From the piece:
In that context, smartphones’ ability to give users the portability and connectivity that they seek, but at a much lower energy cost than is associated with traditional devices, marks a clear and epochal change in the way we use energy.
Smartphones: smart for energy efficiency
When all’s said and done, smartphones prevail as an energy-efficiency winner when it comes to the way we send an email, watch a video, or share a family photo (sorry, digital photo frames). Put simply, a day spent web-surfing and facebooking on a smartphone or tablet is a much more energy-efficient day than doing the same on a traditional computer.
It’s again important to point out that the energy usage statistics we considered here solely represent in-home energy consumption (e.g. charging our phones and keeping our TVs plugged in). They don’t reflect the energy requirements of data centers, whose massive computer servers sustain our nonstop internet usage and smartphone activities.
The other takeaway, from the article, is that the total cost of keeping your smartphone charged, for an entire year, is less than a dollar/pound/euro. So, next time you feel guilty about your phone charging habits, don't. All the messing around with phone chargers (etc) makes hundreds of times less difference than watching 1% less TV on your power-guzzling plasma in the corner of the living room.
Fascinating stuff. Anecdotes and other relevant links welcome, perhaps from around the world!