A method and system for cost effectively converting a feedstock using thermal plasma, or other styles of gassifiers, into a feedwater energy transfer system. The feedstock can be any organic material, or fossil fuel. The energy transferred in the feedwater is converted into steam which is then injected into the low turbine of a combined cycle power plant. Heat is extracted from gas product issued by a gassifier and delivered to a power plant via its feedwater system. The gassifier is a plasma gassifier and the gas product is syngas. In a further embodiment, prior to performing the step of extracting heat energy, there is provided the further step of combusting the syngas in an afterburner. An air flow, and/or EGR flow is provided to the afterburner at a rate that is varied in response to an operating characteristic of the afterburner. The air flow to the afterburner is heated.