Life cycle assessment (LCA) is a comprehensive, supply chain environmental assessment tool that investigates environmental impacts for a product, such as a kilogram of beef. LCA research has previously been conducted in the Australian beef industry by Peters et al. (2009a, b, 2010), who modelled data collected by Davis & Watts (2006).
This project built on previous LCA research in the industry, with particular attention being given to modelling feedlot emissions and impacts. Impacts assessed included global warming potential (GWP), water usage and primary energy (PE) usage. The primary functional unit applied was '1 kg of liveweight (LWT) gain at the feedlot from point of induction to immediately prior to transport for slaughter', representing a 'gate-to-gate' assessment of the feedlot. Upstream and downstream processes were also modelled to contextualise the results.
Feedlot gate to gate GWP ranged from 7.5 kg CO2-e / kg LWT gain to 11.3 kg CO2-e / kg LWT gain, and was dominated by enteric methane emissions. 'Blue' water usage at the feedlot ranged from 151 to 871 L / kg LWT gain. Water usage at the feedlot was dominated by water carried through with irrigated commodities (up to 95% of water usage). Primary energy usage ranged from 34.5 to 49.1 MJ / kg LWT gain. Energy embedded within feed contributed 89 – 90% of total energy usage at the feedlot. GWP, water and energy usage were considerably higher than previously estimated by Davis & Watts (2006) because of the broader scope of this research.