In front of the CO2 booster system in Kerzers (from l.) Kurt Goetz, Alpiq InTec West AG, Marcel Bäbi, Frigo-Consulting AG, Martin Gafner, Alpiq InTec West AG, and Raphael Gerber, Frigo-Consulting AG

First supermarket with full eco-refrigeration system

Coop is aiming to become carbon-neutral by 2023. The company intends to achieve this by, among other things, discontinuing the use of fossil fuels, consistently using waste heat, improving insulation and converting sales outlets to the Minergie standard. The Swiss retailer is being supported in its efforts by Alpiq InTec. The Refrigeration Technology Department in Interlaken installed the first trans-critical booster refrigeration plant in the spring of 2009.

Defective sealing in refrigeration systems using synthetic refrigerants result in carbon emissions of around 30,000 kilograms per year for Coop. Despite major efforts such as preventive maintenance, the release of refrigerants into the atmosphere cannot be fully avoided. Coop has therefore decided to ban the use of cooling agents that are harmful for the climate in its refrigeration systems. The solution is more climate-friendly refrigeration systems that operate using carbon dioxide as a refrigerant. This will reduce carbon emissions to 30 kilograms per year. One positive side-effect is that installing the new refrigeration systems will save Coop more than 100,000 kWh in electricity: equivalent to 20 Swiss households with an annual electricity consumption of 5000 kWh.

No harmful effects on the atmosphere
Two months ago, a Coop supermarket was opened in Kerzers, canton Fribourg, featuring the first CO2-booster system: a compressor system with two external pressure levels which can deliver refrigerated air to all refrigeration points at the required temperatures. The system is operated using carbon dioxide (CO2) as a refrigerant. Designed by Frigo-Consulting AG in Gümligen-Berne, the system was installed by the Refrigeration Technology Department of Alpiq InTec West AG in Interlaken. The CO2 booster system supplies air cooled to temperatures of plus 5 to minus 20 degrees Celsius to all refrigeration and freezer units in the supermarket: refrigeration and freezer cabinets in 90 meters of aisles as well as refrigeration and freezer rooms. The natural refrigerant CO2 circulates in a closed loop in the refrigeration systems, keeping food chilled and where necessary supplying energy for heating and hot water. Because the CO2 used for this purpose is taken from the atmosphere, it causes no harmful effect when returned to the atmosphere.

"More complex than plants using synthetic refrigerants"
The foundation for the successful planning and implementation of this eco-friendly system was a fruitful partnership between the builder, Coop Region Berne, the engineering bureau Frigo-Consulting AG, and the Refrigeration Technology Department of Alpiq InTec West AG. "Using CO2 as a refrigerant calls for a new approach by everyone involved, since due to the higher pressures involved, all processes from planning to installation and maintenance are more complex than with systems that use synthetic refrigerants. This presented the team with a real challenge", says Kurt Goetz of Alpiq InTec West AG, commenting on the successful completion of the project.

• Heating, Ventilation, Air-Conditioning Systems and Sanitary Facilities