Global regulatory frameworks for underground hydrogen storage vary significantly across regions, reflecting differences in geological conditions, energy policies, and existing infrastructure. The EU, US, and Asia each have distinct approaches to permitting, safety standards, and environmental protections, with evolving policies to address the growing role of hydrogen in energy systems.

**Permitting Processes**
In the EU, underground hydrogen storage is governed by a combination of national and supranational regulations. The European Commission’s Hydrogen Strategy and the revised Gas Package provide guidelines for storage permitting, requiring environmental impact assessments (EIAs) and public consultations. Countries like Germany and the Netherlands, with extensive salt cavern storage, have established clear permitting pathways, though delays occur due to stringent environmental reviews.

The US regulatory framework is fragmented, with oversight split between federal and state agencies. The Department of Energy (DOE) and the Environmental Protection Agency (EPA) set broad guidelines, but states like Texas and Utah have their own rules for underground storage in salt caverns or depleted reservoirs. Permitting often involves multiple agencies, leading to prolonged approval times. The Federal Energy Regulatory Commission (FERC) has limited jurisdiction over hydrogen, creating uncertainty for large-scale projects.

In Asia, regulatory frameworks are less developed. Japan and South Korea are advancing policies to support hydrogen storage, but permitting remains ad hoc, with case-by-case approvals. China has begun integrating hydrogen storage into its national energy plans, but clear permitting processes are still emerging.

**Safety Standards**
The EU enforces rigorous safety standards under the Seveso III Directive, which classifies hydrogen storage sites as upper-tier establishments if thresholds are exceeded. The European Industrial Gases Association (EIGA) provides technical guidelines for leak detection, pressure management, and material compatibility. Salt caverns must meet geomechanical stability criteria, with regular inspections mandated.

In the US, safety standards are primarily set by the Occupational Safety and Health Administration (OSHA) and the Pipeline and Hazardous Materials Safety Administration (PHMSA). However, existing regulations were designed for natural gas, creating gaps for hydrogen-specific risks like embrittlement. The American Petroleum Institute (API) has developed recommended practices, but these are not legally binding.

Asia lacks harmonized safety standards. Japan’s High-Pressure Gas Safety Act covers some aspects of hydrogen storage, while South Korea relies on adaptations of LNG regulations. China is drafting national standards but has yet to implement comprehensive rules.

**Environmental Protections**
The EU mandates strict environmental safeguards under the Water Framework Directive and the Habitats Directive. Storage projects must demonstrate no adverse effects on groundwater or ecosystems. Monitoring programs are required to detect leaks, with penalties for non-compliance.

The US relies on the EPA’s Underground Injection Control (UIC) program to protect drinking water sources. Class II wells, used for natural gas storage, are the closest analog for hydrogen, but specific rules for hydrogen are lacking. States with active storage sites, like Texas, impose additional groundwater monitoring requirements.

In Asia, environmental regulations are less prescriptive. Japan requires EIAs for large projects, but enforcement varies. China’s evolving policies emphasize reducing emissions but lack detailed provisions for hydrogen storage impacts.

**Regulatory Gaps**
Key gaps exist in all regions. The EU lacks uniform standards for hydrogen purity in storage, affecting interoperability. The US has no dedicated federal framework for hydrogen storage, relying on outdated natural gas regulations. Asia’s patchwork of national rules hinders cross-border projects.

Emerging trends include the EU’s push for a dedicated hydrogen storage certification system under the Hydrogen and Gas Market Decarbonization Package. The US is exploring updates to the PHMSA guidelines to address hydrogen-specific risks. Asia is moving toward regional cooperation, with ASEAN countries discussing shared standards.

In conclusion, while the EU leads in comprehensive regulation, the US and Asia are playing catch-up. Permitting complexity, inconsistent safety standards, and environmental oversight gaps remain challenges. Future policies must address these issues to enable scalable underground hydrogen storage.