Electricity consumption for cooling energy production represents between 30% and 50% of the total bill of dairies. Therefore, it is obviously crucial to consider the efficiency of refrigeration systems.
Dairy managers often find themselves thinking about the opportunities and costs arising from the replacement of such plants, mainly for two reasons:
a. obsolescence: the efficiency is poor in comparison to the new systems and the continuous maintenance generates outages and important costs;
b. new sizing: the dairy grows and so does the need for cooling energy. The old ice bank tank is no longer sufficient to guarantee an adequate level of service.
Once the need to take action is established, you are in front of a technological crossroads: to replace the generator and maintain the ice storage, or to install a generator with direct production of cooling energy, thus eliminating the ice bank tank? There is no one-size-fits-all solution: you need to analyze the specific situation to determine the optimal renewal. Then, we can draw some guidelines to support those who have to make this decision.
Ice storage offers several advantages:
- with the same amount of supplied energy, it allows to install a smaller generator, resulting in savings in terms of investment;
- it allows to move the operation of the generator at nighttime, when the electricity is cheaper and outside temperature is lower, thus allowing the generator to work at higher efficiency;
- the use of latent heat from ice melting ensures a constant temperature for the user.
These advantages disappear, however, when the size of the plant is no longer able to meet the needs of the dairy:
- as the needs increase, the operation of the generator becomes necessary even during the day and often it is not possible to produce sufficient ice thickness, because of the simultaneous demand for cooling energy from the process. For this reason, the refrigeration unit has to work simultaneously with the loads.
- In addition, the advantage of having a smaller generator turns into a double-edged sword when you have to work directly: likely, it will not be able to meet the peak demand, like, for example, whey cooling.
- While for the production of ice it is necessary that the refrigeration unit works at temperatures in the order of -6/-8 C, the direct production of icy water allows the generator to evaporate even at -2/0 installment C, with a significant increase in efficiency.
There is also the possibility of opting for “mixed” solutions, in which the revamping (modernization, ndr.) of the plant involves the live production of cooling energy, maintaining however an ice storage to be loaded during the night and to be used during the day, in the peak moments of cooling demand.
In conclusion, each situation must be carefully analyzed to understand which solution can be the most suitable to meet the needs of the production process and the company “portfolio”. Thanks to EDSS, the software created by the LIFE TTGG project to measure and improve the environmental impact of the Grana Padano chain and potentially of all the PDO chains, it is possible to obtain a first assessment of the potential savings due to revamping of the cooling production system, by completing a simple questionnaire. It is a solid starting point to start thinking about the possibilities at stake, to plan in a conscious and solid way the path towards sustainability.