To support the impending rollout of the hydrogen fueling infrastructure and fuel-cell electric vehicles (FCEVs), SAE International’s Fuel Cell Standards Task Force has completed two technical standards:
• SAE J2601—“Fueling Protocols for Light Duty Gaseous Hydrogen Surface Vehicles”
• SAE J2799—“Hydrogen Surface Vehicle to Station Hardware and Software.”
The standards have been created to harmonize hydrogen fueling worldwide at both 35 MPa and 70 MPa. Formal adoption of the standards by the SAE Motor Vehicle Council is imminent, the hard work of writing the documents having been completed very recently.
J2601 defines parameters for a hydrogen fueling experience similar to conventional fueling and is considered one of the key standards required for the commercialization of fuel-cell vehicles and hydrogen stations, according to SAE. The standard enables safe, full hydrogen fast-fueling (in 3-5 min), for all light-duty FCEVs. Fueling at 70 MPa, or H70, provides a driving range of 300 mi (480 km) or more.
The fueling protocol uses a look-up table approach and an average pressure ramp rate that has a consistent pressure rise regardless of tank size. The J2601 fueling tables allow a simple control under which the dispenser stops at a target pressure, giving a consistent hydrogen fueling. This protocol, termed “J2601 standard fueling,” has been validated in the laboratory with real automaker hydrogen storage tanks under extreme conditions and also in the field at public stations on two continents with multiple automaker FCEVs.
The speed of hydrogen fueling is directly related to the amount of cooling that the dispenser allows, to offset the heat of compression. An H70-T40 fueling dispenser enables this fast-fueling by providing hydrogen fuel at -40°C (-40°F) to the fuel-cell vehicle.
“Essentially,” said Jesse Schneider (BMW), SAE Sponsor of J2601/J2799, “the team developed the table-based approach to achieve a customer experience similar to conventional fueling today. In order to accomplish this, every vehicle gets filled at the same pressure ramp rate and stops at a target pressure from the empirically based table. For instance, at a H70-rated dispenser, in 3 min hydrogen flows at the ramp rate and stops at a set pressure such as 70 MPa, based on temperature. The hydrogen stations programmed with the SAE J2601 tables allow fueling to be done safely, quickly, and simply."
SAE J2601 has a number of updates from the previous Technical Information Report including allowing “top-off fueling” and “Cold Dispenser fueling” as well as numerous improvements for robust operation at the hydrogen dispenser.
SAE J2799 standardizes wireless communications between the FCEV and the hydrogen station. The advantage of using this optional communications standard, when coupled with J2601 fueling, is that the state of charge can be further improved to 95-100% SOC, allowing for slightly more driving range than without communications. Vehicle tank temperature and pressure are the parameters communicated.
Recognizing innovation, SAE J2601 has a nonstandard appendix describing the MC Default Fill Protocol. This development protocol is currently being tested in the field and may be included in future updates to the SAE J2601 standard.
For questions about these and other SAE standards, contact Pat Ebejer, Standards Specialist, at email@example.com.