Greenhouse gas emissions of packaged fluid milk production in Tehran

The main purpose of this study was first to estimate the carbon footprint (CF) of packaged fluid milk through life cycle assessment (LCA), using regional data in Tehran, and then to identify opportunities for lower greenhouse gas (GHG) emissions. The system boundary for cradle to gate assessment was divided into three life cycle stages: agronomy, animal farm and dairy plant, and data were gathered from multiple sources, e.g. questionnaire, published studies and dairy plant database in 2011–2012. Through the study, the IPCC 2006 methodology and the International Dairy Federation (IDF) Carbon Footprint Guide were used to calculate the CF of milk. The functional unit (FU) was one litre of pasteurized milk packaged in a plastic pouch. The average CF for 1 kg of fat-protein corrected milk (FPCM) at the farm gate was 1.57 kg CO2-eq, however, for the FU, it was 1.73 kg CO2-eq. The main contributors to overall CF of milk product were enteric methane 30%, electricity 14%, diesel 8.9%, manure emissions 8.8% and transportations 8.6%. The average CF of FPCM at farm gate was higher than the previous European reports, but lower than the previous estimate of 3–5 kg CO2-eq/kg milk. Developing the infrastructure to utilize renewable energy sources, such as solar energy, may be a solution for high share of energy-related emissions from the dairy sector. We call for more research on CF and other environmental impacts like eutrophication, and impacts from water consumption in different regions of the country both in traditional and industrial dairy farm systems.