CO2-negative cultivation without loss of quality and yield? KUBO proves that it can be done. In recent years, the Monster-based company has worked hard to further develop its Ultra-Clima® concept, and with results. Practical trials show that it is possible not only to reduce CO2 emissions, but also to take more CO2 out of the air than is emitted.
Text: Jacco Strating
Photography: Sharon Schouten
To grow vegetables, CO2 is indispensable. But why add extra CO2 and emit excess CO2 when the plants can get their exact CO2 requirements from the air outside? With this thought in mind, KUBO set to work. The Ultra-Clima® concept had been around for some time and had caused a furor internationally as a sustainable growing method. But KUBO continued to develop the concept in recent years, with a strong focus on reducing CO2 consumption. With the first CO2-negative cultivation strategy as a result.
Luuk Graamans is Senior Consultant Greenhouse Technology at KUBO. Previously, he worked as a researcher at Wageningen U&R and TU Delft. He indicates that the designation 'CO2-negative greenhouse' often already leads to immediate discussion. "Many people then shout: how can you be completely CO2-negative? You put up a complete building and the tomatoes are grown and eaten, which also releases CO2. That's why it's important to make it clear what we actually mean." The company did that by entering into a "competition" with Schenkeveld. "We wanted to show that we can grow at the same level as one of the best tomato growers in the Netherlands, but with much less CO2," said Graamans. "And we succeeded."
The Ultra-Clima® greenhouse uses renewable energy sources, reusing captured CO2 as well as CO2 from the outside air as fertilization. This reduces emissions significantly. And because this CO2 is always available, residual heat can even be used for CO2-neutral cultivation. In addition, the consumption of water and energy is lower and the semi-closed concept uses innovative ventilation technology. This allows the CO2 footprint to be reduced even further. "We cultivated in our test center BlueLab under the same conditions as Schenkeveld, but we did so with 7 percent less water, 22 percent less electricity and as much as 92 percent less dosed CO2. In addition, we realized comparable yield." The results were validated by an internationally recognized sustainability consulting firm, Graamans points out. "But just as important is that we were able to convince Schenkeveld, not the first to know, that our concept works. Not just based on numbers, but also by how the crop looked."
A greenhouse, according to Graamans, requires all kinds of materials with their own CO2 footprint. "At the bottom the energy and at the top the directly dosed CO2. There is a whole chain attached to all those materials, again with its own CO2 footprint, and the same goes for the water and plant material used. Then on the consumer side you have processing, storage, transport and consumption. So if you want to make the whole chain CO2 neutral, you have to include all those aspects." According to Graamans, if you want a CO2-negative tomato, all you have to do is look at what is actually dosed and how much a tomato absorbs. "That's an easier calculation. But we want to go to a CO2-negative greenhouse, so we also look at the operational inputs, the amount of electricity and energy needed to grow that tomato."
The gold standard in greenhouse farming is still the Venlo greenhouse. A greenhouse that operates primarily with natural ventilation. "The disadvantage compared to the energy and CO2 consumption is that you are dosing a lot at times when there is a lot of light and then the windows open when it is warm and away is the CO2. That's not where we want to go as an industry. The Ultra-Clima® greenhouse is different in that we allow water to evaporate which we use to cool air from outside and make it more humid. That air goes through a heating unit and is circulated under pressure throughout the greenhouse. So the air does not go in and out through the window, but is sucked in centrally and distributed centrally between the plants. As a result, CO2 from outside is also continuously circulated, so you have a continuous supply of CO2 close to the leaf."
According to Graamans, this technique can be applied not only to tomatoes, but also to other products. "A trial is already running with strawberries and we are looking at more crops." With this, he expects that KUBO can contribute to sustainability in various crops in the coming years. And for that, complete new construction is by no means always necessary. "We can certainly also fit the concept into existing farms through retrofit. There is an investment in return, but if you look at the increase in production and quality, that is also quickly recouped." However, Graamans does point out that the Ultra-Clima® greenhouse is a total concept. "If you start leaving things out, the results will also be different. After all, a Ferrari on standard tires also drives less pleasantly."