|MadSci Network: Engineering|
The question has no easy answer, but here are some of the major reasons why there are no currently commercially available hydrogen fueled vehicles and appliances. There is also a misconception that no one is interested in making them in the future. In fact there are many advances currently happening that make hydrogen an ever more viable alternative fuel.
Most of the major negatives to widespread usage of hydrogen are economic. There is currently a large, well established and, yes, entrenched system of delivering hydrocarbon fuels (gasoline, natural gas, propane, etc.) to consumers. To have a hydrogen fueled fleet of cars would require duplicating much of the infrastructure used to deliver gasoline to your local gas station. That would include, but not be limited to, the refineries, gas pipelines, delivery tanker trucks and on-site storage tanks and pump systems. Up to this point, the cost has been too high to justify the expenditures.
Appliances have a similar problem. Your gas stove can be modified with minimal effort to burn hydrogen. Similarly furnaces can be built to use hydrogen. However, a new delivery line similar to your gas line would need to be added to get the hydrogen to your house. Economics again gives an edge to the current electrical, natural gas or propane system.
The other major reason hydrogen is not is widespread usage is safety. Hydrogen is a highly flammable gas. Stored under pressure in a gas cylinder, it could represent a major hazard in a car wreck, for example. Hydrogen is also much harder to contain in normal usage. The extremely small size of the hydrogen atoms allows them to slip through the lattice of metal atoms. As such, metals that hold most gases easily can be permeated by hydrogen. Worse, if the proper metal is not used, the metal can become embrittled by the hydrogen to the point it becomes as brittle as glass. Seals and fittings that will stop natural gas allow hydrogen to pass through with ease.
The technical problems are not unsolvable. For example, use of hydride fuels for cars has been proposed as a method of safely containing the hydrogen in the event of a rupture in a car wreck. Materials have been developed, or are under development, that can be used in a hydrogen-rich environment. A main customer for these materials are hydrogen-fueled rocket motors used by NASA. Others are used for hydrogen handling when methane is cracked into hydrogen and nitrogen.
The economics of the situation are changing as well. The California laws dealing with emissions from cars are forcing automobile manufacturers to re-examine hydrogen fueled vehicles. Clean air regulations may force a choice between economic growth and automobiles. In that case a zero emission vehicle such as a hydrogen fueled car may make economic sense. Chrysler and Daimler-Benz among others have already started work on hydrogen fueled cars. The Hydrogen & Fuel Cell Letter produced by the National Hydrogen Association has several stories on these efforts along with other advances in production, transport, storage and usage of hydrogen as a fuel.
Currently the situation favors a continued use of hydrocarbons. As consumers and the government move to a desire for cleaner air, the situation may change.
While it is possible to make your own hydrogen production equipment and use hydrogen in your own home, make absolutely certain that you are aware of the problems associated with hydrogen before you begin. Hydrogen is a colorless, odorless gas that will collect when there is inadequate ventilation. An example of a prime spot in a typical home is the space between exposed joists in the basement. When it reaches about a concentration of about 4% it becomes a flammable and potentially explosive mixture. Typical sealants such as plumbers dope will not stop hydrogen. Special fittings and seals are required. Also, steel pipes such as those used for natural gas lines are generally susceptible to hydrogen embrittlement. You will also need to be in compliance with all local building codes. These will probably require you to meet national safety codes dealing with the use of hydrogen if they will even allow you to use hydrogen.
With these caveats in mind, it is possible to safely convert your home to hydrogen usage. Contact professional societies and trade groups such as the National Hydrogen Association for further help if you are interested.
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