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    Frequently Asked Questions


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    HYDROGEN AS AN ENERGY CARRIER
    Why is hydrogen used as a fuel?

    How does hydrogen compare with other fuels like gasoline and diesel?


    What is the octane rating of hydrogen?


    PRODUCTION
    How is hydrogen produced?

    How does an electrolyzer produce hydrogen from water?

    How much water is used to make hydrogen?


    How much water would the U.S. use to fuel the entire light-duty vehicle fleet (cars and small trucks) with hydrogen?

    How much energy is required to produce hydrogen via electrolysis of water?

    Doesn't it take too much energy to make hydrogen? Is it worth doing?

    How much hydrogen is produced each year?

    How much hydrogen does the U.S. use?

    How much does hydrogen cost?



    VEHICLES
    How do hydrogen vehicles work?

    If all cars ran on hydrogen, and all hydrogen was made from water, would we run out of water?

    How viable are hydrogen vehicles as an alternative to gasoline-powered cars?

    What happens to the tank in my car if I get rear-ended?


    Will I ever be able to buy a hydrogen-powered vehicle?




    SAFETY
    Is hydrogen safe?

    If hydrogen has a greater flammability range than gasoline, doesn't that make it unsafe to use?

    Is hydrogen harmful to breathe?


    Did hydrogen cause the Hindenburg accident?

    How is burning hydrogen different than the reaction in the H-bomb?




    MISCELLANEOUS
    Where do I find information on investing in hydrogen technologies?


    HYDROGEN AS AN ENERGY CARRIER

    Why is hydrogen used as a fuel?
    Hydrogen has the highest energy content per unit weight of any known fuel-52,000 Btu/lb (120.7 kJ/g). It burns cleanly. When hydrogen is burned with oxygen, the only byproducts are heat and water. When burned with air, which is about 68% nitrogen, some oxides of nitrogen are formed. The process of converting hydrogen to energy using engines or fuel cells is much more efficient than the comparable gasoline counterparts.

    Sources
    U.S. Department of Energy
    National Hydrogen Association



    How does hydrogen compare with other fuels like gasoline and diesel?

    • How does hydrogen compare with other fuels like gasoline and diesel?
    • Hydrogen can be totally nonpolluting (water is the exhaust).
    • Hydrogen can be economically competitive with gasoline or diesel.
    • Hydrogen can be as safe as gasoline, diesel, or natural gas.
    • Hydrogen can help reduce our dependence on imported fuels.
    • Hydrogen can be produced in any country or locale from a variety of energy sources.
    Sources
    U.S. Department of Energy
    National Hydrogen Association




    What is the octane rating of hydrogen?
    Short answer: "130+" according to a study done by the College of the Desert and Sunline Transit Agency

    Longer answer: The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes "knocking" in the engine. Knocking can damage an engine, so it is not something you want to have happening. Lower-octane gas (like "regular" 87-octane gasoline) can handle the least amount of compression before igniting compared to higher octane grades (like "super" 93-octane gasoline).

    The compression ratio of your engine determines the octane rating of the gas you must use in the car. One way to increase the horsepower of an engine of a given displacement is to increase its compression ratio. So a "high-performance engine" has a higher compression ratio and requires higher-octane fuel. The advantage of a high compression ratio is that it gives your engine a higher horsepower rating for a given engine weight -- that is what makes the engine "high performance." The disadvantage is that for gasoline, it costs more.

    Hydrogen has an octane rating of 130 because it can be compressed more than gasoline and 100% octane before the fuel automatically ignites in the engine. (Gasoline with 87-octane has 87% octane, a special kind of hydrocarbon that makes up gasoline and other fuels).

    Here are some other octane ratings:
    • Methane: 125
    • Propane: 105
    • Octane: 100
    • Gasoline: 87
    • Diesel: 30
    Sources
    How Stuff Works

    Hydrogen Fuel Cell Engines and Related Technologies Course Manual



    PRODUCTION

    How is hydrogen produced?
    One of the great advantages of hydrogen is that it can be made from a variety of domestic feedstocks like water, biomass, coal and natural gas. Because hydrogen exists in many different forms, in any one region, there are a variety of local feedstocks from which the hydrogen can be extracted.

    Today, over 95% of the hydrogen produced in the U.S. comes from steam reforming natural gas. As hydrogen moves from its role primarily as an industrial gas to a consumer purchased fuel, we expect other production technologies to add to the mix so that hydrogen is produced using the most cost-effective and environmentally sound method available for a specific region. Some options are: renewable or nuclear electricity and electrolysis; gasification of biomass and other hydrocarbons like coal; and using nuclear reactor heat for high-temperature electrolysis or thermo-chemical production methods.

    For more information, please view our fact sheets.

    Source
    National Hydrogen Association



    How does an electrolyzer produce hydrogen from water?
    An electrolyzer uses an electric current to separate water into its components-hydrogen and oxygen. The electricity enters the water at the cathode, a negatively charged electrode, passes through the water and exists via the anode, the positively charged electrode. The hydrogen is collected at the cathode and oxygen is collected at the anode.


    Source

    U.S. Department of Energy



    How much water is used to make hydrogen?
    Electrolysis does not require significant amounts of water. The hydrogen extracted from a gallon of water using a hydrogen generator could drive a hydrogen fuel cell vehicle as far as gasoline vehicles travel today on a gallon of gasoline.

    Source
    Hydrogenappliances.com



    How much water would the U.S. use to fuel the entire light-duty vehicle fleet (cars and small trucks) with hydrogen?

    Conversion of the current U.S. light-duty fleet (some 230 million vehicles) to fuel cell vehicles would require about 100 billion gallons of water/year to supply the needed hydrogen (1).

    For comparison, the U.S. uses about 300 billion gallons of water/year for the production of gasoline (2), about three times the amount needed for hydrogen, and about 70 TRILLION gallons of water/year for thermoelectric power generation (3). Domestic personal water use in the United States is about 4800 billion gallons/year.

    Sources:
    Turner, John A., "Sustainable Hydrogen Production" Science, Vol 305, Issue 5686, 972-974, 13 August 2004
    1) For an estimate of the amount of water needed for hydrogen-powered fuel cell vehicles, assume a vehicle fuel economy of 60 miles per kg of H2, that vehicle miles traveled = 2.6 X 10^12 miles/year (found at http://www.bts.gov/
    publications/national_transportation_statistics/
    2002/html/table_automobile_profile.html
    ), and that 1 gallon of water contains 0.42 kg of H2. Total water required for the U.S. fleet = (2.6 X 10^12 miles/year)(1 kg of H2/60 miles)(1 gal H2O/0.42 kg of H2) = 1.0 X 10^11 gallons of H2O/year. This represents the water used directly for fuel. If one considers all water uses along the chain; for example, from construction of wind farms to the electrolysis systems (life cycle assessment), then the total water use would be in the range of 3.3 X 10^11 gallons H2O/year.

    2) This is a life cycle analysis (M. Mann and M. Whitaker, unpublished data). The United States used about 126
    billion gallons of gasoline in 2001 [see link above].

    3) See http://water.usgs.gov/pubs/circ/2004/circ1268/



    How much energy is required to produce hydrogen via electrolysis of water?
    The energy required to produce hydrogen at atmospheric pressure via electrolysis (assuming 1.23 V) is about 32.9 kWh/kg. A kilogram is about 2.2 lb. For 1 mole (2 g) of hydrogen the energy is about 0.0660 kWh/mole. Compressing or liquefying the hydrogen would take additional energy. One company produces hydrogen through electrolysis at about 7,000psi at an energy usage of about 60kWh/kg H2.

    Because a Watt is Voltage x Current, this is equivalent to Power x Rate x Time. The power in this case is the voltage required to split water into hydrogen and oxygen (1.23 V at 25?C). The rate is the current flow and relates directly to how fast hydrogen is produced. Time, of course, is how long the reaction runs. It turns out that voltage and current flow are interrelated. To run the water splitting reaction at a higher rate (generating more hydrogen in a given time), more voltage must be applied (similar to pushing down on the accelerator of a car; more gas is used to make the car go faster.) For commercial electrolysis systems that operate at about 1 A/cm2, a voltage of 1.75 V is required. This translates into about 46.8 kW-hr/kg, which corresponds to an energy efficiency of 70%.

    Lowering the voltage for electrolysis, which will increase the energy efficiency of the process, is an important area for research.

    Sources
    U.S. Department of Energy
    National Hydrogen Association



    Doesn't it take too much energy to make hydrogen? Is it worth doing?
    Like all fuels, it takes energy to produce hydrogen and deliver it to a vehicle. The amount of energy required depends on how the hydrogen is made. Some methods require more energy than others.

    While it may take more energy to produce and deliver hydrogen than it takes to produce and deliver gasoline or natural gas, the hydrogen fuel is used more efficiently in hydrogen vehicles. Most hydrogen internal combustion engines (ICEs) are about 25% more efficient than their gasoline counterparts and fuel cells are 100-200% (2-3 times) more efficient. In many cases, the overall "well-to-wheels" energy usage can be much lower for hydrogen vehicles than for gasoline or natural gas vehicles using a conventional internal combustion engine.

    Source
    National Hydrogen Association



    How much hydrogen is produced each year?
    The world economy currently consumes about 42 million tons of hydrogen per year. About 60 percent of this becomes feedstock for ammonia production and subsequent use in fertilizer (ORNL, 2003). Petroleum refining consumes another 23 percent, chiefly to remove sulfur and to upgrade the heavier fractions into more valuable products. Another 9 percent is used to manufacture methanol (ORNL, 2003), and the remainder goes for chemical, metallurgical and space purposes (Holt, 2003).

    Some recent worldwide hydrogen production totals are shown below:

    OriginAmount in billions
    Nm3/year
    Percent
    Natural gas24048
    Oil15030
    Coal9018
    Electrolysis204
    TOTAL500100

    Source
    U.S. Department of Energy



    How much hydrogen does the U.S. use?
    Each year, the United States uses more than 9 million tons (about 90 billion normal cubic meters, 3.2 trillion standard cubic feet) of hydrogen, 7.5 million tons of which are consumed at the place of manufacture. The remaining 1.5 million tons are considered to be "merchant" hydrogen, or hydrogen that is sold. Today, most of this hydrogen is used as a chemical, rather than a fuel, in a variety of commercial applications:
    • Commercial fixation of nitrogen from the air to produce ammonia for fertilizer (about two-thirds of commercial hydrogen is used for this)
    • Hydrogenation of fats and oils, in which vegetable oils are changed from liquids to solids; shortening is an example of a hydrogenated oil
    • Methanol production, in hydrodealkylation, hydrocracking, and hydrodesulphurization
    • Welding
    • Hydrochloric acid production
    • Metallic ore reduction
    • Cryogenics and the study of superconductivity (liquid hydrogen)
    • Preventing oxidation in the manufacturing of semi-conductors
    • Cooling turbines (hydrogen transfers heat very well)
    • Hydrogen's main use as a fuel is in the space program. Today hydrogen fuels both the main engine of the Space Shuttle and the onboard fuel cells that provide the Shuttle's electric power.

    Sources
    U.S. Department of Energy
    National Hydrogen Association



    How much does hydrogen cost?
    The estimated costs for producing and delivering hydrogen to the
    fueling station using today’s technologies vary from $2.10/gallon of gasoline equivalent (gge) to $9.10/gge. These hydrogen costs do not include highway taxes and do include the increased fuel efficiency of fuel cell vehicles compared to gasoline-powered hybrid electric vehicles. That is, the driver of a fuel cell vehicle would pay the same amount to travel 100 miles on hydrogen as the driver of a gasoline-powered hybrid electric vehicle would pay for gasoline if the price was between $2.10/gallon to $9.10/gallon to travel that same distance.

    Source
    National Academy of Engineering, "The Hydrogen Economy:
    Opportunities, Costs, Barriers, and R&D Needs"(2004), Fig. 5-1


    Projected costs using future technology if current R&D efforts are
    successful would reduce the cost of hydrogen to the range between $1.75/gge to $4.25/gge. Thus hydrogen is expected to be competitive with gasoline per mile driven.

    Source
    National Academy of Engineering, "The Hydrogen Economy: Opportunities, Costs, Barriers, and R&D Needs"(2004), Fig. 5-3


    In addition, some NHA member companies are projecting that they can produce and deliver hydrogen economically to fueling stations at costs as low as $1.20/gallon of gasoline equivalent, again untaxed. After adding the average US highway taxes (federal and state) of $0.43/gallon, hydrogen would still be less expensive than gasoline per mile traveled.



    VEHICLES

    How do hydrogen vehicles work?
    There are two main kinds, fuel cell vehicles and hydrogen internal combustion engine (ICE) vehicles.

    Fuel cell vehicles are electric cars. Hydrogen is pumped into a tank in the car, just as with gasoline. The hydrogen gas is then fed into the fuel cell where it is electrochemically converted into electricity -- with no combustion, no moving parts, and no emissions other than water vapor. The electricity is used to power the vehicle. A fuel cell is also 2-3 times more energy efficient than a gasoline engine.

    Hydrogen ICE vehicles use a regular combustion engine modified to use gaseous hydrogen instead of liquid gasoline (much like a natural gas vehicle is modified). They burn hydrogen, but since there is no carbon in hydrogen, there are no CO2 emissions and only trace amounts of NOx (oxides of nitrogen--the air we breathe is 79% nitrogen). Hydrogen ICE vehicles are typically about 30% more efficient than comparable gasoline vehicles.

    Both types can be hybridized for additional gains in efficiency, by adding an electricity storage device like a battery or capacitor.

    Source
    Q&A with Dan Sperling, director of the Institute of Transportation Studies; associate director of the Energy Efficiency Center and professor of Transportation Engineering and Environmental Policy at the University of California, Davis.



    If all cars ran on hydrogen, and all hydrogen was made from water, would we run out of water?
    Conversion of the current U.S. light-duty fleet (some 230 million vehicles) to fuel cell vehicles would require about 100 billion gallons of water/year to supply the needed hydrogen (1). Domestic personal water use in the United States is about 4800 billion gallons/year.

    The U.S. uses about 300 billion gallons of water/year for the production of gasoline (2), and about 70 trillion gallons of water/year for thermoelectric power generation (3).

    Solar and wind power do not require water for their electricity generation. So not only do these resources provide sustainable carbon-free energy, they reduce the water requirements for power generation.

    Sources
    Turner, John A., "Sustainable Hydrogen Production" Science, Vol 305, Issue 5686, 972-974, 13 August 2004

    1) For an estimate of the amount of water needed for hydrogen-powered fuel cell vehicles, assume a vehicle fuel economy of 60 miles per kg of H2, that vehicle miles traveled = 2.6 X 10^12 miles/year (found at ),and that 1 gallon of water contains 0.42 kg of H2. Total water required for the U.S. fleet = (2.6 X 10^12 miles/year)(1 kg of H2/60 miles)(1 gal H2O/0.42 kg of H2) = 1.0 X 10^11 gallons of H2O/year. This represents the water used directly for fuel. If one considers all water uses along the chain; for example, from construction of wind farms to the electrolysis systems (life cycle assessment), then the total water use would be in the range of 3.3 X 10^11 gallons H2O/year.

    2) This is a life cycle analysis (M. Mann and M. Whitaker, unpublished data). The United States used about 126
    billion gallons of gasoline in 2001 [see link above].


    3) See http://water.usgs.gov/pubs/circ/2004/circ1268/


    How viable are hydrogen vehicles as an alternative to gasoline-powered cars?
    In many ways, they are more viable than gasoline. A fuel cell electric vehicle is better suited to modern vehicles that increasingly use electrical systems in place of mechanical and hydraulic to steer, brake, and control the various functions of the vehicle. Also, in a fuel cell vehicle, the entire powertrain can be consolidated into a flat "skateboard" chassis, providing automakers much design freedom in latching all sorts of different vehicle bodies on to the chassis -- without having to work around a protruding, heat-producing engine and large mechanical driveline. A fuel cell is also 2-3 times more energy efficient than a gasoline engine.

    Other vehicles that use hydrogen in a regular combustion engine are also very viable. They use existing engine technology, modified to use gaseous hydrogen. Hydrogen ICE vehicles are about 30% more efficient than comparable gasoline vehicles and produce ultra-low emissions, with no CO2.

    Source
    Q&A with Dan Sperling, director of the Institute of Transportation Studies; associate director of the Energy Efficiency Center and professor of Transportation Engineering and Environmental Policy at the University of California, Davis and the National Hydrogen Association



    What happens to the tank in my car if I get rear-ended?
    Hydrogen tanks, whether they are filled with gaseous or liquid hydrogen are incredibly strong-MUCH stronger than the gasoline tanks found in vehicles today. For example, this car was dropped on its back end from 90 feet (reaching 52 mph as it hit the ground), with a hydrogen tank secured in the trunk. The tank was undamaged and no hydrogen was leaked.

    Source
    Sandia National Laboratories



    Will I ever be able to buy a hydrogen-powered vehicle?
    Every major automaker is developing hydrogen fuel cell vehicles, although some are focusing on internal combustion engines instead of fuel cells. Existing cars can be converted to run on hydrogen, and several major car companies either have demonstration hydrogen cars or are due to release them in the next few years. The successful development of advanced hydrogen storage systems will accelerate the introduction of truly clean fuel cell vehicles.

    There is at least one automaker planning to begin selling them to the public at a reasonable price as early as 2009, and several aiming for a few years after that. But this depends on fuel suppliers building more hydrogen fueling stations and the government offering incentives to buyers (as they do now for hybrid vehicles).


    Source
    U.S. Department of Energy and Q&A with Dan Sperling, director of the Institute of Transportation Studies; associate director of the Energy Efficiency Center and professor of Transportation Engineering and Environmental Policy at the University of California, Davis.



    SAFETY

    Is hydrogen safe?
    Most fuels have high energy content and must be handled properly to be safe. Hydrogen is no different. In general, hydrogen is neither more nor less inherently hazardous than gasoline, propane, or methane. As with any fuel, safe handling depends on knowledge of its particular physical, chemical, and thermal properties and consideration of safe ways to accommodate those properties. Hydrogen, handled with this knowledge, is a safe fuel.

    Hydrogen has been safely produced, stored, transported, and used in large amounts in industry by following standard practices that have been established in the past 50 years. These practices can be emulated in non-industrial uses of hydrogen to attain the same level of routine safety.

    View our Hydrogen Safety fact sheet (215Kb PDF)

    Source
    National Hydrogen Association



    If hydrogen has a wider flammability range than gasoline, doesn't that make it unsafe to use?
    While hydrogen has a wider flammability range than gasoline, the range is only a piece of the story when considering the likelihood of a fire resulting from hydrogen escaping into the atmosphere. Each fuel has different properties that must be considered along with flammability range.

    For example: Gasoline's narrow flammability range is a bit misleading, since this range can easily and often be reached through normal consumer handling of gasoline and certainly if spilled. There are of course gasoline fires but, as we know, fires certainly don't occur every time gasoline vapors are released to the open air, because the vapors fail to find an ignition source in time.

    Hydrogen has a wider flammability range, but because it is lighter than air (50 times lighter than gasoline vapors and even lighter than helium) and diffuses 12 times faster than gasoline vapors do, it is very difficult for hydrogen gas to find a suitable ignition source in an open environment, like a fueling station.

    Hydrogen systems used for vehicular fueling are designed to provide public safety just as gasoline systems are designed to do. While both fueling systems utilize break-away hoses, shear valves, and monitoring systems, hydrogen systems go a step further.

    Hydrogen fuelers are designed as "closed" systems, meaning that the fuel is not exposed to the atmosphere - unlike gasoline which can be spilled fairly easily during refueling. This closed system design approach keeps hydrogen always within proper containment and does not allow oxygen or air to mix with the fuel, thereby eliminating one of the required combustion elements needed to create a fire. This further mitigates hydrogen's low ignition energy property, compared to gasoline, by never allowing a spark or ignition source to have any ability to interact with the hydrogen gas.

    Finally, the National Fire Protection Association (NFPA) and the International Code Council (ICC) have incorporated hydrogen into their standards and model codes. These codes reflect the differences in properties between gasoline and hydrogen (and natural gas as well) through requirements related to setback distances, control systems, and other public safety elements.

    Source
    Shell Hydrogen LLC



    Is hydrogen harmful to breathe?
    Accidentally breathing a small amount of hydrogen won't harm you. Hydrogen is non-toxic to humans, animals and the envionment. Like other commonly-used gases, hydrogen displaces, or pushes away, oxygen. If the oxygen you were trying to breathe was displaced by so much hydrogen that you were breathing very little oxygen, problems could result. Since hydrogen disperses (rises and spreads out) very quickly, there’s a very low risk of breathing too much.



    Did hydrogen cause the Hindenburg accident?
    The fire that destroyed the Hindenburg in 1937 gave hydrogen a misleading reputation. Hydrogen was used to keep the airship buoyant and was initially blamed for the disaster. An investigation by Addison Bain in the 1990s provided evidence that the airship's fabric envelope was coated with reactive chemicals, similar to solid rocket fuel, and was easily ignitable by an electrical discharge. The Zeppelin Company, builder of the Hindenburg, has since confirmed that the flammable, doped outer cover is to be blamed for the fire.

    For more information, view a short video (Real Media)

    Source
    National Hydrogen Association



    How is burning hydrogen different than the reaction in the H-bomb?
    Burning hydrogen, just like burning gasoline, natural gas, or a candle, is a chemical reaction, which means that electrons get shifted around and new compounds are made, like water, but the basic atoms remain the same.

    The thermonuclear explosion from a hydrogen bomb is the consequence of a nuclear fusion reaction. During this reacton, the two isotopes of hydrogen, deuterium and tritium, collide at very high energy to fuse into helium nuclei, releasing tremendous amounts of energy.

    To get these rare isotopes of hydrogen to fuse requires extraordinary temperatures (hundreds of millions of degrees). These temperatures are supplied in a thermonuclear weapon (in this case, an H-bomb) by setting off an atomic, or fission, bomb to trigger the fusion reaction.

    However, commercial hydrogen gas contains no deuterium and no tritium. Without these isotopes, it is physically impossible for ordinary hydrogen gas to produce a thermonuclear reaction under any circumstances.



    Source
    U.S. Department of Energy
    National Hydrogen Association



    MISCELLANEOUS

    Where do I find information on investing in hydrogen technologies?
    The NHA does not offer stock tips, however, we encourage you ask your financial advisor about investing in NHA member companies.

    Here are some other resources for financial information on hydrogen and fuel cell technologies:

    Source
    National Hydrogen Association