Low-cost optimization of geothermal heating system with thermal energy storage for an office building

Abstract

Using geothermal energy to meet office building heating is an effective measure to reduce energy consumption. The heat demand of an office building features a significant intermittent profile; however, the geothermal submersible pump should not be started and stopped frequently within a heating season, which makes it difficult to match the continuity of heat source with the intermittent heat load and thus resulting in a serious waste of geothermal resources. The utilization of thermal energy storage (TES) technology can solve the problem of the mismatch between the supply and demand of the geothermal heating system for an office building. In this paper, aiming at obtaining a low-cost system while promoting the energy supply and demand balance, the geothermal heating system with TES for an office building located in Cangzhou, Hebei province, China is optimized based on a two-stage approach considering the time-of-use tariffs. The results show that the geothermal heating system including TES can effectively meet the heat load of office buildings without a backup facility. Compared with the benchmark system, although the addition of TES leads to an increase in the system capital investment, the system operation cost reduces by 38.10% or so under the optimal operation strategy. Besides, reasonable operation control of the TES as well as the heat pump is the key measure to reduce the system cost. Accordingly, the optimal operation strategy and corresponding equipment selection parameters of the geothermal heating system with TES are determined.