From space station air...
...to greenhouse CO₂
Technology with roots in space research could help greenhouse growers secure a different source of carbon dioxide.
By Rachel Wakefield
Keeping astronauts safe and helping greenhouse crops grow might seem like unlikely partners. Yet both depend on managing carbon dioxide. In a spacecraft, CO₂ exhaled by the crew must be removed from the air. In a greenhouse, growers can use additional CO₂ to support photosynthesis and crop production.
For Dutch company Skytree, that connection provided the starting point for developing technology that captures CO₂ from ambient air for use on Earth.
At GreenTech Amsterdam in June 2026, Skytree and Wageningen University & Research (WUR) explored the possibilities of direct air capture — and the evidence needed to assess its contribution to more sustainable production.
Ot Messemaker, Skytree’s Head of Business Finance, described how technology with European Space Agency origins could address a growing challenge for greenhouse horticulture: securing CO₂ as businesses move away from fossil fuel heating.
“It is not a nice to have, but it is a must have,” he said of CO₂ enrichment.
Securing the next source
A question for protected ornamentals CO₂ enrichment is relevant to both cut flower and pot plant production. Crops such as roses and chrysanthemums can benefit through improved growth and flower or stem quality, although responses depend on the crop and growing conditions.
Within a greenhouse, plants can absorb CO₂ faster than it is replenished. Restricted ventilation, used to conserve heat, can make this depletion more pronounced. Supplementing CO₂ helps prevent it from becoming a limiting factor in photosynthesis, alongside light and temperature.
Moving away from gas boilers and combined heat and power systems therefore creates a challenge beyond replacing the heat: securing a reliable, affordable source of CO₂.
External supplies face pressures too. Messemaker described how the diversion of industrial CO₂ towards permanent storage could affect its availability for horticulture. Alongside supply security and price, growers assessing their production footprint must consider the environmental impact of that CO₂.
Direct air capture could provide an alternative, producing CO₂ close to where it is used. Its practical value will depend on how it integrates with the nursery’s energy system, the cost of supplying CO₂ to the crop and the environmental benefits it can demonstrate.
Connecting capture with greenhouse energy
Making use of available heat Direct air capture uses materials known as sorbents to bind CO₂ from ambient air. The captured gas is subsequently released and collected for use.
Describing Skytree’s Stratus system, Messemaker explained that heat releases the CO₂ from the sorbent. Integrating this process with suitable heat available at a greenhouse site could, he said, reduce the electricity required for capture.
“So what if you can use the heat to make CO₂?” he asked.
Sunny conditions can increase demand for CO₂ enrichment while reducing the greenhouse’s immediate need for heating. Capture and storage could offer flexibility over when CO₂ is produced and when it is supplied to the crop. Whether that delivers an advantage depends on the site’s energy infrastructure, storage arrangements and operating costs.
Testing an alternative supply Changing CO₂ sources raises a practical concern: will the replacement support crop performance without introducing contaminants that could damage plants? WUR’s IDC CO₂ project at Bleiswijk investigates these questions through independent testing. In its first cucumber trial with Skytree’s Cumulus beta unit, from January to June 2024, researchers reported no differences in yield between compartments supplied with captured atmospheric CO₂ and conventional industrial CO₂ from the OCAP network. Researchers observed no signs of phytotoxicity damage to the crop.
These findings provide an encouraging indication that captured atmospheric CO₂ can serve as an alternative supply under the conditions tested. They do not establish performance in ornamental plants or the operating costs and reliability of a commercial installation.
The distinction between systems also matters. WUR’s published Cumulus report cautions that its results are not fully representative of the larger Stratus system. Alexander Boedijn, Programme Manager for Circular Greenhouse Horticulture at WUR, who led the project and trials, confirmed to fci that WUR had not yet tested Stratus and hoped to begin validation work in 2027.
Measuring the wider benefit
Energy use matters alongside supply A different source of CO₂ does not, by itself, establish an environmental improvement. Capturing, concentrating and supplying the gas requires energy, which must be considered alongside its contribution to crop production.
Alexander van Tuyll, Researcher in Circular Greenhouse Horticulture at WUR, explored this question with colleagues in the study Energy intensity of non-fossil CO₂ enrichment in greenhouse horticulture. Using Dutch tomato production as its modelling basis, the research compared CO₂ supplied through ventilation, biogenic sources such as mushroom substrate composting, and direct air capture. It examined whether additional production could be achieved without increasing energy consumption per kilogram of crop. “It is already possible to increase yields with non-fossil CO₂ without increasing the energy intensity of that produce,” van Tuyll explained.
However, this is not achieved in every scenario. The outcome depends on the CO₂ source, its energy requirements, the greenhouse system and the dosing strategy. For direct air capture, reducing the energy required to supply each kilogram of CO₂ is a priority.
The carbon intensity of the energy used also affects the environmental outcome. The study provides an energy assessment rather than a complete lifecycle assessment of a particular commercial system.
Concentration is only part of the picture The research also questions how concentrated an incoming CO₂ supply needs to be. Under the conditions studied, a source containing around one per cent CO₂ by volume was sufficient to make the additional heating demand associated with displaced air largely negligible.
This refers to the concentration of the incoming supply, not the target concentration inside the greenhouse. Increasing source concentration further may offer limited benefit for direct dosing if it requires more energy, although storage and liquefaction have different requirements.
The finding also highlights the potential of locally available CO₂ from biological processes, such as composting or fermentation, provided its quality and availability meet the grower’s needs.
Can non-fossil CO₂ maintain crop production without increasing energy use per unit produced? WUR’s illustration presents this research question using tomatoes; it does not predict results for ornamental crops. Illustration courtesy WUR.
Using CO₂ more effectively
Matching supply to crop benefit Supply is only one part of the equation. Van Tuyll also highlighted the scope to use existing supplies more efficiently.
“If you just eliminate the most wasteful moments in the year, then you can get a very similar yield with far less CO₂,” he said at GreenTech.
The research supports the importance of dosing strategy: much of the additional production can come from a relatively small share of the CO₂ supplied. The scope for improvement depends on how efficiently a grower is already applying it.
The findings are relevant to ornamental horticulture, although the tomato modelling and cucumber trials do not show how individual flower and plant crops would respond. Growers will need to weigh any benefits against their own priorities, including plant quality, stem and flower characteristics, and cropping time.
The practical question is how an alternative supply performs within the whole production system. Reliable delivery, energy demand, crop response and cost all need to be assessed together. Independent research is helping establish where non-fossil CO₂ can contribute, and what still needs to be demonstrated.
Technology with roots in space research may have a place in the greenhouse of the future, but its value will depend on what it delivers for growers and the plants they produce.
CO₂ supply and the energy question
Alexander van Tuyll explains how alternative CO₂ sources affect energy demand in greenhouse production.
