Power 2020

So how much power will the iPad of 2020 need? More less than the one of 2012?

One thought that I have had and I am sure lots of other folks have had this one before me is this, why can't the clothes that we wear and move in and also warm up with our body heat be used to generate power?

Could your jeans or tights have a network of nano generators in them arranged in the right way so that when you are moving around or just sitting there breathing you generate electricity, and if the devices of 2020 are also nano powered and the power they need is a lot less than today why can't they be powered by your clothes?

It's a good idea and I am sure that it will happen, probably not in the way I talk out here, but it will happen.