I am reminded (and partially embarrassed (as I cannot--for the life of me--find the textual reference)) of Peter F Hamilton's description of the advent of high-powered, minimally-sized battery technology.
Maybe first-referenced in the Mandell Series (?).
See: "butterfly-effect", or "armada storm".
I can't re-read the entirety of all his volumes in-time to provide a contextual quotation.
With the ability to house the equivalent power-capacity of 'a diesel locomotive engine into a device the size of a 9v battery', humanity became quite enamored--and quite beholden-to--empowering their everyday activities to such a degree that the collective emissive heat byproduct helped (and ultimately) collapse Earth's eco-system.
As fantastic--and priescentally erudite--as such a cautionary tale may be, our enthusiasm waters the seed of such futures.
To forestall that end (though it may mean that the devices I have, and love to use, will ultimately be remitted to recycled waste) I can't help but support most of AAPL's efforts to reduce power usage.
power-capacity ≠ efficiency