A hydrogen vehicle is a vehicle that uses hydrogen fuel for motive power. Hydrogen vehicles include hydrogen-fueled space rockets, as well as automobiles and other transportation vehicles. The power plants of such vehicles convert the chemical energy of hydrogen to mechanical energy either by burning hydrogen in an internal combustion engine, or, more commonly, by reacting hydrogen with oxygen in a fuel cell to run electric motors. Widespread use of hydrogen for fueling transportation is a key element of a proposed hydrogen economy.
As of 2018, there are three models of hydrogen cars publicly available in select markets: the Toyota Mirai, the Hyundai Nexo, and the Honda Clarity. Several other companies are working to develop hydrogen cars. As of 2019, 98% of hydrogen is produced by steam methane reforming, which emits carbon dioxide. It can be produced by thermochemical or pyrolytic means using renewable feedstocks, but that is an expensive process. Renewable electricity can however be used to power the conversion of water into hydrogen: Integrated wind-to-hydrogen (power-to-gas) plants, using electrolysis of water, are exploring technologies to deliver costs low enough, and quantities great enough, to compete with hydrogen production using natural gas. The drawbacks of hydrogen use are high carbon emissions intensity when produced from natural gas, capital cost burden, low energy content per unit volume at ambient conditions, production and compression of hydrogen, and the investment required in filling stations to dispense hydrogen.
Automobiles, buses, forklifts, trains, PHB bicycles, canal boats, cargo bikes, golf carts, motorcycles, wheelchairs, ships, airplanes, submarines, and rockets can already run on hydrogen, in various forms. NASA used hydrogen to launch Space Shuttles into space. A working toy model car 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. Since the advent of hydraulic fracturing the key concern for hydrogen fuel cell vehicles is consumer and public policy confusion concerning the adoption of natural gas powered hydrogen vehicles with heavy hidden emissions to the detriment of environmentally friendly transportation.
A land-speed record for a hydrogen-powered vehicle of 286.476 miles per hour (461.038 km/h) was set by Ohio State University's Buckeye Bullet 2, which achieved a "flying-mile" speed of 280.007 miles per hour (450.628 km/h) at the Bonneville Salt Flats in August 2008. A record of 207.297 miles per hour (333.612 km/h) was set by a prototype Ford Fusion Hydrogen 999 Fuel Cell Race Car at the Bonneville Salt Flats, in August 2007, using a large compressed oxygen tank to increase power.
In 2013 the Hyundai Tucson FCEV was the first commercially mass-produced hydrogen fuel cell vehicle in the world. Hyundai Nexo, which succeeded the Tucson in 2018, was selected as the "safest SUV" by the Euro NCAP in 2018 and was rated as "Good" in a side crash test conducted by the Insurance Institute for Highway Safety (IIHS)
Toyota launched its first production fuel cell vehicle (FCV), the Mirai, in Japan at the end of 2014 and began sales in California, mainly the Los Angeles area, in 2015. The car has a range of 312 mi (502 km) and takes about five minutes to refill its hydrogen tank. The initial sale price in Japan was about 7 million yen ($69,000). Former European Parliament President Pat Cox estimated that Toyota would initially lose about $100,000 on each Mirai sold. As of 2019, Toyota had sold 5,000 Mirais. Many automobile companies have introduced demonstration models in limited numbers (see List of fuel cell vehicles and List of hydrogen internal combustion engine vehicles). One disadvantage of hydrogen compared to other automobile fuels is its low density.
In 2013 BMW leased hydrogen technology from Toyota, and a group formed by Ford Motor Company, Daimler AG, and Nissan announced a collaboration on hydrogen technology development. By 2017, however, Daimler had abandoned hydrogen vehicle development, and most of the automobile companies developing hydrogen cars had switched their focus to battery electric vehicles.
Trams and trains
In March 2015, China South Rail Corporation (CSR) demonstrated the world's first hydrogen fuel cell-powered tramcar at an assembly facility in Qingdao. The chief engineer of the CSR subsidiary CSR Sifang Co Ltd., Liang Jianying, said that the company is studying how to reduce the running costs of the tram. Tracks for the new vehicle have been built in seven Chinese cities. China plans to spend 200 billion yuan ($32 billion) through 2020 to increase tram tracks to more than 1,200 miles.
An experimental "Hydroflex" train, British Rail Class 799, began tests in Great Britain in June 2019.
As of 2019 Hydrogen fuel cells are not suitable for propulsion in large long-distance ships, but they are being considered as a range-extender for smaller, short-distance, low-speed electric vessels, such as ferries. Hydrogen in ammonia is being considered as a long-distance fuel.
In 2007, Pearl Hydrogen Power Source Technology Co of Shanghai, China, demonstrated a PHB hydrogen bicycle. In 2014, Australian scientists from the University of New South Wales presented their Hy-Cycle model. The same year, Canyon Bicycles started to work on the Eco Speed concept bicycle.
In 2017, Pragma Industries of France developed a bicycle that was able to travel 100 km on a single hydrogen cylinder. In 2019, Pragma announced that the product, "Alpha Bike", has been improved to offer an electrically-assisted pedalling range of 150 km, and the first 200 of the bikes are to be provided to journalists covering the 45th G7 summit in Biarritz, France. If successful, Lloyd Alter of TreeHugger responded to the announcement, asking "why … go through the trouble of using electricity to make hydrogen, only to turn it back into electricity to charge a battery to run the e-bike [or] pick a fuel that needs an expensive filling station that can only handle 35 bikes a day, when you can charge a battery powered bike anywhere. [If] you were a captive fleet operator, why [not] just swap out batteries to get the range and the fast turnover?"
General Motors' military division, GM Defense, focuses on hydrogen fuel cell vehicles. Its SURUS (Silent Utility Rover Universal Superstructure) is a flexible fuel cell electric platform with autonomous capabilities. Since April 2017, the U.S. Army has been testing the commercial Chevrolet Colorado ZH2 on its U.S. bases to determine the viability of hydrogen-powered vehicles in military mission tactical environments.
Motorcycles and scooters
ENV develops 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 Suzuki Burgman fuel-cell scooter and the FHybrid. The Burgman received "whole vehicle type" approval in the EU. The Taiwanese company APFCT conducted a live street test with 80 fuel-cell scooters for Taiwan's Bureau of Energy.
Quads and tractors
Companies such as Boeing, Lange Aviation, and the German Aerospace Center pursue hydrogen as fuel for manned and unmanned airplanes. In February 2008 Boeing tested a manned flight of a small aircraft powered by a hydrogen fuel cell. Unmanned hydrogen planes have also been tested. For large passenger airplanes, The Times reported that "Boeing said that hydrogen fuel cells were unlikely to power the engines of large passenger jet airplanes but could be used as backup or auxiliary power units onboard."
In Britain, 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.
A HICE forklift or HICE lift truck is a hydrogen fueled, internal combustion engine-powered industrial forklift truck used for lifting and transporting materials. The first production HICE forklift truck based on the Linde X39 Diesel was presented at an exposition in Hannover on May 27, 2008. It used a 2.0 litre, 43 kW (58 hp) diesel internal combustion engine converted to use hydrogen as a fuel with the use of a compressor and direct injection.
A fuel cell forklift (also called a fuel cell lift truck) is a fuel cell powered industrial forklift truck. In 2013 there were over 4,000 fuel cell forklifts used in material handling in the US. The global market was estimated at 1 million fuel cell powered forklifts per year for 2014–2016. Fleets are being operated by companies around the world. Pike Research stated in 2011 that fuel-cell-powered forklifts will be the largest driver of hydrogen fuel demand by 2020.
Most companies in Europe and the US do not use petroleum powered forklifts, as these vehicles work indoors where emissions must be controlled and instead use electric forklifts. Fuel-cell-powered forklifts can provide benefits over battery powered forklifts as they can be refueled in 3 minutes. They can be used in refrigerated warehouses, as their performance is not degraded by lower temperatures. The fuel cell units are often designed as drop-in replacements.
Many large rockets use liquid hydrogen as fuel, with liquid oxygen as an oxidizer (LH2/LOX). An advantage of hydrogen rocket fuel is the high effective exhaust velocity compared to kerosene/LOX or UDMH/NTO engines. According to the Tsiolkovsky rocket equation, a rocket with higher exhaust velocity uses less propellant to accelerate. Also the energy density of hydrogen is greater than any other fuel. LH2/LOX also yields the greatest efficiency in relation to the amount of propellant consumed, of any known rocket propellant.
A disadvantage of LH2/LOX engines is the low density and low temperature of liquid hydrogen, which means bigger and insulated and thus heavier fuel tanks are needed. This increases the rocket's structural mass which reduces its delta-v significantly. Another disadvantage is the poor storability of LH2/LOX-powered rockets: Due to the constant hydrogen boil-off, the rocket must be fueled shortly before launch, which makes cryogenic engines unsuitable for ICBMs and other rocket applications with the need for short launch preparations.
Overall, the delta-v of a hydrogen stage is typically not much different from that of a dense fuelled stage, but the weight of a hydrogen stage is much less, which makes it particularly effective for upper stages, since they are carried by the lower stages. For first stages, dense fuelled rockets in studies may show a small advantage, due to the smaller vehicle size and lower air drag.
LH2/LOX were also used in the Space Shuttle to run the fuel cells that power the electrical systems. The byproduct of the fuel cell is water, which is used for drinking and other applications that require water in space.
In 2016 Nikola Motor Company introduced a hydrogen-powered Class 8 heavy truck powered by a 320 kWh EV battery. Nikola plans two versions of the hydrogen powered truck, long haul Nikola One and day cab Nikola Two. United Parcel Service began testing of a hydrogen powered delivery vehicle in 2017. US Hybrid, Toyota, and Kenworth have also announced plans to test Class 8 drayage hydrogen fuel cell trucks.
Internal combustion vehicle
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; the main difference is the exhaust product. Gasoline combustion results in carbon dioxide and water vapor, while the only exhaust product of hydrogen combustion is water vapor.
In 1807 Francois Isaac de Rivaz designed the first hydrogen-fueled internal combustion engine. In 1965, Roger Billings, then a high school student, converted a Model A to run on hydrogen. In 1970 Paul Dieges patented a modification to internal combustion engines which allowed a gasoline-powered engine to run on hydrogen US 3844262.
Mazda has developed Wankel engines burning hydrogen, which are used in the Mazda RX-8 Hydrogen RE. The advantage of using an internal combustion engine, like Wankel and piston engines, is the lower cost of retooling for production.
Fuel cell cost
Hydrogen fuel cells are relatively expensive to produce, as their designs require rare substances such as platinum as a catalyst, In 2014, Toyota said it would introduce its Toyota Mirai in Japan for less than $70,000 in 2015. Former European Parliament President Pat Cox estimates that Toyota will initially lose about $100,000 on each Mirai sold.
The problems in early fuel-cell designs at low temperatures concerning range and cold start capabilities have been addressed so that they "cannot be seen as show-stoppers anymore". Users in 2014 said that their fuel cell vehicles perform flawlessly in temperatures below zero, even with the heaters blasting, without significantly reducing range. Studies using neutron radiography on unassisted cold-start indicate ice formation in the cathode, three stages in cold start and Nafion ionic conductivity. A parameter, defined as coulomb of charge, was also defined to measure cold start capability.
The service life of fuel cells is comparable to that of other vehicles. PEM service life is 7,300 hours under cycling conditions.
Hydrogen does not exist in convenient reservoirs or deposits like fossil fuels or helium. It is produced from feedstocks such as natural gas and biomass or electrolyzed from water. A suggested benefit of large-scale deployment of hydrogen vehicles is that it could lead to decreased emissions of greenhouse gasses and ozone precursors. However, as of 2014, 95% of hydrogen is made from methane. It can be produced by thermochemical or pyrolitic means using renewable feedstocks, but that is an expensive process. Renewable electricity can however be used to power the conversion of water into hydrogen: Integrated wind-to-hydrogen (power to gas) plants, using electrolysis of water, are exploring technologies to deliver costs low enough, and quantities great enough, to compete with traditional energy sources.
According to Ford Motor Company, hydrogen fuel-cell vehicles would generate only three-fifths the carbon dioxide as a comparable vehicle running on gasoline blended to 10 percent ethanol. 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 chiefly its storage on board the vehicle. While the well-to-wheel efficiency for hydrogen from the least efficient manner of producing it (electrolysis) is less than 25 percent, it still exceeds that of vehicles based on internal combustion engines.
The molecular hydrogen needed as an onboard 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. 95% of hydrogen is produced using natural gas, and 85% of hydrogen produced is used to remove sulfur from gasoline. Hydrogen can also be produced from water by electrolysis at working efficiencies in the 50–60% range for the smaller electrolysers and around 65–70% for the larger plants. Hydrogen can also be made 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 fossil energy resources include the emission of greenhouse gasses, a consequence that would also result from the on-board reforming of methanol into hydrogen. Analyses comparing the environmental consequences of hydrogen production and use in fuel-cell vehicles to the refining of petroleum and combustion in conventional automobile engines do not agree on whether a net reduction of ozone and greenhouse gasses would result. Hydrogen production using renewable energy resources would not create such emissions, but the scale of renewable energy production would need to be expanded to be used in producing hydrogen for a significant part of transportation needs. As of 2016, 14.9 percent of U.S. electricity was produced from renewable sources. 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.
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 three times higher specific energy by mass compared to gasoline (143 MJ/kg versus 46.9 MJ/kg). In 2011, scientists at Los Alamos National Laboratory and University of Alabama, working with the U.S. Department of Energy, found a single-stage method for recharging ammonia borane, a hydrogen storage compound. In 2018, researchers at CSIRO in Australia powered a Toyota Mirai and Hyundai Nexo with hydrogen separated from ammonia using a membrane technology. Ammonia is easier to transport safely in tankers than pure hydrogen.
The hydrogen infrastructure consists of hydrogen-equipped filling stations, which are supplied with hydrogen via compressed hydrogen tube trailers, liquid hydrogen tank trucks or dedicated onsite production, and some industrial hydrogen pipeline transport. The distribution of hydrogen fuel for vehicles throughout the U.S. would require new hydrogen stations that would cost between 20 billion dollars in the US, (4.6 billion in the EU). and half trillion dollars in the US.
As of 2018, there were 40 publicly accessible hydrogen refueling stations in the US, most of which are in located in California (compared with 19,000 electric charging stations). By 2017, there were 91 hydrogen fueling stations in Japan.
Codes and standards
Hydrogen codes and standards, as well as codes and technical standards for hydrogen safety and the storage of hydrogen, have been identified as an institutional barrier to deploying hydrogen technologies and developing a hydrogen economy. To enable the commercialization of hydrogen in consumer products, new codes and standards must be developed and adopted by federal, state and local governments.
In 2003, George W. Bush announced an initiative to promote hydrogen powered vehicles. In 2009, President Obama and his Department of Energy Secretary Steven Chu stripped the funding of fuel cell technology due to their belief that the technology was still decades away. Under heavy criticism, the funding was partially restored. In 2014 the Obama administration announced they want to speed up production and development of hydrogen powered vehicles. The Department of Energy planned to spread a $7.2 million investment among the states of Georgia, Kansas, Pennsylvania, and Tennessee to support projects that fuel vehicles and support power systems. The Center for Transportation and The Environment, FedEx Express, Air Products and Chemicals, and Sprint have invested in the development of fuel cells. Fuel cells could also be used in handling equipment such as forklifts as well as telecommunications infrastructure.
Senator Byron L. Dorgan stated in 2013: “The Energy and Water Appropriations bill makes investments in our nation’s efforts to develop safe, homegrown energy sources that will reduce our reliance on foreign oil. And, because ongoing research and development is necessary to develop game-changing technologies, this bill also restores funding for Hydrogen energy research”. In June 2013, the U.S. Department of Energy gave 9 million dollars in grants to speed up technology development, 4.5 million for advanced fuel cell membranes, $3 million to 3M corporation to work on membranes with improved durability and performance, and 1.5 million to the Colorado School of Mines for work on simpler and more affordable fuel cell membranes.
Critics claim the time frame for overcoming the technical and economic challenges to implementing wide-scale use of hydrogen cars is likely to last for at least several decades, and hydrogen vehicles may never become broadly available. They claim 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."
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 2009, "Hydrogen fuel-cell technology won't work in cars. ... Any way you look at it, hydrogen is a lousy way to move cars." The Economist magazine, in 2008, quoted Robert Zubrin, the author of Energy Victory, as saying: "Hydrogen is 'just about the worst possible vehicle fuel'". The magazine noted the withdrawal of California from earlier goals: "In  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." As of 2019, 98% of hydrogen is produced by steam methane reforming, which emits carbon dioxide.
A 2009 study at UC Davis, published in the Journal of Power Sources, similarly found that, over their lifetimes, hydrogen vehicles will emit more carbon than gasoline vehicles. This agrees with a 2014 analysis. The Washington Post asked in 2009, "[W]hy would you want to store energy in the form of hydrogen and then use that hydrogen to produce electricity for a motor, when electrical energy is already waiting to be sucked out of sockets all over America and stored in auto batteries"? The Motley Fool stated in 2013 that "there are still cost-prohibitive obstacles [for hydrogen cars] relating to transportation, storage, and, most importantly, production."
Volkswagen's Rudolf Krebs said in 2013 that "no matter how excellent you make the cars themselves, the laws of physics hinder their overall efficiency. The most efficient way to convert energy to mobility is electricity." He elaborated: "Hydrogen mobility only makes sense if you use green energy", but ... you need to convert it first into hydrogen "with low efficiencies" where "you lose about 40 percent of the initial energy". You then must compress the hydrogen and store it under high pressure in tanks, which uses more energy. "And then you have to convert the hydrogen back to electricity in a fuel cell with another efficiency loss". Krebs continued: "in the end, from your original 100 percent of electric energy, you end up with 30 to 40 percent." The Business Insider commented:
Pure hydrogen can be industrially derived, but it takes energy. If that energy does not come from renewable sources, then fuel-cell cars are not as clean as they seem. ... Another challenge is the lack of infrastructure. Gas stations need to invest in the ability to refuel hydrogen tanks before FCEVs [fuel cell electric vehicles] become practical, and it's unlikely many will do that while there are so few customers on the road today. ... Compounding the lack of infrastructure is the high cost of the technology. Fuel cells are "still very, very expensive".
In 2014, Joseph Romm devoted three articles to updating his critiques of hydrogen vehicles made in his book The Hype about Hydrogen. He stated that fuel cell vehicles still had not overcome the high cost of the vehicles, high fueling cost, and lack of fuel-delivery infrastructure. "It would take several miracles to overcome all of those problems simultaneously in the coming decades." Moreover, he wrote, "FCVs aren't green" because of escaping methane during natural gas extraction and when hydrogen is produced, as 95% of it is, using the steam reforming process. He concluded that renewable energy cannot economically be used to make hydrogen for an FCV fleet "either now or in the future." GreenTech Media's analyst reached similar conclusions in 2014. In 2015, Clean Technica listed some of the disadvantages of hydrogen fuel cell vehicles as did Car Throttle. Another Clean Technica writer concluded that "while hydrogen may have a part to play in the world of energy storage (especially seasonal storage), it looks like a dead end when it comes to mainstream vehicles." A 2016 study in the November issue of the journal Energy by scientists at Stanford University and the Technical University of Munich concluded that, even assuming local hydrogen production, "investing in all-electric battery vehicles is a more economical choice for reducing carbon dioxide emissions, primarily due to their lower cost and significantly higher energy efficiency."
A 2017 analysis published in Green Car Reports concluded that the best hydrogen-fuel-cell vehicles consume "more than three times more electricity per mile than an electric vehicle ... generate more greenhouse-gas emissions than other powertrain technologies ... [and have] very high fuel costs. ... Considering all the obstacles and requirements for new infrastructure (estimated to cost as much as $400 billion), fuel-cell vehicles seem likely to be a niche technology at best, with little impact on U.S. oil consumption. The US Department of Energy agrees, for fuel produced by grid electricity via electrolysis, but not for most other pathways for generation. In 2017, Michael Barnard, writing in Forbes, listed the continuing disadvantages of hydrogen fuel cell cars and concluded that "[B]y 2025 the last hold-outs should likely be retiring their fuel cell dreams." A 2019 video by Real Engineering noted that, notwithstanding the introduction of vehicles that run on hydrogen, using hydrogen as a fuel for cars does not help to reduce carbon emissions from transportation. The 95% of hydrogen still produced from fossil fuels releases carbon dioxide, and producing hydrogen from water is an energy-consuming process. Storing hydrogen requires more energy either to cool it down to the liquid state or to put it into tanks under high pressure, and delivering the hydrogen to fueling stations requires more energy and may release more carbon. The hydrogen needed to move a FCV a kilometer costs approximately 8 times as much as the electricity needed to move a BEV the same distance. Also in 2019, Katsushi Inoue, the president of Honda Europe, stated, "Our focus is on hybrid and electric vehicles now. Maybe hydrogen fuel cell cars will come, but that’s a technology for the next era."
Safety and supply
Hydrogen fuel is hazardous because of the low ignition energy and high combustion energy of hydrogen, and because it tends to leak easily from tanks. Explosions at hydrogen filling stations have been reported. Hydrogen fuelling stations generally receive deliveries of hydrogen by truck from hydrogen suppliers. An interruption at a hydrogen supply facility can shut down multiple hydrogen fuelling stations.
Comparison with other types of alternative fuel vehicle
Hydrogen vehicles compete with various proposed alternatives to the modern fossil fuel powered vehicle infrastructure.
Plug-in hybrid electric vehicles, or PHEVs, are hybrid vehicles that can be plugged into the electric grid and contain an electric motor and also an internal combustion engine. The PHEV concept augments standard hybrid electric vehicles with the ability to recharge their batteries from an external source, 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 grid's AC supply to the PHEV's DC. This is roughly 98% efficient. The battery then must be charged. As of 2007, the Lithium iron phosphate battery was between 80-90% efficient in charging/discharging. The battery needs to be cooled. As of 2009, "the total well-to-wheels efficiency with which a hydrogen fuel cell vehicle might utilize renewable electricity is roughly 20%. ... 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%... four times more efficient than current hydrogen fuel cell vehicle pathways." A December 2009 study at UC Davis found that, over their lifetimes, PHEVs will emit less carbon than current vehicles, while hydrogen cars will emit more carbon than gasoline vehicles.
Internal combustion engine-based compressed natural gas(CNG), HCNG or LNG vehicles (Natural gas vehicles or NGVs) use methane (Natural gas or Biogas) directly as a fuel source. Natural gas has a higher energy density than hydrogen gas. NGVs using biogas are nearly carbon neutral. Unlike hydrogen vehicles, CNG vehicles have been available for many years, and there is sufficient infrastructure to provide both commercial and home refueling stations. Worldwide, there were 14.8 million natural gas vehicles by the end of 2011. The other use for natural gas is in steam reforming which is the common way to produce hydrogen gas for use in electric cars with fuel cells.
A 2008 Technology Review article stated, "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.
A 2013 comparison of hydrogen and battery electric vehicles agreed with the 25% figure from Ulf Bossel in 2006 and stated that the cost of an electric vehicle battery "is rapidly coming down, and the gap will widen further", while there is little "existing infrastructure to transport, store and deliver hydrogen to vehicles and would cost billions of dollars to put into place, everyone's household power sockets are "electric vehicle refueling" station and the "cost of electricity (depending on the source) is at least 75% cheaper than hydrogen." By 2018, the cost of EV batteries had fallen to below $150 per kWh.
Some electric car designs offer limited driving range causing range anxiety. For example, the 2013 Nissan Leaf had a range of 75 mi (121 km), Other EVs, such as the Tesla Model S, have a range of more than 300 mi (480 km). Most US commutes are 30–40 miles (48–64 km) per day round trip, and in Europe, most commutes are around 20 kilometres (12 mi) round-trip
In 2013 John Swanton of the California Air Resources Board, who sees EVs and hydrogen vehicles as complementary technologies, stated that EVs have the jump on fuel-cell autos, which "are like electric vehicles were 10 years ago. EVs are for real consumers, no strings attached. With EVs you have a lot of infrastructure in place. The Business Insider, in 2013 commented that if the energy to produce hydrogen "does not come from renewable sources, then fuel-cell cars are not as clean as they seem. ... Gas stations need to invest in the ability to refuel hydrogen tanks before FCEVs become practical, and it's unlikely many will do that while there are so few customers on the road today. ... Compounding the lack of infrastructure is the high cost of the technology. Fuel cells are "still very, very expensive", even compared to battery-powered EVs.
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On this basis, hydrogen’s energy density is poor (since it has such low density) although its energy to weight ratio is the best of all fuels (because it is so light).
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In order for hydrogen to be used as fuel in a car, it has to be stored in the car. As at the station, this could be done either in the form of super-cold liquid hydrogen or as highly compressed gas. In either case, we come up against serious problems caused by the low density of hydrogen.
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Despite the advantages of hydrogen ICE, the problem of on-board hydrogen storage, which presently limits the driving range, also remains.
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|Wikimedia Commons has media related to Hydrogen vehicles.|
- California Fuel Cell Partnership homepage
- Fuel Cell Today - Market-based intelligence on the fuel cell industry
- Clean Energy Partnership
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- NOVA – Video on Fuel Cell Cars (aired on PBS, July 26, 2005)
- Sandia Corporation – Hydrogen internal combustion engine description
- Inside world's first hydrogen-powered production car BBC News, 14 September 2010