Truly freestanding portable fireplaces are not connected to a flue, vent or chimney. That essentially limits them to either bio-ethanol fuel or electric powered models. Both types can be used indoors or outdoors but have risk and limitations. The exception is a chiminea, which has it’s own built-in chimney.
Bio-ethanol freestanding fireplaces store the liquid fuel in their burner, which must be lit and periodically refilled. The process of filling the burner and lighting it can be dangerous, especially if near flammable materials. Additionally, placement of a bio-ethanol fireplace should be made with careful consideration of foot traffic and the presence of children or pets. Lightweight versions or ones placed in the middle of the action are at risk of being knocked over. Additionally, curious hands and inadvertent tails could be burned if the flame is easily accessed.
Electric portable fireplaces are somewhat limited by their proximity to power outlets and the capacity of any battery pack. They too might tip over if bumped or burn if touched. Depending on the power usage, electrical standalone fireplaces might overwhelm a well-used power strip and cause an electrical short. Typically, these are less common outside as it’s easy to trip on long power cords.
Chimineas burn wood and are used exclusively outdoors. Due to sparks and flying embers, they should be placed on non-flammable surfaces and away from any materials that could accidentally catch fire from burning debris. These freestanding fireplaces also get very hot to the touch, so kids and animals need to stay clear. Some chimineas are ceramic and can shatter if knocked over on concrete floors.