Progress: Not Addressed
Typical fuel cell vehicle demonstration projects generally involve only a handful of vehicles per location, making the installation of hydrogen fueling infrastructure a costly proposition. Also, as initial demonstrations grow and new ones are initiated, mobile fuelers represent fueling infrastructure that can be readily redeployed and therefore has significant advantages.
To address the need for small, mobile fueling infrastructure, several organizations have developed or are developing mobile fuelers, incorporating hydrogen storage and dispensing equipment and sometimes hydrogen generation and compression equipment. The most pressing obstacle in the design of mobile fuelers is the selection of hydrogen storage containers.
At its point of use, the mobile fueler is treated (in some jurisdictions) as stationary equipment. This treatment typically entails that gas storage meet ASME requirements. As this designation would not allow the mobile fueler to be transported over the road with any appreciable amount of flammable gas on board, purging would be required before transport. Purging would greatly reduce the utility of a mobile fueler lacking a means to generate hydrogen. DOT approved storage containers would allow the mobile fueler to be moved with gas on board, but once located for fueling operations, local authorities could refuse to allow its use. Additionally, the weight of high-pressure containers meeting either DOT or ASME requirements (i.e., all steel) makes their use on a mobile fueler impractical to impossible.
There is no specific code or standard coverage for mobile fuelers at this time.
In the near term, designers and users of mobile fuelers need to consider their anticipated areas of operations with respect to local code restrictions and consider operational issues such as the availability of purge gas. DOT approved composite cylinders (either via specification or special permit) would address most issues but local code approval would still be required. ASME is also developing standards for composite pressure vessels for compressed hydrogen used in portable, transportable, and stationary applications under Section VIII Division 3, which could help address mobile fueler storage issues.