It may sound strange that it is possible to fight global warming using CO2, but this is actually the case when it comes to the use of CO2 in refrigeration systems. A wide range of industries generate CO2, and instead of letting it out into the atmosphere, it can be stored in the refrigeration systems. Today, synthetic refrigerants – also referred to as F-gases – are used in these systems worldwide. Their greenhouse effect is 3,000-6,000 times higher than that of CO2, and they contribute significantly to the global warming, because it is very difficult to avoid small emissions. In Europe, about 5% of supermarkets have already completely or partially replaced F-gases with CO2. On a global scale, very few have done the same. Denmark, however, is an exception. Here, all new and rebuilt supermarkets use CO2 in their refrigeration systems thanks to legislation that prohibit designing systems that are filled with more than 10 kilos of F–gases. In this way the supermarkets’ greenhouse effect is typically reduced by 30%.
The world’s biggest CO2 refrigeration system
In January 2010, Danish Supermarkets’ discount retail chain, Netto, began using a new fresh meat warehouse in the western part of Denmark, which currently has the world’s biggest CO2 refrigeration system, with a net performance of 1,000 kW for refrigeration and 300 kW for freezing.
According to Per Holm Johansen, who is the International Technical Manager at Netto, the new warehouse clearly shows that CO2-based refrigeration systems are fully competitive compared to other systems. ”We had no experience with CO2-based systems of this size to draw on,” he says. “So, of course, we were excited when we called for tenders. However, we quickly realised that the task could be solved without harming the efficiency or the economics of the system.” On the contrary, it has actually proven to be very profitable.
In close co-operation with Danfoss, the Danish company Vojens Køleteknik developed the refrigeration system for Netto’s new warehouse building. Danfoss supplied, among other things, electrical valves, pressure transmitters and a complete ADAP-KOOL® control and monitoring system. The system’s refrigeration capacity equals the total capacity of 30 normal Netto supermarkets. The refrigeration space amounts to 9,500 sq m , and the freezing space is approximately 2,000 sq m, with a room height of 11.5 metres.
Jørn Petersen, Managing Director at Vojens Køleteknik, explains: ”It was bit of a pioneering task to construct a CO2-based system this size. All of the components were assessed and adjusted, but we managed, thanks to our close co-operation with Danfoss. The system is probably the most advanced and energy-friendly in the world, and it has turned out that it is possible to develop a refrigeration system which is beneficial both to the environment and the finances.”
Danfoss is leading the market
Danfoss has more than ten years’ experience in the development of CO2 components and, so far, has been involved in the construction of about 500 refrigeration systems that run exclusively on CO2, and more than 1,000 refrigeration systems that combine CO2 with another refrigerant. This makes Danfoss a global market leader in the production of components for CO2 refrigeration systems.
Kristian Breitenbauch, Nordic Sales Manager, Danfoss Food Retail, says: ”So far, it is particularly the supermarkets in the Nordic countries that are making use of CO2. But major international supermarket chains have also begun to set targets and we expect new refrigeration systems using CO2 as the refrigerant to grow significantly. CO2 is a sustainable choice which strengthens the company’s green image and can meet the likely requirements of future amendments to legislation.”
Picture to the right: Danish Supermarkets’ discount retail chain, Netto, has started using the world’s biggest CO2 refrigeration system, which is cooling down fresh meat in a new warehouse in the western part of Denmark