This paper examines current refrigerant options for centrifugal chillers, the type most widely applied in capacities of 1-9 MW (300-2500 RT) though available in capacities as small as 300 kW and as large as 35 MW (90-10,000 RT). The examination addresses global environmental impacts and specifically those for stratospheric ozone depletion, climate change, and similar but still uncertain future issues. It also addresses efficiency and resulting implications for energy use, both at full (peak) load and on a seasonal basis, as well as other resources. The focus includes chlorofluorocarbon (CFC), hydrochlorofluorocarbon (HCFC), and hydrofluorocarbon (HFC) refrigerants as well as alternatives such as ammonia, hydrocarbons (HCs), carbon dioxide, and water, for which selection influences the environment directly and through the resulting efficiency indirectly. Analyses summarized in this paper indicate significant reductions in energy-related greenhouse gas emissions and atmospheric pollutants with upgrading efficiency levels to the best available. The analyses also indicate opportunity to reduce peak electricity demand, potentially avoiding the need for 13 additional gas, 2 coal, or 1 nuclear generating unit(s) per year on a worldwide basis. Additionally, the upgrades identified reduce water usage, chemical treatment for cooling towers, and required fuel imports.
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