Hydrogen Fueling Protocol Spelled out in New SAE International J2601 Standard

July 24, 2014

Patrick Ponticel

J2601 features a lookup-table approach for hydrogen-FCEV fueling.

SAE International recently published J2601 “Fueling Protocols for Light Duty Gaseous Hydrogen Surface Vehicles,” the light-duty hydrogen-fueling protocol that will serve as the baseline for fueling the first generation of hydrogen fuel cell electric vehicle (FCEVs).

This standard will be used worldwide for hydrogen fueling stations.

“SAE J2601 enables a safe and quick hydrogen fueling experience for FCEVs,” said Jesse Schneider, a BMW engineer who serves as Lead of the SAE J2601 (and the complementary J2799) standards committee. “SAE J2601 enables hydrogen stations to have a fueling time within three to five minutes. In addition, with a consistently high end state of charge, this standard allows for fueling of FCHEVs with a resulting range of three-hundred-plus miles," he explained.

Schneider noted for state-of-the-art FCEVs with 60% efficiency, the hydrogen fuel transfer is equivalent to 100-200 kW·h of electrical energy (depending on tank size). In that respect, he said, "SAE J2601 establishes FCEVs as the only zero-emission vehicle technology to meet the same customer fueling and range expectations as conventional vehicles today.”

The standard J2601 fueling protocol uses a look-up table approach and an average pressure ramp rate that has been verified over the past 13 years. The SAE J2601 fueling tables use a simple control in which the dispenser fuels until the target pressure is reached based on initial start conditions, giving a consistent hydrogen fueling. This protocol, termed the “J2601 standard fueling” method, has been validated from the laboratory with test tanks to the field with automaker hydrogen storage under extreme conditions on three continents with test tanks and vehicles.

The data confirming this hydrogen fueling methodology—from automakers and hydrogen fuel providers—is documented in technical paper 2014-01-1833 from the 2014 SAE World Congress.

J2601 standardizes hydrogen fueling for both 35 MPa and 70 MPa pressure classes. Obtaining extended driving ranges in FCEVs with hydrogen fueling is accomplished by compressing hydrogen to 70 MPa (or H70). The speed of hydrogen fueling is directly related to the amount of cooling that the dispenser allows, to offset the heat of compression. Therefore, a H70-T40 fueling dispenser enables this fast-fueling by providing hydrogen fuel at -40°C (-40°F) to the fuel-cell vehicle.

SAE J2601 has a number of updates from the previous Technical Information Report including “top-off” and “fall-back fueling,” along with numerous improvements for robust operation at of the hydrogen dispenser.