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General Motors Corp. today unveiled Hy-wire, the world's first drivable vehicle that combines a hydrogen fuel cell with by-wire technology

Fuel Cell Vehicles
Although they are not expected to reach the mass market before 2010, fuel cell vehicles (FCVs) may someday revolutionize on-road transportation. This emerging technology has the potential to significantly reduce energy use and harmful emissions, as well as our dependence on foreign oil. FCVs will have other benefits as well.

A Radical Departure
FCVs represent a radical departure from vehicles with conventional internal combustion engines. Like battery-electric vehicles, FCVs are propelled by electric motors. But while battery electric vehicles use electricity from an external source (and store it in a battery), FCVs create their own electricity. Fuel cells onboard the vehicle create electricity through a chemical process using hydrogen fuel and oxygen from the air.

FCVs can be fueled with pure hydrogen gas stored onboard in high-pressure tanks. They also can be fueled with hydrogen-rich fuels—such as methanol, natural gas, or even gasoline—but these fuels must first be converted into hydrogen gas by an onboard device called a "reformer."

FCVs fueled with pure hydrogen emit no pollutants—only water and heat—while those using hydrogen-rich fuels and a reformer produce only small amounts of air pollutants. In addition, FCVs can be twice as efficient as similarly sized conventional vehicles and may also incorporate other advanced technologies to increase efficiency.

No Greenhouse Gases
Burning fossil fuels such as gasoline or diesel adds greenhouse gases to the earth's atmosphere. Greenhouse gases trap heat and thus warm the earth because they prevent a significant proportion of infrared radiation from escaping into space. FCVs powered by pure hydrogen emit no greenhouse gases. If the hydrogen is generated by reforming fossil fuels, some greenhouse gases are released, but much less than the amount produced by conventional vehicles.

No Air Pollutants
Highway vehicles account for a significant share of the air pollutants that contribute to smog and harmful particulates. FCVs powered by pure hydrogen emit no harmful pollutants. FCVs that use a reformer to convert fuels such as natural gas, methanol, or gasoline to hydrogen do emit small amounts of air pollutants such as carbon monoxide (CO).

Helps Strengthen National Energy Security
FCVs have the potential to strengthen our national energy security by reducing our dependence on foreign oil. The U.S. uses about 20 million barrels of oil per day, at a cost of about $2 billion a week. In fact, half of the oil used to produce the gasoline you put in your tank is imported. Hydrogen can be derived from many sources, such as methanol, natural gas, and gasoline, as well as renewable resources such as water. This flexibility would make us less dependent upon oil from foreign countries.

More Energy Efficient
Internal combustion engines in automobiles convert less than 20% of the energy in gasoline into power that moves the vehicle. Vehicles using electric motors powered by hydrogen fuel cells are much more energy efficient, utilitizing 40-60% of the fuel's energy. Even FCVs that reform hydrogen from gasoline can use about 40% of the energy in the gasoline.
 

How They Work - Fuel Cells
There are several kinds of fuel cells, but Polymer Electrolyte Membrane (PEM) fuel cells—also called Proton Exchange Membrane fuel cells—are the type typically used in automobiles. A PEM fuel cell uses hydrogen fuel and oxygen from the air to produce electricity.
The diagram shows how these fuel cells work

Fuel Cell Stacks
Most fuel cells designed for use in vehicles produce less than 1.16 volts of electricity—far from enough to power a vehicle. Therefore, multiple cells must be assembled into a fuel cell stack. The potential power generated by a fuel cell stack depends on the number and size of the individual fuel cells that comprise the stack and the surface area of the PEM.

Hydrogen Sources
The PEM fuel cells in most FCVs use hydrogen to produce electricity. The hydrogen, however, can be supplied in several ways.

Design Flexibility
The use of fuel cell stacks and electric motors affords automobile manufacturers a great deal of flexibility in designing vehicles. Fuel cell systems can be designed to fit almost any shape or body style. For example, the prototype on the right houses all of the vehicle's drivetrain components on a skateboard-shaped chassis. Also, instead of one large electric motor, it uses four smaller motors connected directly to each wheel. Fuel cells can provide much more electric power than the 12 volt batteries in conventional automobiles. Therefore, FCVs can be equipped with more sophisticated and powerful electronic systems than those found in conventional gasoline vehicles. For example, some vehicle manufacturers are designing vehicles that use electronic steering and braking. Eliminating the steering column and wheel may make these vehicles safer.

Quieter
Fuel cell vehicles are much quieter than internal combustion engines although wind and road noise will still be present at higher speeds.

Pure hydrogen. FCVs can be fueled with pure hydrogen gas stored in onboard fuel tanks. Since hydrogen gas is diffuse, it must be stored in high-pressure tanks in order to store enough to travel reasonable distances on a full tank of fuel. Currently used tanks, which allow hydrogen to be compressed to 5,000 pounds/square inch (psi) of pressure, can only store enough hydrogen gas to allow FCVs to go about 200 miles before refueling. However, manufacturers are designing and testing tanks that will store more hydrogen at a higher pressure.

In addition to onboard storage problems, our current system for getting liquid gasoline to consumers can't be used for gaseous hydrogen. Therefore, new facilities and systems would have to be built, requiring significant time and resources.

Hydrogen-rich fuels. FCVs can also be fueled with hydrogen-rich fuels, such as methanol, natural gas, petroleum distillates, or even gasoline. These fuels must be passed through onboard "reformers" that extract pure hydrogen from the fuel for use in the fuel cell. Reforming does emit some carbon dioxide (CO2), but much less than gasoline engines do.

The fuels mentioned above contain enough hydrogen to allow FCVs to travel the same distance as a conventional vehicle on a single tank of gas—about 300 to 400 miles. Also, unlike hydrogen gas, liquid fuels like methanol and gasoline wouldn't require a completely new system for delivering fuel to consumers.

Although there are advantages to powering FCVs with these fuels, there are also several disadvantages.

    Onboard reformers add to the complexity, cost, and maintenance demands of a vehicle's fuel cell system.

    If the reformer allows carbon oxides to reach the fuel cell anode, it can gradually decrease the performance of the cell.

    Reformers produce small amounts of greenhouse gases and other air pollutants.

It is not yet clear which method of fueling fuel cells will prevail. Research and development continues for all of these fueling options.

Fuel Cell Systems
PEM fuel cells are the center of an integrated propulsion system—one that is radically different from conventional vehicle systems. The diagram below shows the basic components of a hydrogen-fueled FCV.

FCVs like the one above use pure hydrogen as fuel, stored onboard the vehicle in highly pressurized tanks. Other FCVs are designed to use a liquid fuel such as gasoline or methanol, which is stored in a conventional, non-pressurized tank.

FCVs using these fuels also need a reformer—a fuel processor that breaks down the fuel into hydrogen for the fuel cell, carbon dioxide, and water. Although this process generates carbon dioxide, it produces much less than the amount generated by gasoline-powered vehicles.

Fuel cell vehicles can also be equipped with regenerative braking systems that capture the energy usually lost during braking and store it in an up-sized battery.


Mercedes-Benz A-Class


General Motors

What's New
Automakers DaimlerChrysler, Ford, Honda, Nissan, and Toyota have announced plans to market fuel cell vehicles in the U.S. on a very small scale by 2002-04. Honda plans to lease a limited number of its FCX vehicles in the U.S and Japan by the end of this year. However, these vehicles will only be available on a lease basis and will only be available to a few fleets that have ready access to hydrogen fueling stations. Toyota plans to offer about 20 hybrid fuel cell SUVs based on its Highlander platform by the end of this year. Similar limitations will apply. DaimlerChrysler announced that it would deploy about 60 Mercedes-Benz A-Class "F-Cell" FCVs in the 2003 calendar year. These cars will be operated and tested by customers within joint ventures in the U.S., Japan, and Singapore. Nissan has announced plans to start selling a fuel cell vehicle by 2003, and Ford Motor Co. said it would offer a fuel cell version of the Focus in low-volume production for small fleet operations in 2004.

None of these manufacturers have announced plans for mass marketing these vehicles

First Drive-by-Wire Fuel Cell Vehicle
General Motors recently introduced its new HyWire fuel cell vehicle, the first drive-by-wire FCV prototype. The HyWire takes advantage of two strengths of fuel cell vehicles: design flexibility offered by removing the bulky internal combustion engine and the ability to provide enough electric power for sophisticated electronic systems.

In the HyWire, the driver operates the vehicle via an electronic control unit rather than a steering wheel and pedals. The HyWire is based on GM's AUTOnomy FCV platform that houses all of the vehicle's propulsion and control systems within an 11-inch-thick skateboard-like chassis, maximizing the interior space for five occupants and their cargo. Various body types can be "docked" to the chassis
 

Fuel cells may eventually replace the internal combustion engine as a clean, highly efficient source of power for all types of highway vehicles. A fuel cell is a device that converts hydrogen fuel (obtained from natural gas, gasoline, methanol, propane, etc.) via an oxidation process into electricity. The process is an electrochemical reaction that is similar to the process that occurs in a "normalbattery. The only byproduct of reaction is wate

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