The demand for electricity and heat production is still largely covered by conventional thermal power plants based on fossil fuel combustion. Thermal power stations face a big challenge to meet the environmental requirements constantly keeping high process efficiency and avoiding lifetime shortening of critical components. In recent years, many activities have been observed to reduce pollutant emissions and optimize performance in thermal power plants. Increased share of renewable sources of energy in domestic markets enforces flexible operation and fast adjustment to actual demand. Gas power plants start to play a very important role in this process, allowing for rapid change of load and emission reduction. Operation under changing load together with keeping emissions at the accurate level requires constantly introducing new solutions and technologies as well as carrying out many research and development activities for optimization of the electricity and heat production process. The edited book is aimed to present new technologies, innovative solutions, measurement techniques, tools and computational methods dedicated to thermal power plants in the light of new trends and challenges.