Competitiveness of district cooling in energy efficient supermarkets

Abstract

This thesis concerns utilization of district cooling in supermarkets. Today, district cooling is primarily used in hotels, hospitals, offices and computer centrals. This study investigates the possibility to expand the range of customers to also include supermarkets. The studied use includes comfort cooling as well as condenser cooling. Condenser cooling implies increasing the COP of a chiller by decreasing its condensation temperature. Chillers are inevitable since the temperature levels of chilled and frozen food are too low to directly use the district cooling. The aim of the thesis is to determine the highest possible price of district cooling the supermarket owner is willing to pay in order to connect the supermarket to the district cooling network. Two different reference supermarkets are analysed, one representative for a supermarket today and one representative for a future supermarket. The major difference is the energy efficiency of the display cabinets. Four different system designs are investigated, using district cooling for both comfort cooling and condenser cooling, not using district cooling at all, using district cooling only for comfort cooling and finally, using district cooling only during the warm part of the year. The results show that the prices charged for district cooling are in general too high to make district cooling competitive in a typical supermarket today. In the typical supermarket in the future it is more favourable. Using district cooling in the future reference supermarket for both comfort cooling and condenser cooling implies an annual demand of 331 MWh and a competitive price of 216 SEK/MWh. Using district cooling only when the outdoor temperature exceeds 10 °C implies a demand of 210 MWh/year and a competitive price of 290 SEK/MWh and using district cooling only for comfort cooling implies a demand of 80 MWh/year and a competitive price of 599 SEK/MWh. The typical future supermarket is fully possible to design at the present day, this would decrease the energy demand substantially and make district cooling competitive.