An optimization method for design and operation of combined cooling, heating, and power systems toward a smart grid

Combined cooling, heating, and power systems are regarded as efficient, reliable, and environmentally friendly technologies for energy utilization. Besides, smart grid is an intelligent electricity delivering system, bringing benefits to utilities and consumers as well as improving the energy efficiency and reliability on the grid. The combination of the two provides a promising energy solution for future distributed energy systems. An optimization method was proposed for the design and operation of combined cooling, heating, and power systems toward a smart grid. The program enables optimization of components' sizing, biogas, and electricity on hourly demand. Hence, the program contributes to the smart grid demand side response. A sewage treatment plant in Hong Kong was selected for the case study because of its need for simultaneous heating, cooling, and power from self-generated biogas. The simulation was conducted under different sizing criteria and biogas prices. The combined cooling, heating, and power system can avoid dependency on utilities if the peak-load-sizing is adopted. For sewage treatment plants, it is more economically attractive to adopt a larger system. The optimized strategy revealed that the combined cooling, heating, and power should be operated longer at full load when biogas price is cheap and should be operated at part load, simply to satisfy the heating load, when biogas is expensive.