Mixing of hydrogen into natural gas, as a means of mitigating environmental concerns associated with the use of fossil fuels, poses a question of performance of appliances designed for use with natural gas, when fuelled by blends of hydrogen and natural gas. This study examines the performance of space and water heating appliances fuelled by methane as a natural gas proxy, and methane/hydrogen blends containing up to 15% hydrogen.

This report provides an evaluation by members of the Hydrogen Safety Panel (HSP) of the June 1, 2019 hydrogen release incident at the Air Products and Chemicals Inc. (Air Products) hydrogen trailer transfill (transfill) facility located in Santa Clara, California. This review was requested by the California Energy Commission (CEC) in May 2020 and examines data from Air Products, and the Santa Clara Fire Department to provide an HSP perspective on the incident cause, response, and recommended follow-up actions. 

The ignition of a hydrogen-air mixture that has engulfed a typical set of ambient vaporizers (i.e., an array of finned tubes) may result in a deflagration-to-detonation transition (DDT). Simplified curve-based vapor cloud explosion (VCE) blast load prediction methods, such as the Baker-Strehlow-Tang (BST) method, would predict a DDT given that typical ambient vaporizerswould be rated as medium or high congestion and hydrogen is a high reactivity fuel (i.e., high laminar burning velocity).

Natural gas was first used as a vehicle fuel as far back as the 1930s. The first natural gas vehicles, which ran on uncompressed natural gas, were called “gas bag” vehicles and were used to combat gasoline shortages during World War I [1]. During and after World War II, compressed natural gas (CNG) vehicles using fuel tanks mounted on the roof gained popularity in France and Italy [2]. Today, there are more than 24 million CNG vehicles in service worldwide, including CNG buses that continue the early tradition of mounting fuel tanks on the roof.  

The HSP has reviewed many safety plans for gaseous hydrogen. An emerging trend is the use of liquid (cryogenic) hydrogen in the commercial market, potentially near residential areas, for fueling hydrogen fuel cell vehicles. Finding a “qualified” person to determine liquid hydrogen code compliance is difficult, and the skills necessary of such an individual are not well defined in the codes and standards.

Hydrogen Safety Panel, Safety Knowledge Tools, and First Responder Training Resources 

PNNL’s Hydrogen Safety ProgramWhy Hydrogen Fuel?Hydrogen – A Clean, Flexible Energy CarrierWhy Fuel Cells? H2@scale: Enabling Affordable, Reliable, Clean, and Secure Energy Across SectorsUpward trend with global fuel cell shipments 2018 U.S. Snapshot More details in Slides

Introduce the Hydrogen Safety Panel (HSP)Introduce key hydrogen safety resources that are availableOpen discussion on your hydrogen safety issues and needsExplore how the HSP can help the safe rollout of hydrogen and fuel cell technologiesIdentify projects that could utilize the HSP for impactful safety reviews

The broad use of hydrogen as an energy carrier to tackle the issue of climate change is unavoidable. The emerging hydrogen economy poses new problems to be solved to ensure a level of safety in hydrogen technologies and infrastructure comparable to that for today’s fossil fuels. The pressure of onboard hydrogen storage in early-market

In developing a 70 megapascal (MPa) fueling infrastructure, it is critical to ensure that a vehicle equipped with a lower service pressure fuel tank is never filled from a 70 MPa fueling source. Filling of a lower service pressure vehicle at a 70 MPa fueling source is likely to result in a catastrophic event with severe injuries or fatalities. The Hydrogen Safety Panel recommends that DOE undertake a two‐step process to address this issue.