Economic feasibility of ice storage systems for office building applications: A climate sensitivity analysis

Abstract

The impact of different climatic conditions on the economic feasibility of ice energy-storage systems in a typical office building is investigated. The climate zones cover a range of thermal zones from warm to extremely hot according to the thermal climate zone definitions of ASHRAE Standard 169. Hourly cooling load of the building is simulated for a monthly typical day in five cities representing the aforementioned climate zones. Four different energy storage strategies including full, partial, two-chiller and on-peak window, are also considered for peak-shaving purpose. By analyzing the extra capital cost required for installing an ice energy-storage system instead of a conventional one, and the potential savings due to transferring the cooling load from on-peak to off-peak hours, the economic viability of employing ice storage systems is evaluated for twenty different cases (i.e. five climate zones and four storage strategies). The results show that the payback period is highly sensitive to the climatic conditions, storage strategy and electricity tariff. It is found that the payback period is virtually one order of magnitude lower in very hot zones compared to that in hot zones using the partial storage strategy with the mid-peak electricity tariff of 5.1 ¢/kWh. To generalize the results, sensitivity analyses are performed by varying electricity tariffs and capital investments. A wide range of electricity tariffs from 0.25 ¢/kWh (off-peak) to 40 ¢/kWh (on-peak) are considered for the economic analysis. Considering the partial storage strategy, although in very hot zones, the payback period is less than 7 years for all considered electricity tariffs, the corresponding figure for hot zones varies between 1 and 60 years.