Operation of Energy Storage Systems. Pt. 3. Operation of a Residential Heat Storage Systems

摘要

The operation of a residential heat storage unit has been investigated. This unit is charged during the night with electricity bought at a special night-rate. During the day the heat necessary for heating purposes is drawn from the storage. In the investigation, particular emphasis is put on the prediction of the heat demand during the day. A time-series of heat demand for a specific house was calculated, using a building model and realistic weather data. A number of ways to predict the heat demand from the demand and outdoor air temperature of previous days were developed and compared. A simple mathematical model of the system was also developed. programmed and used for simulating the consequences of changing the storage capacity, storage insultion, prediction method and operational strategy. The results show that, for the specific house, the annual heat loss from the storage system is app. 3000 kWh when the annual heat demand is approximately 18000 kWh. Improved heat demand prediction can reduce the heat loss at unchanged amount of heat, not delivered due to empty storage in the day period (heat deficit). The heat loss reduction, when the heat deficit is held constant, is approximately 6 per cent from the best to the worst of the prediction procedures investigated. Proper storage insulation and operational strategy appears to be equally or more capable, than improved prediction, of reducing the heat loss. A system with off-peak electric heating and heat generating wind turbine was also investigated. In this system, prediction of the net heat demand is more uncertain, and system performance more sensitive to system design and opeation, than in the system without the wind turbine. (ERA citation 09:014013)