Heat Pump, Cold Thermal Storage, Peak Loads, Control Strategies
Demand for space cooling in Canada has significantly increased in the past 20 years, and in conjunction with space heating loads in the winter are placing larger peak loads on the electrical grid. As a result, utilities must increase their generating and transmission capacity to meet the peak annual demand, with much of the capacity going unused for large portions of the year. Additionally, base loads are typically met using cleaner technologies including hydro and nuclear, while the variable peak loads are more commonly met using fossil fuel generation, increasing the greenhouse gas emissions per kilowatt-hour of electrical generation. To reduce this peak load, demand side management strategies are becoming more common, with one potential method for reducing the peak load produced by residential buildings is the pairing a heat pump with thermal storage. This paper outlines the first stage of a multi-stage research project to develop a comprehensive system and control strategy for a residential heat pump with sensible hot and cold thermal storage tanks. It outlines the steps that were taken to optimize the control strategy, with a focus on reducing consumption during peak periods while remaining cost and greenhouse gas emission neutral on an annual basis. It was found that using small scale sensible storage and a standard geothermal heat pump, a reduction in the percent of energy used during peak periods is realized, however the annual consumption, electrical costs, and greenhouse gas emissions increase. This was primarily the result of a significant decrease in heat pump performance as the result of lower source and higher load temperatures into the heat pump.