WASHINGTON, April 21— The Ford Motor Company plans to build a prototype electric car that gets its power from a fuel cell rather than from batteries, the company and the Energy Department said today.

The car will carry compressed hydrogen gas, which the fuel cell will mix with oxygen from the air to make water in a low-temperature chemical reaction that also gives off electric current. The car would probably have the energy supply to travel many more miles than electric cars that run on chemical batteries, according to experts, and could refuel quickly. Ford said the car could be ready for evaluation by 2000.

The car would qualify as a zero-emission vehicle under California clean-air rules, the most stringent in the country, which call for 10 percent of cars and other light-duty vehicles sold in the state to produce zero emission by 2003. It is not clear, though, whether the deadline will be delayed; California previously waived its requirement that 2 percent of cars produce zero emissions in the 1998 model year.

Ford will build the car under the Partnership for New Generation of Vehicles, a coalition of the Big Three American car makers and the Government whose goal is to develop a clean, safe vehicle with very high fuel efficiency at a price consumers will find attractive.

The Energy Department and Ford are still negotiating, but the Government's contribution to the project may be in excess of $10 million. The entire project may cost $30 million.

Also today, the Canadian Government said it would subsidize Ballard Power Systems Inc., a manufacturer in Vancouver, British Columbia, to build a fuel cell that could be used in the Ford vehicle. Two other companies, Mechanical Technology Inc. of Latham, N.Y., and International Fuel Cells of South Windsor, Conn., a unit of the United Technologies Corporation, are also candidates to supply the fuel cell.

Fuel cells under development can vary their power output from zero to 40 or 50 kilowatts in a few thousandths of a second, according to Sandy Thomas, the research director of Directed Technologies Inc. of Arlington, Va., a consulting firm that has worked with Ford on the project. That amount of power is enough for 10 houses.

The announcement is the first big collaboration between a major auto maker and the Government on fuel cells, but the field has attracted strong interest recently. Last May, Daimler-Benz A.G. demonstrated a six-passenger van that ran on fuel cells, and last fall, the Toyota Corporation showed off a fuel cell version of its RAV4 sport utility. In January, the Chrysler Corporation said it would develop a fuel-cell vehicle that converted gasoline to hydrogen and could therefore refuel at conventional gasoline stations.

According to Jason Mark, a transportation analyst at the Union of Concerned Scientists, an environmental group, fuel cells are ''perhaps the most promising technological option from an environmental perspective and a consumer perspective.''

The Ford design might run entirely on the fuel cell, or it might include a small chemical battery to increase energy efficiency by recapturing braking energy that would otherwise be wasted. In a car that is driven by electric motors, the motors can be used as brakes, too, converting momentum into electric current and slowing the vehicle, but to make use of that energy, the car has to have some kind of storage device.

Ford said that for the project it would use the P2000, a family-size car body that is under development and is made of aluminum, titanium, composites and other low-weight materials.