Hydrogen vehicle

Hydrogen vehicle

Hydrogen fueling

A hydrogen vehicle is a vehicle that uses hydrogen as its onboard fuel for motive power. The term may refer to a personal transportation vehicle, such as an automobile, or any other vehicle that uses 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: combustion, or electrochemical conversion in a fuel-cell:

• In hydrogen internal combustion engine vehicles, the hydrogen is combusted in engines in fundamentally the same method as traditional internal combustion engine vehicles.
• In fuel-cell conversion, the hydrogen is reacted with oxygen to produce water and electricity, the latter being used to power an electric traction motor.

Hydrogen fuel does not occur naturally on Earth and thus is not an energy source, but is an energy carrier. It can be made from a number of sources, currently it is most frequently made from methane or other fossil fuels. Hydrogen production via electrolysis of water is generally inefficient and expensive and is rarely used.

Many companies are working to develop technologies that can efficiently exploit the potential of hydrogen energy.

Vehicles

Buses, trains, PHB bicycle, canal boat (hydrogen), cargo bikes, golf carts, motorcycles, wheelchairs, ships, airplanes, submarines, and rockets can already run on hydrogen, in various forms. NASA uses hydrogen to launch Space Shuttles into space. There is even a working toy model car that runs on solar power, using a regenerative 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.

The current land speed record for a hydrogen-powered vehicle is 286.476 mph (461.038 km/h) set by Ohio State University's Buckeye Bullet 2, which achieved a "flying-mile" speed of 280.007 mph (450.628 km/h) at the Bonneville Salt Flats in August 2008. For production-style vehicles, the current record for a hydrogen-powered vehicle is 333.38 km/h (207.2 mph) set by a prototype Ford Fusion Hydrogen 999 Fuel Cell Race Car at Bonneville Salt Flats in Wendover, Utah in August 2007. It was accompanied by a large compressed oxygen tank to increase power. Honda has also created a concept called the FC Sport, which may be able to beat that record if put into production.

Automobiles

Main articles: List of fuel cell vehicles and List of hydrogen internal combustion engine vehicles

Sequel, a fuel cell-powered vehicle from General Motors

Ford Edge hydrogen-electric plug-in hybrid concept

Many companies are currently researching the feasibility of building hydrogen cars, and most of the automobile manufacturers had begun developing hydrogen cars (see list of fuel cell vehicles). However, the Ford Motor Company has dropped its plans to develop hydrogen cars, stating that "The next major step in Ford’s plan is to increase over time the volume of electrified vehicles". Similarly, French Renault-Nissan announced in February 2009 that it is cancelling its hydrogen car R&D efforts. In the same month Nissan started testing a new FC vehicle in Japan.

Most hydrogen cars are currently only available in demonstration models or in a lease construction in limited numbers and are not yet ready for general public use. The estimated number of hydrogen-powered cars in the United States was 200 as of October 2009, mostly in California. Funding has come from both private and government sources.

Daimler had planned to begin its FC vehicle production in 2009 with the aim of 100,000 vehicles in 2012-2013. In early 2008, Hyundai announced its intention to produce 500 FC vehicles by 2010 and to start mass production of its FC vehicles in 2012.

Honda introduced its fuel cell vehicle in 1999 called the FCX and have since then introduced the second generation FCX Clarity. In 2007 at the Greater Los Angeles Auto Show, Honda unveiled the FCX Clarity, the first production model, and announced that the car would be available for lease beginning in the summer 2008. Limited marketing of the FCX Clarity, based on the 2007 concept model, began in June 2008 in the United States, and it was introduced in Japan in November 2008. The FCX Clarity is available in the U.S. only in Los Angeles Area, where 16 hydrogen filling stations are available, and until July 2009, only 10 drivers have leased the Clarity for US$600 a month. Honda stated that it could start mass producing vehicles based on the FCX concept by the year 2020.

Buses

Main article: fuel cell bus

Fuel cell buses (as opposed to hydrogen fueled buses) are being trialed by several manufacturers in different locations. The Fuel Cell Bus Club is a global fuel cell bus testing collaboration.

Hydrogen was first stored in roof mounted tanks, although models are now incorporating inboard tanks. Some double deck models uses between floor tanks.

Hydrogen bicycle

Bicycles

Main article: PHB (bicycle)

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

Motorcycles and scooters

ENV is developing electric motorcycles powered by a hydrogen fuel cell, including the Crosscage and Biplane. Other manufacturers as Vectrix are working on hydrogen scooters. Finally, hydrogen fuel cell-electric hybrid scooters are being made such as the FHybrid.

Tractors

A concept for a hydrogen powered tractor has been proposed.

Airplanes

Further information: Hydrogen planes

The Boeing Fuel Cell Demonstrator powered by a hydrogen fuel cell

Companies such as Boeing, Lange Aviation, and the German Aerospace Center are pursuing hydrogen as fuel for airplanes. Unmanned hydrogen planes have been tested, and in February 2008 Boeing tested a manned flight of a small aircraft powered by a hydrogen fuel cell. The Times reported that "Boeing said that hydrogen fuel cells were unlikely to power the engines of large passenger jets but could be used as backup or auxiliary power units onboard."

In Europe, the Reaction Engines A2 has been proposed to use the thermodynamic properties of liquid hydrogen to achieve very high speed, long distance (antipodal) flight by burning it in a precooled jet engine.

Rockets

Rockets employ hydrogen because hydrogen gives the highest effective exhaust velocity as well as giving a lower net weight of propellant than other fuels. It performs particularly well on upper stages, although it has been used on lower stages as well, usually in conjunction with a dense fuel booster.

The main disadvantage of hydrogen in this application is the low density and deeply cryogenic nature, requiring insulation- this makes the hydrogen tanks relatively heavy, which greatly offsets much of the otherwise overwhelming advantages for this application.

The main advantage of hydrogen is that although the delta-v of a stage employing it is little different to a dense fuelled stage, the GLOW of the stage is rather less. This makes any lower stages lighter.

Internal combustion vehicle

Main articles: Hydrogen internal combustion engine vehicle and List of hydrogen internal combustion engine vehicles

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.

Francois Isaac de Rivaz designed in 1807 the first internal combustion engine on hydrogen Paul Dieges patented In 1970 a modification to internal combustion engines which allowed a gasoline-powered engine to run on hydrogen US 3844262 .

Mazda has developed Wankel engines that burn hydrogen. The advantage of using ICE (internal combustion engine) such as wankel and piston engines is that the cost of retooling for production is much lower. Existing-technology ICE can still be used to solve those problems where fuel cells are not a viable solution as yet, for example in cold-weather applications.

HICE forklift trucks have been demonstrated based on converted diesel internal combustion engines with direct injection.

Fuel cell

Further information: Fuel cell

While fuel cells themselves are potentially highly energy efficient, and working prototypes were made by Francis Thomas Bacon in 1959 and 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.

Fuel cell cost

Currently, hydrogen fuel cells are costly to produce and are fragile. Engineers 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 nanometal catalyst has been under development which may lower the cost of cells.

Fuel cells are generally priced in USD/kW, and data is scarce regarding costs. Ballard Power Systems 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.

Freezing conditions

Temperatures below freezing (32 °F or 0 °C) used to be a major concern with fuel cells operations however Honda first proved sub-freezing temperature startup and operation by leasing fuel cell cars in Albany NY. Operational fuel cells have an internal vaporous water environment that could solidify if the fuel cell and contents are not kept above 0 Celsius ( 32 F). Most new fuel cell designs are now robust enough to survive in below freezing environments. Frozen solid, especially before start up, they can still start up and operate. Once running, heat is a byproduct of the fuel cell process, which keeps the fuel cell at an adequate operational temperature to function correctly. This no longer makes startup of the fuel cell a major concern in cold weather operation. http://www.dec.ny.gov/environmentdec/18701.html Places such as Canada or Alaska where temperatures can reach −40 °C (−40 °F) at startup would now be able to use fuel cells. 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.

Just as early gasoline cars struggled with efficiency and reliability problems before becoming universally practical, so fuel cells have needed to work out startup and long term reliability problems. Early gasoline engines had the characteristic of higher heat dissipation once running, whereas fuels cells emit less heat, making the warm up process somewhat less quick.

Service life

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 for stationary and light-duty. Marine PEM fuel cells reached the target in 2004. Current service life is 7,300 hours under cycling conditions. Research is going on especially for heavy duty like in the bus trials which are targeted up to a service life of 30,000 hours.

Hydrogen

Hydrogen does not come as a pre-existing source of energy like fossil fuels, but is first produced and then stored as a carrier, much like a battery. Hydrogen for vehicle uses needs to be produced using either renewable or non-renewable energy sources. A suggested benefit of large-scale deployment of hydrogen vehicles is that it could lead to decreased emissions of greenhouse gases and ozone precursors.

According to the Department of Energy "Producing hydrogen from natural gas does result in some greenhouse gas emissions. When compared to ICE vehicles using gasoline, however, fuel cell vehicles using hydrogen produced from natural gas reduce greenhouse gas emissions by 60%. While methods of hydrogen production that do not use fossil fuel would be more sustainable, currently renewable energy represents only a small percentage of energy generated, and power produced from renewable sources can be used in electric vehicles and for non-vehicle applications.

The challenges facing the use of hydrogen in vehicles include production, storage, transport and distribution. The well-to-wheel efficiency for hydrogen now exceeds 60% dispelling the inefficiency arguments once made by "experts" using ten-year old data. (Honda FCX Clarity - 2008 Press Information)

Production

Further information: Hydrogen production

The molecular hydrogen needed as an on-board fuel for hydrogen vehicles can be obtained through many 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. Most of today's hydrogen is produced using fossil energy resources, and 85% of hydrogen produced is used to remove sulfur from gasoline. Hydrogen can also be produced from water by electrolysis or by chemical reduction using chemical hydrides or aluminum. Current technologies for manufacturing hydrogen use energy in various forms, totaling between 25 and 50 percent of the higher heating value of the hydrogen fuel, used to produce, compress or liquefy, and transmit the hydrogen by pipeline or truck.

Environmental consequences of the production of hydrogen from methane (natural gas) includes a "well to wheels" greenhouse gas emission reduction of 60% greenhouse gases, a greenhouse gas penalty would result from the on-board reforming of methanol into hydrogen, which is why no automaker uses methanol today. 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 from 40% to 80% in favor of hydrogen. 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. However the same land could be used to create Biodiesel, usable with (at most) minor alterations to existing well developed and relatively efficient diesel engines. In either case, the scale of renewable energy production today is small and would need to be greatly expanded to be used in producing hydrogen for a significant part of transportation needs. As of December 2008, less than 3 percent of U.S. electricity was produced from renewable sources, not including dams. In a few countries, renewable sources are being used more widely to produce energy and hydrogen. For example, Iceland is using geothermal power to produce hydrogen, and Denmark is using wind.

Storage

Further information: Hydrogen storage

Compressed hydrogen storage mark

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 liquid hydrogen in a cryogenic tank or in a compressed hydrogen storage tank, the volumetric energy density (megajoules per liter) is small relative to that of gasoline. Hydrogen has a three times higher energy density by mass compared to gasoline (143 MJ/kg versus 46.9 MJ/kg). Some research has been done into using special crystalline materials to store hydrogen at greater densities and at lower pressures. A recent study by Dutch researcher Robin Gremaud has shown that metal hydride hydrogen tanks are actually 40 to 60-percent lighter than an equivalent energy battery pack on an electric vehicle permitting greater range for H2 cars.

Infrastructure

Further information: Hydrogen infrastructure

Further information: Hydrogen highway

The hydrogen infrastructure consists mainly of industrial hydrogen pipeline transport and hydrogen-equipped filling stations like those found on a hydrogen highway. Hydrogen stations which are not situated near a hydrogen pipeline get supply via hydrogen tanks, compressed hydrogen tube trailers, liquid hydrogen tank trucks or dedicated onsite production.

Hydrogen use would not require an extreme alteration of industry and transport as delivery is being proven today in manners similar to pipeline delivery of natural gas or delivered liquid fuels to gasoline stations. For example, according to GM, 70% of the U.S. population lives near a hydrogen-generating facility but has just about no access to hydrogen today, despite its wide availability for commercial use. The distribution of hydrogen fuel for vehicles in the U.S. would require new hydrogen stations costing, by some estimates, 20 billion dollars over a 20 year span, much less than subsidies provided to oil today. and 4.6 billion in the EU. Other estimates place the cost as high as half trillion U.S. dollars in the United States alone which many say is overstated and again occurs over many years just as our gasoline station network was developed over 100 years. Alleged "facts" cited in Joe Romm's book are seriously flawed and outdated.

Codes and standards

Hydrogen codes and standards are codes and standards (RCS) for hydrogen fuel cell vehicles.

Additional to the codes and standards for hydrogen vehicles, there are codes and standards for hydrogen safety, for the safe handling of hydrogen and the storage of hydrogen.

Codes and standards have repeatedly been identified as a major institutional barrier to deploying hydrogen technologies and developing a hydrogen economy. To enable the commercialization of hydrogen in consumer products, new model building codes and equipment and other technical standards are developed and recognized by federal, state, and local governments.

Criticism

Critics charge that the time frame for overcoming the technical and economic challenges to implementing wide-scale use of hydrogen vehicles is likely to be at least several decades, and hydrogen vehicles may never become broadly available. They believe that the 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. In May 2008, Wired News reported that "experts say it will be 40 years or more before hydrogen has any meaningful impact on gasoline consumption or global warming, and we can't afford to wait that long. In the meantime, fuel cells are diverting resources from more immediate solutions."

K. G. Duleep speculates that "a strong case exists for continuing fuel-efficiency improvements from conventional technology at relatively low cost." Critiques of hydrogen vehicles are presented in the 2006 documentary, Who Killed the Electric Car?. According to 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." The Los Angeles Times wrote, in February 2009, "Hydrogen fuel-cell technology won't work in cars.... Any way you look at it, hydrogen is a lousy way to move cars." A 2007 article in Technology Review stated,

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.

However this shows the bias and misinformation fostered by Joe Romm since comparing a Hydrogen internal combustion vehicle to "fuel cell cousins" is technically and factually a serious error, one an ex DOE official should be ashamed of. The inherent efficiency of todays fuel cell cars dispel the old and biased information fostered by Mr. Romm and should never be compared to internal combustion engines. http://www.afdc.energy.gov/afdc/pdfs/42284.pdf

The Wall Street Journal reported in 2008 that "Top executives from General Motors Corp. and Toyota Motor Corp. Tuesday expressed doubts about the viability of hydrogen fuel cells for mass-market production in the near term and suggested their companies are now betting that electric cars will prove to be a better way to reduce fuel consumption and cut tailpipe emissions on a large scale." In addition, Ballard Power Systems, a leading developer of hydrogen vehicle technology, pulled out of the Hydrogen vehicle business in late 2007. Research Capital analyst Jon Hykawy concluded that Ballard saw the industry going nowhere and said: "In my view, the hydrogen car was never alive. The problem was never could you build a fuel cell that would consume hydrogen, produce electricity, and fit in a car. The problem was always, can you make hydrogen fuel at a price point that makes any sense to anybody. And the answer to that to date has been no."

The Economist magazine, in September 2008, quoted Robert Zubrin, the author of Energy Victory, as saying: "Hydrogen is 'just about the worst possible vehicle fuel'". The magazine noted the retirement of Ballard from the industry and the withdrawal of California from earlier goals: "In March [2008] the California Air Resources Board, an agency of California's state government and a bellwether for state governments across America, changed its requirement for the number of zero-emission vehicles (ZEVs) to be built and sold in California between 2012 and 2014. The revised mandate allows manufacturers to comply with the rules by building more battery-electric cars instead of fuel-cell vehicles." The magazine also noted that most hydrogen is produced through steam reformation, which creates at least as much emission of carbon per mile as some of today's gasoline cars. On the other hand, if the hydrogen could be produced using renewable energy, "it would surely be easier simply to use this energy to charge the batteries of all-electric or plug-in hybrid vehicles." The assumptions used in the Economist article are seriously flawed, expecially pertaining to hydrogen production from methane. Honda and U.C. Davis, and U.C. Berkeley data shows a net decrease in CO2 using steam reformation of methane (natural gas). Despite these flawed criticisms in the Economist, Honda Motors announced on March 30, 2009 that it will put resources into hydrogen fuel cell development, which it sees as "a better long term bet than batteries and plug-in vehicles".

On May 2009 the U.S. Secretary of Energy Stephen Chu announced that since fuel cell hydrogen vehicles "will not be practical over the next 10 to 20 years", the U.S. government will "cut off funds" for development of hydrogen vehicles, although the DoE will continue to fund research related to stationary fuel cells. Energy Secretary Chu did not consult with his own DOE Hydrogen team before making his decision, never drove the current fuel cell models and has since admitted he "may have been wrong" making that decision. The difficulties in the development of the required infrastructure to distribute hydrogen was also mentioned as a justification for cutting research funds however he has since learned that assumption was incorrect after being presented with more recent data. The National Hydrogen Association and other hydrogen groups criticized the decision, arguing that the proposed cuts "threaten to disrupt commercialization of a family of technologies that are showing exceptional promise and beginning to gain market traction." On May 14, 2009, Secretary Chu told MIT's Technology Review that he is skeptical about hydrogen's use in transportation because "the way we get hydrogen primarily is from reforming [natural] gas.... You're giving away some of the energy content of natural gas.... So that's one problem.... [For] transportation, we don't have a good storage mechanism yet.... The fuel cells aren't there yet, and the distribution infrastructure isn't there yet.... In order to get significant deployment, you need four significant technological breakthroughs.... If you need four miracles, that's unlikely: saints only need three miracles". Congress overrode the administration funding cut request after unanimous opposition by every major automaker, restoring funding for hydrogen car research in its appropriations bill for 2010.

Comparison with other types of alternative fuel vehicle

Hydrogen vehicles are one of a number of proposed alternatives to the modern fossil-fuel powered vehicle infrastructure.

PHEVs

Plug-in hybrid electric vehicles, or PHEVs, are ICE-based hybrid vehicles that can be plugged into the electric grid. The PHEV concept augments standard hybrid electric vehicles with the ability to recharge their batteries from an external source while parked, enabling increased use of the vehicle's electric motors while reducing their reliance on internal combustion engines. The infrastructure required to charge PHEVs is already in place, and transmission of power from grid to car is about 93% efficient. This, however, is not the only energy loss in transferring power from grid to wheels. AC/DC conversion must take place from the grids AC supply to the {PHEV's DC. This is roughly 98% efficient. The battery then must be charged, the Lithium Iron Phosphate battery is between 80-90% efficient in charging/discharging. This efficiency will impact twice, once discharging, once charging. The battery then needs to be cooled. The GM Volt's battery has 4 coolers and two radiators. However, "the total well-to-wheels efficiency with which a hydrogen fuel cell vehicle might utilize renewable electricity is roughly 20% (although that number could rise to 25% or a little higher with the kind of multiple technology breakthroughs required to enable a hydrogen economy). The well-to-wheels efficiency of charging an onboard battery and then discharging it to run an electric motor in a PHEV or EV, however, is 80% (and could be higher in the future)—four times more efficient than current hydrogen fuel cell vehicle pathways." An article in Scientific American argues that PHEVs, rather than hydrogen vehicles, will soon become standard in the automobile industry. PHEVs are gaining traction as an alternative to hydrogen.

USA Today reported that PHEVs could increase the output of local particulate matter and ozone in areas where electricity is generated largely from coal.

NGVs

ICE-based CNG or LNG vehicles (Natural gas vehicles or NGVs) use Natural gas or Biogas as a fuel source. Natural gas has a higher energy density than hydrogen gas and has only water and carbon dioxide as waste products. Since the majority of home hydrogen refuelling systems use natural gas as a source for hydrogen, natural gas powered vehicles are easily demonstrated to have a lower carbon dioxide footprint. When using Biogas, NGVs become carbon neutral vehicles which run on animal waste. CNG vehicles have been available for several years, and there is sufficient infrastructure to provide refueling stations in addition to the home refueling systems. The ACEEE has rated the Honda Civic GX, which only uses compressed natural gas, as the greenest vehicle currently available.

BEVs

As Technology Review noted in June 2008, "Electric cars—and plug-in hybrid cars—have an enormous advantage over hydrogen fuel-cell vehicles in utilizing low-carbon electricity. That is because of the inherent inefficiency of the entire hydrogen fueling process, from generating the hydrogen with that electricity to transporting this diffuse gas long distances, getting the hydrogen in the car, and then running it through a fuel cell—all for the purpose of converting the hydrogen back into electricity to drive the same exact electric motor you'll find in an electric car." Thermodynamically, each additional step in the conversion process decreases the overall efficiency of the process.

The Daily Mail in April 2009 reported "Gordon Murray, one of the world's leading automotive engineers, dismisses electric cars as 'too expensive and too heavy'" (see power-to-weight ratio). In a separate statement he says this of electric vehicles:

"Electric vehicles certainly have a place in urban areas and niche, low volume products but with today’s battery technology they have a bad lifecycle footprint and again do nothing for safety, parking and congestion. Car manufacturers are largely ignoring the problems and almost every new model is launched larger and heavier than the last. There have been a few noticeable exceptions like the Smart and the Japenese KEI class cars but none of these help in all the problem areas."

Taking the Mini-E as an example, this can achieve a range of 156 miles (251 km) under optimum driving conditions but Mini have said most users can expect between 100–120 miles (160–190 km). However, most commutes are 30–40 miles (48–64 km) miles per day. Ed Begley, Jr., an electric car advocate, noted, "The detractors of electric vehicles are right. Given their limited range, they can only meet the needs of 90 percent of the population." In addition, new Nickel-metal hydride and lithium batteries are non-toxic and can be recycled, and "the supposed 'lithium shortage' doesn’t exist".

See also

• Alternative fuel car
• Bivalent engine
• Electric vehicle
• Fuel cell vehicle
• Future of the car
• Greenchoice Forze
• Hell and High Water
• Hybrid vehicle
• Hydrogen economy
• Hydrogen highway

• Hydrogen internal combustion engine vehicle
• Hydrogen storage
• Hydrogen technologies
• The Hype about Hydrogen
• Liquid hydrogen
• Liquid nitrogen vehicle
• List of fuel cell vehicles
• Tribrid vehicle
• World Green Car
• Zero-emissions vehicle

External links

• California Fuel Cell Partnership homepage
• Clean Energy Partnership
• C-Net - Hydrogen: More Polluting than Petroleum? Cnet news 2007
• U.S. Dept. of Energy hydrogen pages
• Toronto Star article on hydrogen trains dated October 21, 2007
• NOVA - Video on Fuel Cell Cars (aired on PBS, July 26, 2005)
• Sandia Corporation - Hydrogen internal combustion engine description
• UK Low Carbon and Fuel Cell Knowledge Transfer Network