When do hydrogen technology patents improve ecological performance? Cross-country evidence on mediation and threshold effects in the load capacity factor

This paper asks whether hydrogen technology patents improve ecological performance, and under what conditions. Using a balanced panel of 48 countries over 2000–2024 and a multidimensional patent value index, we estimate two-way fixed effects models for the load capacity factor (LCF), the ratio of biocapacity to the ecological footprint. We find that hydrogen patent value is positively associated with the LCF, with a level-dependent magnitude: a one-standard-deviation increase in transformed patent value is associated with an LCF 4.2% higher for an economy at ecological balance and 6.3% higher for one in ecological deficit. This gain comes mainly from a smaller ecological footprint and only marginally from greater biocapacity. The result holds under a shift-share instrument, heteroskedasticity-based identification, weak-instrument-robust inference, plausible-exogeneity analysis and dynamic panel estimation. Turning to mechanisms, a joint parallel-mediation model attributes 6.8% of the total effect to technical human capital and 7.2% to hydrogen production subsidy policy. The association is positive in both fossil-dependence groups, without a robust difference between them, but significant only in below-median-income economies. Panel threshold estimates show that it strengthens once institutional quality exceeds approximately 0.31 on a 0–1 index, turns from negative to positive once internet penetration passes about 92%, and becomes positive and statistically significant once a country operates three or more carbon capture, utilisation and storage (CCUS) facilities. For policy, hydrogen innovation is better assessed alongside absorptive capacity, digital infrastructure and operational carbon-management capacity than as a standalone environmental instrument.