Walmart opt for NH₃ system for new distribution centre

Walmart’s decision to use ammonia as the sole refrigerant in its distribution centre follows similar installations by Whole Foods and Unilever, who deployed an ammonia system and a CO₂/NH₃ cascade system respectively.

These installations from some of the world’s biggest corporations highlight the growing role ammonia is playing in the United States, both in small, medium and large-scale industrial applications, adopting low-charge, two-stage ammonia and CO₂/NH₃ cascade solutions.

The new Mankato distribution centre located in the state of Minnesota employs more than 400 people to cover its 42,000m² facility that will distribute goods to Walmarts in Minnesota, Iowa, North Dakota, South Dakota and Wisconsin. The total cost of the warehouse equated to US$75 million (€69 million) and has been in the works for 11 years.

Large ammonia system to ensure consistent quality

The distribution centre has various requirements to allow for optimal preservation of the myriad types of stock. The fruit and vegetable storage area must be kept at a constant 13^oC with special requirements for produce such as bananas, which have their own room where climate control is exacted to ensure perfect ripeness.

This is in contrast to the dairy and deli storage warehouse, which must be kept at 1^oC ,the meat storage freezer (-1^oC) and the freezer section (-23^oC).

The 34,000 pounds of ammonia are circulated throughout the distribution centre through five 2,560hp compressors that flow refrigerant throughout 14,000 linear feet of refrigeration piping.

Walmart ensuring its sustainable future

Walmart, one of the world’s largest retailers, is making a global effort to lower its carbon emissions created by refrigerants, and as such, have introduced natural refrigerants to a host of distribution centres dotted around the globe.

In the United Kingdom, Walmart (under the brand Asda) operates a distribution centre using an NH₃/CO₂ cascade system in the Midlands. In Balzac, Canada, Walmart uses an ammonia system in its distribution centre, which is 60% more energy efficient than its other distribution centres.

These installations are in line with Walmart’s plan 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.”