Self-powered equipment
Encyclopedia
Such devices contain electrical generator
Electrical generator
In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge to flow through an external electrical circuit. It is analogous to a water pump, which causes water to flow...
s or an induction
Electromagnetic induction
Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids....
system to recharge their batteries
Rechargeable battery
A rechargeable battery or storage battery is a group of one or more electrochemical cells. They are known as secondary cells because their electrochemical reactions are electrically reversible. Rechargeable batteries come in many different shapes and sizes, ranging anything from a button cell to...
. Separate crank-operated generators
Electrical generator
In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge to flow through an external electrical circuit. It is analogous to a water pump, which causes water to flow...
are now available to recharge battery-powered portable electronic devices such as cell phones. Others, such as mechanically powered flashlights, have the generator integrated within the device itself. A promising alternative to rechargeable batteries for electricity storage is supercapacitor
Supercapacitor
An electric double-layer capacitor , also known as supercapacitor, supercondenser, electrochemical double layer capacitor, or ultracapacitor, is an electrochemical capacitor with relatively high energy density. Their energy density is typically hundreds of times greater than conventional...
s, now being used in some devices such as the mechanically powered flashlight shown here.
Other devices store the energy mechanically, instead of in batteries. Clockwork radio
Clockwork radio
A windup radio or clockwork radio is a radio that is powered by human muscle power rather than batteries or the electrical grid. In the most common arrangement, an internal electrical generator is run by a mainspring, which is wound by a hand crank on the case. Turning the crank winds the spring...
s have a mainspring
Mainspring
A mainspring is a spiral torsion spring of metal ribbon that is the power source in mechanical watches and some clocks. Winding the timepiece, by turning a knob or key, stores energy in the mainspring by twisting the spiral tighter. The force of the mainspring then turns the clock's wheels as it...
which is wound up by a crank, and then turns a generator to power the radio.
Uses
An early example of regular use of human-powered electrical equipment is in early telephoneTelephone
The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...
systems; current to ring the remote bell was provided by a subscriber cranking a handle on the telephone set, which turned a small magneto
Magneto
A magneto is a type of electrical generator.Magneto may also refer to:* Magneto , permanent magnetic alternating current rotary generator* ignition magneto, magnetos on internal combustion engines...
generator. The World War II-era Gibson girl
Gibson Girl
The Gibson Girl was the personification of a feminine ideal as portrayed in the satirical pen-and-ink-illustrated stories created by illustrator Charles Dana Gibson during a 20-year period spanning the late nineteenth and early twentieth century in the United States.Some people argue that the...
survival radio
Survival radio
Survival radios are carried by ships and aircraft to facilitate rescue in an emergency. They are generally designed to transmit on international distress frequencies...
used a hand-cranked generator to provide power; this avoided the unreliable performance of dry-cell batteries that might be stored for months before they were needed, although it had the drawback that the survivor had to be fit enough to turn the crank.
Human-powered devices are useful as emergency equipment, when natural disaster
Natural disaster
A natural disaster is the effect of a natural hazard . It leads to financial, environmental or human losses...
, war
War
War is a state of organized, armed, and often prolonged conflict carried on between states, nations, or other parties typified by extreme aggression, social disruption, and usually high mortality. War should be understood as an actual, intentional and widespread armed conflict between political...
, or civil disturbance make regular power supplies unavailable. They have also been seen as economical for use in poor countries, where batteries may be expensive and mains power unreliable or unavailable. They are also an environmentally preferable alternative to the use of disposable batteries, which are wasteful source of energy and may introduce heavy metals into the environment
Environment (biophysical)
The biophysical environment is the combined modeling of the physical environment and the biological life forms within the environment, and includes all variables, parameters as well as conditions and modes inside the Earth's biosphere. The biophysical environment can be divided into two categories:...
.
Available power
A trained cyclist can produce about 400 watts of mechanical power for an hour or more, but adults of good average fitness average between 50 and 150 watts for an hour of vigorous exercise. While some exercise equipment has been fitted with generators, the amount of energy collected is of low value compared to the cost of the conversion equipment. A healthy well-fed laborer over the course of an 8-hour day can sustain an average output of about 75 watts.Examples
- Batteryless radioBatteryless radioRadio receivers were originally operated by battery. The term batteryless radio was initially used for the radio receivers which could be used directly by AC mains supply ....
- Clockwork radioClockwork radioA windup radio or clockwork radio is a radio that is powered by human muscle power rather than batteries or the electrical grid. In the most common arrangement, an internal electrical generator is run by a mainspring, which is wound by a hand crank on the case. Turning the crank winds the spring...
- Mechanically powered flashlight
- Pedal radioPedal radioThe Pedal Radio is a radio powered by a pedal-driven generator. It was developed by Alfred Traeger in 1929 as a way of providing radio communications to remote homesteads in the Australian outback. There was no mains or generator power available at the time and batteries to provide the power...
- Gossamer CondorGossamer Condor-See also:-Further reading:*Morton Grosser. Gossamer Odyssey: The Triumph of Human-Powered Flight. MBI Press, 2004; Dover Publications, Inc., 1991; Houghton Mifflin Co., 1981*Morton Grosser. On Gossamer Wings. York Custom Graphics, 1982...