in situations where you want or need to look into "uninterruptible power backup" at even a reasonably small scale (e.g. a large apartment building or a hospital

in situations where you want or need to look into "uninterruptible power backup" at even a reasonably small scale (e.g. a large apartment building or a hospital), given the cost and durability of a diesel generator, once you've bought and installed one, turns out you might as well run it. Varying economic and regulatory conditions can make it more or less viable, but it's in the range of feasible.