Massive freezers test integration of renewables using smart grid

Massive freezers test integration of renewables using smart grid

solar and wind power

Editor's Note: To learn more about smart grids and renewable energy, don't miss [email protected] Nov. 12-13 in San Francisco, Calif.

A smart-grid demonstration project announced this week in Switzerland will test how companies can manage industrial power demand to optimize their use of renewable energy.

The test involves three massive freezer warehouses owned by Migros, the country's largest retailer and supermarket chain. The buildings, which cover an area roughly equivalent to 30 football fields, are maintained at a temperature of minus 18 degrees Fahrenheit – which requires 500,000 kilowatt-hours of electricity each month.

It is relatively straightforward to predict and control energy use when the warehouse doors are closed – the freezers are, in effect, thermal storage devices that stay cold for a relatively long time even when their power supply is shut off.

The process isn't as simple during daily deliveries when literally thousands of pallets are transferred to trucks for transportation to Migros' 990 stores. When that happens, the air-conditioning units click on and off constantly to accommodate – similar to what happens when you open your refrigerator door.

Migros is teaming up with IBM, local utility BKW and national grid operator Swissgrid to test how the smart grid can be used to improve the process.

"We asked ourselves, how can we do this smarter?" says Roland Stadler, head of energy purchasing for Migros. "We know when our trucks arrive and depart, and we know the schedule of our employees, therefore if can integrate this data with our energy needs, based on the available renewable electricity, we can maintain the temperature of the warehouse and contribute to the future stability of the grid simultaneously." 

The smart grid pilot -- known as Flexlast -- will use data collected by warehouse sensors along with logistics information from Migros, real-time energy data from BKW and Swissgrid, and technology developed by IBM to determine when to turn the climate controls for the warehouses on and off.

When there are no deliveries scheduled, the climate control systems will run on their highest settings but when the doors are open or renewable energy isn't being generated by the local utility, they will be shut down or run on lower settings to conserve power.

Migros' aim is to optimize its use of solar and wind from the local grid. BKW and Swissgrid, meanwhile, are looking for ways to balance the fluctuating load caused by the warehouses and reduce the chances for grid failures.

"Besides demonstrating the technology behind the project, we also hope to illustrate how industrial energy consumers, like Migros, can also re-engineer their processes for optimal power system integration – it's a financial win-win," says Wolf-Christian Rumsch, project manager for BKW. "For Swissgrid, a key motivation to participate is the potential contribution of FlexLast to improve the stability of the grid – which will have a positive impact on the security of energy supplies."

The Flexlast project will run during 2013.

Switzerland's energy policy calls for renewable energy to supply 10 percent of demand by 2030.

This article first appeared on and is reprinted with permission. 

Image of solar and wind power provided by Vaclav Vollrab via Shutterstock.