Energy Storage Possibilities for Supermarket Refrigeration Units

The refrigeration and the HVAC systems are responsible for over 50% of a supermarket's electricity usage. Energy efficient systems are therefore needed in the refrigerated food sector in order to reduce the costs due to the electricity consumption. CO2 refrigeration systems are the preferred system solution when feasible for the major European supermarket chains, due to the energy efficiency of the systems and their low environmental impact. Cold Thermal Energy Storage (CTES) is currently not available for these systems. CTES could lead to a further reduction in the total energy consumption, the peak power demand and energy costs. This paper presents and analyzes different types of CTE storages, enabling a new way of integrating the refrigeration systems of supermarkets to the smart grid. Charge and discharge operations of the thermal storage devices at favorable and unfavorable boundary conditions are analyzed in order to evaluate the performance of the proposed solutions. One example for a new innovative cold thermal energy storage is the ice storage integrated in the CO2 refrigeration circuit.