Idling current
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Idling current refers to the current trickling through a circuit (or more commonly through transistors) such as an amplifier when the system is on, but doing no useful work. This is also known as quiescent current.
Many electrical appliances including computer and television peripherals, (printers, scanners, DVD players, receivers, etc.), continue to use energy, even after they are apparently turned off. While the button may indicate off, in reality, the device may be in a standby mode, and may draw anything from 0% to 100% of on power 24/7.
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[edit] Amount of standby power
The amount of standby power wasted in each nation is unclear due to lack of studies conducted. Estimates vary significantly, and those with a political agenda can be based on quite unrealistic figures. Alan Meier, an energy analyst who helped raise awareness about the problem while at Lawrence Berkeley National Laboratory in California, estimates that residential consumers in the United States spend more than $5 billion annually on standby power -- about 5 percent of all electricity consumed in the country (Woods, 2005).
[edit] Uses of standby power
Some standby power is necessary and useful, but its use has exploded since 1968 on the consumer electronics scene with the introduction of instant-on televisions. Earlier TVs took anything up to half a minute for the picture to appear as the picture tube warmed up, and valve sets also took several seconds for audio to appear. Standby power has sometimes been used to permit instant-on picture and sound, but in most cases quick picture appearance is due to the improved design of modern equipment.
Some standby power is useful to:
- keep remote controllable appliances such as TVs, VCRs, DVD players etc able to receive remote control instructions.
- allow security alarms to remain on alert.
- allow some refrigerators to use electronic temperature sensors to improve temperature accuracy and thus energy consumtpion a little.
- keep batteries in cell phones and camcorders fully charged
- light up the time display on microwave ovens, videos etc
[edit] Controlling standby power
Most standby power is a waste, consuming energy for no useful task. The reason for such consumption comes down to cost. Additional switching & control, and power supply efficiency do not come for free. In many cases the resulting power consumption is wasteful, but in some the additinal cost and power used to add further control would be greater than the power saved by the appliance in use.
Growing consumer awareness of standby power has led to the marketing of devices that can switch off the standby power consumption of products designed to remain on. Such products include
- Beamingsun's USB Ecostrip which allows the user to effectively control when peripheral devices power off by using patented USB technology.
- OneClickPower's smart surge protector with outlets for a computer, monitor, printer, scanner and other devices. Its circuitry senses when the devices go into a standby mode and automatically disconnects them (£29.95).
- the Smart Strip which monitors power consumption and can sense the difference between when computers and other devices are on or off. Upon figuring this out, it shuts off the power, eliminating the idling current drawn from them (US $32-$35).
- the Wattstopper which has six outlets controlled by occupancy and two outlets which are always on, and use a motion detector to monitor and manage energy use. Devices plugged into the controlled outlets are turned on and off based on occupancy, or the fact that they're currently using energy.
- The "Personal Sensor" connects to the power strip, and automatically turns power to all connected devices on when the accessories and peripherals are in use. These devices will turn off after they go idle and the user-defined time delay elapses (anywhere from 30 seconds to 30 minutes) (US $90). (Dunn, 2005)
