MoMA.org | Interactives | Exhibitions | 1999 | Different Roads


	The fuel cell is the primary alternative to the battery for supplying power to an electric vehicle's motor. Although a fuel cell looks like a battery, the latter stores electric current in its electrodes, whereas the former uses hydrogen fuel to continuously produce electric current. Fuel cells work by chemically combining hydrogen and oxygen, a process that produces electricity and water. Because they produce under one volt each, multiple fuel cells are usually stacked in a row (making up a "fuel cell stack") to produce enough voltage for the motor. Both hydrogen and oxygen are prepared for the fuel cell by processing available substances. Hydrogen can be produced by reformulating a hydrogen-containing fuel, such as gasoline, methanol, or natural gas, or it can be stored in its pure form. Oxygen is taken from the air. To produce electricity, hydrogen is fed into one end of the fuel cell. There it meets a platinum anode that strips an electron from each hydrogen atom, producing a stream of electrons (that is, electric current) and a stream of hydrogen ions. The electric current flows to the electric motor, supplying it with power. At the other end of the fuel cell a platinum cathode combines the stream of hydrogen ions coming from the platinum anode, the electric current returning from the electric motor, and oxygen. These three react to produce water. A fuel cell is very clean, emitting only water. It is two or three times as good as a gasoline engine and runs quietly. Fuel cells can also be packaged into different shapes to fit flexibly into a vehicle's available space. Hydrogen fuel stores power more efficiently than batteries, and refueling takes less time than recharging a battery. Compared to battery-powered electric vehicles, fuel cell powered electric vehicles are projected to have a greater driving range (280 miles vs. 80-100 miles per tank). Fuel cells are currently costly ($200-$500 per kilowatt, compared to $30 per kilowatt for a conventional). The best way to develop a refueling infrastructure is uncertain. Hydrogen gas, which is not available in mass-market quantities, is highly reactive and hence hazardous to handle, and it is also difficult to store at the high density needed to efficiently generate power. The alternative, converting hydrogen by reforming hydrogen-containing fuels such as methanol or gasoline, is less efficient and produces toxic emissions. Methane reformulation is attractive because it produces only small quantities of carbon dioxide along with hydrogen. Gasoline reformulation is difficult, and is being considered mainly because the petroleum-fuel infrastructure is already in place. Fuel cells with alkaline electrolyte have been used on NASA spacecraft. In Diamond Bar, California, the headquarters of the South Coast Air Quality Management District gets its electricity from a fuel cell with phosphoric acid electrolytes. In Brea, California, the Unocal Corporation has a 250-kilowatt power plant that uses fuel cells with molten carbonate electrolytes. Fuel cell technology is less developed than battery technology, and much less mature than internal-combustion technology, but it is advancing at a great rate and appears very promising in the long term.