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Hydrogen vehicle

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Sequel, a fuel cell powered vehicle from General Motors
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Sequel, a fuel cell powered vehicle from General Motors

A hydrogen vehicle is an automobile which uses hydrogen as its primary source of power for locomotion. These cars 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 turned into electricity through fuel cells which then power electric motors.

Hydrogen can be obtained from decomposition of methane (natural gas), coal (by a process known as coal gasification), liquid petroleum products, biomass (biomass gasification), high heat sources (by a process called thermolysis), or from water using electricity (electrolysis). 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 (and very little nitrogen oxides from the nitrogen in the air when burning at high temperatures). 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. However, as explained below, the technical challenges required to realize this benefit may not be solved for many decades, if ever.

The main challenges in using hydrogen in cars are the very high costs and the low energy efficiencies; so far, there is not much likelihood of overcoming these challenges. Consequently, only a few demonstration vehicles have been made at high cost. See The Hype about Hydrogen and hydrogen economy.

Contents

Research and Prototypes

In many hydrogen fuel cells, Hydrogen does not act as a pre-existing source of energy like fossil fuels, but a carrier, much like a battery. It is renewable in a realistic time scale, unlike fossil fuels which can take millions of years to replenish. (A few dispute this. See Abiogenic petroleum origin.) The largest potential advantage is that it could be produced and consumed continuously, using solar, wind and nuclear power for electrolysis. However, current hydrogen production methods utilizing hydrocarbons produce more pollution and cost per mile driven, than would direct consumption of the same hydrocarbon fuel (e.g., methane or gasoline) in a modern internal combustion engine. To reduce pollution and reliance on fossil fuels, sustainable and cost effective methods of hydrogen production and containment would have to be improved beyond current capabilities. The costs of producing, containing, and distributing hydrogen are likely to go up as the costs of fossil fuels goes up from declining supply and increasing demand.

A small number of experimental hydrogen cars currently exist, 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, and space rockets already can run on hydrogen, in various forms at great expense. 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.[Thames & Kosmos kit], [Other educational materials], and [many more demonstration car kits]. One could easily substitute a rechargeable battery for the toy hydrogen system and show far more cost and energy efficiency for the battery than the hydrogen system, as a science fair project.

Hydrogen fuel cell problems

While fuel cells themselves are potentially highly energy efficient, and working prototypes were made by Roger E. Billings in the 1960s, at least four major obstacles exist in the development and use of a fuel cell-powered hydrogen car. The first problem is that hydrogen has a very low density. Even when the fuel is stored as a liquid in a cryogenic tank or in a pressurized tank as a gas, the amount of energy that can be stored in the space available is limited, and it takes energy to compress the gas and make the container, and hydrogen cars therefore have limited range compared to their conventional counterparts. Some research has been done into using special crystalline materials to store hydrogen at greater densities and with margins.

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 are irked by this idea, as it promotes continued dependence on fossil fuels (at least in the case of gasoline). 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 invented.

The second major problem that used to plague hydrogen fuel cells involves the high cost of making reliable fuel cells that would provide electric power in a hydrogen car. Scientists are also working hard to figure out how to produce inexpensive fuel cells that are also robust enough to survive the bumps and vibrations that all automobiles have to handle. Furthermore, freezing conditions have to be handled because fuel cells do 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, and the catalyst can be contaminated by impurities in the hydrogen supply. However, within the past few years, a nickel-tin catalyst has been developed which may lower the cost of hydrogen fuel to help possibly make a fuel cell car an economically viable car.

The third "problem" is due to the fact that while hydrogen can be used as an energy carrier, it is not an energy source. It still must be produced from fossil fuels, or from some other energy source, with a net loss of energy (since the conversion from energy to hydrogen storage and back to energy is not 100% efficient). Using hydrogen in a fuel cell is nearly twice as efficient as traditional combustion engines, which only have an efficiency of 15-25%. Hydrogen fuel cells can achieve thermodynamic efficiencies of 50-60%. The percentage will never be 100% because of the second law of thermodynamics.

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.

Since all energy sources have drawbacks, a shift into hydrogen powered vehicles may require difficult political decisions on how to produce this energy. The US Energy Department has already announced a plan to produce hydrogen directly from Generation IV reactors. These nuclear powerplants 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 a carrier of electricity. 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 is needed. Direct transmission though electric rails, for example in a guided vehicle configuration such as PRT, could make electric vehicles more economic than hydrogen fuel cell vehicles.

Recently, alternative methods of creating hydrogen directly from sunlight and water through a metallic catalyst have been announced. This may provide a cheap, direct conversion of solar energy into hydrogen, a very clean solution for hydrogen production [[Citing sources citation needed]].

Sodium borohydride (NaBH4) a chemical compound may hold future promise due to the ease at which hydrogen can be stored under normal atmospheric pressures in automobiles that have fuel cells. United States President George W. Bush was optimistic that these problems could be overcome with research. In his 2006 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. See The Hype about Hydrogen. The Clinton administration helped the industry develop a 72 mpg diesel hybrid, the Dodge ESX3, which is far closer to energy freedom, because it can run on biodiesel made from sea water algae.

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. Hydrogen internal combustion cars burn hydrogen directly, with no other fuels and produce pure water vapor exhaust. The problem with these cars is the hydrogen fuel that can be stored in a normal size tank is used up rapidly. A full tank of hydrogen, in the gaseous state, would last only a few miles before the tank is empty. However, methods are being developed to reduce tank space, such as storing condensed (liquid) hydrogen or using metal hydrides in the tank.

In 1807, François Isaac de Rivaz built the first hydrogen-fueled internal combustion vehicle. However, the design was very unsuccessful.

It's estimated that more than a thousand hydrogen powered vehicles were produced in Germany before the end of the WWII prompted by the acute shortage of oil.

BMW's CleanEnergy internal combustion hydrogen car has more power and is faster than hydrogen fuel cell electric cars. A BMW hydrogen car ( H2R) broke the speed record for hydrogen cars at 300 km/h (186 mi/h), making automotive history. Mazda has developed Wankel engines to burn hydrogen. The Wankel 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, weaker, but more efficient hydrogen fuel cells instead.

An existing conventional car sleeps in a converter to run on hydrogen, or a mixture of hydrogen and other gasses as produced in a reforming process. Since hydrogen can burn in a very wide range of air/fuel mixtures, a small amount of hydrogen can also be used to ignite various liquid fuels in existing internal combustion engines under extremely lean burning conditions. This process requires a number of modifications to existing engine air/fuel and timing controls. Roy McAlister of the [American Hydrogen Association] has been demonstrating these conversions. Other renewable energy sources, like biodiesel, are also practical for existing automobile conversions, but come with their own host of problems.

In 2005 an Israeli company claimed it succeeded in conquering most of the problems related to producing Hydrogen internal combustion engine by using a device called a Metal-Steam combustor that separates Hydrogen out of heated water. A tip of a Magnesium or Aluminum coil is inserted into the small Metal-Steam combustor together with water where it is heated to very high temperatures. The metal atoms bond with the Oxygen from the water, creating metal oxide. As a result, the Hydrogen molecules become free, and are sent into the engine alongside the steam. The solid waste product of the process, in the form of metal oxide, will later be collected in the fuel station and recycled for further use by the metal industry. The problem is that it takes a lot of energy to make the Magnesium or Aluminum coils.

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 well head-to-wheel, than what currently exists. At the time of this writing, hydrogen fuel cells are roughly equivalent to gasoline combustion, in terms of energy efficiency and pollution; however, if the (energy and pollution) costs in the production of the fuel cell are considered, hydrogen is sorely behind. Other fuel cell technologies (i.e. zinc-air), are currently ahead of gasoline combustion in energy efficiency, and hydrogen in terms of production costs and safety, but have been widely overlooked by the advocates of gasoline combustion alternatives.

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:

A few bus companies are also conducting hydrogen fuel cell research. These include: 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 . Perth 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. BMW has recently released to the media information of a new car that has been manufactured and uses hydrogen or petrol and is completely clean. BMW also plans to release its first publicly available hydrogen vehicle in 2008.

Fuel stations

Since the turn of the millennium, filling stations offering hydrogen have been opening worldwide. Among them:

Planes

Hyfish is a revolutionary general aviation aircraft technology from Swiss Company Smartfish that is highly innovative in terms of safety, economy and emotion. It uses hydrogen fuel to power fuel cells in the world's first fuel cell-powered aircraft, and the design was presented at the Hannover Fair 2006. The plane has been flown with battery power, and installation of the fuel cell system for subsequent test flights is planned for the summer of 2006.

References

See also

External links

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