Safety and Other Considerations in the Development of a Hydrogen Fueling Protocol for Heavy-duty Vehicles

Several manufacturers are developing heavy duty (HD) hydrogen stations and vehicles, as zeroemissions alternatives to diesel and gasoline. In order to meet customer demands, the new technology must be comparable to conventional approaches, including safety, reliability, fueling times, and final fill levels. For a large HD vehicle with a storage rated to 70 MPa nominal working pressure, the goal to meet liquid fuel parity means providing 100 kg of hydrogen in 10 minutes. This paper summarizes the results to date of the PRHYDE project efforts to define the concepts of HD fueling, which thereby, lays the groundwork for the development of the safe and effective approach to filling these large vehicles. The project starts by evaluating the impact of several different assumptions, such as the availability of static vehicle data (e.g., vehicle tank type and volume) and station data (e.g., expected station precooling capability), but also considers using real time, dynamic data (e.g., vehicle tank gas temperature and pressure, station gas temperature, etc.) for optimisation to achieve safety and efficiency improvements. With this information, the vehicle or station can develop multiple maps of fill time versus the hydrogen delivery temperature which are used to determine the speed of fueling. This will also allow the station or vehicle to adjust the rate of fueling as the station pre-cooling levels and other conditions change. The project also examines different steps for future protocol development, such as communication of data between the vehicle and station, and if the vehicle or station is controlling the fueling.