Energy–water–transport nexus modeling for energy transition: A system dynamics approach

Achieving deep decarbonization while safeguarding water and transport is a global priority. Hydrogen (H 2 ) can store variable renewables, decarbonize hard-to-electrify sectors, and couple energy–water systems. This study presents a fully integrated system-dynamics and multi-objective optimization framework that links multi-period capacity planning with cross-sector feedbacks among electricity, water desalination, transport and H 2 synthesis. Applied to Cyprus as a test case, the model compares a renewables—only pathway with a renewables + small modular reactors (SMRs) scenario. Both pathways attain net-zero direct CO 2 by mid-century, but the mixed system overcomes the PV ceiling by adding SMRs capacity from 2035, boosting annual electricity output from 14.7 TWh to 37.2 TWh and H 2 yield six-fold (90,000 million kg to 560,000 million kg) while maintaining zero curtailment. Coordinated deployment of electrolysis and desalination secures > 400 million m 3 of freshwater by the year 2060 and aligns surplus power with green and pink H 2 production, achieving levelized H 2 costs of ∼ 1.78US$/kg by 2060. The integrated SMR pathway elevates demand coverage, exports and system reliability, illustrating that H 2 –centered nexus planning, combining variable renewables with firm SMR baseload, enables economically credible, scalable net-zero energy transitions. The framework offers policymakers a transferable decision-support tool to optimize cross-sector investments under net-zero goals. • System-dynamic, multi-objective model linking power, transport, desalination, hydrogen. • Energy-water-hydrogen co-optimization secures freshwater quantities; aligns surplus power with green/pink hydrogen. • Projection of competitive hydrogen economics for net-zero; linking decarbonization, exports, reliability.