The present disclosure provides methods, assemblies, and systems for power production that can allow for increased efficiency and lower cost components arising from the control, reduction, or elimination of turbine blade mechanical erosion by particulates or chemical erosion by gases in a combustion product flow. The methods, assemblies, and systems can include the use of turbine blades that operate with a blade velocity that is significantly reduced in relation to conventional turbines used in typical power production systems. The methods and systems also can make use of a recycled circulating fluid for transpiration protection of the turbine and/or other components. Further, recycled circulating fluid may be employed to provide cleaning materials to the turbine.