FUEL CELLS—ENERGY FOR A POWER-HUNGRY WORLD - Chemistry: Notable Research and Discoveries - page 144

based on the name of the electrolyte.) Such variety allows fuel cells to op-
erate in a number of different conditions and temperatures.
As in batteries, fuel cells generate an electric potential, measured
in volts, which depends on the reaction. One of the simplest fuel cells
is called proton exchange membrane—a permeable membrane acts as
an electrolyte by conducting positive charges such as protons but not
electrons. This fuel cell generates about 0.7 volts, which is about half
the voltage of a common flashlight battery. Small voltages are sufficient
to power only the tiniest devices. But the lack of high voltage does not
spoil the use of fuel cells since the voltage can be increased by mak-
ing a fuel cell stack. A stack of fuel cells puts a number of fuel cells in
a row, creating a series circuit. As described in the sidebar on pages
142-143, the voltages of batteries in series add or combine to produce a
higher voltage. To create a stronger current, fuel cells should be placed
in parallel.
Although Grove's cell worked, it was inefficient and not practical for
everyday use. The earliest practical fuel cells did not appear until the 1950s.
In 1959, the British engineer Francis Thomas Bacon demonstrated an al-
kaline fuel cell capable of generating enough power to operate a welding
machine. Around the same time, Willard Thomas Grubb, a chemist work-
ing at General Electric, designed a fuel cell using a membrane. These early
fuel cells were expensive, but they soon filled a need for which other avail-
able electricity sources were not well suited—going beyond the planet.
PoWErIngSPACECrAFT
On October 4, 1957, the Soviet Union, as it was then known, launched
Sputnik, the world's first artificial satellite. This feat of technology not
only inaugurated the space age, it also spurred the United States into
investing a lot of time and money in its own space program. The plans
included an ambitious series of manned spaceflights, beginning in the
1960s, eventually leading to a landing on the Moon in 1969.
Spacecraft need power. Rockets provide propulsion, but the equip-
ment needed for control of the spacecraft and to provide life support for
the astronauts also need a source of energy. Much of this equipment runs
on electricity. One possible solution was to use batteries, but the Na-
tional Aeronautics and Space Administration (NASA), the U.S. agency
responsible for space exploration, rejected this idea. The problem with