Energy efficient pepper cultivation

The objective of the Dutch project ‘Energy efficient pepper cultivation' is practically oriented: energy efficient growing while maintaining quality and production. Jeroen Zwinkels of Delphy discussed the principles of this Improvement Centre trial last week. By using double, movable screens and heating only based on temperature demand, gas consumption at the end of cultivation should be no more than 20 m3/m2. There are two rows of peppers per 1.60 m (breed Maranello). The goal is to produce a minimum of 30 kg of peppers per m2.

Quality control is conducted among other things by the intensive use of the double screen to create a homogeneous environment. Radiation is minimized and climate shocks are prevented. Screens will open based on temperature differences above and below the screen. Nivolators are used to achieve slight air circulation in the greenhouse. Three measuring units, a radiation meter (below the screen) and a plant temperature meter have been installed. This equipment ensures that the trial can be properly monitored. 200 kg of pure CO2 is used per ha/hour.

To meet all these requirements screens are used for many hours with little aeration and no concessions to temperature. Also, no minimum tube is used.

In the meantime Wageningen UR is working on a similar trial. The objective here is also to use as little energy as possible and achieve a practice-based production; 14 m3 gas/30kg. Here 25 kg CO2 is administered per m2. Arie de Gelder explained that the objective is the same. The means are different. At Wageningen UR the crop is grown in a highly insulating greenhouse (Venlow Energy Greenhouse). This greenhouse has double glazing in its roof. The interspace is filled with gas. The deck is also coated with 1x low emission and 3x AR. In addition, the greenhouse is fitted with foil. A high-pressure spray system is used. Dehumidifying occurs with Regain. Arie: "Energy efficient dehumidification is not really dehumidification." 

The cultivation strategy for both trials is discussed weekly. The first figures are known. According to Arie: "It's only an intermediate result." Feije de Zwart from Wageningen UR expects that the differences in light transmission in the greenhouses at IC and WUR may also have an effect on production. Feije: "The final report will take this into account. Ultimately it is about learning from the processes and crop reactions in both greenhouses and not about which greenhouse performs best."

This project has partly been made possible by the contribution of the program Kas als Energiebron. Next Generation Growing was set in motion seven years ago. Project leader Aat Dijkshoorn: "Goals were met in all projects. Positive results were in fact achieved even where no investments were made, thanks to a more energy-conscious cultivation strategy. Better measuring allowed for better control and more conscious growing." Following these results Kas als Energiebron developed a Next Generation Growing course. In the meantime 350 growers have taken it. There’s great enthusiasm. The basic course teaches growers how Next Generation Growing can be applied without investing in new technologies.

Paul Arkesteijn of Ludvig Svensson discussed the choice for two screens in the Improvement Centre trial. The upper screen is the 1547 D FR. The 1347 FR H2NO was selected as the lower screen. These screens save 47% on energy separately; 63% jointly. The screens score 76% and 80%, respectively, on light transmission and 61% jointly. Typical of the H2NO fabric is that no condensation drops hang from the bottom of the screen. These are distributed as a water film. Water transmits light very well. This is why the cloth scores so highly on light transmission.

No gaps are allowed in the test both for energy saving and solar radiation. During clear, cold nights the cloth is completely closed to prevent heat radiation. This creates a higher temperature. A net radiation sensor was mounted in the test set-up. It measures solar radiation. Paul: "The crops thrive better by using several screens. That is a conclusion we can already reach."