General Information

Key Hydrogen Messages (235Kb PDF)

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  •   Home > General Information > The Basics

    The Basics

    Hydrogen's Properties
    • Hydrogen is the most abundant element in the universe, accounting for 90 percent of the universe by weight. It is not commonly found in its pure form since it readily combines with other elements. (DOE) It is found in the water that covers 70% of the Earth’s surface and in all organic matter. (Air Products)

    • Hydrogen is a colorless, odorless, tasteless, and nonpoisonous gas under normal conditions on Earth. (DOE)

    • Hydrogen is highly flammable; it only takes a small amount of energy to ignite it and make it burn. It also has a wide flammability range, meaning it can burn when it makes up 4 to 74 percent of the air by volume. (DOE)

    • Hydrogen burns with a pale-blue, almost-invisible flame, making hydrogen fires difficult to see. (DOE)

    • The combustion of hydrogen produces no carbon dioxide (CO2), particulate, or sulfur emissions. It can produce nitrous oxide (NOX) emissions under some conditions. (DOE)

    • Hydrogen can be produced from renewable resources, such as by reforming ethanol (this process emits some carbon dioxide) and by the electrolysis of water (electrolysis is very expensive). (DOE)

    • Today, hydrogen is primarily used as a feedstock, intermediate chemical, or specialty chemical. (DOE) Many envision a hydrogen future which will use hydrogen as an energy carrier or fuel.

    • NASA is the primary user of hydrogen as an energy carrier. (DOE)

    • The energy in one gallon of gasoline is roughly equivalent to 1 kg of Hydrogen. (S&TR)

    • Typically, a gasoline internal combustion engine (ICE) is 18-20% efficient (S&TR); hydrogen ICEs are about 25% efficient (Automotive Fleet); methanol fuel cells are about 38% efficient (AMI); and hydrogen fuel cell vehicles like Toyota’s FCHV-4 are 60% efficient—3 times better than today’s gasoline fueled engines. (Toyota)

    • The amount of energy produced by hydrogen per unit weight of fuel is about 3 times the amount of energy contained in an equal weight of gasoline, and almost 7 times that of coal. (FSEC)

    • Hydrogen energy density per volume is quite low at standard temperature and pressure. Volumetric energy density can be increased by storing the hydrogen under increased pressure or storing it at extremely low temperatures as a liquid. (DOE)


    The U.S. hydrogen industry currently produces 9 million tons of hydrogen per year (enough to power 20-30 million cars or 5-8 million homes) for use in the following processes (DOE):

    • Chemicals production
    • Petroleum refining
    • Metals treating
    • Electrical applications

    Steam methane reforming accounts for 95% of the hydrogen produced in the U.S. (DOE).

    Other methods of hydrogen production inclue:

    • Gasification of fossil fuels (e.g. coal)
    • Splitting water using electricity (electrolysis), heat or light
    • Thermal or biological conversion of biomass (DOE)

    • Hydrogen is currently transported by pipeline or by road via cylinders, tube trailers, and cryogenic tankers, with a small amount shipped by rail or barge. (DOE)

    • Pipelines, which are owned by merchant hydrogen producers, are limited to a few areas in the U.S. where large hydrogen refineries and chemical plants are concentrated, such as Indiana, California, Texas, and Louisiana. (DOE)

    • Hydrogen distribution via high-pressure cylinders and tube trailers has a range of 100-200 miles from the production facility. For longer distances of up to 1,000 miles, hydrogen is usually transported as a liquid in super-insulated, cryogenic, over-the-road tankers, railcars, or barges, and then vaporized for use at the customer site. (DOE)

    • Hydrogen can be stored as a compressed gas or liquid, or in a chemical compound. (DOE)


    Air Products
    Automotive Fleet
    U.S. Department of Energy (DOE)