GreenChill webinar exploring NH₃ retail refrigeration in the US

A webinar on ‘Ammonia Use in Commercial Refrigeration’ was organised last week by the GreenChill Advanced Refrigeration Partnership, the US Environmental Protection Agency (EPA) cooperative alliance with the supermarket industry and suppliers to promote technologies, strategies, and practices that reduce refrigerant charges and emissions of ozone-depleting substances and greenhouse gases.

GreenChill Partnership looking into ammonia

In the US there are no supermarkets yet running on ammonia. Nonetheless, with the Greenchill Parntership motto being “reduce refrigerant charge, reduce leaks, use lowest GWP refrigerant possible for your needs”, it makes sense to look into the option of ammonia refrigeration for supermarkets and share information with stakeholders, as it could make sense for both the environment and retailers’ bottom line.

Prior to the webinar, GreenChill conducted a survey on hurdles facing ammonia in commercial refrigeration, which have so far prevented retailers from pursuing this option. Some of the identified hurdles are real hurdles while some are perceived ones.

Challenges and solutions facing ammonia in supermarkets

After looking into the environmental impact and the performance factors regarding ammonia, the first webinar presentation by Caleb Nelson, CTA Architect Engineers, looked into the hurdles identified by the GreenChill survey and discussed potential solutions to them.

• Multiple code and regulation demands: This is mostly a perceived hurdle. SNAP has already approved NH₃ for commercial use as primary refrigerant in secondary applications. Moreover, there are no major deterring restrictions found in the international code for a rooftop NH₃ chiller. Placing NH₃ on the roof alleviates all “machinery room” requirements. In addition there is no requirement for having an engineer on site 24/7/365, as often perceived, while implementing OSHA’s Project Safety Management Plan is again not required for systems with less thant 10,000 pounds refrigerant (a typical supermarket would have about 250 pounds of refrigerants).

• System costs: This is one of the real hurdle facing ammonia refrigeration in supermarkets. Indeed there are not yet economies of scale for ammonia commercially. However, it only applies to part (high side) of the system.

• Refrigerant costs: NH₃ is very cheap in comparison to fluorocarbons.

• Availability: NH₃ is widely in use in the US (more than 100 years). Equipments manufacturers provide a variety of components in different sizes that can be applied to commercial systems, while there are several US commercial manufacturers considering ammonia systems.

• Training/Education: “Are contractors up to speed with ammonia?”. This is a real hurdle which can however be overcome. We are already seeing a shift with CO₂ commercial refrigeration, and ammonia could follow a similar path.

• Design/Installation/ Service demands: Concerning design, the challenge is focused mainly on the secondary portion of the system (hydronic design). The ammonia chillers will be assembled in the factory, while the ammonia chiller sizing is not challenging. Regarding installation, one can expect more factory installation and less field installation, demanding less from the refrigeration contractor. Finally regarding service demands, schedules maintenance and inspection demands should be provided by manufacturer. However, any increase in service demand is expected to be insignificant.

• Lack of performance data: It is true that there is lack of such data in the US, as there are no ammonia supermarkets in the country. However, there is data from installations in other countries, including Australia, Hungary and South Africa.

• Liability fears with regards to toxicity and flammability: The presenter pointed out that charges in supermarkets are much smaller than in industrial applications, the distinctive odour of the refrigerant, the fact that is would be used in secondary application (no contact with customer area) and the fact that NH₃ is lighter than air (does not tend to concentrate). With regards to flammability, NH₃ is considered non flammable in outdoor applications, while leak detection/exhaust systems can assure safety. Moreover, there are voluntary guidelines for the safe implementation of ammonia available for example by OSHA and EPA, the IIAR, ASHRAE and ANSI.

• Applicability for conversions/remodels: although ammonia is not suitable for drop-in refrigerant conversions due to a large part to the copper non-compatibility and the fact that it needs to be applied in secondary systems, there is a lot of potential in using ammonia for remodels. Many remodels are moving towards secondary system. As you already have an HFC chiller in the system you can just apply an NH₃ chiller instead without affecting anything inside the store. NH₃ could also be used for store expansions.

• Limitations on site locations: ammonia is applied in densely populated areas already in the US. It is being applied in many different locations on rooftops for other applications, so hence why not also on supermarket rooftops?