I recently ran across a "gel fuel fireplace" and had to look it up and see what this new (at least to me) fuel was about. After browsing around the web, I found that gel fuel is an alcohol-based product that isn't supposed to give off smoke or odors (that's what the various suppliers say, anyway). This means you don't need a chimney/vent to install a gel fuel fireplace. It sounds like gel fuel, unlike gas, doesn't give off much heat and is more about creating flickering flames and ambiance. You basically plug in a canister and it runs for a few hours.
Some of the main manufacturers of gel fuel are:
Amazon sells gel fuel fireplaces online. Examples: