A certain high-tech gadget draws, roughly speaking, 1.5 Watts.
So, in a month, it'll consume a bit over 1 KWH.
Which, in the context of your electric bill, is basically zilch.
But, if you want to run it nonstop for a month without plugging it in?
You're looking at a seriously big, heavy battery, costing hundreds of dollars.
There are a lot of hours in a month. Never seems like enough, with regard to getting stuff done, but a great plenty when it comes to draining batteries.
The proposed location isn't even that far off-grid. But, alas, off the grid it is.
Another way to look at it is that batteries have very low energy density.
Still.
Posted by: philip.ngai | Saturday, 22 November 2014 at 19:22
Yup. I worked on a feasibility study, back in the 90s (when chips took more power, and batteries were about the same as they are now) for a system of wirelessly-updated supermarket shelf tags. Had to run on self-contained power for a few years.
Can we power it using photovoltaics and the overhead lighting?
No.
Can we put a Tesla coil in the middle of the store?
NO.
Can we use RTGs?
NO.
Turned out a lithium coin cell was our energy budget... and, with a clever protocol for only turning on the radio at prearranged times, we could just about meet the requirement, using the ASIC technology of a Swiss company that specialized in digital watches (which, back then, people still thought were a pretty neat idea).
The follow-on project (implementation) never went anywhere, but the study was certainly educational.
Posted by: Eric Wilner | Saturday, 22 November 2014 at 21:48