Thermal storage for supermarket refrigeration system
The purpose of the project is to save energy in the running of the cooling system by transfer the consumption from day to night. This is done by saving energy in ice and reduce the energy consumption the followering dag by using the storaged energy.
The purpose of the project is to save energy in the running of the cooling system by transfer the consumption from day to night. This is done by saving energy in ice and reduce the energy consumption the followering dag by using the storaged energy. This has followering potentiale:
- The storaged cooling energy can be produced with a energy saving up to 50 % for those days where the difference between the day and night temperature is highest.
- Compressors energy consumption can be reduced with 50 % most of the day.
- The heat recovery effect can be adjusted after the need for heat.
- Opportunity to fit systems with smaller compressor capacity (down sizing).
- Opportunity to fiiting in cooling systems in the smart grid strategy.
The project contains tests of two concepts for supermarket cooling systems with CO2 and analyses of the energy saving potential that form the basis for economical assessment with regard to the business of investments in energy storages in consideration of different scenarios for development in electricity prices.
The project analyses the potential for use of ice storage in connection with supermarket refrigeration systems. The storage enables the transition of a part of the power consumption to the night-time where the outdoor temperature is lower, and the refrigeration process is more efficient. Likewise, a reduction in running cost is achievable as the power price at night often will be lower, where the load on the grid is lower. The technology thus has the potential to contribute to a greater flexibility on the grid.
The project utilises an indirect method for connecting the storage requiring a very limited intervention in the refrigeration system and therefore it is expected to be relatively inexpensive to install. As a result of this, the storage cannot be used to directly cool the goods in the supermarket but will instead contribute to increase the efficiency of the refrigeration system, which will still need to be in operation.
The ice storage was demonstrated on a test set up, close to a real supermarket refrigeration system. It was shown that the storage and the integration with the refrigeration system worked according to the plan and that the storage enabled the transition of the refrigeration system load on the grid from daytime to nighttime.
However, the calculations for economic potential was less promising. The analysis revealed that the large potential for saving energy is present in the daytime on warmer days. These conditions are only present a minor part of the year, and the resulting accumulated potential over the year is limited.
Likewise, the mean price differential between the power price at night and day is quite small. There will be limits to the practicability of controlling the ice build and melt in the storage following fast fluctuations in the power price from hour to hour. This constrains the potential to use the span between day and night prices with the present tariff structures for the electric power in Denmark.
In the project, is demonstrated that it is feasible and relatively simple to integrate an ice storage in a traditional supermarket refrigeration system. However, the analysis performed in the project has shown that the potential for realising savings in operating cost are severely limited with the present tariff structures. It is therefore concluded that the incitement for investments in the technology presently is low.
Key figures
Category
Participants
| Partner | Subsidy | Auto financing |
|---|---|---|
| ADVANSOR A/S | ||
| Danfoss A/S | ||
| SUPER KØL A/S | ||
| Danmarks Tekniske Universitet (DTU) |
