Trying to use a carbon neutral energy source for emergency power is very likely to have a higher carbon footprint overall due to the fixed cost of a rarely used

Trying to use a carbon neutral energy source for emergency power is very likely to have a higher carbon footprint overall due to the fixed cost of a rarely used infrastructure. For example, on a much smaller scale, before leds were so incredibly cheap, incandescent bulbs were more energy efficient overall than alternatives such as fluorescent lights for places that were rarely visited. Think cellars, attics, service closets ...