Coal- and gas-based power plants currently supply the largest proportion of the world's power generation capacity. Demands for improved efficiencies and cleaner generation mean that higher temperature combustion and advanced emissions controls need to be incorporated into power plant, which combines with requirements for more diverse fuel compositions (i.e. fuel-flexibility) to intensify plant degradation and put an energy penalty upon the plant's power output. With higher cycles to maintain net power output, the importance of plant protection is likewise intensified, requiring the utilization of improved materials, systems and components to ensure overall plant performance improvement and life management. This book critically reviews the fundamental degradation mechanisms that affect conventional power plant systems and components, noting mitigation routes alongside monitoring and assessment methods. Maintenance and replacement routes are further extended through chapters on the management and refurbishment of advanced systems and components.