The FlexLast Project

Refrigerated warehouses store energy for smart
energy grid
IBM, Migros, BKW and Swissgrid are collaborating in the smart grid pilot project FlexLast supported by the Swiss Federal Office of Energy. Based on two scenarios, this interactive diagram demonstrates how refrigerated warehouses at Migros, the largest Swiss retail company, act as a buffer to help balance fluctuations of the availability of sun and wind energy on the energy grid.

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Power line
Data line
High power production from renewable energy
Oversupply of power
Internal temperature of the refrigerated warehouses
Heat wave forecast
High turnover of goods
Two days before a public holiday
External temperature 36°C
Regulation power requested
Target temperature
Current temperature
Oversupply of power will be compensated
Internal temperature will be reduced to
Increased power consumption
Low power supply from renewable energy
Insufficient power supply
Internal temperature of the refrigerated warehouses
Low temperature forecast
Low turnover of goods
External temperature 10°C
Regulation power requested
Internal temperature of the refrigerated warehouses
Target temperature
Insufficient power supply will be compensated
Internal temperature increases to −26°C
Reduced power consumption
Cooling systems are
ramped down

Refrigerated warehouses as “flexible loads”

The Migros refrigerated warehouses are so well insulated that the internal temperature can be maintained for several hours even when the cooling is off. The target temperature range is between −24 and −29°C. Based on this range, IBM analytics technology determines the minimum and maximum energy requirement for the following week. Within this permitted range, the energy supplier BKW can adapt the energy consumption level dynamically to help balance the energy grid. The refrigerated warehouse becomes an energy storage and a source of so-called regulation power. This “flexible load control” (Last is German for load) gave the project its name.

Grid stability and power transmission

The Swiss national grid operator Swissgrid is responsible for network stability. The power grid is stable when supply and demand are in balance. With the increasing proportion of renewable energy sources, this will become a significant challenge for the future energy grid because wind and solar energy are not always available when needed. Swissgrid is therefore interested in finding additional sources of regulation power.

Energy production and supply

The power generation company BKW distributes electricity throughout the Canton of Bern. To balance fluctuations in the power supply, it delivers and obtains regulation power to or from Swissgrid, respectively. Now within the FlexLast project, BKW can also rely on the refrigerated warehouses.

Analytics for FlexLast

Using analytics, forecasting and optimization software developed by IBM Research – Zurich, the minimum and maximum energy consumption for the refrigerated warehouses is calculated for the pending week. The system allows a precise forecast of the energy requirement and of the flexibility for providing regulation power. The IBM software uses a range of information such as measured data (internal and external temperatures, power consumption of the cooling systems etc.), weather forecasts, power grid data from BKW and Swissgrid, expected changes to the inventory (e.g. before public holidays) as well as parameters that ensure the quality of the stored goods.