USNWG Commercial H2 Measurement Standards 

2009 August. Fuel Specifications Subcommittee (FSS)

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U.S. National Work Group for the 

Development of Commercial Hydrogen Measurement Standards 

Fuel Specifications Subcommittee (FSS) 

A Proposed Method of Sale and Quality Specification

for Hydrogen Vehicle Fuel 

Summary of Current Information 

The Chairman of the FSS is: Robert W. Boyd 

Linde North American, Inc. 

a. Initially the proposed method of sale and quality specification for hydrogen vehicle fuel was 

presented at the Western (WWMA) and Southern (SWMA) Weights and Measures Association 

Annual Meetings in the fall of 2008. The proposal was adopted by the WWMA with a 

recommendation that it be submitted as an Information Item on the National Conference on 

Weights and Measures (NCWM) Laws and Regulations agenda at the 2009 Interim Meeting 

which was held January 11-14, 2009 in Daytona Beach, Florida. This item was also presented at 

the two remaining regions, the Central (CWMA) and Northeastern (NEWMA), Annual 

Conferences in the spring of 2009. The proposal was again presented at the 2009 NCWM 

Annual Conference, held July 12-16, 2009 in San Antonio, TX. 

b. The current recommendations of the FSS are based, in part, on the subcommittee’s April 2009 

review of the proposed method of sale for hydrogen engine fuel where the:

i. The FSS agreed to use the current proposal as a foundation for the fuel quality standard 

for hydrogen. The FSS will continue to consider further refinement of the definitions 

for hydrogen vehicle fuel based on input from SAE should they be deemed necessary to 

finalize the standard. 

ii. The FSS noted that FTC’s Fuel Rating Rule (16 CFR Part 309) see the requirements in 

“Labeling of Alternative Fuels” (http://www.ftc.gov/bcp/edu/pubs/business/autos/bus29.shtm) 

requires dispensers to bear a declaration of minimum hydrogen content determined 

according to the test methods described in “Standard Test Method for Analysis of 

Natural Gas by Gas Chromatography (ASTM D1946-90). 

iii. The FSS further modified the proposed HB 130 language to recognize the language in 16 

CFR Part 309.15 Posting of non-liquid alternative vehicle fuel rating. 

Section I. Prologue 

The discussion paper that follows “The Starting Point: A Discussion Paper Describing a Proposed Method

of Sale and Quality Specification for Hydrogen Vehicle Fuel originally published in June 2008 has been

updated to include the August 2009 FSS position. The paper includes corresponding proposals are for the 

method of sale and fuel quality. 

This paper describes proposals for a new uniform method of sale and fuel quality specifications on 

hydrogen vehicle fuels developed by the USNWG Fuel Specifications Subcommittee (FSS). The purpose 

of this document is to organize, focus, and record the work of the FSS. Participation in the work of the 

subcommittee is open to anyone intending to make a positive contribution to the process. 
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2009 August. Fuel Specifications Subcommittee (FSS)

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The States have always had a leadership role in establishing and enforcing the laws and regulations for 

legal metrology and fuel quality in the United States. The goal of this effort is to develop proposals for 

inclusion in NIST Handbook 130 “Uniform Laws and Regulations in the areas of Legal Metrology and 

Engine Fuel Quality”1 which is a source for model laws that the States use in developing their legal 

requirements. Some states adopt the regulations in that handbook by reference or citation in law, and this 

approach has provided national uniformity in regulation of a number of significant issues including 

packaging and labeling, net quantity of contents, and fuel quality. 

The FSS includes hydrogen producers, dispenser and component manufacturers, weights and measures, 

air resource, and fuel quality officials and other interested parties. This document is presented to invite 

comments from automotive and fuel cell manufacturers, marketers, weights and measures and other state 

officials and other experts who certainly will have questions, concerns, and suggestions as these proposals 

are developed in the National Conference on Weights and Measures – Laws and Regulations Committee. 

The members of the FSS recognize that when small groups develop standards for emerging technologies 

it is impossible to be knowledgeable about all aspects of a subject which is, by its nature, changing even 

as a meeting takes place or a report of its progress is being composed. With this in mind please review 

this document and contribute your knowledge, understanding, and ideas to this effort. 

Section II. Method of Sale and Fuel Quality Standard 

Participants at the first FSS meeting in March 2008 considered a proposal for a Method of Sale for 

Hydrogen Fuel that was prepared by the National Institute of Standards and Technology (NIST). Recent

FSS work to update the proposed Method of Sale requirements are presented in Section 2. below. Also 

discussed was the need for a quality standard. The basis for that discussion was the proposed Hydrogen 

Fuel Standard developed by the California Department of Food and Agriculture; Division of 

Measurement Standards (CDFA/DMS) contained in a March 3, 2008, regulatory notice.2

 The FSS 

recognizes and commends the State of California for sharing its knowledge and experience in providing a 

starting point for a national standard for hydrogen fuel. This document should be interpreted as neither an 

endorsement nor criticism of the CDFA/DMS proposal by either the FSS or NIST unless otherwise stated. 

For the most recent FSS updates on the fuel quality proposal refer to Section III. 

Uniform Method of Sale for Hydrogen Vehicle Fuel 

Defining a legal requirement for a uniform method of sale for commodities is the most practical and 

efficient way that weights and measures uses to ensure that consumers can make value comparisons 

between competing sellers of the same commodity. The purpose is to ensure that their purchasing 

decisions enable them to obtain the greatest value for their money. A uniform method of sale also ensures 

that sellers advertise and deliver a commodity using a single unit of measurement so comparisons can be 

quick and simple. Typically commodities (e.g., gasoline, diesel fuel, food, milk, wine, sand and gravel, 

and others) are sold by weight, measure (volume or dimensions, including area), or count. 

Establishing a method of sale for any product is a critical first step in the development of a fair and 

competitive marketplace for any commodity especially one that is just emerging and for which there is

not a traditional method of sale for the commodity on which to build. History has shown that when 

products are introduced into the marketplace without a legally defined standard, confusion and unfair 

 

1 See the 2009 Edition of NIST HB 130 at http://www.nist.gov/owm 

2 Available at http://www.cdfa.ca.gov/dms/hydrogenfuel/hydrogenfuel.html. 
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2009 August. Fuel Specifications Subcommittee (FSS)

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competitive practices can quickly evolve and potentially harm the consumer’s perception of the product

and business reputation of the seller. 

The need for a method of sale was stated in the 2005 “Hydrogen Delivery Technology Roadmap”3 which 

called on retailers and appropriate government agencies to establish a legal unit of measurement for 

hydrogen (see endnote i for more discussion). 

The FSS recommends that all retail sales of hydrogen vehicle fuel be by mass using the 

kilogram as the unit of measurement. 

The industry’s pre-market practice has been to dispense hydrogen using the kilogram as the unit of 

measurement. The use of mass was strongly favored by the FSS participants who agreed that it should be 

the basis for retail commercial transactions. By requiring use of the kilogram as the unit of measurement 

for all retail dispensers consumers can make value comparisons between competing retailers. Dispensing

hydrogen by mass using the kilogram is specified in Section 2.4.2. Indications of OIML R 139 

“Compressed Gaseous Fuel Measuring Systems for Vehicles” (Edition 2007) and is the method of sale 

used in other countries so the U.S. method of sale will be consistent with that used in the global 

marketplace. As this fuel becomes fully commercialized, consumers considering the lease or purchase of 

a hydrogen vehicle will need to learn the fueling process for their hydrogen vehicle and be educated that 

their fuel purchases will be made on the basis of mass using the kilogram. The FSS considered, but does 

not support a gasoline gallon equivalent (GGE) units for use in retail commercial sales (see endnote ii). 

This proposal presents the kilogram as the unit of measurement to be used in commercial sales. (See 

Figure 1 [pg 5] for an example of how the unit of measurement may appear on the dispenser, and see 

Figure 2 [pg 7] that illustrates how the street signs will display the unit price). The unit can be shown 

using the term “kilogram” or by use of its accepted abbreviation “kg,” which is its prescribed symbol in 

NIST Special Publication 330 – “The International System of Units (SI).”4

 

Nothing in the proposal should be interpreted as prohibiting the use of a Hydrogen GGE for information

purposes to facilitate general comparisons with other fuels in advertisements and other literature. 

Consumers who are considering the lease or purchase of a hydrogen vehicle should be informed that they

will be purchasing fuel by the kilogram and that they can make reliable value comparisons using that 

method of sale. 

The FSS recommends that in retail sales “HXX” be the symbol used to represent Hydrogen vehicle 

fuel, where the capital “H” represents hydrogen and precedes the “XX” which represents the 

service pressure of the hydrogen fuel offered for sale (expressed in the SI unit megapascal [MPa]). 

 

3 Available at http://www1.eere.energy.gov/vehiclesandfuels on the Internet.

4 See NIST Special Publication 330 – 2008 “The International System of Units (SI).” Ambler Thompson, Editor. 
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2009 August. Fuel Specifications Subcommittee (FSS)

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Product Identity 

The FSS agreed to support the use of the capital letter “H” as the symbol for hydrogen instead of the letter 

with the subscript number two (H2) to simplify product identification of Hydrogen Vehicle Fuel sold at 

the retail level. 

Service Pressures shall be shown in the SI Unit Pascal (MPa) 

Knowing the service pressure of the dispenser is a critical factor for consumers as the storage tanks on 

their vehicle is designed to be filled at one of those pressures. In addition to needing this information for 

safety and vehicle filling purposes participants at the March 2008 FSS meeting indicated that retailers 

may charge different prices depending on the delivery pressure at which the fuel is dispensed. Some 

dispensers currently are marked with service pressures in units of bar5

 (e.g., 350 bar and 700 bar) or 

megapascals (MPa) which are the pressures available to service hydrogen vehicles. A few dispenser 

manufacturers use megapascal (MPa) in trade publications and in declaring dispenser delivery pressures. 

The FSS agreed that the service pressure at which the product is dispensed must be posted on the user’s 

interface of all dispensers. 

While the bar is accepted for use with the International System of Units (SI), the metric system, the 

primary SI unit for pressure is the pascal (international symbol - Pa). Typical values encountered for 

dispenser service pressures in pascals, bar, and pounds are 35 MPa (350 bar) (approximately equivalent to 

5 000 psi) and 70 MPa (700 bar) (approximately equivalent to 10 000 psi). The FSS agreed that in using 

the SI unit for pressure, the pascal would standardize industry practice and enable it to easily present this 

information in a consistent manner. It will also simplify the manner used to declare service pressures on 

dispensers, street signs, and in advertisements. 

Unit Pricing in Whole Cents 

The FSS also agreed that the conditions for sale, when unit pricing is based on features such as operation 

pressure, should be stated with the unit price in whole cents per kilogram in street signage to inform

drivers of hydrogen vehicles of the service pressures available at the retailer’s fueling facility. The 

proposal does not mandate street signs, but will require that when street signs are available they must 

display the unit price and service pressure of the dispensers. The requirement is only applicable when 

retailers voluntarily post or present the price of fuel in advertisements and on street signs. 

The FSS agreed the traditional practice of using decimal fractions of a cent in unit pricing in 

advertisements, the unit price, or in the calculation of total price should not be extended to sales of 

hydrogen fuel. Under the proposed method of sale that practice is prohibited (e.g., “$3.499 per kg” would 

not be permitted but “$3.49” per kg would be permitted). 

 

 

5

 A bar is an atmospheric pressure defined as 100 kilopascals. See NIST Special Publication 330 – 2008 “The 

 International System of Units (SI).” Ambler Thompson, Editor. 
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2009 August. Fuel Specifications Subcommittee (FSS)

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Figure 1. Examples of the Product Identity, Measurement Unit, Unit Price, and Service Pressure on the User’s 

Interface of a Hydrogen Fuel Dispenser 

Total Sale

Delivered 

Quantity 

H35

$3.70 per kg

8.635 kg

$31.95

Unit Price

35 MPa

Total Sale

Delivered 

Quantity 

H70

$3.70 per kg

8.635 kg

$31.95

Unit Price

70 MPa

Service Pressure
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2009 August. Fuel Specifications Subcommittee (FSS)

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A Competitive Marketplace 

Figure 2 depicts how a fueling station in the marketplace might display required information. The 

purpose of the graphic is to illustrate that a uniform method of sale in a single unit of measurement and 

other requirements for posting of service delivery information will facilitate value comparison in a 

competitive marketplace and provide users with critical information. The graphics of the signage shows 

how posting the unit of measurement and service pressure provides drivers with information to permit 

them to make product and service pressure value comparisons between retailers. 

Figure 2. Showing the use of the Uniform Unit of Measurement and Posting of Product Identity, and Service 

Pressure to Enable Value Comparison 

One alternative to the posting of service pressures (perhaps even unit prices) may be found in the growing 

prevalence of vehicle navigation systems and satellite information services. If drivers of hydrogen 

vehicles have access to real-time price and service pressure information through those systems and use

them to make their purchasing decisions the current approach of using street sign pricing may not 

continue in this marketplace. 
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2009 August. Fuel Specifications Subcommittee (FSS)

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The FSS supports the following method of sale for petroleum: 

Recommendation: The August 2009 FSS supports including the proposal in NIST Handbook 130: 

Section IV: Uniform Regulations, Part B Uniform Regulation for the Method of Sale of Commodities. 

The FSS presented the following recommendation for consideration at the July 2009 NCWM Laws and 

Regulations Committee. The NCWM was made aware of the FSS's modifications to paragraph 

2.XX.4.2 to include the units of megapascals. 

Section 2. Non-food Products [Note 1, page 103] 

2.XX. Retail Sales. - Hydrogen Fuel (H).

2.XX.1. Definitions – Hydrogen Fuel (H).

2.XX.1.1. Hydrogen Fuel. - a fuel composed of the chemical hydrogen intended for 

consumption in a surface vehicle with an internal combustion engine or fuel cell.

The symbol for hydrogen vehicle fuel shall be the capital letter "H" ( the word 

Hydrogen may also be used.)

2.XX.2. Method of Retail Sale and Dispenser Labeling. - All hydrogen fuel kept, offered, 

or exposed for sale and sold at retail shall be in terms of the kilogram. 

2.XX.3. Retail Dispenser Labeling. 

2.XX.3.1. A computing dispenser must display the unit price in whole cents on the basis 

of price per kilogram.

2.XX.3.2. The service pressure(s) of the dispenser must be conspicuously shown on the 

user interface in bar or the SI Unit of Pascal (Pa) (e.g., MPa). 

2.XX.3.3. The product identity must be shown in a conspicuous location on the 

dispenser.

2.XX.3.4. National Fire Protection Association (NFPA) labeling requirements also 

apply. 

2.XX.3.5. Hydrogen shall be labeled in accordance with 16 CFR 309 – FTC Labeling 

Alternative Fuels.

2.XX.4. Street Sign Prices and Advertisements. 

2.XX.4.1. The unit price must be in terms of price per kilogram in whole cents (e.g., 

"$3.49 per kg" not $3.499 per kg).

2.XX.4.2. The sign or advertisement must include the service pressure (expressed in 

megapascals) at which the dispenser(s) delivers hydrogen fuel (e.g., H35 or H70). 
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2009 August. Fuel Specifications Subcommittee (FSS)

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Section III. Hydrogen Vehicle Fuel Quality Specification 

The FSS will continue, where necessary, to develop a model regulation to specify the quality 

requirements for hydrogen vehicle fuel for addition to the Uniform Fuels and Lubricants Regulation 

(UFLR) in NIST Handbook 130. The UFLR cites ASTM International and SAE International standards 

for gasoline, diesel and other fuels. At least 11 states use that model regulation as a basis for their rules 

on fuel quality. As with other fuels the regulations in Handbook 130 will reference standards from 

appropriate standards organization and utilize the test methods authorized and referenced by those 

standards. The proposed regulation will likely include standards developed by ASTM International, SAE

International, and the International Organization for Standardization (ISO) or other American National

Standards Institute (ANSI) accredited organization.

The State of California has been at the forefront in establishing a fuel quality standard for hydrogen to 

meet a legislative mandate.6 At its first meeting in March 2008, the FSS participants reviewed the March 

3, 2008 draft developed by the California Department of Food and Agriculture’s/Division of 

Measurement Standards (CDFA/DMS) so that it could be used as a starting point in the development 

process for a national standard. This approach takes advantage of California’s expertise and because it has 

been published for comment as part of that state’s rulemaking process which means that it has received

public review. The CDFA/DMS proposal provided an interim standard for hydrogen fuel. 

Once ANSI has adopted fuel standard the CDFA/DMS is required by law to adopt that standard by 

reference. Since test procedures have not yet been finalized to measure the properties specified in the 

CDFA/DMS interim standard, that agency will adopt sampling and test procedures in regulation as they 

are developed. The agency will begin enforcement of its regulations and require compliance once sample 

and test procedures have been adopted by an accredited organization and its regulation are finalized. 

 

6 See http://www.cdfa.ca.gov/dms/hydrogenfuel/hydrogenfuel.html for more information on the California Division 

of Measurement Standards Hydrogen Fuel Program. (Viewed 4/11/08)
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2009 August. Fuel Specifications Subcommittee (FSS)

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Proposed Specification for Hydrogen Fuel 

The FSS identified several quality criteria where there was tentative agreement with their associated 

values and the ability to test to those values with current technology available today (see properties 6, 7, 

8, 9, 12, 14, and 16 which are highlighted in green) in the proposed Table 1. Hydrogen Fuel Quality 

Specification. 

The FSS did not agree on all of the properties contained in the DMS proposal because there was either not 

enough research data or test methods available to support a decision (see properties 1, 2, 3, 4, 5, 10, 11, 

13, and 15 which are highlighted in yellow) in Table 1 below. In the interim these properties will receive 

further consideration by the FSS and other properties may eventually be added to the quality standard in 

the future when such action is supported by research. 

FSS supports including the proposed new definitions in NIST Handbook 130 Section IV. Uniform 

Regulations Part G. Uniform Engine Fuels and Automotive Lubricants Regulations to address gaseous 

hydrogen refueling applications as follows: 

Section 1. Definitions 

1.XX. Fuel Cell. - an electrochemical energy conversion device in which fuel and an 

oxidant react to generate energy without consumption of its electrodes or electrolyte.

1.XX. Hydrogen Fuel. - a fuel composed of the chemical hydrogen intended for 

consumption in a surface vehicle with an internal combustion engine or fuel cell 

1.XX. Internal Combustion Engine. - a device used to generate power by converting 

chemical energy bound in the fuel into mechanical work to power a vehicle. 

FSS supports including the proposed new hydrogen fuel standard in NIST Handbook 130 Section IV. 

Uniform Regulations Part G. Uniform Engine Fuels and Automotive Lubricants Regulations Section 2. 

Standard Fuel Specifications to address gaseous hydrogen refueling applications. 

Cite the appropriate reference for the hydrogen fuel quality standard below that was developed by the 

California Division of Measurement Standards in NIST Handbook 130 Section IV. Uniform Regulations 

Part G. Uniform Engine Fuels, Petroleum Products, and Automotive Lubricants Regulations Section 2. 

Standard Fuel Specifications and modified by the April 2009 FSS as follows: 

2.XX. Specification for Hydrogen Fuel for Internal Combustion Engines and Fuel Cells 
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2009 August. Fuel Specifications Subcommittee (FSS)

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Table 1. Hydrogen Fuel Quality Specification* 

Property Value Unit Limit Test Method(s) 

1 Ammonia 0.1 ppm v/v Maximum to be specified

2 Carbon Dioxide 2 ppm v/v Maximum to be specified

3 Carbon Monoxide 0.2 ppm v/v Maximum to be specified

4 Formaldehyde 0.01 ppm v/v Maximum to be specified

5 Formic Acid 0.2 ppm v/v Maximum to be specified

6 Helium 300 ppm v/v Maximum to be specified

7 Hydrogen Fuel Index 99.97 % (a) Minimum to be specified

8 Nitrogen and Argon 100 ppm v/v Maximum to be specified 

9 Oxygen 5 ppm v/v Maximum to be specified

10 Particulate Concentration 1 mg/kg Maximum to be specified

11 

Total Allowable NonHydrogen, Non-Helium, 

Non-particulate constituents 

100 ppm v/v Maximum to be specified 

12 Total Non-Hydrogen Gases 300 ppm v/v (c) Maximum to be specified

13 Total Halogenated 

Compounds 0.05 ppm v/v Maximum to be specified

14 Total Hydrocarbons 2 ppm v/v (d) Maximum to be specified

15 Total Sulfur Compounds 0.004 ppm v/v Maximum to be specified

16 Water 5 ppm v/v Maximum to be specified

Footnotes to Table 1 – 

a. Hydrogen fuel index is the value obtained with the value of total gases (%) subtracted from 100%. 

b. Total Gases = Sum of all impurities listed on the table except particulates. 

c. Total Hydrocarbons may exceed 2 ppm v/v only due to the presence of methane, provided that the total 

 gases do not exceed 300 ppm v/v. 

*The FTC’s Fuel Rating Rule (16 CFR Part 309) see the requirements in “Labeling of Alternative Fuels” 

at http://www.ftc.gov/bcp/edu/pubs/business/autos/bus29.shtm requires dispensers to bear an declaration 

of minimum percent of hydrogen determined according to test methods described in “Standard Test 

Method for Analysis of Natural Gas by Gas Chromatography (ASTM D1946) 

The FSS will monitor national and international standard activities, research, and other programs to avoid 

duplication of effort and ensure that its work provides a fuel specification for hydrogen vehicle fuel that 

serves the needs of the this emerging marketplace. Quality standards are currently under development in 

SAE International (i.e., SAE J2719 “Hydrogen Specification Guideline for Fuel Cell Vehicles”) and in 

ASTM International (see www.astm.org for a list of the work underway in its Committee D03.14 on 

Hydrogen and Fuel Cells and that organizations other committees). 

Quality standards are under consideration around the world including the European Union, Japan, and 

other countries. Also of interest are the efforts of Working Group 12 of ISO’s Technical Committee 197

on Hydrogen which is very active in this area.7

 ISO’s website indicates that its fuel quality standard will 

 

7 

http://www.iso.org/iso/standards_development/technical_committees/list_of_iso_technical_committees/iso_technica

l_committee.htm?commid=54560. (Viewed 9/2/09)
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2009 August. Fuel Specifications Subcommittee (FSS)

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be finalized within a few years. Much of the national and international work was considered in the 

development of the FSS's proposal. 

When a quality property and numerical value (defining a maximum or minimum limit) is added to the 

specification appropriate test methods must then be identified. As test methods are identified and adopted 

by the FSS they will be added to Column 6 in Table 1. 

Future work of the FSS may include the development of recommendations for field sampling equipment 

and handling procedures, along with suggestions about what type of test equipment is appropriate for 

establishing a hydrogen vehicle fuel quality laboratory. 

For Further Information or to Comment Contact: 

Please send comments and suggestions concerning the proposals presented in this document to Lisa 

Warfield or Ken Butcher, Technical Advisors to the USNWG Fuel Specifications Subcommittee at 

lisa.warfield@nist.gov or 301-975-3308 or kbutcher@nist.gov or at 301-975-4859. Faxes may be sent to 

301-975-8091. 

Fuel Specifications Subcommittee 

U.S. National Work Group for the 

Development of Commercial Hydrogen Measurement Standards 

NIST Weights and Measures Division 

Laws and Metric Group 

100 Bureau Drive, MS 2600 

Gaithersburg, Maryland 20899
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2009 August. Fuel Specifications Subcommittee (FSS)

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End Notes 

 

i Additional Information on the Importance of a Method of Sale - Establishing a uniform method of sale ensures 

marketplace integrity and increases consumer confidence while ensuring fair trade practice in a competitive 

marketplace. In past experience, the lack of a legal standard of sale has resulted in sellers establishing different 

methods of sale for the same product. This resulted in investments in weighing and measuring equipment and 

spending on packaging and marketing programs only to find that the units of measurement used were not 

appropriate for the commodity. Once a new standard was established existing measuring equipment, labeling, and 

sales literature had to be retrofitted or discarded. Establishing a method of sale early in the process informs the 

designers of weighing and measuring devices about how they are to design the device and the user interface. It also 

enables marketers to create sales and promotional programs for the product using a consistent unit of measurement 

throughout the system. Past experience with conflicting methods of sale has taught weights and measures and 

sellers many valuable lessons over the years. One of the most important lessons is that consumers are intelligent and 

willing to learn new methods of sale and readily accept products and services, if the information they receive from 

different sellers is informative, uniform, and accurate. Establishing a uniform method of sale will also inform 

automobile and fuel cell manufacturers about how they will need to educate consumers in sales literature and 

owners' manuals about the fuel and how it will be measured for dispensing into the vehicles and other refueling 

applications. Decisions are needed so that as marketing and promotional ideas are being considered and developed 

the uniqueness of the fuel and dispensers can be addressed using a single unit of measurement. 

ii Additional Information on the Gasoline Gallon Equivalent – A question at the FSS March 2008 meeting was 

whether the marketing of hydrogen vehicles against those that use fuels sold on the basis of a gallon would benefit 

from the establishment of a gasoline gallon equivalent (GGE). GGEs are based on energy content of fuels. GGE for 

hydrogen is mentioned in the media and government literature as 1 kg = 119,823 kilojoules (kJ) (113,571 BTU 

(lower heating value). GGE is used to compare the fuel in terms of price per gallon and to introduce hydrogen as a 

commercial vehicle fuel. This approach facilitates those comparisons as long as it is also understood that the energy 

content in a gallon of fuel varies widely with the fuel. When the GGE for Compressed Natural Gas (CNG) was 

developed as a legally defined value in the 1990’s, one reason for its adoption was to allow consumers to compare 

the cost of competing fuels on street signs and on dispensers in a unit of measurement that was comparable among 

fuels such as gasoline. Thus, consumers could determine the potential savings when choosing a vehicle capable of 

using one type of fuel over another. In 1994 the GGE was set at 2.567 kg for CNG by NCWM using the lower 

heating value of gasoline which was then given at 120,401.7 kJ (114,118.8 BTU). It should be noted that the 

adoption of the GGE for CNG was somewhat contentious. A proposal to add a Diesel Gallon Equivalent (DGE) for 

CNG is expected to be on the NCWM’s agenda in 2009.

 

It is difficult to make accurate comparisons between fuels because energy content varies by fuel, by region, and 

season for gasoline. Currently the Transportation Energy Data Book lists the net energy of a gallon of gasoline at 

121,753.4 kJ (115,400 BTU) and diesel as 135,785.7 kJ (128,700 BTU). Variations in energy content increase 

when gasoline is blended with Ethanol (E10 or E20) and E85 (15 % gasoline + 85 % ethanol) which contains only 

89,679.76 kJ (85,000 BTUs) according to the National Ethanol Vehicle Coalition. Hydrogen fuel, which is expected 

to come into the marketplace as a commercial fuel within the next ten years, will be competing for customers who 

have far more fuel choices than are currently available. If a GGE is considered for hydrogen the question that should 

be asked is “Would a GGE based on today’s net energy content for Hydrogen be a valid tool 10 years from now to 

compare it against gasoline, CNG, E85, diesel, and other fuels and the new electric cars expected from automobile 

manufacturers?” 

Because of constant changes in energy policies and environmental concerns new fuels and blends will continue to 

emerge in the marketplace. This constant state of change impacts the validity of GGEs. One question that must be 

raised if a GGE for hydrogen is proposed will these artificial comparison tools be periodically reviewed to ensure 

they provide an equitable means of ensuring reasonable and reliable comparisons between fuels.