Bridge fuels and climate policy integration: The case of low-carbon hydrogen in the European Union

Hydrogen is central to climate neutrality in the European Union (EU), particularly in hard-to-abate sectors. The EU promotes fossil-based low-carbon hydrogen (LCH) as a bridge fuel supporting the development of a renewable hydrogen economy, despite risks of insufficient emission reductions and diverted investments. Climate policy integration (CPI) research has not addressed hydrogen and lacks a benchmark for bridge fuels. Earlier studies permitted a constrained role for natural gas, whereas recent work deems fossil fuels inherently incompatible with CPI, but without examining the transitional role of bridge fuels. Analyzing 182 legal acts and communications, this article provides the first systematic CPI assessment of the EU hydrogen framework. It provides a CPI benchmark for bridge fuels with three jointly necessary conditions (significant emission reductions, temporal limitation, support for target technologies), assessed through the thickness and quality of the policy mix across four indicators (policy goals, policy instruments for emission reductions, funding/financing, and procedural instruments). The hydrogen framework reaches a medium level of CPI. Its policy mix is thick but lacks quality, applying the conditions of bridge fuels only selectively. The framework thus commits neither to a net-zero pathway nor to an end date for fossil-based LCH. Conceptually, the article shows that the compatibility of fossil-based technologies with CPI depends on the climate policy paradigm underlying the benchmark. Under a purely emission-based decarbonization benchmark, they are not inherently incompatible with CPI. Where fossil-free alternatives exist, however, they should align with CPI only as temporally limited bridge fuels, following a defossilization paradigm.