A heat recovery steam generator (HRSG) is coupled to a gas turbine engine that is configured to combust a fuel in air to produce shaft power and a flow of exhaust gases including oxides of nitrogen (NOx). The HRSG includes at least one duct burner for heating the exhaust gases and at least one NOx reduction element coupled downstream from the at least one duct burner and configured to facilitate reducing an amount of NOx in the exhaust gases that are channeled into the at least one NOx reduction element.