Inter-regional power grid planning up to 2030 in China considering renewable energy development and regional pollutant control: A multi-region bottom-up optimization model

China's energy resources and electricity load show reverse regional distribution, along with serious imbalance of energy supply and demand between eastern and western regions. Inter-regional power transmission is considered to be the key strategic measure to balance the national resources allocation and satisfy various regional long-term benefits. In this study, a multi-region power sector optimization model is developed from the perspective of bottom-up modeling. Power transmission technologies are considered in detail. Moreover, the sub-module of inter-regional coal transportation is introduced into the model. Based on above framework, this study analyzes quantitatively the optimum inter-regional power transmission planning under various policy scenarios, and estimates its impacts on renewable energy, NOx and SO2 emissions, and coal transportation from a long-term perspective. The results show that ultra high voltage lines will become the main carrier of inter-regional power transmission in the future. The construction of transmission line between some regions such as from East Inner Mongolia to northern China, and from northwest China to central China can bring economic savings. Inter-regional power transmission is an effective way to promote the utilization of renewable energy in Inner Mongolia and northwest China, and plays an important role in controlling NOx and SO2 emissions in central and eastern China but has limited effect on the national total emissions. Moreover, it could reduce the inter-regional coal transportation significantly.