Talk to me about bio ethanol fuel fires.

We’re thinking of getting one as we have no means to install a wood burner in our 70’s property (not without significant work and cost) so we are looking at getting a bio ethanol fire for our living room. My main concern really is getting a real idea of how long the fuel will burn for, how much heat will be produced and whether gel or liquid forms of fuel are better or the same as one another.

Anyone have one who could advise on burn time?