|SAE J2601 enables fast refueling for all light-duty fuel cell vehicles. Photo courtesy of Shell. Click to enlarge.|
SAE has published the J2601 standard, “Fueling Protocols for Light Duty Gaseous Hydrogen Surface Vehicles”, the light duty hydrogen fueling protocol which will serve as a baseline for the first generation of infrastructure for refueling Fuel Cell Electric Vehicle (FCEVs). (Earlier post.)
This standard will be used to harmonize the protocol for hydrogen fueling stations worldwide for both 35 MPa and 70 MPa. Obtaining extended driving ranges with hydrogen fueling is accomplished by compressing hydrogen to 70 MPa (or H70).
SAE J2601 enables safe, full hydrogen fast-fueling (3-5 minutes) for all light-duty FCEVs, including models with a range of 300 or more miles (500 km+). SAE J2601 fuels FCEVs, hydrogen storage systems quickly to a high state of charge (SOC) without exceeding the storage system operating limits, explained Jesse Schneider, Lead of both Standards SAE J2601 & J2799 (which standardizes wireless communications between the FCEV and the hydrogen station). SAE 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.
|“Hydrogen Fueling is the only ZEV infrastructure technology proven to achieve ‘same as today’s’ fuel delivery rates and equivalent driving range for all vehicle segments.”|
SAE J2601 establishes safety limits and performance requirements for gaseous hydrogen fuel dispensers. The criteria include maximum fuel temperature at the dispenser nozzle; the maximum fuel flow rate; the maximum rate of pressure increase; and other performance criteria based on the cooling capability of the station’s dispenser.
This SAE standard hydrogen fueling protocol uses a look-up table approach and an average pressure ramp rate that has a constant pressure rise which gives consistent fueling times for all vehicles. The J2601 fueling tables allow a simple control where the dispenser stops at a target pressure, based on ambient temperature and initial fuel pressure, giving a reliable hydrogen fueling (with a high state of charge).
|SAE J2601 lookup table approach. Click to enlarge.|
This protocol termed the “J2601 standard fueling” method has been validated in the laboratory with automaker hydrogen tanks under extreme conditions and also in the field at public stations on two continents with multiple automaker FCEVs. The data confirming this hydrogen fueling methodology—from automakers and hydrogen fuel providers—was documented in the 2014 SAE World Congress Technical Paper (2014-01-1833).
With the current state-of-the-art FCEV with 60% efficiency, the hydrogen fuel transfer is equivalent to 100-200 kWh electrical energy (reference 5-10 kg H2, dependent on vehicle tank) all in less than 5 minutes. This is a leap forward in zero-emission fueling. SAE J2601 establishes FCEV zero-emission vehicle technology as the only one currently to meet the both the fueling and range expectations currently provided bv petroleum fuels, Mr. Schneider indicated.
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 to the fuel cell vehicle.
The SAE J2601 Standard document applies to light duty vehicle fueling for vehicles with storage capacity from 2 to 10 kg for 70 MPa and 2.4 to 6 kg for 35 MPa. Separate J2601 documents will cover fueling heavy-duty vehicles and forklifts. SAE J2601 has a number of updates from the previous Technical Information Report (TIR) including allowing “top-off fueling” and “Fall-Back Fueling” as well as numerous improvements for robust operation at the hydrogen dispenser.
|Hydrogen refueling for light- and heavy-duty vehicles. Click to enlarge.|
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.
|J2799 wireless FCEV to H2 station standard. Click to enlarge.|
Recognizing innovation, SAE J2601 also has a non-standard appendix describing the MC Default Fill Protocol. This development protocol is currently being tested in the field and may be included in future standard updates to SAE J2601.