There are a number of ventless linear burners that can be used to create an outdoor fire feature. Alcohol fueled burners are constructed in stainless steel and the high quality brands are marine grade. The key is to keep rainwater out of the burner elements with lids or place in a fireplace like you see here. Stainless steel fireplaces are available as a set including the burner ready to build around. Custom sizes are available as well. Or, you can construct your own non-combustible firebox, line it with tiles or stone, and insert the burner of your choice.
You can view your options for linear burners and fireplaces at www.myurbanconcepts.com and see loads of design ideas at www.ecosmartfire.com.