Cogeneration is a total energy system based on the concept of energy cascade utilization, integrating (including heating and heating) and power generation processes. Its biggest feature is the step-by-step utilization of different qualities of energy. The higher temperature, the higher available energy is used to generate electricity, while the lower temperature low-grade heat is used for heating or cooling. This not only improves energy efficiency, but also reduces emissions of carbides and harmful gases, and has good economic and social benefits. Under the guidance of the principle of scientific energy use and energy cascade utilization, the cogeneration system can achieve more efficient use of energy, fully meet the requirements of building a conservation-oriented society, and is an important technical way to solve China's energy and environmental problems. A key technology for a new generation of energy systems.