Transition pathways towards a deep decarbonization energy system—A case study in Sichuan, China

China has set ambitious carbon emission reduction targets to combat climate change, however, there has been little scientific focus on the achievement of deep decarbonization at the provincial level. The contradiction between rapid economic development and increasing energy utilization exacerbates the difficulty of achieving this goal. Here, we explored the feasibility of fulfilling deep decarbonization in the energy system by 2050 in Sichuan, one of the leading provinces in economic growth in China. Three transition pathways sustained by imported electricity, biomass, and natural gas were developed and simulated using the EnergyPLAN model. All the pathways utilized local hydropower, wind power, and solar photovoltaic resources. These pathways were evaluated using multi-dimensional analysis considering energy self-sufficiency, environmental sustainability, and economic affordability. We found that the energy self-sufficiency rate of the 100% electricity pathway was less than 68%, whereas those of the other pathways were nearly 100%. The CO2 emission reduction differed by pathway, with 100% electricity achieving 91.52%, biomass achieving 90.48%, and natural gas achieving 58.17%. Moreover, all the pathways achieved zero direct CO2 emissions with carbon capture and sequestration (CCS) technology. From an economic perspective, the highest system cost, i.e. 1.3 times that of the reference system, appeared in the 100% electricity pathway after introducing CCS technology, and was comparable to the energy system costs of other provinces in 2050. The methods and results of this study can serve as a basis for facilitating decarbonization in any provincial energy system in the long term.