This textbook provides a detailed description of the procedures and methodologies for plant accounting in energy technology. It equips students and engineers with a comprehensive toolkit for the planning and optimization of facilities. In addition to fundamental equations, modeling approaches, and numerical methods, material and energy accounting is demonstrated through a variety of example calculations. The book covers a wide range of topics, from the functioning of components to the fundamentals of thermodynamics, reaction calculations, phase equilibrium calculations, and material value calculations, all the way to computer-based implementation. All relevant components of energy technology are considered, including combustion chambers, turbines, compressors, heat exchangers, equilibrium stages, and synthesis reactors.