Quantifying energy–cost–carbon tradeoffs in China's onshore wind expansion: A life cycle-based turbine design optimization

China's onshore wind expansion must reconcile electricity generation, life-cycle cost, and life-cycle carbon emissions across heterogeneous wind regimes. We develop a region-specific assessment and turbine-design optimization framework linking rotor diameter and hub height to annual energy production, life-cycle cost, and greenhouse gas emissions from component manufacturing to grid delivery. Spatial screening identifies 2.61 million km² of eligible land, representing 27.2% of China's land area. Under a uniform-design assessment using the reference wind speed, maximum geometric capacity reaches 10.1 TW, with gross generation of 30 PWh/yr and 10.6 PWh/yr after an idealized infinite-array adjustment. Separate national optimizations select turbine configurations across wind-speed zones under generation, cost, and carbon constraints, assuming full development of eligible land and using gross generation. The minimum-unit-cost solution generates 38.2 PWh/yr at 0.25 CNY/kWh and a carbon intensity of 15.0 g CO₂-eq/kWh. Minimizing carbon intensity lowers it to 13.3 g CO₂-eq/kWh but raises unit cost to 0.75 CNY/kWh, with generation of 40.2 PWh/yr. Selected turbine dimensions and rated powers generally decrease beyond their respective peaks in low-to-intermediate wind-speed zones; the minimum‑carbon-intensity solution generally favors larger rotors and higher-rated turbines. By quantifying energy–cost–carbon trade-offs, the framework supports turbine selection tailored to regional wind conditions and economic or carbon objectives.