Millions of shiny new tablets, smartphones and PCs have been taken into use in late December and early January. Someone who reads ebooks on an ereader, listens to digital music on a smartphone and watches movies on a tablet may have multiple mobile devices that have to be charged every now and then. How much valuable energy do these electrical devices consume?

Forbes has put together information about energy consumption of common mobile devices, and the results are actually pretty green. Portable electronics are truly efficient with electricity. Let’s look at a few examples.

Tablet: Apple iPad

In typical use, an iPad is fully charged once in every 48 hours. The annual energy consumption is 12 kWh, which makes about $1.50 per year (in US electricity prices).

Smartphone: iPhone

If you have to daily charge your iPhone from empty to fully-charged, the annual electricity consumption of the smartphone is 2 kWh. It means 25 cents per year.

Laptop

An average laptop in average use consumes about 72 kWh worth of electricity per year. The annual cost of energy required by a laptop is $8.

For comparison: a light bulb

A traditional 60W light bulb is a wonderful source of heat during cold winter days, but the price is high: 220 kWh per year (10 hours a day). The cost for lighting up, for instance, a reading nook is $26 per year. A LED light bulb that provides similar amount of light consumes far less energy: $4.40 per year.

Especially when traveling it may feel that the battery dies just when you were about to capture the best photo of the whole trip or when you are about to reply to an urgent email message waiting in your tablet’s inbox. At these energy consumption levels, it should be fine to ask a shop owner, café proprietor or taxi driver to lend some energy to a mobile device.