An eco-profile of thermoplastic protein derived from blood meal Part 1: allocation issues

Abstract

Purpose A renewable thermoplastic called Novatein Thermoplastic Protein (NTP) has been developed from blood meal—a low-value by-product of the meat processing industry. The aim of this research was to develop a non-renewable energy and greenhouse gas emission eco-profile for cradle to gate production of NTP. Environmental impacts of supplying blood meal as a raw material were investigated using different allocation methods for farming and blood meal production. These included mass, economic, treating low-value by-products as waste and system expansion by substitution. In part 2, the entire system will be analysed on a cradle to gate basis and include the production of thermoplastic (NTP). Methods A theoretical NTP production facility was analysed for non-renewable primary energy use and greenhouse gas emissions. Data for feedstocks and process steps were obtained from published papers, government agency reports and engineering models. Mass and economic allocation models treating low-value by-products as waste and substitution were applied, and a sensitivity analysis was used to evaluate the impact of different methods of allocation on environmental impact. Results and discussion Non-renewable energy use in blood meal production varied between 5 (substitution) and 38 MJ (simple mass allocation) per kg of NTP. Greenhouse gas emissions varied between 0.4 (substitution), or even less if the biogenic carbon content is considered a credit, and 14 kg (mass allocation) CO2e per kg NTP. Conclusions It was concluded that both mass allocation and a waste assumption should be considered for the cradle to gate system. Mass allocation is common in other attributional studies and allows for a more transparent comparison. The most appropriate treatment of allocation in an attributional profile was to consider blood as a waste with regard to farming and meat processing, but include blood drying. This takes into account the motivations for farming and meat processing, but also recognises that there are other treatment options for blood that do not produce blood meal used in manufacturing NTP. This would allow NTP to be compared to other bioplastics as well as identifying hot spots in its cradle to gate production. It was also anticipated that results may be adapted in future cradle to grave assessments as product systems are developed.