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A hydrogen vehicle is a vehicle that uses hydrogen as its on-board fuel for motive power. The term may refer to a personal transportation vehicle, such as an automobile, or any other vehicle that use hydrogen in a similar fashion, such as an aircraft. The power plants of such vehicles convert the chemical energy of hydrogen to mechanical energy (torque) in one of two methods: electrochemical conversion in a fuel-cell, or combustion :

• In combustion, the hydrogen is burned in engines in fundamentally the same method as traditional gasoline cars.
• In fuel-cell conversion, the hydrogen is reacted with oxygen to produce water and electricity, the latter of which is used to power an electric traction motor.

The molecular hydrogen needed as an on-board fuel for hydrogen vehicles can be obtained through various thermochemical methods utilizing natural gas, coal (by a process known as coal gasification), liquefied petroleum gas, biomass (biomass gasification), by a process called thermolysis, or as a microbial waste product called biohydrogen or Biological hydrogen production. Hydrogen can also be produced from water by electrolysis. If the electricity used for the electrolysis is produced using renewable energy or nuclear power, the production of the hydrogen would (in principle) result in no net carbon dioxide emissions.

Hydrogen is an energy carrier, not an energy source, so the energy the car uses would ultimately need to be provided by a conventional power plant. A suggested benefit of large-scale deployment of hydrogen vehicles is that it could lead to decreased emissions of greenhouse gases and ozone precursors.^[1] Further, the conversion of fossil fuels would be moved from the vehicle, as in today's automobiles, to centralized power plants in which the byproducts of combustion or gasification can be better controlled than at the tailpipe. However, there are both technical and economic challenges to implementing wide-scale use of hydrogen vehicles, as well as better and less expensive alternatives. The timeframe in which challenges may be overcome is likely to be at least several decades, and hydrogen vehicles may never become broadly available.^[2][3][4][5]

Contents 1 Research and prototypes 2 Hydrogen fuel difficulties 2.1 Low volumetric energy 2.2 Fuel cell cost 2.3 Freezing conditions 2.4 Hydrogen production cost 2.5 Hydrogen infrastructure 2.6 Service life 2.7 Political considerations 2.8 Alternatives 3 Hydrogen internal combustion 4 Automobile and bus makers 5 Bicycles 6 Motorcycles 7 Airplanes 8 Fuel stations 9 References 10 See also 11 External links

Hydrogen does not come as a pre-existing source of energy like fossil fuels, but rather as a carrier, much like a battery. It can be made from both renewable and non-renewable energy sources. A potential advantage of hydrogen is that it could be produced and consumed continuously, using solar, water, wind and nuclear power for electrolysis. Currently, however, hydrogen vehicles utilizing hydrogen produced using hydrocarbons produce more pollution than vehicles consuming gasoline, diesel, or methane in a modern internal combustion engine, and far more than plug-in hybrid electric vehicles.^[6][4] This is because, although hydrogen fuel cells generate no CO₂, production of the hydrogen creates additional emissions.^[7] While methods of hydrogen production that do not use fossil fuel would be more sustainable,^[8] currently such production is not economically feasible, and diversion of renewable energy (which represents only 2% of energy generated) to the production of hydrogen for transportation applications is inadvisable.^[4]

The recorded number of hydrogen-powered public vehicles in the United States was 200 as of April 2007, mostly in California,^[9] and a significant amount of research is underway to try to make the technology viable. The common internal combustion engine, usually fueled with gasoline (petrol) or diesel liquids, can be converted to run on gaseous hydrogen. However, the more energy efficient use of hydrogen involves the use of fuel cells and electric motors. Hydrogen reacts with oxygen inside the fuel cells, which produces electricity to power the motors. One primary area of research is hydrogen storage, to try to increase the range of hydrogen vehicles, while reducing the weight, energy consumption, and complexity of the storage systems. Two primary methods of storage are metal hydrides and compression.

The current land speed record for a hydrogen powered vehicle is 207.279 mph set by a prototype Ford Fusion Hydrogen 999 Fuel Cell Race Car at Bonneville Salt Flats in Wendover, Utah on August 16, 2007. The car was designed and built by Ford engineers in collaboration with Ohio State University, Ballard Power Systems and Roush.^{[citation needed]}

High-speed cars, buses, motorcycles, bicycles, airplanes, submarines and rockets already can run on hydrogen, in various forms at great expense. NASA uses hydrogen to launch Space Shuttles into space. There is even a working toy model car that runs on solar power, using a reversible fuel cell to store energy in the form of hydrogen and oxygen gas. It can then convert the fuel back into water to release the solar energy.^[10]

For more details on this topic, see Fuel cell.

While fuel cells themselves are potentially highly energy efficient, and working prototypes were made by Roger E. Billings in the 1960s, at least four technical obstacles and other political considerations exist regarding the development and use of a fuel cell-powered hydrogen car.

Hydrogen has a very low volumetric energy density at ambient conditions, equal to about one-third that of methane. Even when the fuel is stored as a liquid in a cryogenic tank or in a pressurized tank, the volumetric energy density (megajoules per liter) is small relative to that of gasoline. Because of the energy required to compress or liquefy the hydrogen gas, the supply chain for hydrogen has lower well-to-tank efficiency compared to gasoline.^[6] Some research has been done into using special crystalline materials to store hydrogen at greater densities and at lower pressures.

Currently, hydrogen fuel cells are costly to produce and fragile. Scientists are studying how to produce inexpensive fuel cells that are robust enough to survive the bumps and vibrations that all automobiles experience. Also, many designs require rare substances such as platinum as a catalyst in order to work properly. Such a catalyst can also become contaminated by impurities in the hydrogen supply. In the past few years, however, a nickel-tin catalyst has been under development which may lower the cost of cells.^[11] Fuel cells are generally priced in USD/kW, and data is scarce regarding costs. Producer Ballard is virtually alone in publishing such data. Their 2005 figure was $73 USD/kW (based on high volume manufacturing estimates), which they said was on track to achieve the U.S. DoE's 2010 goal of $30 USD/kW. This would achieve closer parity with internal combustion engines for automotive applications, allowing a 100 kW fuel cell to be produced for $3000. 100 kW is about 134 hp.^[12]

Freezing conditions are a major consideration because fuel cells produce water and utilize moist air with varying water content. Most fuel cell designs are fragile and can't survive in such environments at startup but since heat is a byproduct of the fuel cell process, the major concern is startup capability. Ballard announced that it has already hit the U.S. DoE's 2010 target for cold weather starting which was 50% power achieved in 30 seconds at -20 °C.^[13]

For more details on this topic, see Hydrogen production.

Molecular hydrogen can be derived chemically from a feed stock, such as methanol, but can also be produced electrochemically from water. Current technologies for manufacturing hydrogen use energy in various forms, totalling between 25 and 50 percent of the higher heating value of the hydrogen fuel, to produce, compress or liquefy, and transmit the hydrogen by pipeline or truck.^[14] Electrolysis, currently the most inefficient method of producing hydrogen, uses 65 percent to 112 percent of the higher heating value on a well-to-tank basis.^[15] Environmental consequences of the production of hydrogen from fossil energy resources include the emission of greenhouse gases, a consequence that would also proceed from the on-board reforming of methanol into hydrogen. Studies comparing the environmental consequences of hydrogen production and use in fuel cell vehicles to the refining of petroleum and combustion in conventional automobile engines find a net reduction of ozone and greenhouse gases in favor of hydrogen.^[1] Hydrogen production using renewable energy resources would not create such emissions or, in the case of biomass, would create near-zero net emissions assuming new biomass is grown in place of that converted to hydrogen. The scale of renewable energy use today is insufficient and would need to be greatly increased to meet demand for widespread use in transportation. For example, hydroelectricity accounts for approximately 6 percent of global energy use, whereas other renewable resources, such as geothermal, solar and wind comprise only about 1.4 percent of energy production as of 2004.^[16] Development of renewable sources faces barriers, and although the amount of energy produced from renewable sources is increasing, as a percentage of worldwide energy production, renewables decreased from 8.15% in 2000 to 7.64% of total energy production in 2004 due to the rapid increase in coal and natural gas production.^[16] However, in some countries, hydrogen is being produced using renewable sources. For example, Iceland is using geothermal power to produce hydrogen,^[17] and Denmark is using wind.^[18]

In addition to the inherent losses of energy in the conversion of feed stock to produce hydrogen which makes hydrogen less advantageous as an energy carrier, there are economic and energy penalties associated with packaging, distribution, storage and transfer of hydrogen.^[6]

In order to distribute hydrogen to cars, the current gasoline fueling system would need to be replaced, or at least significantly supplemented with hydrogen fuel stations. Hydrogen stations are being built in various places around the world.^[19] Private and state initiatives like California's "California Hydrogen Highway" are already starting the infrastructure transition in advance of any manufacturers mass producing hydrogen cars.^[20] Replacement of the existing extensive gasoline fuel station infrastructure would cost a half trillion U.S. dollars in the United States alone.^[21]

Although service life is coupled to cost, fuel cells have to be compared to existing machines with a service life in excess of 5000 hours. As of today, however, no medium or low temperature fuel cells have been tested for more than two thousand hours.^[22]

Most all of today's hydrogen is produced using fossil energy resources.^[23] While some advocate hydrogen produced from non-fossil resources, there could be public resistance or technological barriers to the implementation of such methods. For example, the United States Department of Energy currently supports research and development aimed at producing hydrogen utilizing heat from generation IV reactors. Such nuclear power plants could be configured to cogenerate hydrogen and electricity. Hydrogen produced in this fashion would still incur the costs associated with transportation and compression or liquefaction assuming direct (molecular) hydrogen is the on-board fuel. Recently, alternative methods of creating hydrogen directly from sunlight and water through a metallic catalyst have been announced. This may eventually provide an economical, direct conversion of solar energy into hydrogen a very clean solution for hydrogen production.^[24]

Some in Washington advocate schemes^[25] other than hydrogen vehicles to replace the petroleum-based internal combustion engine vehicles. Plug-in hybrids, for example, would augment today's hybrid gasoline-electric vehicles with greater battery capacity to enable increased use of the vehicle's electric traction motor and reduced reliance on the combustion engine. The batteries would be charged via the electric grid when the vehicle is parked. Electric power transmission is about 95 percent efficient and the infrastructure is already in place (though substantial grid expansion would be needed if a sizeable fleet of plug-in hybrids were to be deployed.) Tackling the current drawbacks of electric cars or plug-in hybrid electric vehicles is believed by some to be easier than developing a whole new hydrogen infrastructure that mimics the obsolete model of oil distribution. A plug-in hybrid transportation system would face the same thermodynamic hurdles as would a system of hydrogen vehicles relying on electrolysis for its molecular hydrogen. The current electric grid, which is dominated by fossil energy resources in the United States, has a fuel-to-power efficiency of roughly 40 percent. Both the plug-in hybrids and the electrolytic hydrogen system would be subject to these comparative inefficiencies.

United States President George W. Bush was optimistic that these problems could be overcome with research. In his 2003 State of the Union address, he announced the U.S. government's hydrogen fuel initiative,^[26] which complements the President's existing FreedomCAR initiative for safe and cheap hydrogen fuel cell vehicles. Critics charge that focus on the use of the hydrogen car is a dangerous detour from more readily available solutions to reducing the use of fossil fuels in vehicles. K.G. Duleep speculates that "a strong case exists for continuing fuel-efficiency improvements from conventional technology at relatively low cost."^[5] Challenging perspectives to many such critics of hydrogen vehicles in particular and of a hydrogen economy in general were presented in the contentious, 2006, documentary film, Who Killed the Electric Car?

President Bush's hydrogen car goals, in the opinion of some writers, are slipping away because "there are quicker, cleaner, safer and cheaper ways to reduce the tail-pipe emissions from cars and trucks that pollute the air and contribute to global warming." According to physicist and former U.S. Department of Energy official Joseph Romm, "A hydrogen car is one of the least efficient, most expensive ways to reduce greenhouse gases." Asked when hydrogen cars will be broadly available, Romm replied: "Not in our lifetime, and very possibly never."^[5] General Motors disagrees with that sentiment and has announced that it will start hydrogen vehicle production in 2010. However, GM's chief engineer on the fuel cell project, Mohsen Shabana, said hydrogen infrastructure would not be in place by then, and he noted that GM had produced only two test units of the Sequel (pictured above) so far.^[27] As an article published in the March/April 2007 issue of Technology Review argued,

In the context of the overall energy economy, a car like the BMW Hydrogen 7 would proba­bly produce far more carbon dioxide emissions than gasoline-powered cars available today. And changing this calculation would take multiple breakthroughs--which study after study has predicted will take decades, if they arrive at all. In fact, the Hydrogen 7 and its hydrogen-fuel-cell cousins are, in many ways, simply flashy distractions produced by automakers who should be taking stronger immediate action to reduce the greenhouse-gas emissions of their cars.^[4]

GM has announced that it plans to introduce more than 100 hydrogen powered Chevrolet Equinox cars into the U.S. market beginning with the third quarter of 2007.^[28]

PHEVs

A 2006 article, "Hybrid Vehicles Gain Traction", in Scientific American (April 2006), co-authored by Joseph J. Romm and Prof. Andrew A. Frank, argues that ICE-based hybrid cars that can be plugged into the electric grid (Plug-in hybrid electric vehicles), rather than hydrogen fuel-cell vehicles, will soon become standard in the automobile industry.^[29]

EVs

Battery electric vehicles, such as the General Motors EV1 are typically more efficient than fuel cell-powered vehicles on a well-to-wheel basis.^[30] For this reason, Battery vehicles are gaining popularity, particularly with the introduction of new models like the Tesla Roadster.^[31].

Hydrogen internal combustion engine cars are different from hydrogen fuel cell cars. The hydrogen internal combustion car is a slightly modified version of the traditional gasoline internal combustion engine car. These hydrogen engines burn fuel in the same manner that gasoline engines do. As in hydrogen fuel cell vehicles, the volume of the vehicle that the tank occupies is significant. Research is underway to increase the amount of hydrogen that can be stored onboard, be it through high pressure hydrogen, cryogenic liquid hydrogen, or metal hydrides.

In 1807, François Isaac de Rivaz built the first hydrogen-fueled internal combustion vehicle. However, the design was very unsuccessful. It is estimated that more than a thousand hydrogen-powered vehicles were produced in Germany before the end of the World War II prompted by the acute shortage of oil.^{[verification needed]}

Mazda has developed Wankel engines to burn hydrogen. The Wankel engine uses a rotary principle of operation, so the hydrogen burns in a different part of the engine from the intake. This reduces intake backfiring, a risk with hydrogen-fueled piston engines. However the major car companies such as DaimlerChrysler and General Motors Corp, are investing in the more efficient hydrogen fuel cells instead.^[32] Ford Motor Company is investing in both fuel cell and hydrogen internal combustion engine research. Because of the large heat exchanger necessary for fuel cells and their limited load change and cold start capability, they are certainly first choice as range extender for battery electric vehicles. The Wall Street Journal, reviewing BMW's new internal combustion hydrogen vehicle concluded: A more efficient route for car makers would be to focus on high-mileage gasoline-powered vehicles. They are far simpler and less sexy than hydrogen cars... but for now they stack up as the cleaner option.^[33]

For more details on this topic, see List of fuel cell vehicles.

Many companies are currently researching the feasibility of building hydrogen cars. Funding has come from both private and government sources. In addition to the BMW and Mazda examples cited above, many automobile manufacturers have begun developing cars. These include:

• BMW — The BMW Hydrogen 7 is powered by a dual-fuel Internal Combustion Engine and with an Auxiliary power based on UTC Power fuel cell technology. The BMW H2R speed record car is also powered by an ICE. Both models use Liquid Hydrogen as fuel.
• Daimler AG — F-Cell, a hydrogen fuel cell vehicle based on the Mercedes-Benz A-Class.
• Ford Motor Company – Focus FCV, a hydrogen fuel cell modification of the Ford Focus, and E-350 buses, which began being leased in late 2006.
• General Motors — multiple models of fuel cell vehicles^[34] including the Hy-wire and the HydroGen3
• Honda – currently experimenting with a variety of alternative fuels and fuel cells with experimental vehicles based on the Honda EV Plus, most notable the Honda FCX, powered by a front-mounted 80 kW AC electric motor, with 20 kW pancake motors providing supplemental power to the rear wheels. Electrical energy is provided by a 100 kW hydrogen fuel cell, with regenerative braking energy stored in ultracapacitors. The first production version of the FCX, dubbed the FCX Clarity, was announced at the 2007 Greater Los Angeles Auto Show. The vehicle is expected to be available in limited numbers for lease only in the Los Angeles area. mid-2008.^[35] In November 2007, Honda announced its new Home Energy Station IV that uses steam reforming of natural gas to derive hydrogen from both the steam and natural gas in equal parts. The Home Energy Station IV is 75-percent smaller than older units and provides hydrogen for a car as well as heat and electricity for the home.
• Hyundai — Tucson FCEV, based on UTC Power fuel cell technology
• Mazda - RX-8, with a dual-fuel (hydrogen or gasoline) rotary-engine^[36]
• Mazda - Mazda Premacy Hydrogen RE Hybrid, with a dual-fuel (hydrogen or gasoline) rotary-engine ^[37]
• Nissan — X-TRAIL FCV, based on UTC Power fuel cell technology.
• Morgan Motor Company – LIFEcar, a performance-oriented hydrogen fuel cell vehicle with the aid of several other British companies
• Toyota – The Toyota Highlander FCHV and FCHV-BUS^[38] are currently under development and in active testing. In November 2007, ten new hydrogen powered Prius cars were delivered to three companies in Iceland by VISTORKA, a shareholder in Icelandic New Energy. [3]

• Volkswagen also has hydrogen fuel cell cars in development.

A few bus companies are also conducting hydrogen fuel cell research. These include:

• Daimler AG, with thirty-six experimental units powered by Ballard Power Systems fuel cells completing a successful three-year trial, in eleven cities, in January 2007.^[39][40]
• Thor Industries (the largest maker of buses in the U.S.), based on UTC Power fuel cell technology
• Irisbus, based on UTC Power fuel cell technology
• Fuel Cell Bus Club

Supporting these automobile and bus manufacturers are fuel cell and hydrogen engine research and manufacturing companies. The largest of these is UTC Power, a division of United Technologies Corporation, currently in joint development with Hyundai, Nissan, and BMW, among other auto companies. Another major supplier is Ballard Power Systems. The Hydrogen Engine Center is a supplier of hydrogen-fueled engines.

Most, but not all, of these vehicles are currently only available in demonstration models and cost a large amount of money to make and run. They are not yet ready for general public use and are unlikely to be as feasible as plug in biodiesel hybrids.

There are, however, fuel cell powered buses currently active or in production, such as a fleet of Thor buses with UTC Power fuel cells in California, operated by SunLine Transit Agency.^[41] Perth, Australia is also participating in the trial with three fuel cell powered buses now operating between Perth and the port city of Fremantle. The trial is to be extended to other Australian cities over the next three years.

Mazda leased two dual-fuel RX-8s to commercial customers in Japan in early 2006, becoming the first manufacturer to put a hydrogen vehicle in customer hands. Ford began leasing E-350 shuttle buses in late 2006. BMW also plans to release its first publicly available hydrogen vehicle in 2008, as does Honda.

Pearl unveiled a hydrogen bicycle at the 9th China International Exhibition on Gas Technology, Equipment and Applications in 2007.

ENV is developing electric motorcycles powered by a hydrogen fuel cell, including the Crosscage and Biplane.

For more details on this topic, see Hydrogen planes.

Companies such as Boeing and Smartfish are pursuing hydrogen as fuel for airplanes. Unmanned hydrogen planes have been tested and Boeing is currently planning a manned flight for 2008.

For more details on this topic, see Hydrogen station.

Since the turn of the millennium, filling stations offering hydrogen have been opening worldwide.^[42] However, this does not begin to replace the existing extensive gasoline fuel station infrastructure, which would cost a half trillion U.S. dollars in the United States alone.^[43]

Alternative fuel car Bivalent engine Early adopter Electric vehicle Future of the car Hell and High Water Hydrogen storage Hydrogen economy Hybrid vehicle

Hydrogen highway Hydrogen technologies Liquid hydrogen List of fuel cell vehicles The Hype about Hydrogen Tribrid vehicle World Green Car Yoshiro Nakamatsu Zero-emissions vehicle

• California Fuel Cell Partnership
• Clean Energy Partnership
• C-Net - Hydrogen: More Polluting than Petroleum?
• Does a Hydrogen Economy Make Sense?
• EERE - FreedomCAR
• European Fuel Cell Forum
• Hydrogen Cars Now
• National Alternative Fuels Training Consortium - Technical Library
• ELECTRIC MOBILITY NEWS PORTAL
• Toronto Star article on hydrogen trains dated October 21, 2007
• NOVA - Video on Fuel Cell Cars (aired on PBS, July 26, 2005)
• Physorg - The Car that Makes its Own Fuel
• Sandia National Laboratory - Hydrogen Engine
• Spirit of Ma'at - Video of an engine running on hydrogen from water
• UK Low Carbon and Fuel Cell Knowledge Transfer Network
• New Hydrogen-Powered Land Speed Record from Ford
• Who Killed The Electric Car? (2006)