Passive energy storage using distributed electric loads with thermal storage

This paper presents the concept of controlling distributed electric loads with thermal energy storage as a passive electric energy storage system (PEESS). Examples of such loads include different types of thermostatically controlled appliances (TCAs) such as hot water heaters, air conditioners, and refrigerators. Each TCA can be viewed as a thermal cell that stores electricity as thermal energy. A centralized control mechanism can be used to control the timing of each thermal cell to consume electric energy so that the aggregated electricity consumption of the thermal cells will vary against a baseline consumption. Thus, when the aggregated consumption is higher than the baseline, the PEESS is charging; otherwise, the PEESS is discharging. The overall performance of a PEESS will be equivalent to that of a battery energy storage device. This paper presents the configuration and formulates the control of a PEESS. The modeling results demonstrate the feasibility of implementing the PEESS.