The deployment of hydrogen-powered autonomous vehicles (AVs) requires navigating a complex regulatory landscape that varies significantly across key global markets. Jurisdictions such as the European Union, the United States, and Asia have developed distinct frameworks governing tank certifications, autonomous driving software, and refueling protocols. While harmonization efforts are underway, substantial barriers remain to achieving global interoperability for hydrogen AV fleets.

**Tank Certification Standards**
Hydrogen storage systems in AVs must meet rigorous safety and performance criteria, with certification requirements differing by region. In the EU, the Regulation on type-approval of hydrogen-powered motor vehicles (EU 2019/2144) mandates compliance with UNECE R134, which specifies standards for compressed hydrogen storage. Tanks must undergo cyclic pressure testing, permeation evaluations, and environmental stress tests. The US follows similar principles but relies on SAE J2579 and FMVSS 307, which include additional burst pressure requirements and material compatibility assessments. Asia, particularly Japan and South Korea, aligns closely with ISO 15869, though Japan’s High-Pressure Gas Safety Act imposes stricter inspection intervals for tank recertification.

Key differences emerge in testing protocols. The EU emphasizes lifetime durability under dynamic driving conditions, while the US prioritizes extreme scenario testing, such as bonfire and crash simulations. China’s GB/T 35544 standard incorporates unique provisions for composite material degradation, reflecting regional material supply chain considerations.

**Autonomous Driving Software Regulations**
Autonomous functionality in hydrogen AVs intersects with broader AV policies, which remain fragmented globally. The EU’s Automated and Connected Vehicles Directive requires AVs to comply with ALKS (Automated Lane Keeping Systems) regulations, mandating cybersecurity safeguards and fail-operational redundancy. Hydrogen-specific additions include hydrogen leak detection integration into the vehicle’s diagnostic system.

In the US, NHTSA’s Federal Automated Vehicles Policy lacks hydrogen-specific provisions but enforces stringent data recording requirements for AVs. California’s DMV further mandates reporting of disengagement incidents, which applies equally to hydrogen and battery-electric AVs. Asia presents a mixed approach: Japan’s SIP-adus program includes hydrogen AVs in its national testing corridors, while South Korea’s Act on Promotion of Autonomous Vehicles exempts hydrogen AVs from certain urban deployment restrictions to accelerate adoption.

**Refueling Protocols**
Refueling infrastructure standardization is critical for hydrogen AV fleets. The EU’s Alternative Fuels Infrastructure Regulation (AFIR) enforces mandatory hydrogen refueling station (HRS) interoperability, requiring compliance with SAE J2601/2 for 70 MPa fueling. The US adopts a more decentralized approach, with California’s CARB enforcing SAE J2601 but allowing proprietary nozzle designs in early deployments. Asia diverges significantly: Japan’s JIS S 0008 standard prescribes uniform nozzle interfaces, while China’s GB/T 31138 permits dual-pressure (35/70 MPa) dispensers, complicating fleet compatibility.

**Harmonization Efforts and Barriers**
Global alignment is progressing through initiatives like the International Partnership for Hydrogen and Fuel Cells in the Economy (IPHE), which advocates for unified tank testing methodologies. The UNECE’s Working Party on Automated/Autonomous and Connected Vehicles (GRVA) has proposed cross-recognition of AV software certifications, though hydrogen-specific clauses are still under discussion.

Persistent barriers include:
- **Material Standards:** Regional disparities in allowable composite materials for tanks hinder reciprocal approvals.
- **Refueling Pressure Profiles:** Differences in fueling protocols (e.g., EU’s pre-cooling requirements vs. US’s temperature-based pressure adjustments) limit fleet interchangeability.
- **Cybersecurity Frameworks:** Hydrogen AVs face additional layers of regulation due to the dual risks of autonomous system hacking and hydrogen safety breaches, with no global consensus on risk thresholds.

**Conclusion**
The regulatory environment for hydrogen AVs reflects a patchwork of regional priorities, particularly in tank safety, autonomous software, and refueling infrastructure. While harmonization initiatives are reducing friction, achieving global interoperability will require resolving material, pressure, and cybersecurity discrepancies. Without convergence, hydrogen AV fleets may remain regionally siloed, delaying scalability.