R744.com: In our last interview in 2013, you had just installed the first CO2 store in Portugal. What sort of savings have you measured in terms of energy and costs since the system start-up?
Amad Hafez: In my presentation at ATMOsphere Europe 2015 I talked about the hybrid CO2 refrigeration installations we completed in 2013 and 2014, which did not yield huge savings for us compared to traditional HFC systems. Although we are trying to do something different with cascade systems given the initial investment we made, and compared to the measured energy savings, we didn’t see a real difference from HFC systems. This is a problem for us because we are implementing systems that are beneficial for the environment but not suitable in terms of energy consumption. What we saw for the hybrid CO2 cascade system was a significant decrease in energy consumption for low temperatures, but the energy consumption was higher at the medium temperatures, so the system’s overall consumption was the same as an HFC system.
R744.com: In light of these results are you considering other natural refrigerants systems?
Hafez: We are thinking about whether to look for a new solution to replace R134a as the primary refrigerant in the cascade system. It is a good option in sub-critical systems, as the savings are significant for CO2 in the lower temperatures, however, in the mid-temperature range the savings are not good enough, which makes us uncomfortable.
R744.com: In 2013, you weren’t really thinking about transcritical systems, but given the less than ideal performance of your CO2/ammonia system, is CO2 transcritical still not a consideration?
Hafez: This is a difficult question for us because we don’t have many pilot refrigeration systems in our stores, which means we do not have much data to present, making it very difficult to explain the situation to our executive board. At present we have two pilot stores with CO2/NH3 cascade systems, one installed in a 10,000 ft2 (929 m2) store and the other pilots are subcritical CO2/ HFC stores. For only one of these we have measured energy consumption that would enable us to decide whether it is suitable or not.
Looking at the situation today, to my knowledge there are only a handful of CO2 transcritical systems functioning in Spain. For us, this is not enough to decide whether this technology is suitable or not. We want to see more.
For now we are in a situation where we already have two different pilot systems and we can’t go with another solution right now, because the pilots installed so far gave us results we did not expect. If we were to add a third type of technology as a pilot store, using a transcritical system, and using additional technology such as ejectors, we would need to really investigate what system suppliers can offer in terms of efficiency improvements.
R744.com: What is your company’s take on the direction future regulation will take and whether to change refrigeration systems now in order to avoid having to change systems again in the future?
Hafez: We are not attached to one system. Of course we will comply with the EU F-Gas Regulation, but as I said we already have pilots, and when we saw their numbers, we saw what was rhetoric and what was the reality. Complying with the Regulation will mean a big phasedown for us, as we have 74% of stores using R404A. This is a problem for us, as right now our subcritical CO2 systems have not achieved the savings we expected, whilst we do no yet know how the two pilot NH3/CO2 stores will behave over the long run. Searching for a substitute for R404A is not easy for us. At this stage we aren’t thrilled with the energy consumption of naturals at high temperatures, but our commitment is of course to meet the F-Gas Regulation.
R744.com: When you first began these pilot stores, did your technicians have trouble getting used to the new systems?
Hafez: Yes, of course, in my last interview with R744.com, I mentioned that we would start with only CO2 subcritical systems in smaller stores – we have three store sizes, a small, medium and a hypermarket size. We decided to put these systems in the small sized stores, so that the technicians could become familiar with these systems and improve their know-how step-by-step.
R744.com: As you mentioned, you cannot keep on introducing pilot natural refrigerant stores without better results. However, with the new F-Gas Regulation revision, do you see retailers beginning to use more natural refrigerants?
Hafez: We already use propane in our cabinets in small and medium-sized stores. Since 2013 all our promotional cabinets use propane. For R744 my goal would be to see the energy savings for CO2 transcritical that we already saw in the lower temperatures of our installed cascade systems. It would be amazing if we could achieve these savings because the decrease in consumption is very high. But having seen the numbers, this is not yet the case.