Good biofuels are odorless when burning. This happens, when the biofireplace has reached its operating temperature which, in most models, takes up to few minutes.During the first minutes of burning, you might notice a smell of biofuel, which vaporized, instead of combusting. In the case of good biofuels the smell is “alcohol”. Smelling “chemicals” like rubber, plastic or any kind of smoke means that the quality of the biofuel is on the lower side.