Please look at the wikipedia article about thermal coherent states. We can only consider the states centered at the origin (##\alpha## = 0). If i understand what is written the vacuum is a pecular thermal state in the limit of a null temperature. I can understand that no energy can be borrowed from a system at this temperature. But this is because we used the word "temperature". How can we compute the energy that can be borrowed from a thermal coherent state? Is it N k T? Thanks.