SRI Research Confirms that Electrostatic Discharge Can Play a Role in the Self-Ignition of Hydrogen
Scientists have long known about electrostatic discharge - the process of quickly releasing accumulated charge. It is familiar to anyone who has received a shock after walking across a carpet and then touching a door knob. Now researchers from SRI International, working in partnership with Sandia National Laboratories, have confirmed the mechanism explaining how particulate electrostatic discharge can cause hydrogen to ignite in the rare event of an uncontrolled hydrogen release, even in the absence of a known ignition source.
Research findings about the role of particulate electrostatic discharge, to be presented at the 2011 International Conference on Hydrogen Safety, point to actions hydrogen producers, users, and regulators can take to improve safety.
"Our research findings begin to close a knowledge gap in hydrogen safety," said Erik Merilo, M.S., research engineer in SRI International's Poulter Laboratory, which specializes in studying explosions, impacts, fires, and their effects on materials and structures. "Based on our findings, hydrogen users can now take steps to improve safety and reduce the probability of ignition. These steps could include removing particles that may be present and establishing proper grounding."
In order to test their ideas about hydrogen self ignition, SRI's research team designed and conducted a series of experiments verifying that if particles, such as iron oxide, are present in hydrogen, the conditions necessary for electrostatic ignition can occur. During an accidental hydrogen release, particles can accumulate charge if they move quickly against a vessel's wall. The ignition happens when there is a sudden release of accumulated charge, and the discharged energy is more than required to ignite hydrogen in a hydrogen-air mixture. Hydrogen is typically stored in a pressurized system into which particles can be introduced if the storage vessel or connections are contaminated, corroded, or not cleaned properly.
Merilo will present his findings at the 2011 International Conference on Hydrogen Safety, September 12-14, in San Francisco. His paper is titled "Self-Ignition of Hydrogen Jet Fires by Electrostatic Discharge Induced by Entrained Particulates." Results from experiments conducted by SRI will also be featured in papers presented by researchers at Sandia National Laboratory, "Experimental Investigation of Hydrogen Release and Ignition from Fuel Cell Powered Forklifts in Enclosed Spaces," and " Hydrogen Fuel — Cell Forklift Vehicle Releases in Enclosed Spaces."
SRI's hydrogen safety research is supported by the U.S. Department of Energy's Fuel Cell Technologies (FCT) program, under a contract from Sandia National Laboratories.
