Energy Cascading in Large District Heating Systems

District heat transfer is the most economical utilization of the waste heat of power plants. Optimum utilization and heat transfer over large distances are possible because of a new energy distribution system, the “energy cascading system,” in which heat is transferred to several consumer regions at different temperature ranges. It is made more profitable by the use of heat pumps. The optimum flow-line temperature is 368 K, and the optimum return-line temperature is 288 K, resulting in an ∼50% reduction of electric power loss at the power plant.