GREEN-MAC-LCCP©: Life-Cycle Climate Performance Metric for Mobile Air Conditioning Technology Choice

Most refrigerants used today are potent chlorofluorocarbon (CFC), hydrochlorofluorocarbon (HCFC), and hydrofluorocarbon (HFC), greenhouse gases (GHG) that can contribute significantly to anthropogenic climate change and stratospheric ozone depletion. In a business-as-usual scenario, HFC emissions in 2050 have been predicted to be equivalent to 9-19% (CO(2)-eq. basis) of projected global CO(2) emissions. This percentage increases to 28-45% if projected CO(2) emissions result in a 450-ppm CO(2) stabilization scenario. Half of current direct HFC emissions are from mobile air conditioning (MAC) and alternative refrigerants with lower global warming potential (GWP) should have higher energy efficiency. The European f-Gas Directive phases out the use of refrigerants with GWP > 150, including HFC-134a (GWP = 1430) from MACs by 2017. Life-Cycle Climate Performance (LCCP) identifies environmentally superior technology to minimize GHG emissions from refrigeration and air conditioning applications. The comprehensive LCCP model, GREEN-MAC-LCCP (c) focuses on the current choice among alternative refrigerants that meet the f-Gas requirement starting in 2011. Using GREEN-MAC-LCCP (c) we estimate that the current MAC technology based on HFC-134a refrigerant demands additional fuel during vehicle A/C operation in the: USA by 7%, in the EU by 7%, in Japan by 9%, in India by 15-20%, and in China by 7-10% depending on the humidity. We compare these data with the projected LCCP CO(2)-eq. savings by the year 2017 when HFC-134a will be replaced by a low GWP alternative (GWP < 150) according to the f-Gas rule. We find that refrigerant HFO-1234yf has the potential to reduce global LCCP CO(2)-eq. greenhouse gas emissions by about 7% in 2017, whereas greenhouse gas emissions from air conditioning systems using R-744 (carbon dioxide) refrigerants are estimated to be about 2% greater, compared to the current HFC-134a MAC baseline systems. (C) 2010 American Institute of Chemical Engineers Environ Prog, 30: 234-247, 2011