so, when a patients heart has stopped, how much power does it take to artificially keep the blood flowing?
If a person’s heart is temporarily stopped then we still have a living body – so I think it is pointless using that example.
Rather, let’s take a mechanical hydraulic system. Your potatoes might have some potential energy but hydraulic systems use a lot of energy. The energy lost from what is put into the pump (see above) to what is generated in lift by the hydraulic cylinder, is about 80%. And this is with ideal conditions; (nice wide piped to carry the hydraulic fluid, and the shortest possible distance from pump to hydraulic cylinder).
Try making the diameter of the pipe 8 microns, and the distance from the pump to the hydraulic cylinder 128,000 kilometres, and you have lost 100% efficiency. Or as I pointed out in my original post to this thread; if you attempt to pump through just 128 mill of 8 micron pipe you will lose 100% of your energy – zero efficiency.