Unveiling the industrial synergy optimization pathways in Beijing-Tianjin-Hebei urban agglomeration based on water-energy-carbon nexus.

Urban agglomerations play an increasingly important role in bolstering regional economic growth; meanwhile bring with substantial water and energy consumption and carbon emissions. Its sustainable development needs synergistic management of water-energy-carbon (WEC), which is vitally linked by industrial activities. Taken Beijing-Tianjin-Hebei (BTH) urban agglomeration in China, this study adopts material flow analysis to clarify WEC nexus footprint patterns of the urban agglomeration, initially develops a multi-regional dynamic synergistic development model to explore industrial optimization pathways for WEC system management from 2020 to 2035. The complex model is constructed and simulated by integrating input-output modeling, system dynamics, and multi-objective programming. Simulation results revealed that optimal industrial restructuring with regional corporation, including equipment manufacturing are in a leading position, whereas conventional manufacturing that achieve cross-regional synergy can still release locational advantages without adverse environmental impacts. Through above industrial roadmap, a symbiotic industrial chain among urban agglomerations could be formed; the integrated optimization of resource efficiency improvement and emission sinks could be achieved coherently, with eco-efficiency increasing by 24.4%, 21.8%, and 42.4% for water, energy, and carbon; moreover, key sectors for industrial transfer within the urban agglomeration (e.g., water- and energy-intensive, high emission sectors) will be critical areas for coordinated management (contributing over 68% of resource consumption and CO emissions). In addition to industrial structure optimization, the marginal potential for carbon reduction through energy structure optimization is more prominent than energy efficiency gains. The findings offer policymakers valuable insights into integrated resource management within industrial collaboration for urban agglomerations, providing guidance in formulating effective environmental policies and economic strategies aligned with sustainable development goals.