Australian supermarket chain Woolworths has emphasized the importance of training as it works to adopt natural refrigerants, such as CO2 (R744) and hydrocarbons, across its 1,076 stores.

According to Dario Ferlin, National Sustainable Engineering Manager at Woolworths, as the company expands its transcritical CO2 footprint and moves into more rural areas of Australia, it is having to overcome a number of challenges, especially training.

Details of Woolworths’ transcritical CO2 rollout and training efforts were presented by Ferlin during the State of the Industry – Australia and New Zealand online session on the second and final day of the ATMOsphere APAC Summit 2022 on June 28. The conference, which took place in Tokyo, was organized by ATMOsphere, publisher of

With a goal of reducing its carbon footprint by 63% by 2030 and achieving net-zero emissions by 2050, part of Woolworths’ efforts is to transition to natural refrigerants.

Having first adopted transcritical CO2 refrigeration in its supermarkets in 2017, Woolworths now has the technology in 53 of its supermarkets, up from 39 stores in April 2021. Twenty-six of these 53 stores use the transcritical CO2 systems to provide space heating, removing the need for gas boilers or synthetic-based heat pumps. Twelve of these 26 stores also use the systems for space cooling.

Woolworths has previously said that it aims to build all new stores with transcritical CO2 refrigeration systems where possible.

According to Ferlin’s presentation, Woolworths is also “preparing the terrain for the uptake of flammable refrigeration systems, specifically hydrocarbons.” This move is in response to the growth of hydrocarbon solutions within the HVAC&R sector, such as propane (R290)-based heat pumps, chillers and split air-conditioning systems, as well as self-contained R290 retail display cases.

Training for natural refrigerants

In recent months, Woolworths has installed transcritical CO2 systems in the more rural areas of New South Wales, such as Canberra, Young and Wagga Wagga, where the lack of experienced CO2-trained technicians is an acute challenge.

“We’re seeing transcritical CO2 systems approaching completion in regional areas of New South Wales where technicians are not necessarily familiar with electronic controls, let alone transcritical CO2 systems,” said Ferlin. “They’re much more familiar with mechanical controls and synthetic refrigerant systems, and there may be some apprehension as we’re designing, installing and servicing transcritical systems in these remote regional areas.”

“We’re seeing transcritical CO2 systems approaching completion in regional areas of New South Wales where technicians are not necessarily familiar with electronic controls, let alone transcritical CO2 systems.”

Dario Ferlin, Woolworths

According to Ferlin, it’s “imperative” that project teams in rural areas are supported with the necessary in-person training to provide them with the skills and confidence they need to work with CO2-based systems.

Transcritical CO2 in hotter climates

In addition to upskilling technicians, Woolworths is striving to overcome the challenges of operating transcritical CO2 systems in Australia’s hotter cities, like Perth and Adelaide, where it would not have been considered a feasible option until very recently, according to Ferlin.

In warmer climates, transcritical systems generally require an adiabatic gas cooler to operate efficiently. Adiabatic gas coolers use a small amount of water to help cool the system’s CO2, but problems can arise when there are issues with the quality of a location’s water. As explained by Ferlin, areas with high concentrations of calcium carbonate can cause limescale on the system’s coils. Similarly, water with high chloride content can corrode a system’s copper tubes and aluminum fins.

To overcome these issues, Woolworths is working with its suppliers and technology partners to ensure the company can operate its systems reliably and efficiently in the long term in these warmer regions.

Woolworths is also working on developing a transcritical CO2 system for its supermarkets in Australia’s subtropical climates, where there are months of hot and humid weather.

“We have worked with our suppliers, technology partners and install teams to try to understand how we could make a transcritical system that operates reliably and efficiently [based on] total cost of ownership including annualized energy consumption,” said Ferlin. “We’re still in a favorable position, notwithstanding the very onerous weather to which the system is exposed.”

Want to find out more, or have something to say about this story? Join the ATMO Connect network to meet and engage with like-minded stakeholders in the clean cooling and natural refrigerant arena.