Optimizing the New Generation of Grocery Refrigeration

Russ Landry, P.E.

Following the European and growing U.S. industry trends, at least three grocery chains have started installing carbon dioxide (CO2) refrigeration systems in Minnesota. CO2 is a natural refrigerant that has minimal impact on global warming compared to the previous industry-standard refrigerants. As the grocery industry moves to the use of CO2 as a refrigerant, its summertime energy use is increasing. CEE's CARD funded refrigeration market study identified these trends and the shortage of information available for Minnesota utilities to make informed program design decisions regarding CO2 refrigeration systems. 
This project will field test design features that provide savings opportunities in carbon dioxide refrigeration systems and have not yet been addressed by Minnesota’s utility programs. Efficiency features such as parallel compression, adiabatic gas coolers, ejectors, and mechanical subcooling have begun to be used in warmer U.S. climates and other countries, but their year-round energy and demand reduction potential in cold climates has not been as widely recognized or validated. This project will conduct detailed field monitoring and validated modeling of local installations to evaluate their performance and cost-effectiveness against typical CO2 system designs. We will also develop recommendations for rebate program measures and guidelines.

This project is supported by a grant from the Minnesota Department of Commerce, Division of Energy Resources through the Conservation Applied Research and Development (CARD) program, which is funded by Minnesota ratepayers.  

Project Info


Conservation Applied Research and Development (CARD) grant program  


To evaluate the savings and program potential for design features to increase efficiency of transcritical CO2 systems in Minnesota’s climate. 


  • Technology and market review

  • Select measures and sites

  • Oversee installation and commissioning

  • Monitoring

  • Calculate savings

  • Evaluate costs and program potential

  • Dissemination  

Non-energy benefits

  • Reduced maintenance

  • Longer equipment life

  • Noise reduction

  • Reduced greenhouse gas emissions  

Russ Landry