Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Klimaat, energieverbruik en bloem temperatuur bij twee Gerbera telers : als onderdeel van het monitoringsproject
Vanthoor, B.H.E. ; Tsafaras, I. - \ 2018
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Rapport / Wageningen University & Research, BU Glastuinbouw WPR-741) - 38
This report provides an overview of the Gerbera companies -Holstein Flowers and Zuijderwijk Witzier. Both growers have a blackout screen, energy screen and an illumination system. Holstein Flowers dehumidifies the greenhouse air by means of blowing in heated outside air (using air ducts) and Zuijderwijk Witzier uses a Ventilation Jet system. Both growers screen a lot using a screen gap and they close very rare the screens for 100%. At Holstein Flowers the calculated energy consumption is 22.7 m3/m2/year and at Zuijderwijk 23.8 m3/ m2/year. With a thermal camera, the crop and flower temperatures were measured and they were rarely below the dew point. By carrying out plant sap analyses at 4 growers, a statistical relationship between the plant sap composition and the chance of rot heads (‘rotkoppen’) has been demonstrated. However, it is unknown whether this relationship is also a causal relationship, other factors could also have caused the rot heads. If the mechanism behind the development of Botrytis/rot heads were known, then a grower could - depending on the plant balance, evaporation and the chance of getting Botrytis/rot heads –grow with lower moisture deficits, which could then lead to energy savings
Vergelijking tomatenteelten met een Ventilation Jet systeem : als onderdeel van het monitoringsproject
Vanthoor, B.H.E. ; Tsafaras, I. - \ 2018
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Rapport / Wageningen University & Research, BU Glastuinbouw WPR-744) - 26
De belichte tomatenbedrijven Greenco en Gardener’s Pride telen een kleine tomaat en zijn uitgerust met een: Ventilation Jet (VJ) systeem, SON-T belichting systeem, verduisteringsscherm en een energiescherm. Het berekende energieverbruik wat via de buizen bij Gardener’s Pride de kas in was gebracht was tussen 1 december 2016– 1 december 2017 37.8 m3/m2/jaar en bij Greenco 25.4 m3/m2/jaar. Het hogere energieverbruik bij Gardener’s Pride kon verklaard worden doordat: (1) Sunstream een ras is dat generatief gestuurd wordt; (2) Gardener’s Pride niet zo’n hoge relatieve vochtigheden durfde aan te houden door het ontbreken van het werkende VJ systeem en (3) Gardener’s Pride minder heeft geschermd. Met de Ventilation Jets waren de tuinders goed in staat om het verduisteringsdoek (bijna) 100% gesloten te houden op momenten dat er belicht werd. Gedurende bepaalde periodes hebben beide tuinders besloten om het Ventilation Jet systeem minder te gebruiken. De telers hebben het vermoeden dat de luchtbeweging die veroorzaakt wordt door de recirculatieventilator soms zorgt voor een te generatieve gewasreactie. Bij Gardener’s Pride bleek dat nog geen 3% van de lucht die ingeblazen wordt door de VJ, de kas verlaat via de kier op het middenpad. Onder deze omstandigheden kan dus geconcludeerd worden dat deze kier niet nodig is---The tomato companies Greenco and Gardener’s Pride grow a small tomato and are equipped with a: Ventilation Jet (VJ) system, SON-T lighting system, blackout screen and an energy screen. The energy consumption that was brought into the greenhouse by the heating pipes at Gardener’s Pride was 37.8 m3/m2/year between 1 December 2016 and 1 December 2017 and 25.4 m3/m2/year at Greenco. The higher energy consumption at Gardener’s Pride could be explained by: (1) Sunstream is a variety that is grown very generative; (2) Gardener’s Pride did not dare to hold high relative humidity levels due to the lack of a working VJ system and (3) Gardener’s Pride had fewer screening hours. Thanks to the Ventilation Jets, the growers were able to keep the blackout screen (almost) 100% closed at times when the lighting system was on. During certain periods both growers have decided to use the Ventilation Jet system less. The growers suspect that the air movement caused by the recirculation fan ensures sometimes undesired extra generativity. At Gardener’s Pride, it turned out that less than 3% of the air blown in by the VJ leaves the greenhouse through the gap at the central path. It can therefore be concluded that under these circumstances this gap is not necessary
Ervaringen met het Ventilation Jet systeem bij Dekker Chrysanten : als onderdeel van het monitoringsproject
Vanthoor, B.H.E. ; Tsafaras, I. - \ 2018
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Rapport / Wageningen University & Research, BU Glastuinbouw WPR-743) - 22
The purpose of the Ventilation Jet (VJ) system at Dekker Chrysanten is to reduce the temperature of the grow pipe in order to save energy. Dekker Chrysanten encountered problems with circles in the crop in the VJ compartment in many cultivation rounds in 2016 and 2017. Early flowering took place at these circles, which occasionally resulted in poorer quality and shorter stems. Due to these cultivation problems, Dekker Chrysanten did not want to reduce yet the minimum grow pipe in the Ventilation Jet compartment. Due to the efforts of the growers and the monitoring project, potential causes have been identified and solved such as (1) the prevention of dry spots in the soil by: switching off the VJ when there is irrigation, switching on the VJ later in the short day period and by irrigating more (this is done companywide); (2) lowering the relative humidity setpoint in the VJ compartment at night so that a higher night evaporation is achieved; (3) improving the air flow profile of the bottom fan and (4) adjusting the climate computer software, resulting in a much more stable temperature and RH in the VJ compartment. The above learning experiences are now applied which has resulted in a good quality chrysanthemum in the past cultivation period (harvest January 2018).
Perchloraat in kasgrond Bioteelt : Resultaat uitspoelproef voor vermindering perchloraat concentratie in de biologische kasteelt
Voogt, Wim ; Winkel, Aat van - \ 2018
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Rapport WPR 765) - 22
certain fertilisers. This ion can be taken up by plants quite easily and will be transported partly into fruits, hence the norms for ClO4 - will be exceeded easily. Experiments have been carried out to leach out the soil by flushing. It appeared that ClO4 - can be leached out quite easily, but it requires a lot of water and the strategy has to be adapted to the soil type.
Precisietechnologie Tuinbouw: PPS Autonoom onkruid verwijderen : D2.4 Literatuurstudie spectrale reflectie-eigenschappen van planten en onkruiden; D2.5 Lab en veldexperimenten spectrale reflectie-eigenschappen van planten en onkruiden
Blok, Pieter ; Hemming, Jochen ; Holterman, Henk-Jan ; Michielsen, Jean-Marie ; Ruizendaal, Jos - \ 2018
Bleiswijk : Wageningen Plant Research, Business unit Glastuinbouw (Rapport WPR 751) - 118
This report contains the two deliverables of the research project “autonomous weed removal” that deal with the topic hyper- and multispectral weed detection. In the literature of the past 10 to 15 years, there are sufficient indications that a good distinction on the basis of spectral characteristics can be made between various plant species. For the hyperspectral lab measurements, various crops and weeds have been cultivated. The reflection spectrum of all plants was measured between 400 and 1000 nm and between 900 and 1700 nm on different growing stages in the laboratory. In particular the reflection in the chlorophyll range (650-670 nm) and in the green range (around 550 nm), red-edge (700 nm) and near-infrared (800 nm) show a distinctive power between the crops and weeds studied. With field measurements it was investigated whether it is possible to detect green weeds in a green lettuce crop using hyperspectral camera images. The accuracy of a correct classification on both measurement days was 6.9% and 9.9%, respectively, below the previously set target value of 90%. In order to exclude the effect of the use of different cameras on the test result, a comparative follow-up study is recommended.
Precisietechnologie Tuinbouw: PPS Autonoom onkruid verwijderen : Eindrapportage
Hemming, Jochen ; Blok, Pieter ; Ruizendaal, Jos - \ 2018
Bleiswijk : Wageningen Plant Research, Business unit Glastuinbouw (Rapport WPR 750) - 42
Work package 2 of the Precision Technology Horticulture program focuses on autonomous weed removal. This final report contains four deliverables: D2.1 Module for recognition of red lettuce, D2.2 Vision based crop row guidance module, D2.3 Machine for hoeing more than 8 crop rows simultaneously, and D2.6 Actuator for controlling weeds in full field crops. D2.1 reports on the software for an extra colour segmentation algorithm that has been added to the Steketee IC-cultivator. With this algorithm it is possible to adequately detect and distinguish non green plants, such as red lettuce, from weeds. For D2.2 a standalone module for crop row guidance for hoeing between the row has been developed. D2.3 describes is the extension in hardware and software that makes it possible to hoe up to 24 crop rows simultaneously. For D2.6, research has been conducted into different robotic arms to move the end effector to the right spot for weed control in full field crops. Different arms are compared and the maximum possible driving speed was be calculated. A test device for full field weed control was build based on a x-z position unit. The chapter publications and media provides an overview of the dissemination of the project results throughout the duration of the project.
Voorkomen en bestrijden emissies kasteelten : Fase I: 2017
Beerling, Ellen ; Blok, Chris ; Cornelissen, Emile ; Eveleens-Clark, Barbara ; Gozales, Jorge ; Harmsen, Danny ; Koeman, Nienke ; Leyh, Romain ; Os, Eric van; Palmen, Luc ; Roest, Els van der; Ruijven, Jim van; Stijger, Ineke ; Voogt, Wim - \ 2018
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Rapport WPR 748) - 46
In this project, solutions are developed to minimise leaching of nutrients and pesticides from greenhouses to the environment (esp. surface water), in order to comply with legislation and societal demands. In 2017 the following questions have been addressed: To prevent emission, drain solutions are reused or purified. Other water flows may deviate in compositionand possibilities for reuse or purification. The option for reuse or purification for these water flows has been investigated, and a working methodology for the end of a cultivation (e.g. cleaning) has been developed. Applications of Forward Osmosis in horticulture have been investigated. Water extracted from the discharge flow with Forward Osmosis using the concentrated nutrient solution holds prospects, but extracting irrigation water from brackish groundwater seems less feasible. In a long-term experiment, sodium (Na) standards for sweet pepper have been reinterpreted. It was shown that an increase in the Na standard up to 8-10 mmol/l causes no damage or loss in pepper production. Inaddition, it was shown that the split-root system can be used for uptake of extra Na without growth hampering. Furthermore, applying humate can prevent negative sodium effects at high sodium levels (Chinese cabbage). Finally, insight was gained into the risks associated with the use of chlorinated cleaning products in zero-discharge cultivations.
Programmeringsstudie Meeldauw : Invloed van bestaande en nieuwe interventies op geïnduceerde weerbaarheid tegen biotrofe schimmel
Hofland-Zijlstra, J.D. ; Breeuwsma, S. ; Noordam, M. ; Stevens, L. - \ 2018
Bleiswijk : Wageningen University & Research, Business unit Glastuinbouw, (Wageningen Plant Research rapport WPR-749) - 46
Purpose of this TKI project Programming study powdery mildew is to generate new knowledge about existingand new interventions aimed at prevention of mildew development in horticultural crops. This research isconducted by Wageningen University & Research greenhouse horticulture business unit. The project is supportedby LTO Glaskracht Nederland. To test the impact of existing interventions on the natural defenses of a plant testsin climate chamber were carried out with total daylight sum, CO2 and relative humidity. After three weeks theinfluence on the production of pathogen related proteins, which is a measure for induced resistance, was veryminor. However, it is confirmed that relative humidity and the daily light sum influence the mildew developmentdirectly and to a higher extent than the CO2. In addition, changes in nutritional composition of plants may be oneof the first indicators for enhanced disease risk (e.g. sodium).
Het winterlicht gewas : proof off principle met komkommer
Kempkes, Frank ; Meinen, Esther ; Janse, Jan ; Elings, Anne ; Visser, Pieter de; Raaphorst, Marcel ; Vukadinovic, Danijela - \ 2018
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Wageningen University & Research, BU Glastuinbouw rapport WPR-725) - 58
In de winter is licht in Nederland voor vrijwel alle gewassen de limiterende factor voor de productie. In de zoektocht naar het maximaal gebruik maken van het beperkte licht in de wintermaanden is het belangrijk het licht zo optimaal mogelijk om te zetten in gewasproductie. Om de mogelijkheden beter in kaart te brengen, is in aansluiting op de opgedane kennis in het project ‘Verbetering lichtinval winterlicht’, waar de lichttoetreding door het kasdek is geoptimaliseerd voor de wintermaanden. In dit project is de gewaskant aan bod gekomen. Het werk in dit project is gefinancierd door het onderzoeksprogramma Kas Als Energiebron. Dit onderzoeksprogramma is een samenwerkingsverband tussen het ministerie van Landbouw, Natuur en Voedselkwaliteit en LTO-Glaskracht Nederland. Voor maximalisatie van de lichtonderschepping is een oost-west pad richting de eerste stap. De raseigenschappen van het gekozen komkommer ras vragen door de variatie in bladafmeting tijdens de teelt van groot naar klein een adaptatie van het gewasmanagement aan de veranderende plantvorm in de tijd. Een smalle gootafstand om hier eenvoudig op in te spelen blijkt te veel gewasbeschadiging op te leveren. De beste resultaten kwamen naar voren bij de grootste gootafstand
Luchtzuivering door kamerplanten : een literatuurstudie
Visser, Pieter de - \ 2018
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Wageningen University & Research, BU Glastuinbouw rapport WPR-695) - 26
Within the project ‘Plant champion air purification’, a public-private cooperation within Topsector Horticulture and Starting materials, a literate survey was carried out by WUR Greenhouse Horticulture to explore recent findings on the possibilities of plants to purify indoor contaminated air. Literature was searched in academic journals, on the internet and within reports recently carried out for the horticultural sector. Here this knowledge is shortly described. Plants generally have the capacity to assimilate hydrophilic Volatile Organic Compounds (VOCs) like formaldehyde without harm. Lipophilic VOCs are less well assimilated and follow different uptake pathways. Differences between plant species can sometimes be related to amount of leaves, wax layer composition, stomatal conductance or hairs. Apart from the green plant parts, the roots, the micro-organisms and rooting medium have a role in air purification. The research in plant chambers mainly generated knowledge on short term uptake of volatiles, but the uptake mechanisms and the long-term performances of plants are only partly understood. The research on upscaling of lab results to air purification in rooms within buildings is currently rapidly evolving. A few good studies have been done and show promising results. More research is needed to extrapolate the findings from lab research to practice in a reliable way
Feasibility study thin glasses for greenhouse roof designs
Hemming, Silke ; Mohammadkhani, Vida ; Kempkes, Frank ; Peters, Anton ; Lieffrig, Vincent ; Harada, Keitaro ; Spronsen, Michiel van; Werff, Tjibbe van der; Louter, Christian - \ 2018
Bleiswijk : Wageningen University & Research, BU Greenhouse Horticulture (Wageningen University & Research, BU Greenhouse Horticulture report WPR-732) - 50
In this study, the feasibility of the application of flexible thin glass in greenhouses was investigated. With the development of thin but very strong glass plates like for mobile phones, new possibilities are being created for new greenhouse roof designs, the usage in multi-layered glass roof give possibilities for high-insulation greenhouse coverings. Flexible thin glass is a tempered glass. While standard tempered glass goes through a thermal process, this is a chemical process, which makes the glass five times stronger, creating the possibility of thickness reduction and bending. By adding nanocoatings the reflection can be reduced and the light transmission can be increased. Multi-layered greenhouse roofs can be created, resulting in a higher light transmission than currently available multilayer polycarbonate (PC) sheets, but also a higher transmission than today’s insulating double glass. The study shows that such glass combinations lead to an additional 20% energy savings based on heat demand for Phalaenopsis. Thin glasses are particularly strong and can also be used in curved form. This makes new greenhouse roof designs with these glasses possible. Especially the low weight offers advantages here. Important mechanical aspects and bottlenecks for the use in greenhouses have been mapped out. Due to limitations in today’s available dimensions and high prices, the use of thin glass in greenhouses will be further away in the future
Integrated pest management component of the Ethio-Dutch Program for Horticulture Development : contribution of Wageningen University and Research - final report
Elings, Anne ; Messelink, Gerben ; Kruidhof, Marjolein ; Leman, Ada ; Cuesta Arenas, Yaite ; Wurff, Andre van der - \ 2018
Bleiswijk : Wageningen University & Research, BU Greenhouse Horticulture (Wageningen University & Research, BU Greenhouse Horticulture report WPR-711) - 114
The Ethiopian Horticulture Producer Exporters Association (EHPEA) is responsible for the Ethio-Dutch Program for Horticulture Development (EDPHD). One of the components of this program is the Integrated Pest Management (IPM) which has been executed by Wageningen University and Research, Business Unit Greenhouse Horticulture in collaboration with Ethiopian research organizations and EHPEA. This final report of the WUR team reports on the following project activities: 1) Technical advice on formulation of the best microbial bca’s obtained from the conducted research, 2) Survey, collection and commercialization of indigenous natural enemies for the management of major horticultural pests, 3) Support and advice on the study of the biology of identified potential indigenous natural enemies, 4) Support and advice on small-scale mass production for evaluation trials and methods to establish persistent populations in crops, 5) Technical advice on the efficacy trials under laboratory and field conditions on the identified predators and parasitoids, 6) Review of IPM course delivered at Jimma University, 7) Sharing information with growers and companies, 8) Train the trainer, and 9) All collection and other missions
Diffuus licht en lichtspectrum in relatie tot bestuiving, zetting en insecten bij tomaat : literatuuronderzoek in opdracht van Koppert Biological Systems
Janse, Jan - \ 2017
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Rapport / Wageningen University & Research, BU Glastuinbouw WPR-702) - 30
On behalf of Koppert Biological Systems, a desk study has been carried out on effects of diffuse greenhouse coverings and coverings with a different light spectrum on pollination and seed setting in tomatoes. The information in the literature was found to be limited. Under diffuse glass, production increases by bigger and sometimes more fruits, but it is unknown whether this is partly due to a better seed setting. Red and pearl netting above the crop does increase production. Yellow and pearl nets reduce the virus attack by less activity and rejection of harmful insects. Higher UV-light absorption increases the protection against harmful insects, but may reduce the search behavior of predators and bumblebees
Strategic development of vegetable supply chains in Dezhou : result of the fact finding mission from February 27 to March 2, 2017
Visser, Chris de; Snels, Joost ; Poot, Eric ; Tong, Qiu Yu - \ 2017
Lelystad : Stichting Wageningen Research (Stichting Wageningen Research rapport 756) - 58
Eindrapportage monitoringsproject Meer schermen in Gerbera zonder kwaliteitsproblemen : Seizoen '16-'17
Vanthoor, B.H.E. ; Tsafaras, I. ; Persoon, Stefan ; Mei, Martin van der - \ 2017
Wageningen University & Research, BU Glastuinbouw - 17 p.
Gerbera HNT rapportage 2016-2017
Modelinstrumentarium Toelating Gewasbeschermingsmiddelen en Biociden (PEARL) : Tussenrapportage WOT-04-008-024
Berg, F. van den; Tiktak, A. ; Boesten, J.J.T.I. ; Linden, A. van der - \ 2017
Wettelijke Onderzoekstaken Natuur & Milieu (WOt-interne notitie 205)
LED en energiezuinigheid en kwaliteit bij Red Naomi!
Gelder, Arie de; Burg, Rick van der - \ 2017
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Wageningen Plant Research rapport WPR-708) - 66
In order to achieve a signifi cant energy saving, WUR Greenhouse Horticulture and Delphy conducted research under a lighting system with Deep Red / Blue Top- LED. Objectives were consistent growth by uniform light level, improvement of fl ower size and stem weight and 25% saving on electricity. In the summer of 2016, the climate through LED and cooling using OPAC heat exchangers was nice for good quality roses. In the winter 2016/2017 the quality of the roses was strongly reduced by the occurrence of small leaves, many 7 leafl ets leaves and small buds. The colour of leaf, fl ower and stem became too dark and had a high thorn density. In spring these effects became less severe, with positive effect on quality. The reason for the quality deterioration has been extensively discussed. Temperature, cutting strategy and light spectrum are considered. Despite the quality problems, production in stems and kg per m2 was fi ne. The light use effi ciency in the full-LED test was similar to that of the SON-T test a year earlier. The energy saving for lighting achieved the desired 25%. However, more heat must be added to allow the crop to experience a higher temperature, especially at times when there is only artifi cial light
Plantmonitoring op basis van fotosynthese sensoren : Praktijktesten in de teelt van tomaat en gerbera
Kaiser, Elias ; Baeza Romero, Esteban ; Meinen, Esther ; Raaphorst, Marcel ; Kempkes, Frank ; Elings, Anne ; Pot, Sander ; Jalink, Vincent ; Voogt, Jan ; Dieleman, Anja - \ 2017
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Wageningen Plant Research rapport WPR-712) - 46
Wageningen University & Research, Business Unit Glastuinbouw has investigated two methods of monitoring crop photosynthesis that might be used in greenhouse horticulture: the crop photosynthesis monitor and the CropObserver. This project was funded by ‘Kas als Energiebron’ and executed together with PhenoVation and PlantDynamics. The data of the crop photosynthesis monitor were compared to those of the photosynthesis module of the crop growth model INTKAM. Furthermore, the pattern of stomatal opening during the day was calculated with the Stomata sensor. Measurements showed that the crop photosynthesis monitor was too sensitive to changes in window opening and in CO2 supply to determine the crop photosynthesis accurately. The CropObserver was useful in determining the relative light use efficiency of the crop. The best methods to accurately and reliably determine crop photosynthesis might be the following: 1. By a photosynthesis model (as in INTKAM) to calculate the crop photosynthesis, coupled to a sensor that monitors the crop status to register when the performance of the crop deviates from what might be expected, or 2. Via the CropObserver to which a module is added that determines the stomatal conductance and a measurement of the CO2 concentration which is necessary to translate the signal of the CropObserver to CO2 uptake by the crop
Gerbera: maximale isolatie en lichtonderschepping : De invloed van spouwscherm, lichtsom, daglengte in winter, balans licht-temperatuur, en bladsnoei in de winter op productie, kwaliteit en energiegebruik
García Victoria, Nieves ; Gelder, Arie de; Kempkes, Frank ; Weerheim, Kees ; Lagas, Peter ; Haaster, Bram van; Dings, Eugenie - \ 2017
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Rapport / WPR 698) - 105
With the objective of further reducing energy consumption in gerbera cultivation and financed by the program “Greenhouse as Source of Energy” and the Knowledge Cooperation Gerbera, research was conducted from July 2016 to July 2017 at WUR Greenhouse Horticulture in Bleiswijk. In the test, the insulation of the greenhouse was increased by separating the existing 2-layers of the light tight screen, creating an air layer of 5 cm in between them. This improved the temperature layering between the greenhouse and the greenhouse cover, resulting in very low net radiation losses by the crop. The applied light-dependent temperature strategy proved technically and physiologically suitable between November and May. The day length in winter was gradually extended to 13 or 15 hours, with a proportional increase of the average day temperature (at least 16°C) according to the light dependent temperature strategy. This saved some energy on heat, but required more electricity without improving production or quality; on the contrary, the crop showed an increased vegetative growth. All the leaves that intercept light seem to contribute actively to the photosynthesis. As a result, leaf pruning in winter, regardless of the age of the leaf removed, led to a reduced flower production.
Verwarming van de glastuinbouw in een post-fossiele energie infrastructuur
Vanthoor, B.H.E. ; Zwart, H.F. de - \ 2017
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Rapport GTB 1448) - 14
In the near future the greenhouse horticultural sector wants to produce free of fossil energy. To be able to worktowards this purpose, it is important that the possible roads are mapped out on time. In this report, these roadsare presented in a qualitative sense. In fact, there are 2 types of primary energy sources, namely green electricityand residual heat/geothermal energy, each requiring other technical solutions depending on the type of cultivation(divided in this report into cold extensive crops, not, -moderate and -heavily artificial lighted crops).If greenhouses are heated by electricity, then the heat pump in combination with heat-cold storage, is thebest solution both energetically and economically wise. When using residual heat or geothermal energy, theheat pump can play a role, but less prominent than in an all-electric energy infrastructure. In all cases a gooddehumidification system is important. Energy systems in a fossil-free infrastructure are characterized by highfixed costs and low variable costs. These high fixed costs can be reduced by lowering the capacities using betterisolation and low temperature heating systems.This report has set the spot on the horizon for a CO2 neutral horticulture. How we get there depends on thepreconditions that will change on the way. This calls for energetic and economic indicators for different crops andoptions for the primary energy source that take into account those changing preconditions
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