Importing or self-dependent: energy transition in Beijing towards carbon neutrality and the air pollution reduction co-benefits

Beijing has implemented air pollution control policies and transitioned its energy system with lower carbon emissions to tackle severe air pollution. However, further advancing to a carbon–neutral future necessitates comprehensive measures far beyond the air-quality-oriented policies. This study aims to explore and compare different transition strategies of the Beijing energy system to achieve carbon neutrality and assess the associated air pollution reduction co-benefits by using an integrated modelling framework consisting of an energy system model MESSAGEix-Beijing and an air quality assessment model GAINS. Three scenarios are developed, namely, baseline (BS), indigenous (IND), and imported electricity-dependent (EIMP). The two distinct low-carbon pathways differ in cost-optimal technological solutions and the associated impacts of air pollution reduction. Compared to the BS scenario, the IND and EIMP scenarios could reduce the carbon dioxide emissions in Beijing by 94 to 96% in 2050 and achieve substantial air pollution co-benefits. In the IND scenario, the NOx, SO₂, and PM2.5 emissions would decrease by 50%, 84%, and 30% in 2050, respectively. Importing full electricity from other provinces, as indicated by the EIMP scenario, would achieve even higher emissions reduction for air pollutants. The results highlight the necessity for concerted regional development of adjacent provinces to avoid the spillover of carbon emissions and air pollution.