Hydrogen fuel cars are gaining popularity and attention from the public, especially since the recent rise in gas prices. These types of vehicles use hydrogen as a fuel for propulsion, instead of more traditional fossil fuels, such as gasoline or diesel fuel. There are two ways that vehicles operating on hydrogen can convert its chemical energy to mechanical energy (torque required to move the car).
In combustion engines, the hydrogen is burned inside the engine in a similar way to gasoline in a conventional car engine. In fuel-cell conversion, the hydrogen is reacted with oxygen in order to produce water and electricity. The electricity is then used to power an electric motor that transfers the energy to the wheels, therefore making the vehicle move.
Many automotive manufacturers, such as General Motors are currently performing research on hydrogen fuel cars. However, these vehicles are not yet available for sale to the general public, most are demonstration models built for car shows and events. Others are constructed only for leasing to a few individuals. There are only about 200 hydrogen powered vehicles currently in circulation in the United States as of 2008.
Funding for research in alternative fuels such as hydrogen has come from various sources, both from Governments and private sources. However, it is estimated that it may still take a few decades before hydrogen vehicles can have any impact in lowering our dependency on fossil fuels.
Research and development is still in its early stages, and there are many challenges that are yet to be overcome before such vehicles become mainstream. Current hydrogen fuel cells are costly to produce and reliably fragile. Also, freezing temperatures below 32 degrees are of a great concern. Operational fuel cells have an internal vaporous environment that could solidify if the surrounding temperature dips below the freezing point. Most current hydrogen fuel cells are not yet built in a manner where they can operate effectively in freezing temperatures, this is why the major of cars using them are driven in warm states, such as California. Engineers are currently testing devices that could provide heat to the fuel cell to prevent freezing, however such a device would need to have a low enough power consumption as not to drain the car's battery too much.
There is also some criticism about developing technologies for hydrogen fuel cars. Before wide-scale implementation can be achieved, there are many hurdles that would need to be passed, both economic and technical. There is also some controversial, due to the fact that most of today's hydrogen supplies are produced using technologies that require fossil energy resources for its production. Some critics say that since we are still very far from being able to use hydrogen to its full potential as a fuel, efforts should be made instead on researching technologies that seem more likely to be used in the near future. There are several alternatives available, such as electric cars, or hybrids that can use both electricity and gasoline for fuel.