FUTURE CONSUMPTION AND EMISSIONS OF HYDROFLUOROCARBON (HFC) ALTERNATIVES TO CFCs: COMPARISON OF ESTIMATES USING TOP-DOWN AND BOTTOM-UP APPROACHES

摘要

Two methods of estimating the future requirements for chloroflurocarbons (CFCs) are compared. The top-down method, in which growth in demand is factored from the global Gross National Product (GNP), and the bottom-up method, where the demand is calculated by extrapolating the historic demand for CFC-12 and HCFC-22, are shown to produce very similar results. A market in the region of 150 000 tonnes/year for the principal replacement, HFC-134a, is predicted for 1995/1996, rising to 310 000 tonnes/year in 2020/2025. The methods differ in the descriptions of the growth; the top-down method predicts increasing growth and the bottom-up approach predicts a diminishing growth rate typical of a market reaching saturation. Of the two, the diminishing growth rate is more likely for this type of material. Demand for a compound such as HFC-32, which could substitute for HFC-22, is predicted to reach a plateau of 80-90 000 tonnes/year by 2025. Potential emissions of the compounds may be considerably less than predicted if even present-day technology for containment is adopted.