A flashlight battery supplies electricity without moving mechanical
parts. It converts the chemical energy of its contents _directly_ into
electrical energy.
Early direct conversion devices such as Volta’s battery, developed in
1795, gave the scientists Ampere, Oersted, and Faraday their first
experimental supplies of electricity. The lessons they learned about
electrical energy and its intimate relation with magnetism spawned the
mighty turboelectric energy converters—steam and hydroelectric
turbines—which power modern civilization.
We have improved upon Volta’s batteries and have come to rely on them as
portable, usually small, power sources, but only recently has the
challenge of nuclear power and space exploration focused our attention
on new methods of direct conversion.
To supply power for use in outer space and also at remote sites on
earth, we need power sources that are reliable, light in weight, and
capable of unattended Operation for long periods of time. Nuclear power
plants using direct conversion techniques hold promise of surpassing
conventional power sources in these attributes. In addition, the
inherently silent operation of direct conversion power plants is an
important advantage for many military applications.
The Atomic Energy Commission, the Department of Defense, and the
National Aeronautics and Space Administration collectively sponsor tens
of millions of dollars worth of research and development in the area of
direct conversion each year. In particular, the Atomic Energy Commission
supports more than a dozen research and development programs in
thermoelectric and thermionic energy conversion in industry and at the
Los Alamos Scientific Laboratory, and other direct conversion research
at Argonne National Laboratory and Brookhaven National Laboratory.
Reactor and radioisotopic power plants utilizing direct conversion are
being produced under the AEC’s SNAP[1] program. Some of these units are
presently in use powering satellites, Arctic and Antarctic weather
stations, and navigational buoys.
Further applications are now being studied, but the cost of direct
conversion appears too great to permit its general use for electric
power in the near future. Direct techniques will be used first where
their special advantages outweigh higher cost.