Techno-economic and environmental assessments of hydrogen-based CCHP system for data centers under different hydrogen pathways and climate zones

• Hydrogen-based CCHP system for data center achieves efficient multi-stage waste-heat utilization. • Hybrid cooling strategy lowers electric cooling demand and reduces annual average PUE to 1.10. • Winter waste-heat recovery rate exceeds 90.94%, with an annual average of 41.07% in Guiyang. • The assessment of hydrogen pathways reveal cost, emissions and policy implications trade-offs. A hydrogen-based combined cooling, heating, and power (CCHP) system is proposed to enable deep decarbonization of data centers by integrating a proton exchange membrane fuel cell (PEMFC), an absorption transformer unit (ATU), and a climate-responsive hybrid cooling strategy. The system enables multi-grade waste-heat recovery and seasonal coordination between cooling and heating demands, thereby enhancing overall energy efficiency and operational flexibility. A comprehensive thermodynamic, exergetic, techno-economic, and environmental assessment framework is established to evaluate system performance under three representative hydrogen production pathways (gray, blue, and green hydrogen). In addition, the climate adaptability of the proposed system is systematically examined across five representative climate zones in China, ranging from cold-temperate to tropical regions. For a benchmark 150 kW data center with 80% IT load, the annual hydrogen fuel costs account for approximately 70%–85% of total operating expenses. In Guiyang, the proposed system achieves a waste-heat recovery rate of 90.94% in winter, and an annual average of 41.07%, while reducing the annual average power usage effectiveness (PUE) to 1.10. From a life-cycle perspective, green hydrogen yields the lowest greenhouse gas emissions (53 t CO 2 eq yr −1 ), representing a 91% reduction relative to grid electricity, albeit with a 47.5% increase in annual cost. Climate-adaptability analysis reveals that the proposed system in cold-temperate regions achieves the best overall performance, with a minimum PUE of 1.075, a waste-heat utilization rate of 54.21%, and an overall energy efficiency of 67.2%, whereas tropical regions are constrained by high cooling demand and limited waste-heat recovery potential.