How can retailers save money?
Accelerate Europe compares how ozone-friendly natural refrigerants CO2 and hydrocarbons are helping to reduce energy consumption in supermarkets.
Supermarkets are estimated to be responsible for around 3–4% of the total energy consumed in an EU country, according to a 2016 report by the EU-funded SuperSmart project. As Europe’s food retail sector strives to improve its energy efficiency, Accelerate Europe compares how ozone-friendly natural refrigerants CO2 and hydrocarbons are helping to reduce energy consumption in supermarkets.
The SuperSmart report, which was funded under the EU’s Horizon 2020 programme and put together by partners including shecco, noted that a large proportion of the average European supermarket’s total energy costs come from lighting, heating, ventilation and air conditioning, with the biggest share coming from refrigeration.
Analysis collated by SuperSmart revealed that refrigeration typically takes up 35–50% of total energy use. Reducing the energy consumption of supermarket refrigeration systems, therefore, can deliver significant cash savings.
Dealing with warm ambient climates
Efficient heating and cooling depends not just on the choice of refrigerant but also the location of the system. CO2 used to be seen as inefficient in warm climates as the refrigeration system gets closer to the transcritical point. But developments like ejectors, parallel compression and adiabatic cooling are helping to mitigate this.
“Thanks to the parallel compressor and the ejector, the summer COP is now very good and comparable with the HFC gases,” Enrico Zambotto, refrigeration director at Arneg (a leading provider of commercial refrigeration equipment using both hydrocarbons and CO2), told Accelerate Europe.
David Guthörl, head of the ‘Energy/CO2 Sustainability Unit’ at Swiss retailer Coop, agrees: “The difference in climate can be mitigated by the ejector which provides the necessary efficiency boost of the CO2 technology (in cold as well as in warm climates). In the cold climate more heat is needed for heating [through heat reclaim], which is comparable with cooling at high ambient temperatures.”
“[In hydrocarbon cabinets] the energy usage still is far from efficient as the waste heat emitted has to be dealt with separately.”
– David Guthörl, Coop
In hydrocarbon cabinets, Guthörl asserts, “the energy usage still is far from efficient as the waste heat emitted has to be dealt with separately”.
Integral water-cooled systems cited in the Emerson/ILK study can solve this problem. “The study was based on self-contained hydrocarbon cabinets with a condensing water loop,” says Emerson’s Tomski. “Therefore, heat is transferred outside of the store.”
Emerson’s Winandy told Accelerate Europe that both of the tests done by ILK took place in Germany, in relatively low ambient temperatures. They conducted a sensitivity analysis showing that using hydrocarbon cabinets in Barcelona gains a 10% efficiency edge over CO2, as propane works better in warmer conditions. In the colder climate of Gothenburg, CO2 gained 4% over hydrocarbon technology.
AHT, who manufacturers hydrocarbon-based cabinets including integral water-loops, hails the energy savings from using the heat that is rejected by hydrocarbon cabinets. “During spring, autumn and winter, you can save energy, because the ‘rejected heat’ will be re-used to heat the store,” argues AHT’s laboratory manager Werner Schwaiger. “For us it is clear — hydrocarbons are the best technology in terms of energy saving (reduction of CO2).”
While comparisons between CO2 and hydrocarbon systems are difficult to make given the many variables in play, it is clear that many European retailers are opting for natural refrigerants.
To learn more about how retailers are deciding between one natural refrigerant and another, please read the full version of this Accelerate Europe ‘Technology Focus’ here.
Originally published on Jul 17, 2018:
Related news:
