Harmonization of Guidelines for Hydrogen Fuel Specifications
Karen Hall, National Hydrogen Association


As reported previously in the Safety Report, both SAE and ISO TC 197 have efforts to develop guidance for hydrogen fuel for use in hydrogen vehicle demonstrations. Ultimately, it is envisaged that these efforts may lead to standards, at the appropriate time. In the meantime, the documents will be available to assist demonstrations by providing a specification for hydrogen fuel that protects vehicle performance.

Currently, both the ASE and ISO efforts are harmonized with respect to limits on contaminants in hydrogen fuel in all respects but one. The remaining issue relates to concentration of particulates. The difference in suggested limits is based in part on a difference in philosophy, and in part on a lack of data.

The philosophy issue is as follows: The initial SAE draft is seeking to specify constituent limits on the fuel as delivered, assuming no additional contamination from the dispensing equipment or other sources, like storage vessels. While this is not the endpoint, it is the baseline from which to build as more knowledge is gained. The ISO effort is seeking to specify constituent limits on the fuel at the nozzle. It recognizes that there are sources of contamination after delivery of the hydrogen fuel, and ISO is taking a first step to understand real-world conditions, while still protecting vehicle performance.

In both draft documents, particulates greater in size that 10 µm are unallowable. For particulates smaller than 10 µm, SAE is recommending a maximum allowable concentration of 1 µg/L, while ISO is recommending a maximum of 10 µg/L. Both groups are seeking feedback from industry to update some of the values in the specifications in future revisions, based on industry experience.

By the time this article is published, it is likely that the SAE Technical Information Report will be in publication, and the ISO TC 197 Technical Specification will have been submitted to the ISO TC 197 Secretariat for editing and balloting.

There will likely be one or more workshops over the next 12 months to address cost trade-off issues, research needs, and testing methods in support of the longer-term development of these specifications. The NHA will post details of such workshops on our Calendar of Meetings/Events.

Should you require any additional information, feel free to e-mail me at info@hydrogenassociation.org. You are also encouraged to visit the archives of the Hydrogen and Fuel Cell Safety Report. This site has posted several articles describing the efforts to develop hydrogen fuel specifications.