U.S. Department of Energy - Energy Efficiency and Renewable Energy

Fuel Cell Technologies Office – Hydrogen Storage

High-Pressure Hydrogen Tank Testing

Many types of compressed hydrogen tanks have been certified worldwide and demonstrated in several prototype fuel cell vehicles. The following information discusses high-pressure hydrogen tank testing, codes and standards, and certifications.

Background

High-pressure tanks (3,600 psi) have been used safely in compressed natural gas vehicles (NGV) for many years. Improved versions of these tanks made of high-strength composite materials are now used to store hydrogen at higher pressures (5,000 and 10,000 psi) to achieve greater driving range in hydrogen-fueled vehicles. High-pressure hydrogen tanks are designed not to rupture and are held to rigorous performance requirements. Furthermore, these tanks undergo extensive testing to make sure that they meet these performance requirements. A table of standards enacted or under development and various required tests are shown in Table 1.

Table 1. Current Standards Compliance for 25-(MegaPascal) MPa, 35-MPa, and 70-MPa Pressure Vessels
Storage Pressure Standards Compliance
25 MPa (3.6 ksi) NGV2-2000 (modified)
DOT FMVSS 304 (modified)
35 MPa (5 ksi) E.I.H.P. / Rev 12B
ISO 15869 is derived from EU 97/23/EG
NGV2-2000 (modified)
FMVSS 304 (modified)
Reijikijyun Betten 9
70 MPa (10 ksi) E.I.H.P. / Rev 12B
ISO 15869 is derived from EU 97/23/EG
FMVSS 304 (modified)
Betten 9 (modified)

For example, during testing tanks are subjected to more than twice the maximum pressure they experience under normal service conditions to ensure they do not fail. At the end of life they are tested to approximately twice their working pressure, according to the Society of Automotive Engineers (SAE), Journal 2579. In addition, hydrogen filling stations have numerous redundant overpressure protection systems so that it is not possible to over-pressurize a vehicle fuel system. Worldwide, it has been estimated that millions of high-pressure composite tanks are in use in various commercial and industrial applications, and the overall safety record of these tanks has been excellent.

Testing

To further ensure safety, these tanks undergo cycling tests in which they are pressurized and depressurized many more times than they would be during their lifetime on a vehicle. For example, advanced carbon-composite tanks have been cycled more than 500,000 times to maximum operating pressure without leaking, whereas a tank on a vehicle filled once a week for 20 years undergoes slightly more than 1,000 cycles. Tanks are exposed to pressures above normal to simulate fault management. The tanks are also dropped 6 feet when empty, shot with a rifle, burned, and exposed to acids, salts, and other road hazards to validate that they are safe even under severe or unusual conditions.

Safety

In the unlikely case that an advanced composite tank leaks, it can be removed from service without incident. It is highly unlikely that these tanks will fail in a way that will directly endanger the occupants of a hydrogen-fueled vehicle. These tanks have remained intact in collisions and in vehicle fires, and, when tested after such events, have passed various pressure tests. (See Table 2). In case of vehicle fires or events in which fire from another vehicle may engulf the tank, the tank's pressure relief device is activated when the temperature of the tank exceeds a set point (typically 102°C/ ~216°F). When the pressure relief device is activated, the hydrogen gas in the tank is released in a safe manner. This safety procedure is validated through performance tests conducted in accordance with an existing standard (NGV2-2000).

Table 2. Pressure Tests to Ensure Tank Manufacturing Quality
Validation Tests
  • Hydrostatic Burst
  • Extreme Temp. Pressure Cycle
  • Ambient Temp. Pressure Cycle
  • Chemical Exposure
  • Bonfire
  • Gunfire Penetration
  • Flaw Tolerance
  • Accelerated Stress
  • Drop Test
  • Permeation
  • Hydrogen Cycle
  • Softening Temperature
  • Tensile Properties
  • Resin Shear
  • Hydrogen-Compatible Material
  • Numerous Internal Tests

Future Work

Additional standards are being developed and validated (SAE J2579, ISO 15869) to further improve and validate safety standards for high-pressure hydrogen tanks. Vehicle manufacturers (domestic and foreign) are working closely together with tank manufactures and others to develop robust test procedures to ensure the safety of the tanks and the entire vehicle.

Codes and Standards Organizations

The organizations below have detailed information on hydrogen codes and standards worldwide.

Additional Information

The links below provide additional information related to hydrogen codes, standards, safety, and testing.