Greenhouse gas life cycle assessment of products arising from the rendering of mammalian animal byproducts in the UK.

Animal byproducts (ABP) are unavoidable byproduct of meat production that are categorized under EU legislation into category 1, 2, and 3 materials, which are normally treated by rendering. Rendering is a thermal process that produces rendered fat and protein. Heat is provided from the combustion of natural gas and self-produced rendered fat. The main objectives of the study were (i) to assess energy intensity in the UK rendering industry, and (ii) to quantify the greenhouse gas emissions associated with the production of mammalian rendered products using life cycle assessment. Thermal energy requirements were 2646 and 1357 kJ/kg, whereas electricity requirements were 260 and 375 kJ/kg for category 1 and 3 ABP respectively. Fossil CO(2) emissions were -0.77 and 0.15 kg CO(2)e/kg category 1 and 3 mammalian rendered fat respectively and 0.15 kg CO(2)e/kg processed animal protein. These were low relative to vegetable products such as palm oil and soya bean meal because (i) ABP were considered wastes that do not incur the environmental burden of their production, and (ii) the rendering process produces biofuels that can be used to generate energy that can be used to offset the use of fossil fuels in other systems.