Life cycle assessment of fossil- and bio-based polyurethane foams:a review

Polyurethane (PUF) foam market has grown rapidly in recent years due to its wide variety of applications. Their environmental impact is a matter of significant concern as so far, the production of PUF is essentially dependent on fossil raw materials, namely isocyanates and polyols. With the purpose of reducing climate change and decoupling economic growth from resource use, the use of renewable polyols is already a reality in the PUF industry, namely vegetable oils, recycled polyols, and CO2-based polyols. However, this only contributes in part to the total polyol used in some formulations in various industrial-scale applications. Even though there are other potential renewable polyol counterparts (e.g. lignin, as well as alternative synthetic routes to produce PUF including variations of the so-called via Non-Isocyanate Polyurethane (NIPU)), there are still several limitations compared to the conventional manufacturing processes involving petroleum-derived raw materials, which hampers the availability of these alternatives. The possible benefits of these potentially greener alternatives need to be quantified and compared with the environmental performance of well-established conventional processes. This review work encompasses the results from a systematic literature analysis regarding Life Cycle Assessment (LCA) studies on PUF produced using a variety of raw materials, classified as four different feedstocks in this work. This timely work identifies the main trends in methodological choices, including functional unit, system boundaries, multifunctionality, impact assessment methods, and sensitivity analysis, and enables the understanding of their effect on the environmental sustainability of PUF, namely in the most evaluated impact category-the climate change (CC). A wide range of CC variation was observed, ranging from 2.95 kgCO2eq/FU for a fossil-based to 7.67 kgCO2eq/FU for a recovered fossil polyol. The main issues for this high variability are addressed, highlighting the need for further harmonization and consistency in data collection and methodological choices used in LCA studies.