Integrating mitigation of air pollutants and greenhouse gases in Chinese cities: development of GAINS-City model for Beijing

Abstract

Strong economic growth in China has fueled development of cities where increase in energy demand and transportation lead to severe air pollution. The cities contribute also a significant share of the national greenhouse gas emissions. We identify strong synergies between air quality and climate relevant measures that would allow improving cost-efficiency of air pollution policies. In order to help local policy makers to identify viable and efficient solutions, we developed a city-scale emission model (GAINS-City) based on the Greenhouse Gas and Air Pollution Interactions and Synergies (GAINS) model developed by the International Institute for Applied Systems Analysis (IIASA, Austria). The GAINS-City model relies on a technology-based approach to evaluate the co-benefits of various policies. This approach allows for estimation of emission reductions of several pollutants (including SO2, NOX, PM) and CO2 for individual policies and support evaluation of co-benefits. In addition, a reduction index, an integrated rank of the individual reductions potential, was defined to recommend the priority of policies implementation. The approach will have great potential to be applied in many large cities with local input data and/or minor structure modifications. We conducted a case study in Beijing to demonstrate the model features. Based on the technology-based evaluation approach, policy packages were designed and implemented in policy scenarios. The emissions under three scenarios (Baseline, Air Quality, and Strict Air Quality) in base year (2005) and future years (2020 and 2030) were estimated. The results indicate a significant reduction potential. In 2030, implementation of Air Quality and Strict Air Quality scenarios could result in reductions of 39–48% of SO2 emissions, 38–42% of NOX emissions, 37–55% of PM2.5 emissions and 5–22% of CO2 emissions respectively, compared with the Baseline scenario. The results demonstrated air quality policies and measures could also have co-benefits of reducing CO2 emissions. However, there is no significant difference of reductions between the two policy scenarios, which indicates the limited further reduction potential in the stricter air quality case. This calls for a wider application of cleaner technologies, such as IGCC and CCS, and more aggressive air quality measures by neighboring provinces to control regional air pollution.