AT&T has announced an interesting “ZERO Draw” phone charger that draws no power when not charging a phone.  There are some exaggerated claims out there that phone chargers waste 95% of the energy they consume and many people are weary of the ads telling them to unplug their chargers to save the planet, but there is cumulative effect of chargers and the total energy consumption is significant.

The AT&T press release cited some fairly reasonable numbers of 0.17 watt power consumption per charger rather than some of the more exotic claims that “vampire power” draws as much power as charging the actual phone.  My measurements seem to be very close to the 0.17 watt claim when I measured across 5 separate chargers and I also measured 3 watts when charging my Samsung cell phone.  That would mean that if my chargers spend 17.65 hours in idle for every hour of charging, then the charger uses just as much total energy in idle as it uses while charging the phone.

While this 50% waste level is far from the exaggerated 95% waste claim, it isn’t a trivial amount of energy because it amounts to 47 million watts for 277 million people assuming one device per person.  I would guess that the average person has 3 of these chargers plugged in and some of them consume more than 0.17 watts so it could easily add up to more than 100 megawatts of power.

Realistically speaking I don’t think we are going to get people to unplug their chargers from the wall.  People can save a lot more power if they turned off unused lights or cut their shower time by 1 minute or turned their winter heater from 70 degrees to 69 (I personally prefer 65).  But if it is possible to build zero power chargers and eliminate 100 megawatts of power consumption, that would seem to make a lot of sense.