Analysis of Policy Incentive for Chillers With Thermal Storage: a Case Study From India

Centralized chiller plants with thermal energy storage helps in saving electrical costs in utilities with differential tariff system but its effect on energy savings needs investigation. Even regarding cost savings, life cycle analysis is required to be done. The recent studies have highlighted the potential of energy savings from the centralized chiller plants with the thermal energy storage in commercial complexes response to the differential electricity prices. Traditionally Glycol storage is used for the diurnal load shifting in large multi-chiller plants in India. However, modeling and the dynamic analysis of these thermal storages are not reported extensively in the literature and rule of the thumb for sizing is a practice which leads to the erroneous sizing of the storage and ultimately energy losses. To help the modeling of the thermal energy storages, this paper presents the analysis of the actual data captured from the existing 1050 TR chiller plant of the commercial complex with the glycol storage. The system is analyzed for the effect of the diurnal thermal storage on the performance of the chillers and potential cost savings under various times of the day tariff rates. Deficiencies of the thermal energy storage sizing by comparing with the cooling load curve and time of day tariffs are highlighted. The over sizing of the thermal storage leads to the significant increase in energy up to 43% and cost is increased by 27%. The methodology presented here exemplified the need of fully coupled analysis of thermal storage with respect to the differential tariff and variation of COP of the system in site specific assessment