There are some ethanol fireplaces made specially for outdoor uses. In addition if you have a floor standing or table model you can certainly move it to a patio whenever you would like as long as you have a flat sturdy surface to place the fireplace on. You should however avoid drafts, and in no circumstances should you expose your fireplace to rain unless you have an outdoor model. Even a fireplace attached to a wall can be moved when you remodel the house, or if you decide to move to another apartment or house.
