Network analysis of policy contagion in the supply chain of hydrogen fuel cell vehicles in China

The implementation of hydrogen fuel cell vehicle (HFCV) policies represents a crucial strategy in addressing global warming within the transportation sector. This study assesses the impact of these policies on HFCV-related stock returns from 2019 to 2023, utilizing static and dynamic contagion tests to construct a contagion network. The results indicate several key findings: (1) both fuel cell (FC)- and hydrogen-oriented policies exhibit significant contagion effects across the HFCV supply chain, particularly between FC/hydrogen sectors and their upstream, midstream, and downstream counterparts, with stronger contagion pre-2021 and a modest decline post-2022; (2) in 2020, FC-oriented policies dominated contagion dynamics, with a notable shift towards hydrogen-oriented policies after 2021; (3) prior to 2021, contagion rates reached as high as 80%, largely driven by higher-order co-moments rather than linear correlations, but declined to below 25% after 2021; (4) upstream sectors within the HFCV supply chain are more sensitive to policy contagion compared to midstream and downstream sectors; and (5) among the 10 policies analyzed, the 2021–2023 New Energy Vehicle Industry Development Plan had the most substantial impact, both driving and receiving policy shocks within the HFCV network. These findings offer critical insights into the energy-economic interactions shaping the HFCV market, providing valuable guidance for policymakers and industry stakeholders aiming to promote sustainable transport strategies.