Discover the Truth About So-called "Natural" Refrigerants

So-called "Natural" Refrigerants: Myth vs. Fact

• MYTH: When ammonia refrigerant leaks from a system, it floats away harmlessly since its lighter than air.

  FACT:

  Ammonia vapor is lighter than air and therefore should rise and dissipate over time and distance. This is not always the case. Dangerous air concentrations of ammonia may remain close to the ground depending upon relative humidity, temperature, and wind speed. Cooler temperatures with high relative humidity will encourage the vapor to hover near the ground. Be aware of downwind depressions that may collect and hold toxic ammonia vapor.

  The white cloud that develops with most significant ammonia releases is a poor indicator of the extent of the plume. Dangerous air concentrations of ammonia can extend far beyond the visible white cloud.

  Supporting Resources:

  Chron News: Town Evacuated After Ammonia Leak

  EPA Alert-Hazards of Ammonia Releases @ Refrigeration Facilities

  Minnesota Fire Department Response Plan to Ammonia Release

  Seward Ammonia Spill

• MYTH: Ammonia makes better ice than other refrigerants.

  FACT:

  Ice quality in skating rinks is determined by only 3 factors: water quality, building conditions, and rink slab temperature.

  For typical rink systems, the slab temperature is controlled by flow of a low temperature heat transfer fluid (brine or glycol) under the floor so the ice surface is separated physically from any refrigerant within the refrigeration system (located outdoors or in the machine room). In other words, the rink slab has no way of knowing what refrigerant is inside of the system since it only sees brine, and therefore, as long as the brine temperature and flow remain adequate, the ice is indifferent.

• MYTH: CO₂, Hydrocarbons and Ammonia are "natural" refrigerants

  FACT:

  "Natural" is a marketing buzz word, not based on engineering or sound science. Refrigerant grade CO₂, hydrocarbons and ammonia sold and used in the HVACR industry are not extracted from nature. Rather, they are made through industrial processes like all other refrigerants.

  SUPPORTING RESOURCES:

  • An Expert's Take on So-called "Naturals": Future of Refrigerants
  • EFCTC Fact Sheet - Natural Refrigerants
  • "No Such Thing as Naturals" — Video
  • The Cold Truth: A look at what is real, speculation, and hype in the HVACR Industry
  • Chemical & Engineering News - CO₂ emissions from Industrial ammonia production

• MYTH: "Natural" refrigerants are the best solution because of their GWP

  FACT:

  GWP is just one factor out of many in the selection of a refrigerant. As highlighted in Section 3.1 of the ASHRAE Position Document on Refrigerants and their Responsible Use: "Selection of refrigerants and their systems must be based on a holistic analysis including energy efficiency and performance attributes, environmental impacts, employee and public safety, and economic considerations. A refrigerant should not be selected based on any one single factor such as GWP, operating pressure, flammability, etc. The wide range of HVAC&R applications and their requirements throughout the world necessitates a variety of refrigerants to meet these needs."

  SUPPORTING RESOURCES:

  • ASHRAE: Position Document on Refrigerants & Their Responsible Use

• MYTH: All Supermarkets are using CO₂

  FACT:

  In the US, public data reported by EPA GreenChill partners indicate that in 2019, CO₂ us as a % of install refrigerant remained <1%. Supermarket retailers have a variety of needs for existing and new stores and technology adoption trends vary by region. CO₂ is not a solution for existing system designs and requires purchase and installation of all new equipment. Supermarkets worldwide have had great success using retrofit refrigerants like Opteon™ XP40 (R-449A), resulting in lower GWP, while staying on track with their sustainability goals. In addition, an increasing number of refrigeration design engineers and end-users are exploring ultra-low GWP HFO solutions with new system architectures as a means to deliver the performance, cost, and sustainability they need to maintain seamless operations.

  SUPPORTING RESOURCES:

  • Grocers' Growing Interest in HFO Solutions
  • CO₂: The Incovenient Truth
  • Brief Video: Major UK Retailer, ASDA, Chooses A2L Refrigerants
  • Emerson E360 Webinar: Preparing for the Safe Use of A2L Refrigerants in Commercial Refrigeration

• MYTH: Ammonia is a more efficient refrigerant

  FACT:

  The efficiency of a refrigeration system is largely determined by design, equipment selection and operating conditions. In fact, many modern systems with fluorinated refrigerants have equivalent, or better, efficiency compared to ammonia R-717 plants. Modern refrigeration system designs are constantly being innovated and improved, especially when optimizing energy efficiency. To truly assess the performance of any refrigeration plant requires a deep and expert engineering analysis considering the specific details of the system, application, locality and operational conditions. Blanket statements simply comparing refrigerants, without consideration of other factors is an oversimplification and could lead to potentially inaccurate conclusions.

  SUPPORTING RESOURCES:

  • System Efficiency is More Important Than GWP
  • ORFA Spring 2019 Publication: Efficiency 2.0

• MYTH: CO₂ leaks are inconsequential because its "natural"

  FACT:

  Due to their high pressure operation, CO₂ systems are significantly more susceptible to loss of full charge during power outages and maintenance. In fact, for safety reasons, emergency discharge valves are built into CO₂ systems to encourage the release of charge if/when required. A 2018 study in the US of ~200 transcritical systems found them to have a very high leak rate (~48.3%), which means each store is losing the equivalent of their entire charge every other year. 

  The loss of a full system charge of CO₂ can lead to loss of refrigeration for several hours or longer, depending on qualified service technician availability and supply. In order to avoid business disruptions, most retailers are installing back-up refrigeration systems to cool the receiver or are storing full CO₂ system charges on-site and paying the associated cylinder rental fees. All of these mitigations add cost to the owner/operator.

  SUPPORTING RESOURCES:

  • Emerson Climate Conversations: CO₂ as a Refrigerant — R-744 Advantages/Disadvantages
  • Five Facts to Consider Before Switching to CO₂

• MYTH: Ammonia refrigerants have zero manufacturing footprint or environmental impact.

  Although marketed as a "natural" refrigerant, the production of refrigerant grade ammonia contributes significantly to green house gas and fossil fuel use.

  https://globalfact.org/wp-content/uploads/2021/02/globalFACT-Ammonia-Infographic.pdf

  https://www.coolingpost.com/world-news/scientists-seek-way-to-make-ammonia-production-more-sustainable/

• MYTH: CO₂ is non toxic

  Large carbon dioxide leaks can displace oxygen and cause an asphyxiations risks. Also the Acute Toxicity Exposure Limit (ATEL) for R-744 is 30,000 ppm and exposures above this even for short times can be of concern.

  https://e360blog.emerson.com/co2-as-a-refrigerant-five-potential-hazards-of-r744/