Abstract: A low emission and environmentally friendly apparatus and method is used to generate a high pressure stream of thermal vapor. The thermal vapor stream may be injected into a subterranean formation for recovery of highly viscous petroleum or used to turn a steam turbine for driving an electrical generator. In one implementation, the high pressure stream of thermal vapor is generated by burning a high temperature fuel, including any short or long chain hydrocarbon products from methane to coal, in an enclosed vessel to produce combustion gases. Various techniques may be used to improve heat distribution and lower the temperature of the combustion gases. Water may be used to quench the combustion gases and produce the superheated steam or vapor. The water may be introduced onto the combustion gases by spraying, weeping, dripping, and the like.