Hydrogen vehicle

From Wikipedia

A hydrogen vehicle is a vehicle, such as an automobile, aircraft, or any other kind of vehicle that uses hydrogen as its primary source of power for locomotion. These vehicles generally use the hydrogen in one of two methods: combustion or fuel-cell conversion:

• 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 electric motors.

Hydrogen can be obtained through various thermochemical methods utilizing natural gas, coal (by a process known as coal gasification), liquefied petroleum gas, biomass (biomass gasification), or from water by electrolysis or by a process called thermolysis. A primary benefit of using pure hydrogen as a power source would be that it uses oxygen from the air to produce water vapor as exhaust. Another benefit is that, theoretically, the source of pollution created today by burning fossil fuels could be moved to centralized power plants, where the byproducts of burning fossil fuels can be better controlled. Hydrogen could also be produced from renewable energy sources with (in principle) no net carbon dioxide emissions. There are both technical and economic challenges to implementing wide-scale use of hydrogen vehicles, and the timeframe in which such challenges may be overcome is likely to be at least several decades.^[1]

^{COMPARING HYDROGEN to ELECTRIC}

 Research and prototypes

 

Hydrogen powered Ford Focus

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, produces more pollution than vehicles consuming gasoline, diesel, or methane in a modern internal combustion engine, and far more than plug-in hybrid electric vehicles.^[1] This is because, although hydrogen fuel cells generate less CO₂ than conventional internal combustion engines, production of the hydrogen creates additional emissions.^[2] While methods of hydrogen production that do not use fossil fuel would be more sustainable,^[3] 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.^[1]

The recorded number of hydrogen-powered public vehicles in the United States is 200 as of April 2007,mostly in California ^[4] 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 instead of a traditional engine. 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.

High-speed cars, buses, submarines, airplanes 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.^[5]

 Hydrogen fuel cell difficulties

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.

 Low volumetric energy

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 as a gas, 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. Some research has been done into using special crystalline materials to store hydrogen at greater densities and at lower pressures.

Instead of storing molecular hydrogen on-board, some have advocated using hydrogen reformers to extract the hydrogen from more traditional fuels including methane, gasoline, and ethanol. Many environmentalists object to this idea, as it promotes continued dependence on fossil fuels, at least in the case of gasoline and methane, unless it is derived from recently decayed biomass. However, vehicles using reformed gasoline or ethanol to power fuel cells could still be more efficient than vehicles running internal combustion engines, if the technology can be developed.

 Fuel cell cost

Currently, fuel cells are costly to produce and fragile. However technologies currently under development may, in the future, result in robust and cost-efficient versions.

Hydrogen fuel cells were initially plagued by the high production costs associated with converting the gas to electricity ultimately required to power a hydrogen car. Scientists are also studying how to produce inexpensive fuel cells that are robust enough to survive the bumps and vibrations that all automobiles have to handle. Furthermore, 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. Also, many designs require rare substances such as platinum as a catalyst in order to work properly. Such a catalyst can be 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.

 Hydrogen production cost

Chemically pure hydrogen is derived from a feed stock. The energy to drive this conversion can be produced from fossil fuels, or renewable energy sources etc. Thus, hydrogen is not a harvestable energy source comparable to fossil fuels, solar energy, and wind energy. The conversions to produce hydrogen will have inherent losses of energy that make hydrogen less advantageous as an energy carrier. Additionally, there are economic and energy penalties associated with packaging, distribution, storage and transfer of hydrogen. Current technologies use between 165% to 212% of the higher heating value to produce the hydrogen.^[6]

Hydrogen fuel cells are theoretically (without auxiliary devices to run the fuel cell) more efficient than internal combustion engines, achieving efficiencies of 50-60%. While some hydrogen fuel cells produce only water (SOFC and MCFC do produce CO₂, but for MCFC it might be reused in the FC) as its byproduct, the production of hydrogen using fossil fuels creates emissions of greenhouse gases, which adds an additional environmental cost. This problem could theoretically be solved by phasing out fossil fuels as an energy source and replacing them with clean energy sources, such as solar and wind, but those sources currently yield less than 2% of energy used worldwide, and development of such renewable sources still faces major barriers for the forseeable future.

 Hydrogen infrastructure

Fourth, 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.

 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 twenty years. As of today, however, no medium or low temperature fuel cells have been tested for more than several hundred hours.

 Political considerations

Since all energy sources have drawbacks, a shift into hydrogen-powered vehicles may require difficult political decisions on how to produce this energy. The United States Department of Energy has already announced a plan to produce hydrogen directly from generation IV reactors. These nuclear power plants would be capable of producing hydrogen and electricity at the same time. The main problem with the nuclear-to-hydrogen economy is that hydrogen is ultimately only an energy carrier. The costs associated with electrolysis and transportation and storage of hydrogen may make this method uneconomical in comparison to direct utilization of electricity. Electric power transmission is about 95% efficient and the infrastructure is already in place, so tackling the current drawbacks of electric cars or hybrid vehicles may be easier than developing a whole new hydrogen infrastructure that mimics the obsolete model of oil distribution. Continuing research on cheaper, higher capacity batteries are needed. Direct transmission through electric rails, for example in a guided vehicle configuration such as personal rapid transit, may turn out to make electric vehicles more economic than hydrogen fuel cell vehicles. As a 2007 article in 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.^[1]

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.^[7]. Sodium borohydride (NaBH₄) a chemical compound may also hold future promise due to the ease at which hydrogen can be stored under normal atmospheric pressures in automobiles that have fuel cells.^{[citation needed]}

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, 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^[3].

 Alternatives

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 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.^[8] To achieve lower emission goals, the power grid re-charging these vehicles will need to contribute significantly less emissions and wean themselves from fossil fuels for energy conversion.

 Hydrogen internal combustion

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]}

BMW's CleanEnergy internal combustion hydrogen car has more power and is faster than hydrogen fuel cell electric cars. A BMW hydrogen car (BMW H2R) broke the speed record for hydrogen cars at 300 km/h (186 mi/h), and BMW has an even newer Hydrogen 7 model. 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 like DaimlerChrysler and General Motors Corp, are investing in the slower (also in terms of load change), weaker, but more efficient hydrogen fuel cells instead. 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.^[9]

Outside of specialty and small-scale uses, the primary target for the widespread application of fuel cells (hydrogen, zinc, other) is the transportation sector; however, to be economically and environmentally feasible, any fuel cell based engine would need to be more efficient from wellhead-to-wheel, than what currently exists.

 Automobile and bus makers

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:

Hyundai Tucson FCEV in the background (on the left) and Toyota Highlander FCHV in the foreground (on the right) during UC Davis's Picnic Day activities

• 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 power by an ICE. Both models use Liquid Hydrogen as fuel.
• DaimlerChrysler — F-Cell, a hydrogen fuel cell vehicle based on the Mercedes-Benz A-Class.
• Ford Motor – 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 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.
• Hyundai — Tucson FCEV, based on UTC Power fuel cell technology
• Mazda - RX-8, with a dual-fuel (hydrogen or gasoline) rotary-engine ^[10]
• 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^[11] are currently under development and in active testing.
• Volkswagen also has hydrogen fuel cell cars in development.

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

Mercedes-Benz (DaimlerChrysler) Citaro fuel-cell bus in Aldwych, London, on 19 October 2005

• DaimlerChrysler, with thirty-six experimental units powered by Ballard Power Systems fuel cells completing a successful three-year trial, in eleven cities, in January 2007.^[12][13]
• 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.^[14] 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.

Los Altos High School in Hacienda Heights, California is the only high school that has built a hydrogen fuel cell car.

Fuel stations

Since the turn of the millennium, filling stations offering hydrogen have been opening worldwide, new are the home stations [2].

Planes

Many companies such as Boeing and Smartfish are pursuing hydrogen as fuel for planes. Unmanned hydrogen planes have been tested and Boeing is currently planning a manned flight for 2007.

References