Sustainable: drying plugs with geothermal heat

Publication date: 09-02-2021

Van der Knaap recently opened a drying area for Obturo® plugs. Obturo® plugs are excellent for drying and then rewetting. This has several advantages: dried plugs have a longer shelf life and it saves weight. To save energy costs, we have devised a solution that is as sustainable as it gets: we dry with geothermal energy!

Since 2018, our innovation centre ‘de Kas’ in Honselersdijk has been connected to the geothermal energy network ‘Aardwarmte Vogelaer’. The innovation centre is certainly not a major consumer, which means that some of the geothermal energy is also available for other applications. The return water (i.e. after being used in our cultivation greenhouses) is sufficient to heat the required air for the drying room through a heat exchanger. Because we use the geothermal energy efficiently, we return cooler water. This increases the efficiency of geothermal energy consumption.

To dry the plugs, they are placed on trolleys in a separate cell. The moisture is absorbed from the plugs with warm and dry air. After delivery, the plugs can easily be returned to the correct moisture percentage. Obturo® plugs absorb moisture with ease.

The main advantage of dried plugs is their increased shelf life. Living organisms such as bacteria can consume nitrate (NO3) in plugs that are kept moist for a long period of time in sealed packaging. This happens especially when the oxygen present has been consumed by the presence of aerobic bacteria. When this happens, the bacteria will feast on the oxygen that is bound to NO3, with N eventually escaping as nitrogen gas. In addition to this process, other important nutrients, such as calcium and magnesium, also disappear over time. However, drying the plugs halts these processes and the nutritional elements will not or hardly be consumed. This allows the plugs to be stored and transported without loss of quality.

Obturo® plugs can be tailored to customer requirements. The size, tray, cutting holes and potting soil mixture can be adjusted in consultation. In this way, Obturo® offers all the flexibility to perfect the cultivation process.

This article appeared in newsletter Grow-How! no. 30

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