| Technical progress, electronics in
transport, life, and medicine stimulated development of portable
sources of power supply, amongst which, the chemical sources of power,
in magnitude relation, occupied foreground by becoming product of mass
consumption. Portable luminaries (lighting fixtures), tape-recorders
and radio, television sets and portable medical equipment, means of
railway transport, automobiles, tractors, aircrafts, artificial
satellites, space crafts, communication means and many other are
equipped with small power supply sources. .
Theory of sources of power supply envisages study of all electrical
current generation stages on the basis of modern representations about
physics of solid body, liquid and gas, about transfer process of
charges and electrochemical reactions. Theory of power supply sources
also studies optimization issues, including how to select the initial
parameters, ensuring optimum output characteristics of sources of
power as well as developing the methods to forecast the
characteristics of future power sources. The following form the main
characteristics of power sources: Efficiency, power consumption (or
specific power consumption), rating (or specific power rating,
attributed to unit mass, volume etc), service life, quality of
generated electrical energy (frequency, voltage, capability to
withstand overloads, pricing and reliability).
Chemical sources of power supply: Facilities, generating electrical
energy due to the oxidation- reduction reactions of chemical reagents.
With respect to operating circuit and capability to produce energy
into electrical network, chemical sources of power supply are divided
into primary, secondary and reserve and also electrochemical
generators. Primary source of power supply (Galvanic cells and
batteries) allow, as a rule, single-time usage of energy of chemical
reagents.
Secondary source of power supply (individual batteries and storage
batteries) allow multiple (hundreds and thousand charging-discharging
cycles) usage of energy of constituent chemical reagents.
Reserve sources of power supply allow only single time energy usage of
chemical reagents. Unlike galvanic cells and batteries, in reserve
sources of power supply, electrolyte is galvanically never connected
with electrodes during storage. Storage life of latest reserve sources
of power supply exceed 10-15 years.
Electrochemical generators (Fuel cells) represent themselves as a
variety of chemical power sources. Electrochemical generators are
capable to continuously generate electrical current for long-term as
a result of energy conversion of chemical reagents (gaseous or
liquefied), received into generator from external supply.
Physical sources of power supply: Facilities, converting heat,
mechanical, electromagnetic energy and also energy of radiation and
nuclear disintegration into electrical current. In conformity with
most frequently used classification, the following belong to physical
sources of power supply: Electric generators, thermo-electrical
generators, thermo-emission converters and also generators, converting
energy of solar radiation and atomic decay.
Electric generators, converting mechanical energy into electrical
energy - widely used type of electrical sources , based on latest
power engineering. They can be classified with respect to rating
(ranging from fractions of watts to hundreds of watts), as per
purpose and operating characteristics (stationary, transport, reserve
etc), as per type of primary motor (Diesel generators, turbo, and
hydro-treaters), according to working body (vapor, water and gas) etc.
Thanks to significantly long time spent on theoretical, design and
technological upgrade, characteristics of this type of power
source attained values, close to permissible values.
Probable usage areas of thermoelectric generator (TEG): Autonomous
power supplies (in transport, in communication technology and in
medicine), anti-corrosive protection (on trunk pipelines) & others.
Working principle of power source, converting energy of solar
radiation, is based on internal usage purpose. Photoelectric generator
(solar battery) is a collection of valve-type photoelectric cells,
converting energy of solar radiation into electrical energy. Direct
conversion of solar radiation energy was practically possible only
after developing the high-effective photoelectric cell from
mono crystal silicon in the year 1953. Best samples of silicon
photoelectric cells have efficiency of approximately 15% and service
life practically unlimited. Solar batteries are used mainly in
aerospace technology, where the batteries occupy dominating position
as energy sources in artificial Earth satellites, orbiting space
stations and space crafts and also for supplying power to regions,
which are yet to be supplied electricity, with maximum sunny days in a
year.
Power sources, converting the atomic decay (atomic batteries) use
kinetic energy of electrons, formed during the decay. These power
sources were invented by 1971 during the development stages and
practical usage require solutions to several design and technological
issues. Efficiency of atomic batteries is not so high (up to 1%) and
field of application can be determined only after accumulating
sufficient experience in using them. |
US Department of Defense announced the open competition for the best design of a portable power system for troopers. The requirements are: the device has to weigh within 8 pounds and be able to power most electronic equipment - radios, global positioning systems, night vision devices - for a single trooper for a period of four days. The new power generator device will replace the current wearable power systems used the US army - they weigh over 19 pounds and include battery pack and solar panel generator with the accessories. DOD will announce the three winners in 2008, and the chosen design will get a $1 million check for the exclusive right to use the design for mass production in the US military.
