Mobile technology presents interesting advantages versus conventional technology. While a conventional PC could exceed even 400 watts a laptop should not demand more than 30 watts, being less than 20 watts pretty usual. And this is not specially related with screen size, although the rule says that smaller means less power requirements.
In smartphone technology the software developers normally think two times before creating power intensive applications because the users are not willing to accept them easily if there are other substitutes without that problem. However the specifications of these devices are increasing, which causes the psychological consequence of abundance when there's no pressure to stand up headaches in optimization and the programming languages go to a higher and higher level very distanced from machine language and the dreaded assembler with specific routines for each processor.
Laptops, netbooks, tablets and smartphones are quieter, and that's because they have fewer fans or none. A PC mixes normally three fans, adding a constant buzzing that it's counterproductive in general.
A PC processor is in the 45 – 110 watts range, with special cases reaching 150 watts. Intel Xeon E5-2687W v2 @ 3.40GHz is an example. That is like 20 laptops working without too much overload!
The PC sector is a field where this kind of realities start to be daily routines, with graphic cards near 200 watts or the possibility of using two connected by a cable, so that's why there are power supplies with more than 500 watts in the market. Ten children and that's 5 kW, a hundred 50 kW and one thousand 500 kW in exchange for a wasted afternoon and pollution because electricity still not comes 100% from renewable energies.
The same comparison, a thousand children playing with laptops at 15 watts, is 15 kW versus 500 kW and for sure, they will have comparable fun. The responsibility is from adult people, but... what happens when they also play without worrying about resources?
More energy consumed, a greater bill to pay thus mobile technology helps you to save economic resources while it helps the environment —let's insist here for the importance— when the electricity comes from sources that pollute air or create nuclear waste.
Relevant factors to choose or recommend mobile instead of conventional technology.