The challenge
In 2014, the European Alternative Fuels Infrastructure Directive (AFID) stipulated that hydrogen provided to fuel cell vehicles must meet the purity specifications listed in ISO 14687. NPL has been working in collaboration with hydrogen producers to ensure this was achievable for industry.
Hydrogen refuelling stations, whether they make the hydrogen directly or buy it in, must prove that they comply with ISO 14687, which specifies the maximum allowed levels of 13 gaseous impurities in hydrogen that can cause fuel cell damage. These limits are extremely low, below that for conventional petrol, and require correct sampling, state-of-the-art gas analysis methods and reliable gas standards to ensure accurate measurements.
The solution
To meet the requirements 
of ISO 14687, NPL produced and validated a new suite of hydrogen primary reference gas mixtures which were used to develop new hydrogen purity methods using state-of-the-art gas analysers. NPL also developed sampling methods to allow for representative gas samples be taken directly from hydrogen refuelling stations providing hydrogen at 700 bar.
These techniques are now available as a unique commercial service, with accreditation to ISO 17025, for industry to ensure the quality of their product meets regulations. One example of the impact of these facilities was to support ITM Power, the UK’s largest provider of hydrogen technologies, by carrying out quality assurance certification of the hydrogen produced by their commercial electrolysers before supplying hydrogen to commercial fuel cell vehicles such as the Toyota Mirai and Hyundai ix35.
A ‘hydrogen impurity enrichment device' (HIED) has also been developed and validated. It utilises a palladium-based membrane to remove hydrogen from the sample, thereby concentrating all the impurities. This allows ISO 14687 measurements to be performed very accurately using routine analysers such as GC-MS rather than needing a full suite of gas analysers that would usually cost over £500,000.
The impact
NPL is the first laboratory that can provide accredited quality assurance measurement for the purity of hydrogen gas used in fuel cell vehicles in the UK. This has, for the first time, enabled the specifications in ISO 14687 for hydrogen purity to be rigorously and traceable enforced across Europe, ensuring appropriate regulation, facilitating fair completion, and encouraging innovation in the hydrogen industry.
NPL’s hydrogen purity laboratory has supported the growth of the hydrogen economy by providing this testing technology for new and existing refuelling stations so that all hydrogen provided to fuel cell vehicles can be purity tested to show that it complies with ISO 14687. NPL supported the opening of the UK’s first ‘zero-emissions’ hydrogen filling station through performing the required quality assurance certification.
According to a recent report by UK H2Mobility, such underpinning analysis technology removes a significant technical barrier which, within the UK alone, will lead to 1.6 million fuel cell vehicles on the road and 1,100 hydrogen refuelling stations in operation in the UK by 2030.