Energy efficiency of power supplies
Some estimates claim that a Google search consumes as much electricity as an energy-efficient lightbulb does in an hour. The blame lies with the inefficient electrical consumption of today's huge server farms. Even if the savings potential using modern power supplies were only one percent, assuming a total number of 30 million servers (projection for the year 2011), the potential savings would be 360 Megawatts, or the output of an entire hydroelectric plant in a year.
PC-based Telephony and VoIP
If a caller is working on the PC while talking over PC-based telephony, the additional power requirement remains minimal. For private users, however, this is seldom the case, so all the power channeled into the PC is used for PC-based telephony alone. And that can be as much as 250 watt-hours for a desktop PC or 30 to 40 watt-hours for a notebook. If PC-based telephony is used only for outbound calls, the costs incurred remain within reasonable limits. At a rate of 15 cents per kilowatt-hour, the charge is about 4 cents per hour. However, if the PC is left running around the clock to cover inbound calls as well, this alone can add up to an electricity bill of as much as 300 USD per annum. Aware of this, some BC-based telephony operators are now also selling Wifi phones that use just 1.5 watt-hours during a call and around 150 milliwatt-hours in standby mode.