From green hydrogen Hubs to electric vehicle Highways: Crafting feasible sustainable solutions for clean transportation

The global transportation sector is responsible for nearly a quarter of global carbon emissions, and finding cleaner mobility solutions is essential. By examining how budget allocations for green hydrogen technology influence the adoption of electric vehicles, this research addresses a key sustainability challenge: integrating complementary low-carbon technologies into transportation systems. Despite growing interest in both hydrogen and electric vehicles, little is known about how uneven funding levels shape their joint diffusion across different economic contexts. To fill this gap, we pose the question: How do variations in green hydrogen technology budgets impact electric vehicle stock across ten leading adopters? We address this issue using the Quantile-on-Quantile method, transforming annual R&D and electric vehicle data (2012–2023) into a monthly series, testing for nonlinearity and structural breaks, and estimating asymmetric, quantile-specific effects. The findings reveal that green hydrogen budgets significantly boost electric vehicle adoption in most selected nations, uncover strong positive effects at upper quantiles, and highlight mixed patterns in the UK and France. This asymmetric insight provides policymakers with a nuanced framework for tailoring incentives for hydrogen and electric vehicles. It contributes to the sustainable transport literature by demonstrating the added value of Quantile-on-Quantile analysis in assessing joint technology diffusion.