A district energy system based on “thermal bus” was proposed, in which the heating and cooling water transmission processes shared one set of the distribution pipe network. Combined with the gas energy stations, ground source heat pumps, small-scale photovoltaic power stations and rooftop solar collectors and other facilities, it provided the users in the region with heating in winter, cooling in summer and power supply all year round. From the perspective of the bidirectional (supply/return) flow of heat energy along the thermal bus, the mathematical model of the main equipment applied for the source, pipe network, load and storage was established. The optimization model with the lowest system operation cost was proposed considering the fuel cost, the external electricity purchase fee and the satisfaction degree of all users’ energy demand. The operation cost and energy consumption of the regional energy system scheme and the traditional distributed energy system scheme are studied by a practical case study. The results showed that the new scheme reduces the operating cost by 21.5% and 16.8% respectively under the typical weekly scenarios of cooling in summer and heating in winter. When no storage equipment was used, the new scheme reduced the amount of purchased electricity in summer and winter by 4.1% and 5.2% respectively.
Keywords thermal bus, distributed energy system, district heating, district cooling, optimized operation, energy planning