The Dutch horticultural sector aims to be climate-neutral in 2040. Thus, Wageningen researchers have built a low-emission demo-greenhouse for the cultivation of vegetables, fruit and flowers in an effort to find ways to reduce CO2 emissions as well as the use of crop protection agents and artificial fertilisers to zero. Pathogens and diseases are tackled biologically, and the energy-efficient greenhouse reuses water and nutrients as much as possible.
This leads to cleaner cultivation as well as improved yield. Today the demo-greenhouse KAS2030 was officially opened by the US Secretary of Agriculture Sonny Perdue and the US ambassador Pete Hoekstra, accompanied by Dutch minister Carola Schouten & WUR President Louise Fresco.
Samen met haar Amerikaanse collega @secretarysonny opende minister Schouten dinsdagmorgen Kas2030 van @WUR. In deze innovatieve kas kunnen groenten, fruit en siergewassen klimaatneutraal en emissieloos worden verbouwd.— Ministerie van Landbouw, Natuur & Voedselkwaliteit (@minlnv) January 28, 2020
Meer weten? ⤵️https://t.co/6HZpL6SfTm pic.twitter.com/i9AUhqGhYi
"In the coming years, greenhouse horticultural entrepreneurs will have to decimate their natural gas consumption and ultimately reduce it to zero. In addition, they will have to comply with the new guidelines on water and zero emissions for minerals and crop protection products. In recent years, major steps have been taken in the case of high-energy crops, in which the Innovation and Demonstration Centre for Energy (IDC), and the Dutch platform Kas als Energiebron, play an important role. For a large part of the sector, particularly the middle segment in terms of energy consumption and in the floriculture sector, there is still much to be gained from the sustainability aspects of energy, water and emissions of nutrients and crop health", is how the researchers explain the importance of this project.
Strawberries, Anthurium, Gerbera & Freesia
In order to achieve the desired acceleration here, a demonstration greenhouse was opened in Bleiswijk in April 2019. The project as commissioned by WUR was realised turn-key by Bom Group, was realised in close cooperation with Hoogendoorn and Elektravon Haket.
Four different crops will be carried out in sections of 350 m2 to demonstrate the possibilities and challenges of fossil and emission-free cultivation.
In the demo-greenhouse KAS2030, situated in Bleiswijk, Wageningen researchers are currently growing strawberries, the houseplant anthurium and the flowers gerbera and freesia.
Especially freesia is a popular flower in bridal arrangements. “Every two to three weeks, horticulturists visit to take a look and discuss our progress. The demo-greenhouse offers us the opportunity to experiment in ways that are impossible in actual practice. Through understanding what is required for emission-free cultivation, we can help the horticultural sector advance,” says Frank Kempkes, researcher Energy and Greenhouse Climate.
Dutch horticulturalists sorely need this help since the sector has agreed to be fully CO2-neutral by the year 2040. The CO2 emissions produced by the sector totalled 5.7 megatonnes in 2017, which they aim to reduce to 2.2 megatonnes of CO2 by 2030.
Reducing energy usage is key in creating a climate-neutral greenhouse. In the winter, heating is generated through the use of natural gas, just as in houses, and this produces CO2 emissions. Better insulation can contribute to lower energy use, but this can cause unwanted levels of humidity.
“Plants will always evaporate, so we must take measures to stop fungi from taking over. The plants in the demo-greenhouse are cultivated at relatively low temperatures. In combination with the improved isolation, this makes it more challenging to dehumidify the greenhouse; which consumes a lot of energy. For this reason, we maintain a higher temperature in the winter, while using special installations to extract moisture from the air. With these dehumidification installations, we reclaim heat at the same time,” Kempkes explains. In the summer the greenhouse is open and there is little or no heating.
The fact that an increasing number of horticulturalists are now using alternative sources of heating such as geothermal heat or a heat pump rather than heating with natural gas is reason to rejoice, according to Kempkes. A heat pump also heats the demo-greenhouse. “But even an energy-efficient greenhouse still needs heating. In the future, this heat will be obtained from renewable energy sources instead of fossil fuel.” The researcher stresses that the possibilities of storing the energy generated by the greenhouse as a solar collector, are expected to increase in the future. He is researching how the energy generated in the summer can be collected and stored. Energy is currently stored in a layer of groundwater. “In the summer, it is usually possible to harvest sufficient energy to get through the winter.”
The 2030 greenhouse therefore does not use gas for heating. It is in fact an all-electric greenhouse, with full LED lighting, among other things. A heat pump is used to dehumidify the greenhouse. This recovers latent heat and keeps the greenhouse closed in winter and spring. The greenhouse does not generate its own electricity; it is purchased as green electricity.
An intelligent system that lifts rows of plants individually allows us to increase the number of plants by 20 per cent in the same space. Credit: Photostudio Gerard-Jan Vlekke / Fotovak
Reduviidae and parasite-wasps
Furthermore, the demo-greenhouse has a standing army of biological exterminators such as linopodes, Reduviidae and parasite-wasps. These prevent the spread of pathogen insects such as thrips, whitefly and plant louse. The greenhouse contains plants that house these insects and that they use for breeding, and they are fed. Normally, a horticulturist will only order biological exterminators once an infestation has started. “This takes time, and meanwhile, the pathogen can spread. So our team of entomologists is now researching what conditions we need for a continuous presence of biological exterminators, and what effect this has. This requires precision”, states Kempkes.
He continues: “The conditions in the greenhouse must be favourable to the survival of the exterminators. Besides, not every pathogen insect has a known natural enemy.” When researchers have sufficient experience and knowledge of this method, the use of chemical agents to prevent infestations can be significantly reduced, leading to reduced emissions. That naturally also saves the costs for the cultivators.
Greenhouse 2030 is funded through the programme Greenhouse as an Energy Source (Kas als Energiebron), which stimulates energy conservation and use of renewable resources in greenhouse farming and which is funded by Glastuinbouw Nederland (Greenhouse Horticulture Netherlands) and the Ministry of Agriculture, Nature and Food Quality. Kempkes: “In the Netherlands, fruit, flowers and vegetables are grown in some 9500 hectares of greenhouses. Three hundred of those hectares are renewed annually in the form of replacement of obsolete greenhouses.” A simple calculation shows that this pace is too low to use all possibilities to be completely emission-free in 2040. The knowledge and insights gained through the demo-greenhouse can hasten this process, according to the researcher.
By the time 2030 nears, this greenhouse will likely be obsolete. “Greenhouses are increasingly constructed from smart materials. Glass will have seasonal characteristics, allowing it to insulate in the winter, while cooling in the summer,” Kempkes describes.
Source: Wageningen University & Research