Institutional coordination expansion in power sector reshapes renewable energy system layout and trans-administrative region power grid

The increasing volatility of renewable energy systems necessitates large-scale institutional coordination in the power sector (ICPS) to enhance regional integration and mobilize flexible resources—including traditional thermal/hydro power and the load-shifting capacity of green hydrogen production. However, the economic viability of ICPS expansion and its dependence on trans-administrative regional power grid (TARPG) structures remain insufficiently explored. This study addresses this gap by developing a socio-economic-energy spatial optimization model, using China as a case, to evaluate renewable energy layouts and TARPG configurations under varying ICPS scales. Key findings reveal that by 2050, a nationwide ICPS could reduce annual energy system costs by ¥1060 billion (vs. no ICPS) and ¥450 billion (vs. provincial ICPS), while shifting renewable energy system layout toward renewable-rich Northwest China. Yet, nationwide ICPS also increases transmission demand at key western nodes by 62.5 % relative to the no ICPS scenario. Spatial analysis demonstrates that TARPG adoption could reduce transmission costs by 70 % compared to traditional provincial grid structures. Moreover, incorporating hydrogen-production flexibility reduces system costs by around 10 %, but also further concentrating infrastructure in the Northwest. Importantly, national ICPS deployment lowers regional electricity supply cost in Northwest China and increased rural residents income by carbon tax transfer, indicating improved energy equity. These results underscore the complex trade-offs between ICPS scale, grid structure, and socio-economic outcomes, providing practical insights for policymakers to balance infrastructure investments with equitable energy transitions.