File photo shows a scene of China Huaneng Group's Beijing Thermal Power Plant in Chaoyang District of Beijing, capital of China. The last coal-fired power plant in Beijing finished operation on March 18, 2017. Beijing witnesses a great change in the past five years and the city will keep focusing on the coordinated development in Beijing, Tianjin and Hebei regions and objective of removing non-capital functions. (Xinhua/Zhang Chenlin)