I also agree that this estimate is way off, but I think the idea is to think of the total energy use of the phone when you include the energy used by the servers that provide the services you use in apps. That is much harder to measure. Luckily Google, Facebook and Twitter invest a lot in energy saving at their data centers so it's one of the leanest ways of using compute power. I think that even when you put that energy into the equation, it's still nowhere near a refrigerator.