First I want to know how much energy a human needs in coma. Then - for comparison - how much energy a hedgehog, a bear or anything but my PC needs to hibernate. Are there species (like the Polar Bear - I know this is not true) that hibernates at warm temperatures (cidadas) …and you can go on after this…
Targeted hypothermia is a real experimental treatment for humans, but it is not continued for months, so energy requirement is not a limiting factor.
Bears can hibernate for months without eating, true, but they need to eat up first since they end up losing 25% of their body mass. Energy required is about 0.09 MJ/kg⋅day to maintain lean muscle mass.