The newly equipped Sainsbury supermarket in Crayford, Kent, UK, has introduced a number of firsts, including the addition of a closed loop borehole system integrated with CO₂ refrigeration, and the ability to produce both heating and cooling simultaneously from renewable sources. The combination of these two key groundbreaking technologies and an intelligent energy management system have resulted in the elimination of gas as an energy source, leading to a total store energy consumption reduction of at least 30%.

Transcritical CO₂ Booster system for highest efficiency

A transcritical CO₂ booster is a refrigeration system that covers both medium temperature and low temperature demands of small to large-size supermarkets. This technology combines the advantages of natural refrigerants with that of achieving higher efficiencies than systems using HFC refrigerants. A water-based borehole cooling system further enhances these efficiencies, and greatly assists in optimising CO₂ refrigeration system performance.

Geo-exchange technology

Geoscart™ technology, known as geo-exchange, uses a series of closed loop boreholes drilled to 200 metres underground to access the natural geothermal potential within the Earth. The boreholes deliver geothermal temperature-conditioned cooling fluid to the refrigeration packs. This enables the system to capture and store the waste heat, which is later released to provide heating and hot water in the store via heat pumps.

SWEP heat exchangers for efficiency maximisation

SWEP has provided brazed plate heat exchangers (BPHE) for both systems: the supermarket refrigeration pack and heat pumps for heating.

“We are very happy to be part of this innovative project. In the summer, the store is cooled with cold ground water, and in the winter, the same ground water is used for heating. This way, all available energy is reused, making it a very efficient and sustainable system. Careful attention was given when selecting the BPHE’s, as it is necessary to use a very close temperature approach. The heat exchangers were chosen for the purpose of maximizing system efficiency at Sainsbury’s,” says Stefano Bellada, Application Manager at SWEP.

Transcritical CO₂ refrigeration pack supplied by SCM Frigo

“This project is a big step forward towards the integration of refrigerating and heating systems, with renewable energy sources. Integrated design and integrated energy management create a synergy that gives great results in terms of efficiency and of carbon footprint reduction. Being part of such a cutting edge project makes us proud because this witnesses the great results achieved from our company during the last years in the development of new, environmentally friendly products,” says Mirko Bernabei, Technical Director at SCM FRIGO S.p.A.

Thermal energy beneficially reused thanks to Geoscart™

The boreholes form part of the proprietary geoscart™ thermal energy management system.

“We are delighted to work with Sainsbury’s, and their partners, on such an important and exciting project. The store’s revolutionary integrated design indeed allows effective thermal energy management between refrigeration, heating and central control and storage systems. The technical challenge is highlighted by the total capacity of the integrated systems exceeding 2MW thermal, and covering a wide range of loads, from -34 °C (low temperature refrigeration) to 70 °C (domestic hot water services). All thermal energy is beneficially reused by storing excess seasonal heating or cooling energy for the following season, making it a very efficient and sustainable system. Careful attention was given when selecting all components; for example, maximizing efficiency of the integrated system for Sainsbury’s depended on a very close temperature approach in the heat exchangers together with linked load parameters. Similarly, the overall success of this project depended on a very close cooperative approach in all parties working together!,” states Dmitriy Zaynulin, Chief Technology Officer for geoscart™.

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SIMPLIFIED INSTALLATION SCHEME