PICTURE yourself behind the wheel of a car in the dawning years of the 21st century.
Before you is the open road. Behind you is clean air.
Your only "exhaust" is the water that results from the electrochemical reaction in the fuel cells that power your vehicle.
The fuel is hydrogen, the simplest and most abundant element in the universe. Where today an internal-combustion engine would be burning gasoline in mini-explosions, the new car runs on an array of fuel cells that mix hydrogen with oxygen to form water. In the reaction, electricity is given off.
The oxygen comes from the air around you. The hydrogen comes from an on-board fuel tank, supplied by a filling station.
The scenario may sound far off, but the "hydrogen age" is surely coming, says Steve Misiaszek, senior engineer with Energy Partners, a company in West Palm Beach, Fla.
Energy Partners expects to have a working prototype of the hydrogen car ready in a month. The trick then will be bringing the manufacturing cost down to where fuel cells can compete with internal-combustion engines - a process that could take six years, Mr. Misiaszek estimates. Hydrogen fuel probably won't be in widespread use for 10 or 20 years, he says.
Fuel cells were invented in 1839 by the British scientist William Grove and supplied power for United States astronauts on the Appollo and Gemini missions.
Now American and Japanese companies are marketing fuel cells for commercial uses, such as supplying power to buildings. Southern California Gas Company has ordered 10 "fuel-cell power plants" from United Technologies Corporation (UTC) of Hartford, Conn. One plant will provide electricity and water heating in a hotel.
Gas companies see fuel cells as one way of competing with electric utilities to supply power. But if this market is to grow, the key again is bringing costs down, says William Podolny, chairman of UTC's fuel-cell unit. He expects fuel cells to become attractive economically when mass production cuts costs.
Another reason for gas-company interest: Hydrogen is typically derived from hydrocarbon fuels like natural gas or methane. Although this gives off some carbon dioxide and carbon monoxide pollution, the fuel cells do not create nitrogen oxides and sulfur oxides, as combustion does.
An even cleaner option - one that Misiaszek hopes will become widespread - is to use solar photovoltaic cells to derive hydrogen from water in a reaction that is basically the opposite of the fuel cell's. The solar energy is thus "stored" in the hydrogen for later use in the fuel cell.
In the Energy Partners car, about half the energy produced by the fuel cells is captured as electric power and half is given off as heat, Misiaszek says. For comparison, he notes that only 20 percent of the energy from an internal-combustion engine goes to move the vehicle, and 80 percent is heat.
Acceleration is aided by a 500-pound pack of supplementary batteries under the seats. The batteries can be recharged by the fuel cells. The fuel cells are packaged in two 150-pound stacks, each 1-foot square and 2-feet long.
The fuel cells can keep the car going for 300 to 400 miles on a tank of hydrogen - comparable to gasoline and much better than current vehicles powered by electric batteries. Also, those batteries require several hours to recharge.
When asked about safety, Misiaszek acknowledges that hydrogen is combustible but says a University of Miami test found it less risky than gasoline. Energy Partners is working on a "burst valve" that, if a collision damaged the fuel tank, would release all the hydrogen into the air in a split second, reducing risk to the vehicle occupant.
General Motors Corporation and Los Alamos National Laboratory are also working on a hydrogen-fuel-cell vehicle.