To address the dual structural challenges faced by new energy bases under high renewable energy penetration—strong reliance on traditional fossil fuels for peak load regulation and weak intermittent power absorption capacity—electro-hydrogen conversion technology offers a novel capacity allocation pathway. This paper proposes a capacity optimisation model for new energy bases that incorporates electro-hydrogen conversion. First

a generalized energy storage system modeling framework with bidirectional coupling between electricity and hydrogen is established. Through the synergy mechanism of electrolyzers (EL)

hydrogen storage (HS)

and hydrogen fuel cells (HFC)

it achieves cross-seasonal energy transfer from surplus wind/solar power during wet seasons → hydrogen energy → electricity gap compensation during dry seasons. This enhances the system's spatiotemporal regulation flexibility and elucidates the spatial-temporal coordination mechanism of hydrogen storage in matching dynamic source-load profiles. Then

with the dual objectives of minimising system lifecycle costs and reducing carbon emissions

the model integrates constraints on power balance

reserve capacity

and carbon emissions to form a configuration scheme that coordinates high proportions of renewable energy with electro-hydrogen energy storage. Finally

a case study is conducted on a new energy power-exporting base in Gansu Province. The results indicate: 1) Under the bidirectional electro-hydrogen conversion mode

the system's confidence robustness reaches 0.91

with renewable energy accounting for 45% of electricity generation

an annual average comprehensive cost of 3.398 billion yuan

and hydrogen fuel cells effectively compensating for power shortages under the most adverse scenarios; 2) Under the unidirectional electro-hydrogen conversion mode

the proportion of renewable energy in electricity generation increases to 67.1%

hydrogen sales revenue reached 256 million yuan

and the cost per kilowatt-hour dropped to 0.161 yuan/(kW·h)

offering superior economic performance; 3) Compared to energy storage technologies

pumped storage demonstrated the best overall performance before 2030. After 2035

the ‘electricity-hydrogen unidirectional + pumped storage’ mode achieved a comprehensive evaluation index of 0.91

with carbon emissions intensity reduced by 42.7 g/(kW·h)

and the cost of electro-hydrogen conversion equipment decreases (electrolyser costs drop to 2

380 yuan/kW by 2040)

significantly enhancing system efficiency. Therefore

the model proposed in this paper

by integrating electro-hydrogen conversion with multi-scenario confidence interval theory

effectively enhances renewable energy absorption capacity

balances economic and environmental benefits

and provides a quantitative decision-making tool and practical reference for low-carbon planning of renewable energy bases under the new power system.