Various policy interventions have been proposed to decarbonize the Chinese economy through the electricity sector. This study is the first to use generation-by-plant data to analyze the emissions from the electricity sector in a Chinese region and evaluate the environmental impacts of various policy interventions. Using regression techniques, the average emission factor, marginal emission factor, and marginal displacement factor, are estimated for different pollutants of Guangdong, the most affluent and populous province in China. Results reveal a decline in average emission factors over the sample period of 2017-2021, owing to the expansion of renewable energy. This study also finds a less pronounced disparity between marginal emission factors and average emission factors compared with that in developed countries, probably due to the prevalence of coal-burning plants and lower renewable energy penetration in Guangdong. Using the estimated emission factors, this study also examines the environmental effect of time-of-use tariffs, indirect emissions of electric vehicles, and carbon displacement effect of wind energy. The conclusions reveals that the time-of-use tariffs moderately reduced CO2 emissions, and the extensive adoption of electric vehicles and wind energy substantially reduces carbon emissions, indicating that decarbonizing the economy needs the coordination of various policies.