The title of this post would read just as well as "Power Waste on an Idle Laptop".
I also see "Usage" quite a lot on GitHub Readme pages, where I think "Use" would suffice.
Many words seem to be shortened for common use. E.g. Photograph to photo.
Why extend the length of other words?
Of the six potential uses, I think this one is most relevant:
"Forming nouns indicating a process, action or result. E.g. blockage, slippage, shrinkage"
Yet in this case the extension to "wastage" still feels somehow redundant. For example, I wouldn't say "Household wastage in modern society".
http://www.ourcivilisation.com/smartboard/shop/gowerse/abc/w...
I guess in this case I would read "wastage" as the reduction of available power over time. That is, the power was wasting away. Rather than the "waste" of power (frivolous use) by too many CPU cycles.
Anyway, English, wonderful language.....
Traditional Unix 'man(1)' pages are against you.
(And those were by the famously concise /usr, /bin and 'creat()' guys, though that last one was later regretted in a moment of weakness ;-)