While I agree that there are few things that can be declared impossible, there are some. You can't make 2 + 2 = 38.4 because of the way the numbers and the concepts of addition and equality are defined. This is like that. The way in which science defines the term energy, means that it can't exist by itself.
It probably is impossible.
But they used to think life couldn't exist without oxygen, until they discovered volcanic vents that supported life without the things they considered vital.
Before the Big Bang, wouldn't there have been some form of energy in existence to have created the Big Bang in the first place?
Someone said, can't remember who, that energy couldn't be destroyed.
According to this it can't be created or destroyed
http://www.scientificamerican.com/article/energy-can-neither-be-created-nor-destroyed/We have another poster who comes in, now and again who seems to believe this energy is God.
Nicholas
I have no idea if an energy life form is possible.
Not as far as we know, I guess