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10 Questions Regarding SAE Hydrogen Fueling Standards

November 7, 2014 - 4:03pm

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The Department of Energy's (DOE's) Fuel Cell Technologies Office has made significant investment in hydrogen and fuel cell research and development (R&D) over the last decade, helping to cut fuel cell cost in half and enabling the commercialization of fuel cells for several early market applications. Working closely with industry has been successful over the years. One example is in the area of codes and standards. While DOE does not develop the codes and standards, it funds R&D that provides the data and information that validates and enables appropriate codes and standards development.

In this article, DOE interviews one of the world's leading experts who spearheaded the development of the recently established Society of Automotive Engineers (SAE) standards, known as J2601. These standards establish a fast hydrogen fueling protocol enabling a driving range equivalent to internal combustion gasoline engine vehicles. Jesse Schneider (BMW), the lead of the SAE hydrogen fueling standards SAE J2601, describes the background and development for hydrogen fueling standards below. Mr. Schneider also notes the importance of releasing the standards now, due to the impending deployment of fuel cell electric vehicles (FCEVs) by the automotive companies. Seven automakers have announced plans to sell or lease FCEVs—some as early as this year—and several of these auto companies have also entered partnerships to support this launch, for example BMW-Toyota, Daimler-Ford-Nissan, and Honda-GM.

Kristen Nawoj, from DOE's Fuel Cell Technologies Office, posed the following 10 questions related to hydrogen fueling. Jesse Schneider’s responses are provide below.

1. How many hydrogen fueling stations are there?

Japan, Europe, and parts of North America are actively supporting the development of hydrogen fueling infrastructure. It is expected that more than 230 hydrogen stations will be in operation by 2016 and more than 1,400 additional hydrogen stations will be in operation by 2025 (totaling roughly 1,680 new stations announced to date).The figure below provides an overview of the worldwide status of hydrogen infrastructure.

Graphic showing the number of hydrogen stations in the United States, Europe, and Japan.
 

Internationally, there are a number of government and industry initiatives to support the initial development and commercialization of hydrogen infrastructure as well as FCEVs. In the United States, DOE, along with industry stakeholders, announced the public-private partnership H2USA in May 2013 to address hydrogen infrastructure and assist in deployment of FCEVs in the United States. H2Mobility is supporting the development of hydrogen infrastructure throughout Europe and the Fuel Cell Commercialization Project (FCCJ) and HySUT are actively supporting the build out of hydrogen infrastructure and the introduction of FCEVs into the market in Japan. These organizations have supported SAE in the standardization of hydrogen fueling.

2. What do the SAE fuel cell standards cover?

SAE International is standardizing the hydrogen fueling protocol and the interface between the FCEV and hydrogen stations. To date, there are a number of standards published including the geometry of the fueling nozzle-receptacle interface (SAE J2600), hydrogen fuel quality (SAE J2719), FCEV to hydrogen station communication (SAE J2799), and hydrogen fueling (SAE J2601). The standardization activities at both SAE and the ISO have taken lessons learned from experience with AC and DC charging standards and harmonized the hydrogen nozzle-receptacle coupling connection. SAE J2600 and its ISO equivalent for the hydrogen nozzle and FCEV vehicle receptacle are essentially identical and are harmonized worldwide for both 35 MPa and 70 MPa.

3. How does the standard compare to the SAE J1772 for battery electric vehicle (BEV) charging?

The maximum electrical storage of a battery electric vehicle (BEV) equipped with a SAE J1772 charging connector is 30–85 kWh today compared to 100–200 kWh for an FCEV equipped with a SAE J2601 fueling interface connector. The current status of 60% efficiency for FCEVs means that a hydrogen FCEV equipped with SAEJ2601 fueling interface connector has up to 2.5–3.0 times the energy storage than that of a BEV.

4. How long does the fueling take and what is the FCEV range compared with a BEV?

Most of the BEV charging is done in 3–8 hours at 220 V per SAE J1772. The average electric vehicle (with 30 kWh of storage) will achieve a range of 160 km (100 miles) and require overnight charging. Even with DC fast charging, 20–60 minutes are required. In contrast, hydrogen fueling according to SAE J2601 requires only minutes. Fueling of FCEVs to the SAE J2601 Hydrogen Fueling Standard requires only 3–5 minutes and gives a high state of charge (SOC) equaling a range of 300 miles or more (500 km+). This is on par with gasoline internal combustion vehicles.
To further optimize fueling and provide a consistent high (95%–100%) SOC, the recently published SAE J2799 standardizes wireless communications between FCEVs and hydrogen stations. This optional technology utilizes Infrared Data Association technology to transfer vehicle and tank information to the hydrogen dispenser.

5. How was the SAE J2601 Fueling Protocol created?

The standard hydrogen fueling protocol, SAE J2601, was created by an SAE Technical Committee and was validated over 12 years in both the laboratory and the field to produce a robust method for fueling worldwide. The SAE Technical Committee first developed a model to simulate fueling. Seven automakers shared information pertaining to their FCEV tank components and four hydrogen suppliers shared their station dispenser properties to support the development of the model. The first lookup tables were then generated by the model. The tables were then tested in the laboratory under extreme conditions with a range of tanks from the automaker, representing all expected tank volume categories.

6. Where was the fueling protocol validated?

The J2601 standard hydrogen fueling protocol was validated in the field with real FCEVs and hydrogen stations in Europe (Denmark, Germany), North America (U.S.), and Asia (Japan) by five original equipment manufacturers (OEMs). The tests resulted in a state of charge between 90%–100% within the specified 3–5 minutes. The fueling data from the J2601 validation on OEM FCEVs and hydrogen stations in addition to extreme case studies were documented in the SAE Technical Report "Validation and Sensitivity Studies for SAE J2601."

7. How does the hydrogen fueling protocol work?

The SAE J2601 standard for light duty FCEVs uses a pressure targeted fueling or a "lookup table" approach for 35 MPa and 70 MPa fueling. These lookup tables can be programmed into the hydrogen dispenser's programmable logic control (PLC) to control the fueling process. There are three types of dispensers used for the J2601 lookup tables which use different hydrogen gas cooling temperatures or "T-ratings" to offset the heat of hydrogen compression. These tables use the initial gas pressure from the FCEV when it pulls up to a station, the ambient temperature, and the dispenser's T-rating to determine the fueling rate and target pressure at which the dispenser stops fueling.

In the example given on a recent webinar, a vehicle pulls up to a H70-T40 dispenser (70 MPa nominal working pressure, -40˚C rated gas category) with a pressure of 10 MPa remaining in the tank on a 20˚C day. The SAE J2601 standard lookup table is used to determine a 21.8 MPa/minute average pressure ramp rate (APRR) and an 86.8 MPa stop pressure for the fueling. This results in a 4 minute fueling time. If the dispenser is cold due to multiple back-to-back fuelings, a separate "cold dispenser" table can be used; the resulting fueling time can be reduced to as low as 3 minutes in this example.

8. Why is it important to standardize hydrogen fueling protocol?

It is important to standardize and establish a baseline protocol for fueling at all hydrogen stations to not exceed the storage limits and to ensure that the customer gets a consistent fast fueling. The SAE J2601 tables accomplish this. At the same time, it is important to keep the door open for innovations in hydrogen fueling, which is the reason for allowing development fueling such as the "MC Method" to continue.

9. How will we know that a station is providing a SAE J2601 fill?

At hydrogen station commissioning it is important to validate that dispensers meet the performance and communication standards specified in SAE J2601 and J2799 by a Hydrogen Station Test Apparatus (HSTA). Organizations such as the California Air Resources Board (CARB) and DOE in the United States, ENAA and HySut in Japan, and CEP in Germany are in the process of developing and implementing HSTAs. In addition, both ISO and CSA are working on hydrogen station validation standards.

10.  Where can we learn more?

There will be an in-depth, face-to-face training for the SAE Hydrogen Fueling Standards at the Fuel Cell Seminar and Energy Exposition (FCS&EE) in Los Angeles, California, on November 10 from 9 to 11 a.m. PST. For further details see the FCS&EE website.

These above-mentioned SAE Hydrogen Fueling standards are available on the SAE website:

On September 11, DOE's Fuel Cell Technologies Office hosted a webinar to introduce the SAE standards related to the hydrogen fueling of FCEVs. View the webinar presentation and materials.

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