USA – The American retail giant Walmart have announced that they will henceforth use ammonia as the sole refrigerant in its distribution centres. Walmart’s announcement follows on from similar declarations made by Whole Foods and Unilever, who installed an ammonia system and a CO2/NH3 cascade system respectively.

These recent installations, coming as they do from some of the world’s biggest corporations, only serves to underline the growing role ammonia is playing in the United States, both in small, medium and large-scale industrial applications which are opting to adopt low-charge, two-stage ammonia and CO2/NH3 cascade solutions.

Walmart have therefore decided to equip their new Mankato distribution centre in Minnesota with an ammonia only system. The new distribution centre employs more than 400 people to cover its 42,000m2 facility that is used to distribute goods to Walmart stores in Minnesota, Iowa, North Dakota, South Dakota and Wisconsin. The distribution centre must fulfil various requirements necessary for optimal preservation of the many types of stock, with the fruit and vegetable storage area, for example, needing to be kept at a constant 13oC with special requirements for produce such as bananas, which must have their own room where climate control is exacted to try and ensure perfect ripeness. On the other hand, the dairy and deli storage warehouse must be kept at 1oC, while the meat storage freezer should be maintained at -1oC and the freezer section needing a chilly -23oC.

More than 15,000 kilos of ammonia are needed for the distribution centre and the ammonia is circulated throughout the centre via five 2,560hp compressors that ensure the flow of refrigerants throughout 14,000 linear feet of refrigeration piping.

This decision by Walmart to introduce natural refrigerants to a host of distribution centres around the world is in keeping with the company’s commitment to “begin phasing out HFC refrigerants by 2015 and replacing them with non-HFC refrigerants where these are legally allowed and available for new purchases of point-of-sale units and large refrigeration installations.”
Previous examples of this commitment include the UK where Walmart (under the brand Asda) operates a distribution centre using an NH3/CO2 cascade system in the Midlands and also in Balzac, Canada, where Walmart uses an ammonia system in its distribution centre, which, the company claims, is 60% more energy efficient than its other distribution centres.