New onion storage: quality always wins

Smits Akkerbouw is a family business consisting of three cousins ​​who are active at various locations in the Noordoostpolder in the cultivation of, among other things, seed and consumption potatoes and yellow and red seed onions and carrots. The storage and processing activities of the various crops are divided over the three business locations. Now all onions and part of the potatoes are stored at the location in Nagele. This is more efficient in terms of logistics and ultimately benefits the quality. There has also been a desire for some time to switch to box storage and to store as few onions as possible in bulk. Box storage ensures a nicer color of the product and it provides flexibility in terms of delivery options. In addition, there were plans to do more with the generation of sustainable energy and to use this in a smart way in storage. To this end, a new storage facility will be built in 2022 for box storage with a total capacity of 4,000 tons of product.

Make plans with custodian advisor

"I already had a Vision Control storage computer from Tolsma-Grisnich in the existing storage facility, which is why I invited storage consultant Paul den Engelsen together with the construction company to discuss the plans for the new building," says Smits. "In any case, I also wanted to talk about condensation drying." The reason for consciously opting for condenser drying was that it benefits the quality of the product because storage can be carried out at a lower temperature without temperature fluctuations. In addition, the relative humidity can be kept at around 80% independently of the outside air by means of condensation drying. This keeps a nice color on the onions.

Although the initial idea was to purchase one new central fixed cooling installation that would also replace the existing cooling, it was ultimately decided to gear the design of the storage to the use of plug & play condenser drying units. The fact that these units are also equipped with the natural refrigerant propane fitted well with the desire to realize a sustainable storage facility. An additional advantage is that they fall under the Energy investment deduction scheme. Ultimately, four cells were included in the design, of which two cells are fitted with a suction wall and two cells of 1,000 tons each are equipped with the condensation drying units. The storage cells are located to the left and right of a spacious covered storage/processing area.

Experiences after first storage season

When asked about his first experiences with the new system, Jac quickly starts talking about the storage temperature of his onions, which is now at 5 °C instead of around 7 °C. And the relative humidity that remains nice and constant and low. "With this condenser drying installation you can simply dry with air that has the same temperature as the onions," he says enthusiastically. "You can't do that with just outside air". This is also beneficial to dry a single onion that is not healthy so that it does not cause problems later on.

The quality of the onions is now, at the end of March, simply good. The onions are sharp, don't go bald and certainly don't show 'worn'. A single sick onion has dried up nicely. Due to the lower dumping height compared to bulk, Smits also expects less 'square' onions on delivery. He cannot yet say much about the operating hours of the system compared to the old situation. His main concern is to be able to deliver a good product because 'quality always wins in the end".

Further optimize energy management

With the expansion, the Vision Control has now also been updated with the energy management module. The great thing about this is that at times when power is generated with the solar panels, the Vision Control automatically lowers the storage temperature somewhat. The generated power is used by the mechanical cooling. Energy management is also able to smooth out peak consumption. The storage computer offers many options for optimizing energy consumption on the farm. To get the most out of it, you have to gain some experience with it, says Smits: "The only way to get the maximum benefit from this is by doing it". By carefully following what happens with the temperatures and relative humidity in storage, you can adjust the storage computer better and better. "You do have to keep checking whether what you expect actually happens with the settings you have made". You will learn a lot from this and you can further optimize the storage yield. For the future, Jac Smits sees even more opportunities to further optimize energy consumption at his company. "I have regular contact with Paul den Engelsen and I will continue to talk about it."