The University of Birmingham, supported by Emerson, reported the energy efficiency of propane systems as a key finding of its new research on retail refrigeration.
The University of Birmingham – supported by Emerson – yesterday released a report on Retail Refrigeration: Making the Transition to Clean Cold finding that the benefits offered by propane systems in supermarkets could save millions through their energy efficiency and other operational costs compared to alternatives.
The report, authored by Professor Toby Peters of the University of Birmingham, cites research by Emerson on an integral propane system (meaning a stand-alone or plug ‘n’ play system as opposed to a remote refrigeration system) showing that it has a lower total equivalent warming impact (TEWI) than a standard remote HFC system.
TEWI is reduced in hydrocarbon systems by 8% compared to CO2 transcritical and almost double compared to HFC/HFO blends. The table below (taken from the report) shows this is achieved through a ‘combination of lower energy consumption and zero impact from direct emissions’:
The analysis has not been independently tested. The report also cites a study conducted by independent refrigeration research institute ILK Dresden for Emerson that shows in a discount store with 10 display cases, integral propane systems are €29,000 cheaper to install compared to CO2 systems.
UK retailer Waitrose has opted for integrals running on propane or propene, according to the report, and has now converted 133 of its 292 stores including 37 of its 50 convenience stores.
“The third-generation system that Waitrose has installed comprises hydrocarbon integrals for store cabinets with a water cooling loop connected to an external dry air cooler, reducing the power needed to cool the water,” the report writes.
The retailer has also has reported good results compared to its previous remote system running on R404A. Each store that it has converted to an integral system saved 7% in electricity consumption and 60% in gas consumption, since the waste heat from the cooling loop is used to provide space heating.
This reduces operating costs by £65,000 per store per year, and the capital cost of each new system saves the company around £85,000 compared to an R404A system.
German retailer Lidl has been found to consume 10% less electricity with hydrocarbon chillers in a food market compared to a conventional HFC system, according to another report by the Climate & Clean Air Coalition, published last year (Lower-GWP Alternatives in Commercial and Transport Refrigeration: An expanded compilation of propane, CO2, ammonia and HFO case studies).