A power plant includes a turbine having a plurality of turbine stages and an extraction port in fluid communication with one or more of the turbine stages. The extraction port provides a flow path for a stream of combustion gas to flow out of the turbine. An exhaust duct is disposed downstream from the turbine and receives exhaust gas from the turbine. The exhaust duct is fluid communication with the extraction port. A coolant injection system injects a coolant into the stream of combustion gas to provide cooled combustion gas to the exhaust duct. The cooled combustion gas flows into the exhaust duct at a temperature that is higher than a temperature of the exhaust gas, thereby increasing the temperature of the exhaust gas within the exhaust duct. The increase in thermal energy may be used to produce steam downstream from the exhaust duct.