In recent years, Chinese environmental authorities have expressed interest in the use of Tradable Discharge Permits (TDP) as a regulatory instrument to control pollutant emissions. Environmental professionals still have not had enough experience, however, in designing and managing TDP systems, especially for non-uniformly dispersed pollutants. As an empirical study, this paper proposes an interzonal TDP system and analyzes its effectiveness in cost savings and environmental protection for reducing water pollutant COD (chemical oxygen demand) in Tianjin, China. Zonal permit system (ZPS) and emission permit system (EPS) are discussed for comparison. The inter-zonal TDP system is demonstrated to improve cost efficiency by allowing permit trades between zones, as long as water quality constraints are satisfied. The transactions are assumed to proceed in a multilateral sequential way and are simulated with a circularly running linear programming (LP) model. The simulation of permit transactions among 20 firms shows that to reach the same COD removal target, ZPS, interzonal TDP system, and EPS lowered the total reduction cost by 12.8%, 14.6%, and 15.8%, respectively. EPS, however, brought about "hot spots" problem. Finally, the transaction costs and the sensitivity of the three TDP systems to changes in both COD reduction rate and the initial permit allocation are discussed, and policy implications are addressed.
IntroductionA transferable discharge permit (TDP) system is one of the economic instruments for pollution control. It has been successfully used in the reduction of SO2 (sulfur dioxide) in the United States and is being tried worldwide in efforts to abate other pollutants (CO2, BOD (biochemical oxygen demand), etc.) by virtue of its cost efficiency and flexibility in attaining control targets (1, 2).In China, the TDP system is attracting more and more attention. Environmental management measures of "total emission control", "declaration and registration of pollutant discharges", and "pollutant discharge permits" provide support for implementation of the TDP system from the perspective of both policy and relative information and data (3). Although the regulatory/administrative framework to institute a TDP system is yet to be developed in China, several cases of permit transfers have occurred in Shanghai, Beijing, and Zhejiang that have involved water pollutants such as COD (chemical oxygen demand), suspended solids, copper, nickel, and zinc (4, 5). In 2002, the State Environmental Protection Administration (EPA) of China started a pilot project of SO2 emission trading in some provinces and cities. Some pilot provinces or cities, such as the province of Jiangsu or the city of Taiyuan, have formulated a provisional method for managing SO2 emission trading (5).The TDP scheme is still in its beginning stages in China. The successful experiences of foreign countries help formulate general guidelines for permit trading; whereas, empirical studies in specific regions for specific pollutants in China could provide mor...