Microsoft, along with a team of Perdue University researchers, released a study examining the energy consumption of free smart-phone applications. Everyone knows that free apps such as Angry Birds, Facebook, and New York Times rely on advertising to pay their wages, but not many people know just how much energy those Angry Birds are consuming.

The study's findings show that, in one case, up to 75% of an app's energy consumption was spent on powering advertisements. These studies were performed on Android and Windows Phone (iOS restrictions made iPhone testing unlikely) and used a standard 3G connection. Chris McClelland, director of Belfast-based app developer Ecliptic Labs, said he was not surprised by the findings. "Advertising needs to connect to the server and send information about location," he explained.  "That just takes up so much battery. It seeps up the energy."

Take, for example, the wildly popular and addicting Rovio game Angry Birds. Only 20% of the total energy usage was attributed to the actual game, while 45% of the rest is used for GPS and targeted advertising purposes. When you factor in the “3G tail” - those ten seconds of 3G connection that exists after the data is downloaded to your phone – the power drain really starts to be seen.

The easiest way around this is by purchasing the paid counterpart. If it’s an app you use often, and you have a dollar lying around, the decision may be a no-brainer. Some bloggers suggest switching your phone to “airplane mode” to skirt the issue, while others are telling users to root their phone (voiding warranty), install AdAway, and enjoy all the ad-free gaming they could want. 

While it’s no surprise that free versions of apps use ads, it’s interesting to see the economics first-hand. Whether you buy the full version of the app or not, the developers are still getting paid. Yet another way free stuff isn't always worth it.

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