Planning model for electro–hydrogen coupling systems for multistage emission reduction and carbon–green-certificate markets

Hydrogen, as a zero-carbon secondary energy carrier, provides a unified pathway for low-carbon energy transformation. In electro–hydrogen coupling systems (EHCSs), surplus renewable power is stored via water electrolysis and later reconverted to electricity using fuel cells or gas turbines, enhancing the system’s flexibility and reliability in support of deep decarbonization. This study constructs an electricity–hydrogen energy-recycling model based on a coupling relationship considering the bidirectional conversion between electricity and hydrogen. A multistage carbon-emission-reduction indicator constraint is also established. Additionally, the green-certificate and carbon trading markets are introduced to optimize equipment investment and operation costs while achieving carbon-emission reduction. A case study reveals that the proposed EHCS planning model effectively allocates carbon emissions across different system stages, while mitigating economic repercussions, thus ensuring closer alignment with China’s emission-reduction policies. Incorporating diverse market mechanisms significantly enhances the system’s economy and decision-making flexibility, particularly in addressing future challenges in the energy market.