concerns over non-renewable fossil fuel supply and climate change have been driving the Renaissance of
bio-based materials. To substantiate environmental claims, the impacts of bio-based materials are typically
quantified by applying life cycle assessment(LCA). The internationally agreed LCA standards provide
generic recommendations on how to evaluate the environmental impacts of products and services but do
not address details that are specifically relevantfor the life cycles of bio-based materials. Here, we provide
an overview of key issues and methodologies explicitly pertinent to the LCA of bio-based materials. We
argue that the treatment of biogenic carbon storage is critical for quantifying the greenhouse gas emissions
of bio-based materials in comparison with petrochemical materials. We acknowledge that biogenic
carbon storage remains controversial but recommend accounting for it, depending on product-specific
life cycles and the likely time duration of carbon storage. If carbon storage is considered, co-product allocation
is nontrivial and should be chosen with care in order to:(i) ensure that carbon storage is assigned to
the main product and the co-product(s) in the intended manner and (ii) avoid double counting of stored
carbon in the main product and once more in the co-product(s). Land-use change, soil degradation, water
use, and impacts on soil carbon stocks and biodiversity are important aspects that have recently received
attention. We explain various approaches to account for these and conclude that substantial methodological
progress is necessary, which is however hampered by the complex and often case- and site-specific
nature of impacts. With the exception of soil degradation, we recommend preliminary approaches for
including these impacts in the LCA of bio-based materials. The use of attributional versus consequential
LCA approaches is particularly relevant in the context of bio-based materials. We conclude that it is
more challenging to prepare accurate consequential LCA studies, especially because these should account
for future developments and secondary impacts around bio-based materials which are often difficult to
anticipate and quantify. Although hampered by complexity and limited data availability, the application
of the proposed approaches to the extent possible would allow obtaining a more comprehensive insight
into the environmental impacts of the production, use, and disposal of bio-based materials.
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