The eco-profile of thermoplastic protein derived from bloodmeal

Abstract

Life cycle assessment (LCA) is a method that can be used to evaluate the eco-profile of a product over a portion of its life cycle. Novatein Thermoplastic Protein (NTP) is a second generation bio-based polymer being developed at the University of Waikato, using bloodmeal as a feedstock. The objective of this study was to estimate the cradle to gate eco-profile of a hypothetical commercial process producing NTP. Specific objectives were to: ● Estimate non-renewable energy use and greenhouse gas emissions. ● Identify which portions of the cradle to gate system have the greatest contribution to such impacts. ● Evaluate this material against other polymers. It was found that the allocation method used for the multiple outputs of farming and meat processing had a significant influence on the non-renewable primary energy and greenhouse gas emissions attributed to NTP. This resulted in great differences between the eco-profile of NTP relative to other polymers. The production of bloodmeal was found to have the largest contribution to both non-renewable primary energy use and greenhouse gas emissions of all life cycle phases. This was even more pronounced when impacts from farming and meat processing were allocated to blood or bloodmeal on a mass basis. This is in contrast to fermentation based polymers, which typically have impacts dominated by energy supply for fermentation and recovery, rather than production of biomass. If allocation from farming is based on the mass of blood as proportion of live weight, 13 kgCO₂e/kg polymer are attributed to NTP, considerably higher than the 1 - 2 kgCO₂e/kg polymer typical of other bio-based plastics (when using conventional energy) and conventional commodity polymers. Non-renewable primary energy in this scenario is 48.28 MJ/kg polymer, similar to that of other bio-based polymers. If allocation is based on the mass of bloodmeal, excluding wastes and losses, only 28.41 MJ/kg polymer are attributed to NTP. Emissions are still slightly higher than other bio-based polymers at 2.82 kgCO₂e/kg polymer, but in the same order of magnitude. Alternatively, blood can be considered a waste with regard to farming and meat processing, and only the impacts of blood drying and associated transport are attributed to bloodmeal. In this case 24.03 MJ non-renewable primary energy and 0.35 kgCO₂e/kg polymer greenhouse gas emissions are attributed to NTP. For comparison, the production of polyethylene uses 72.3 MJ/kg non-renewable primary energy and releases 1.89 kgCO₂e/kg polymer. It was concluded that the most appropriate allocation scenario is to only attribute the impacts of blood drying (and associated transport) to bloodmeal, and not any impacts from farming and meat processing. Under such as scenario, the production of NTP has the potential to reduce non-renewable primary energy use and greenhouse gas emissions by replacing synthetic polymers or other bio-based polymers. For each potential application, however, a full cradle to grave life cycle system should be considered to ensure that impacts from the use and end of life phases do not outweigh any differences in impacts from manufacture.