Disclosed herein is a method for generating steam, comprising oxidizing a fuel to generate heat via a flameless reaction; and using the heat generated via the reaction to convert water to steam. In an embodiment, the amount of NOx present is flue gas from the reaction is less than about 10 PPMv. In an embodiment, the reaction temperature is less than about 2600° F. (1430° C.). In an embodiment, the method further comprises controlling the reaction temperature to minimize the formation of NOx. In an embodiment, controlling the reaction temperature further comprises sensing one or more process variables and adjusting a process controller in response to the sensed process variable. Also disclosed herein is a steam generator comprising a reaction zone wherein fuel is oxidized to generate heat via a flameless reaction and a heating zone wherein water is converted to steam via heat from the reaction.