Analyzing the environmental impact of innovative bio-based products from multifunctional systems

Abstract

The European Green Deal requires unlocking the full potential of all types of locally sourced bio-based "residues” by transforming them into value-added products. Use of “residues” avoids concerns about food security and land competition. In addition, residues are usually cheaper than dedicated crops and does not require transoceanic imports.

This thesis presents the first environmental life cycle assessments (LCAs) of four emerging products from bio-based residues: polypropylene from hydrotreated used cooking oil, bioenergy from a solid oxide fuel cell (SOFC) combined heat and power plant (CHP) relying on gasification of wood chips, a bio-jet fuel from acetone-butanol-ethanol fermentation of potato by-products, and bio-based asphalts with lignin from the kraft pulping process used as the binder.

The LCAs of these four products showed a generally better climate change performance than their fossil counterparts. The climate change impact reductions were 30-70% for top-layer lignin-based asphalts, 86-96% for energy from wood chips via gasification-SOFC CHP, 5-60% for a bio-jet fuel from potato by-products, and 40–62% for polypropylene from used cooking oil. However, trade-offs were observed with conventional (fossil) products for several impact categories.

One of the major modelling uncertainties of these four LCAs was the selection criterion for allocating environmental impacts between the co-products. Accordingly, this thesis broadly discusses the effect of the allocation practices applied at the feedstock and processing levels. The thesis also broadly reviews allocation practices in other LCAs of bio-based products and the causes of different interpretations of ISO recommendations on this methodological matter.