Static electricity poses a significant ignition hazard in hydrogen storage facilities due to the gas’s low minimum ignition energy (0.017 mJ) and wide flammability range (4–75% in air). Unlike other flammable gases, hydrogen’s small molecular size increases leakage risks, while its rapid diffusion can create unseen flammable mixtures. Effective grounding and bonding protocols are critical to dissipate static charges that may accumulate during transfer, storage, or handling operations.

**Electrostatic Discharge Risks in Hydrogen Systems**
Electrostatic discharge (ESD) occurs when accumulated static electricity finds a path to ground or another conductive surface, generating sparks capable of igniting hydrogen-air mixtures. Common scenarios include:
- Flow-induced charges during hydrogen transfer through pipes or hoses
- Frictional charging from particles or droplets in gaseous or liquid hydrogen
- Isolated conductors (e.g., ungrounded equipment, tools, or personnel)

The NFPA 77 (Standard on Static Electricity) and IEC 60079-32-1 (Explosive Atmospheres – Electrostatic Hazards) provide frameworks for mitigating these risks. Key requirements include maintaining a resistance-to-ground below 10 ohms for conductive components and below 1 megohm for dissipative materials.

**Grounding and Bonding Design Principles**
1. **Storage Tanks and Vessels**
- All metallic components must be electrically continuous, with welded or bolted connections tested for continuity.
- Non-conductive linings (e.g., polymer coatings) require embedded conductive mesh bonded to the tank shell.
- Floating roof tanks must have shunts or grounding brushes to maintain contact with walls.

2. **Piping and Transfer Systems**
- Metallic pipes must be bonded every 20 meters or at flange connections, with resistance measurements below 1 ohm across joints.
- Flexible hoses must incorporate conductive cores or spiral wiring, with end fittings bonded to piping.
- Flow velocities are limited to 7 m/s for gaseous hydrogen and 1 m/s for liquid hydrogen to reduce charge generation.

3. **Personnel and Equipment**
- Workers must wear static-dissipative footwear (resistance 100 kΩ–100 MΩ) and grounding straps when handling equipment.
- Mobile containers (e.g., dewars) require grounding clamps before any transfer operation.
- Conductive flooring (resistance < 1 GΩ) is mandated in areas with hydrogen handling.

**Case Studies: Static-Related Incidents**
1. **1983 NASA Incident (LH2 Loading)**
A hydrogen fire occurred during liquid hydrogen transfer at Kennedy Space Center due to an ungrounded flexible hose. Subsequent investigation revealed static accumulation from high flow rates, igniting residual hydrogen in the vent stack.

2. **2007 Chemical Plant Explosion (Germany)**
A hydrogen release during compressor maintenance ignited via static discharge from a non-conductive plastic tool. The facility lacked bonding protocols for portable equipment.

3. **Contrast with Natural Gas Handling**
Natural gas requires higher ignition energy (0.29 mJ) and has a narrower flammability range (5–15%). While static control is still necessary, hydrogen’s lower ignition threshold demands stricter adherence to grounding standards.

**Material Selection and Compliance**
- Conductive materials: Carbon steel, stainless steel, and aluminum are preferred for storage and piping.
- Dissipative materials: Conductive polymers (surface resistivity 10^5–10^9 Ω/sq) are used for gaskets and seals.
- Prohibited materials: Non-conductive plastics or rubbers without static control measures.

NFPA 55 (Compressed Gases and Cryogenic Fluids Code) and IEC 60079-14 mandate regular inspection of grounding systems, including:
- Annual resistance testing of all bonds and grounds
- Continuous monitoring systems for critical transfer operations
- Documentation of all maintenance and testing

**Operational Protocols**
1. Pre-transfer checks must verify grounding connections using calibrated megohmmeters.
2. Bonding cables must attach before opening any container and remain until transfer completes.
3. Humidity control (maintaining >40% RH) reduces static accumulation but is secondary to grounding.

The unique properties of hydrogen necessitate exceeding conventional flammable gas safety measures. By implementing rigorous grounding and bonding practices aligned with NFPA and IEC standards, facilities can mitigate electrostatic ignition risks inherent in hydrogen storage and handling operations.