A new shade of green for grocery stores

Wednesday, June 19, 2019

The supermarket Aktiv & Irma in Oldenburg, Germany, has pressed the start-button to a solution enabling it to store and generate electricity. The grocery store’s manager calls it a leap forward in energy supply. Danfoss and SMA have helped make it happen. Learn how.

Technicians, who enter the cooling control room in Aktiv & Irma, Oldenburg, Germany, will see brand stickers from Danfoss and SMA Solar Technology on a very large part of all the digital monitoring equipment, valves, frequency converters, solar inverters, and controllers inside.

With good reason. The two companies have supplied most of the key components enabling the store to run with an energy consumption-level roughly 20 percent below average European supermarkets.

One of the latest additions is a digital energy management solution with Danfoss’ AK-SM 800 System Manager and SMA’s ennexOS unit as the main ingredients. Combined, the two components provide the store with a kind of intelligent, two-way connection to the electricity grid. The benefits are clear.

Power from the cooling counters

For example, the solution will allow the supermarket to function almost like a giant battery that can store electricity when there is too much of it in the grid.

"This solution provided by Danfoss and SMA is a leap forward in the food retail industry and maybe energy-supply as such. For sure, it is one of the first examples of supermarkets' energy-management potential, says Günter Walter, General Manager, aktiv & irma, Oldenburg.

The supermarket’s refrigeration and cooling counters are key to making it function like a giant battery.

In windy and sunny weather, the local power plant will typically have excess availability of sun or wind power. In that situation, the supermarket can cool down its counters a little more than necessary – drawing extra energy from the grid.

When the weather turns, and the power plant needs electricity, the supermarket's counters are colder than necessary. And then, it can spend less electricity for a while – without damaging food safety.

Future proof solution

"It's what we call functional storage. It will help us contribute, as a supermarket, to creating a more flexible, sustainable, and green energy system. The Danfoss and SMA solution is future proof – so much, in fact, that our energy laws have trouble following suit. The legal incentives for power plants to send wind or sun energy our way when they have excess capacity are simply not in place yet. But that, of course, is bound to change soon. And then we are ready," says Günter Walter, General Manager, aktiv & irma, Oldenburg.

aktiv & irma is a supermarket chain in Northwestern Germany.

aktiv & irma has installed a 60kW lithium-ion battery in its control room.

SMA’s ennexOS unit can connect and manage energy flows from different sources to and from the store - including solar or wind power, battery storage power and so on. It functions as a kind of electronic brain deciding which source to use – and when – in the most energy effective way. In the photo: Kenny Arzo.

aktiv & irma has installed a 60kW lithium-ion battery in its control room. It provides the store with a so-called peak-shaving ability. When the store spends extra electricity to keep its counters cool, for example on a hot summer day, the battery covers some of the need. This saves money for the store. The reason is that the per kilowatt price, which a supermarket pays for electricity, is based on its peak usage-day the previous year. In the photo: Dirk Leinweber.

Multi Ejector

Refrigerated by CO2

Supermarkets can use C02 as a natural refrigerant that does not contribute to global warming. Still, some opt for other refrigerants. One reason is that CO2, by some, is still perceived as an alternative solution that requires higher installation costs and skills and use more energy. But the industry has long overcome these initial challenges. Thanks to Danfoss’ so-called Multi Ejector Solution™, for example, aktiv & irma’s cooling counters use C02 and still spend less energy than most stores using other refrigerant types. The reason is that the Multi Ejector – a sophisticated type of expansion valve – captures the high pressure, which the supermarket’s cooling compressors build up, and sends it back into the compressors. As a result, the compressors spend less electricity. Play the video and learn more about the Multi Ejector Solution™