Anyone looking outside from the canteen at bell pepper grower Duijnisveld in De Kwakel on Friday afternoon sees only blue skies and the sun. Good weather for solar panels, for growing, but also perfect weather for a thermal battery. Based on the centuries-old technique of the fruit wall, Thermeleon has developed a system that can both heat and cool.
"Free sun is now being vented by growers," observes Peter de Munck, a grower since January 1 and well acquainted with Thermeleon's system. When venting, you also lose CO₂, an increasingly valuable resource that plants need to grow. Sunshine alone is not enough. In fact, too much sunshine can also be a hindrance.
Peter himself considered investing in the technology of the Rotterdam-based scale-up a few years ago, but it didn't come to that. Koppert Cress did. The system has been running there for a year and a half now. Jildou de Jong, founder and director of Thermeleon, and Peter shared the first results on Friday afternoon, April 11, during a knowledge café at Greenport Aalsmeer.
Passive technology
"Hands up," says Peter when five reasons to invest in a thermal battery are displayed on the presentation screen. Just like in 2022, when Thermeleon conducted a small survey, most hands go up again for payback time. Crop quality is also important to the attending growers, besides the fact that investing in a thermal battery is also sustainable. Those who heat and cool their greenhouse with the thermal battery use no fossil fuels and no electricity.
Thermeleon's thermal battery is a passive technology. It uses so-called Phase Change Materials (PCM) in the greenhouse, which has a heat surplus due to the 'greenhouse effect'. These elements charge and discharge passively through this heat surplus and temperature differences. No power cable is involved, and it contains no harmful chemicals. This makes the battery truly different from traditional battery systems, Jildou emphasizes.
Heating and cooling
Those who understand the principle realize that the stored energy can be used to heat a greenhouse. Thermeleon's PCM retains 13 times more heat than a brick fruit wall. The heat is slowly released from the battery, contributing to a better greenhouse temperature, with the desired setting that the grower can pre-set together with Thermeleon.
During his discussion of the first practical results on a hectare scale, Peter also explicitly points out the cooling effect of the Thermeleon battery. He shows that at Koppert Cress in the greenhouse, where a 1-hectare greenhouse with a thermal battery was compared to a greenhouse without one, it was less warm in the summer. Those few degrees cooler make a big difference, Peter points out. And also importantly: heating can start later in the fall.
The New Growing
Those who think after hearing the story that after installing the thermal battery the boiler can be discarded are mistaken. Just like with many new energy technologies, it seems that Thermeleon's thermal battery is also a great technique for the 'energy mix'. With the thermal battery, a grower can cover the base load. By being able to use multiple techniques, growers are more flexible, and the energy demand during peak hours is lower. Not unimportant now that the government makes a rather fickle impression, and it's difficult to look ahead, as new measures from The Hague keep coming.
After the plenary session, the group of about thirty growers and other interested parties sit down with Jildou, Peter, and engineer Wouter Bentvelsen for more details. Growers want to know how it works with charging in the winter. Even then, there are days when there is enough sun to charge the system, as data from the greenhouse at Koppert Cress shows, and in addition, the thermal battery retains heat better.
They also ask how best to integrate the system? That varies per crop and is possible in different places in the greenhouse to create an even climate. The technology fits well with The New Growing. Those who grow more closed have an interest in cooling without excessive venting.
Jildou in conversation with a table full of interested people.
Minimum heating temperature
Peter also had the questions that the growers asked on Friday. Seeing the results in practice made him increasingly enthusiastic. "There is something to gain for every crop. Most profit is to be gained in spring and summer, but do not underestimate the effect in autumn and winter."
Thermeleon sees the greatest opportunities for the system in crops with a heating temperature of 17 degrees Celsius. Jildou: "In addition, the system also offers value to growers who consciously choose a cultivation strategy with minimal energy use: in that situation, retaining heat is extra important."
If a number of subsidies are used, the system can be recouped in a few years. The exact payback time depends on the type of crop and the integration choice, Jildou emphasizes. "Because the system is passive, there are no operational costs, and energy costs are saved each year after installation. For growers who benefit from more CO2 retention and an even greenhouse climate, these are additional benefits."
For more information:
Thermeleon
Van Nelleweg 1
3044 BC Rotterdam
[email protected]
www.thermeleon.nl