No, it is not safe to use large Traeger models in a garage. The temperature will rise too high, and it may catch on fire or, worse, explode! However, with smaller, portable models such as the Tailgater, you can use them if your garage is large enough. For this purpose, you will need a power supply. This means that you would either need to have an outlet in the garage or be able to run a cord from another room of your house into the garage.