While Coca-Cola chose CO2, Unilever chose the hydrocarbon, propane. In 1994, Unilever, one of the world’s biggest ice cream manufacturers, was one of the first company’s to transition to HFC-based freezer cabinets and have already moved to phase these systems out. By the end of 2007, about 200,000 hydrocarbon-based freezer cabinets were installed throughout Europe. According to the company, lab tests suggest these hydrocarbon cabinets are energy efficient, using up to 12-17 percent less energy than previous units. According to Alan Gerrard, Unilever’s Global Project Leader for this project, field-testing showed efficiency gains of around 9 percent.
While the company had planned all along to phase out HFCs, it was uncertain about which natural refrigerant to choose. After testing many alternatives, they decided to back propane for a couple reasons. bv
The second, more important reason, dealt with thermodynamics. Gerrard says that to reach the operating temperature that they require (–18 DegF) using a CO2 system would have meant using two compressors in order to reach the same energy efficiency as the hydrocarbons.
The Coca-Cola Company is working to phase-out HFC refrigerant-based equipment and replace it with CO2 equipment. The company is focusing on emissions from its vending machines and coolers after an audit of their carbon footprint. What they found surprised them, says Bryan Jacob, energy and climate protection manager for The Coca-Cola Company. They found that equivalent CO2 emissions from this type of equipment far outstripped emissions from manufacturing and fleet operations. In 2000, more than 15 million metric tons equivalent of carbon dioxide was released from this source as compared to about 5 MMT from the company’s 900 manufacturing operations, and 3 MMT from the company’s 200,000 diesel-powered trucks.
This led the company into making cabinet and refrigeration efficiency a priority. They looked at all of the refrigerants on the market and chose CO2 after conducting a survey analyzing the worldwide regulatory landscape. They felt that CO2 would be the best refrigerant in the long-term.
In efficiency testing, natural refrigerants did better than they initially expected, says Jacob. He says that the CO2 systems compared to the HFC systems were 4 to 7 percent better. Their testing found that CO2 systems work better at somewhat lower ambient temperatures, below 35 DegC, than did the HFC systems.