How Safe Are High Pressure Hydrogen Fuel Tanks?

Hydrogen fuel cell electric vehicles carry on-board one or more high pressure cylinders of compressed hydrogen fuel. The hydrogen is typically stored at pressures of 70 MPa, or over 10,000 psi. The history of hydrogen airships, and the use of the term “hydrogen” bomb, has helped to create a distorted view in the public’s mind regarding the safety of using hydrogen as a fuel type. Added to this perceived danger is the concern of transporting compressed hydrogen on-board their vehicles at very high pressures.

This paper will describe the experience involving the use of compressed gaseous fuels on-board vehicles in other industries, and the testing that is performed to ensure the safety of hydrogen pressure vessels in automotive service. In particular, the paper will demonstrate how storing compressed hydrogen at higher pressures is inherently safer than storage at lower pressures. Testing data will also dispel some of the myths surrounding the characteristics of hydrogen when it is released. The presentation will include videos of tests conducted on hydrogen storage systems, including fire exposure, gunfire penetration, and drop impact testing. Data will also be presented of testing at extreme temperatures, chemical exposure, pressure cycling both hydraulically and with hydrogen gas, and burst testing.