The new Makro Riversands stores boasts one of the largest CO2 installations in Africa thanks to its impressive world-class trans-critical CO2 refrigeration system.
The store officially opened on 29 November 2017, and the installation was handled by Commercial Refrigeration Services (CRS).
Out of the 21 Makro stores, this is the 15th environmentally friendly, energy-efficient store. There has been a big push towards such ‘green’ engineering after the Walmart acquisition of Makro, bringing the local stores in line with its global policy. Makro stores are now some of the most environmentally friendly stores on the African continent.
The phase out of CFC and HCFC refrigerants and the unknown future of their replacement refrigerants, have led the supermarket industry having to look to alternative, long-term, energy-efficient solutions. Carbon dioxide (R744) is rapidly becoming the industry choice for an alternative refrigerant due to its favourable environmental properties (ODP = 0, GWP = 1).
CO2 is a low global warming potential (GWP) refrigerant and an excellent choice when it comes to reducing greenhouse gas emissions. CO2 provides high performance and exceptional properties for heat reclaim, due to its high heat transfer capabilities. CO2 has excellent volumetric efficiency (more than five times the cooling effect per volume as R22), resulting in reduced compressor and pipe sizes for the same cooling effect, low consumption ratio (the ratio between inlet and outlet pressures from the compressor) and low viscosity (making it easier to pump). CO2 is widely available as a by-product in several industries and the cost of CO2 gas is very low. Another advantage to using a trans-critical CO2 system is that it operates on one gas as opposed to a cascade system.
A case study was done on Makro Strubens Valley, a store that previously ran on a freon refrigerant. The store was upgraded with an additional 100kW cooling capacity in April 2016. The new CO2 system implemented showed a 53% reduction in energy usage.
Although there are no official figures yet for Riversands, the same technology was applied to ensure optimal results.
The energy-efficiency gain by using CO2 is not only due to the properties of CO2 as a refrigerant, but also due to highly advanced implementations by CRS to reduce the energy consumption.
Some of the following technology has been implemented to reach energy reduction:
Hot gas defrost has been implemented into this store, where heat from the refrigeration system is used to defrost the evaporators, therefore eliminating the use of electrical defrost completely.
Heat reclaim of the CO2 refrigeration system is used to heat the store during cool periods and is to be used in the bathroom and kitchen facilities. Therefore, Makro does not use electrical heating to generate hot water at its facility.
Condensate water is captured from the evaporators instead of being dumped into the stormwater drains. This water is used within the refrigeration system to increase energy efficiency, and extra water captured is used to irrigate the garden around the store.
A sustainable future
Electricity for refrigeration constitutes 50% of the total energy consumption of the store. Makro has an ambition to cut down this consumption year by year as part of their sustainability programme. Another goal is to switch to natural refrigerants like CO2 to cut the carbon footprint. With installing the CRS CO2 refrigeration system in Makro Riversands, their environmental and sustainability goals are not only being met, but also exceeded.