Norway: No-venting in Greenhouse Pushes Tomato Yield to 160kg per m2

"At NIBIO, we don't use natural gas to heat anymore so we do not benefit from waste carbon dioxide. With DAC technology, we capture carbon dioxide from outside and put it in the greenhouse. While using hydroelectric energy, allows us to be a zero-emission system," says Michel Verheul, Senior Research Scientist at NIBIO in Særheim, Norway.

In September 2023, NIBIO began a three-year research project focused on emission-free greenhouse farming, funded by the Norwegian Research Council. The project seeks specifically to reduce energy needs in a closed greenhouse using an Environmental Control System (ECS) provided by GreenCap Solutions, also a Norwegian company.

This technology focuses on controlling temperature, humidity, and carbon dioxide in the greenhouse to optimize production. A heat pump system removes excess heat and humidity from the greenhouse. While excess heat is stored for later use, the removed water (i.e., condensate) is ready to be treated and reused in the greenhouse. Meanwhile, the direct-air-capture (DAC) system captures carbon dioxide from the air and enriches the greenhouse.

"The work by NIBIO and GreenCap is exciting for the industry. The increase in production and reduction of input factors is a winning formula," says Andreas Grünbaum, Finance Manager at GreenCap.

Impressive Tomato Yields Combining LED and DAC

Having set a high yield target of 120 kg per square meter for tomatoes, Michel wasn't quite sure what to expect in terms of improvements and thus tested production both without and with supplemental lighting. With 500 µmol/m2/s of supplemental lighting, productivity jumped from 40 kg/m2 to 120 kg/m2. Then, with the GreenCap system, yield further jumped to 160 kg/m2.

"Most growers using LED lighting are producing roughly 110-115 kg per square meter, with much higher light intensities than in the Netherlands due to our low winter light levels. This 160 kg/m2 is from the combination of lighting and ECS and DAC technology, and it will become the new standard," says Michel.

As Michel and Andreas note, implementing this technology requires a closed greenhouse system, ideally under glass and not plastic. Under these conditions, NIBIO has found 1200-1600 ppm of carbon dioxide to be the ideal level for plant growth, given the high light levels installed in the greenhouse.

"This system is building on what was done by Wageningen 20 years ago. We are circulating the air so that we don't need to open the vents, so there is no energy or carbon dioxide lost. We can be completely emission-free," says Michel.

Source: Hortidaily