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The Impacts of Technology and CO2 on the Future of System Architecture

DerekGosselin_Blog-Title Derek Gosselin | Technical Product Support Director


I recently spoke at Emerson’s Chicago’s E360 Forum and spelled out the challenges and benefits of CO2 systems. For a complete look at the costs and opportunities, we encourage you to watch the full presentation.


Regulatory changes to the use of refrigerants are creating difficult business decisions — and more change is coming. Reducing Global Warming Potential (GWP) is going to be an issue, so it’s worth looking at how this industry trend may influence your refrigeration strategies.

HFC/HFO blends lower GWP, but only moderately. In contrast, CO2 is a zero-ozone depleting natural refrigerant that has a GWP of 1. Non-toxic and non-flammable, it’s classified as an A1 refrigerant by ASHRAE. In today’s uncertain environment, it offers a potentially future-proof solution to your long-term plans. You won’t have to retrofit out of CO2.

Because CO2 is more efficient, it has more cooling capacity. That allows you to have smaller compressors and line sizes, reduce installation, and use less refrigerant within a store.

Best of all, the technology isn’t new. CO2 already has a majority of the market share in Europe. Since 2013, the total number of CO2 transcritical booster systems in North America has grown from 30 to 310. More than 60 of these systems are located in warmer climates, operating efficiently with just a few modifications.

CO2 system costs are also coming down, thanks to the growing involvement of OEMs, wholesalers, contractors and end users.

When considering CO2, understand the total cost of ownership. The lower first cost of traditional HFC systems offers only one-time savings. While CO2 systems have higher first cost, their lower installed cost and lower energy and maintenance costs offer savings annually throughout their lifecycles. Some organizations are even lowering first costs by collaborating with local energy utilities to secure rebates and incentives.

For a complete look at the costs and opportunities, we encourage you to watch the full presentation.


National Grocery Chain Makes Transition to Transcritical Refrigeration

With increasing regulations prompting a shift toward sustainable alternative refrigerants, retailers are looking more closely at CO2 transcritical booster systems to anchor their refrigeration operations, even in warmer climates. Sprouts Farmers Market is among the first retailers in North America to do just that. They opened their first store in suburban Atlanta in July 2014, and when they did, they set out to prove CO2 transcritical booster systems aren’t only for cool climates.

Like many food retailers, Sprouts has historically employed more traditional refrigeration systems based on common hydrofluorocarbon (HFC) refrigerants. These HFC systems operate with what’s traditionally seen as acceptable temperatures and pressures. CO2’s low critical point temperature and high operating pressure (around 1,500 psig) are characteristically not found in traditional HFC-based refrigeration. These are the primary reasons for the reluctance to move toward CO2. But, with advances in system technology and architecture, CO2 can be a game changer for retailers seeking to improve energy efficiencies, achieve sustainability targets and cross the finish line on regulatory compliance.

Changing their refrigeration philosophy and moving to a CO2 transcritical system architecture was a giant step for Sprouts, especially for this store in the hot, humid climate of Atlanta. To pull this off, they turned to OEM partner Hillphoenix, and Hillphoenix, seeing the challenge presented by installing a CO2 transcritical booster system in a warm climate, turned to Emerson Climate Technologies.

Emerson’s E2 Facility Management System was installed to oversee the CO2 transcritical booster system. It manages nearly 50 electronic case control units and optimizes the facility’s overall energy management profile.
The E2 system helps improve performance in multiple ways:

  1. Controls the variable speed of the fans on the adiabatic condenser in response to operating conditions
  2. Optimizes compressor coefficient of performance by regulating system discharge pressures via Emerson’s high-pressure CO2 controller
  3. Provides complete oil management control of all CO2 refrigeration compressors
  4. Communicates with and captures information from individual case control units
  5. Provides complete control of building HVAC and refrigeration systems, and supports the retailer’s energy and maintenance reduction strategies


The E2 system also allows Sprouts operators to run diagnostics, monitor the system remotely through Emerson’s ProAct Service Center and, if necessary, shut down the system components before failure.

The condenser manages both low- and medium-temperature refrigeration requirements on the same system using only CO2 as the refrigerant, another unique aspect to the transcritical booster system. Running both requirements from the same condenser enhances the efficiency of the system across the store.

It’s understandable why stateside end users are hesitant to switch to CO2 transcritical booster systems. Concerns over operating pressures, maintenance levels and energy have prompted careful and steady evaluations to understand the true cost of ownership for their enterprises. Emerson technology helped ease those concerns for Sprouts. Their Atlanta-area store is operating efficiently and effectively on the transcritical system.

This blog is a summary of the article National Grocery Store Chain Makes Transition to Transcritical Refrigeration from our recent edition of E360 Outlook. Click here to learn more on our involvement with Sprouts’ Atlanta store.

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