Optimizing the New Generation of Grocery Refrigeration Equipment

Russ Landry, P.E.
Supermarket fridge

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.

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 and standard alternatives. We will also develop recommendations for rebate program measures and guidelines.

Project Summary


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


  • Task 1: Technology and market review
  • Task 2: Select measures and sites
  • Task 3: Oversee installation and commissioning
  • Task 4: Monitoring
  • Task 5: Calculate savings
  • Task 6: Evaluate costs and program potential
  • Task 7: Dissemination

Non-energy benefits

  • Reduced maintenance
  • Longer equipment life
  • Noise reduction
  • Reduced greenhouse gas emissions