Under the carbon peaking and carbon neutrality goals, integrated energy systems (IESs) cut regional carbon emissions through multi-energy complementarity and cascaded utilization, yet their combined economic and emission reduction benefits stay unclear when several electricity-carbon market mechanisms operate jointly. Existing models often treat carbon capture and power-to-gas (P2G) as independent modules and overlook the bridging role of hydrogen, so the synergistic mitigation potential of electricity-carbon-hydrogen coupling stays underused. Moreover, most carbon-trading studies count only direct operational emissions and thus misjudge the real reduction under full-life-cycle accounting. The green certificate (GC), green electricity (GE), and Chinese certified emission reduction (CCER) mechanisms have mostly been studied independently, and their interaction in IES dispatch has seldom been examined. The objective was to quantify and coordinate the economic and low-carbon performance of an electricity-hydrogen IES that participates simultaneously in the CCER, GC, and GE markets under life-cycle carbon accounting.

An electricity-hydrogen IES architecture was established, and mathematical models were built for the wind turbine (WT), the photovoltaic array (PV), the methane reactor (MR), the carbon capture, utilization and storage (CCUS) unit, the electrolyzer (EL), the hydrogen fuel cell (HFC), the hydrogen storage tank (HST), and other energy-conversion and energy-storage devices. Electricity-carbon-hydrogen coupling was achieved through water electrolysis and CO₂ methanation, which formed a carbon capture, hydrogen conversion, and gas utilization cycle. The actual certified emission reduction was quantified from internally consumed renewable generation, directly stored CO₂, and CO₂ converted in the methane reactor. Under the principle of unique environmental rights certification, a synergistic trading method was formulated for the CCER, GC, and GE markets, and a price-coupling coefficient was introduced to merge the three market signals into a single marginal criterion for renewable allocation. A life-cycle-assessment (LCA) carbon-accounting model was developed for equipment production, transportation and construction, operation, commissioning, and decommissioning, in which a carbon-intensity-per-unit-electricity (CIUE) index was defined to unify device-level emissions. A tiered carbon-trading cost was embedded, and a dispatch model that minimizes the total cost, namely annualized investment, operation and maintenance, energy purchase, carbon, GC-trading, and CCER costs, was constructed. The mixed-integer linear programming model was solved by the GUROBI solver through YALMIP in MATLAB. A typical-day case of an industrial park in southwest China supplied the inputs, with measured wind speed, solar irradiance, and ambient temperature, and five scenarios were compared: a conventional IES; the same system with a hydrogen subsystem; the hydrogen system further combined with GC and GE, with CCER, and with all three mechanisms together.

The hydrogen subsystem builds an electricity-hydrogen-methane path that consumes captured CO₂; relative to the conventional system, it lowers total carbon emissions by 10.53%, carbon trading cost by 16.32%, and gas-purchase cost by 3.74%, raises operation and maintenance cost by 43.63%, and reduces total cost by 2.14%. Under the GC and GE mechanism, the value of self-consumed renewable power, including certificate revenue plus avoided purchase and lower carbon-trading cost, exceeds the revenue from electricity sales, so on-site sales fall by 37.89%, with renewable curtailment of 1 702.17 kW•h; the carbon-capture rate stays at 75.32%, as end-of-pipe capture receives little direct incentive. The CCER mechanism shifts the strategy from source-side cleaning to coordinated source-and-end abatement, cuts carbon-trading cost by 51.15%, raises the capture rate to 79.40%, and lowers curtailment to 1 123.81 kW•h. The combination of all three mechanisms yields the lowest total cost, 39 375.96 yuan, 19.38% below the baseline scenario; stronger hydrogen-production economics push the methane reactor and the capture unit to high-intensity operation, raise the capture rate to 83.91% and captured CO₂ to 38 354.28 kg, hold the net traded carbon to 6 828.04 kg despite the largest CO₂ generation of 45 708.78 kg, and achieve zero renewable curtailment. The three mechanisms couple through the renewable-allocation constraint rather than act as independent additive incentives.

The hydrogen subsystem links carbon capture with gas supply and turns captured CO₂ into a usable carbon source, so the electricity-carbon-hydrogen coupling improves both economy and emissions over a conventional IES. The CCER, GC, and GE mechanisms act on dispatch through a shared renewable-allocation constraint and produce synergistic amplification rather than a linear sum of separate incentives. Coordinated participation in the three markets achieves the joint optimization of cost reduction, emission mitigation, and renewable accommodation and provides a reference for the planning and operation of IESs in industrial parks.