Ervaringen met diffuus licht in de kas

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1 Ervaringen met diffuus licht in de kas Groententelers Sint-Katelijne-Waver, België, 1 januari 211 Programma Kas als Energiebron Eén integrale aanpak met 7 transitiepaden: Energie besparen Duurzame energiebronnen Fossiele energie efficiënt inzetten Overig Silke Hemming, Wageningen UR Glastuinbouw Teeltstrategieën Licht Zonne-energie Aardwarmte Biobrandstoffen Duurzame(re) elektriciteit Duurzame(re) CO₂ Energie innovatieve kasdekmaterialen Een ander kasdek op mijn kas? Een ander kasdek op mijn kas? lichtdoorlatendheid Traditioneel glas 9% 83% Diffuus glas (!?!) 9% 74-83% Anti-reflectie glas 96% 89% PMMA 89% 76% ETFE 93% 86% 1 scherm 3 schermen andere setpoints Een ander kasdek andere op setpoints mijn kas? ontvochtigen buitenlucht ontvochtigen buitenlucht warmteterugwinning komkommer praktijk HNT diffuus dubbel Energieverbruik Warmte [m 3 /m 2 ] Elektriciteit 1) [kwh] Totaal verbruik [m 3 a.e./m 2 ] Gewasopbrengst [kg/m 2 ] Energie efficiency [m 3 a.e./kg].53 1%.35 66%.33 62% Demo in najaar in kas IDC, Bleiswijk.19 36% Conclusie Een ander kasdek op mijn kas? Meer productie / hogere energie efficiency (diffuus, AR) Situatie nu: Isolatie door 1-3 schermen in winter erg veel lichtverlies (25-35%) Grote sprongen te maken in energiegebruik (dubbel glas) Lichtverlies door condensatie kan verminderen Gewasreactie (koptemperatuur kan veranderen) is een? Beschikbaarheid CO 2 wordt punt van aandacht 1

2 Diffuse light Greenhouse covering materials are able to scatter light rays, transforming direct light into diffuse light Natural Light Conditions 4% 2% 7% 6% 4% 85% 5% % Haze Breuer and Van de Braak (1989) Materials & Methods Cucumber Clear/Diffuse, duplicated greenhouses Cucumber Controlled and logged climate (temperature, humidity, radiation, light, CO 2, ventilation) Results Light in greenhouse inside PAR [mol m -2 dag -1 ] 6 y =.777x R² = y =.72x R² = Clear North Diffuse North outside 3-5% less light under diffuse covering Δ-5% Δ-3% Results - Light interception cucumber Crop height [cm] April May rd May 3 rd th, 26, 26 Clear Diffuse Clear Diffuse Light interception [%] 2

3 Results - Photosynthesis cucumber Results - Yield cucumber Number of fruits (# per m 2 ) Average fruitweigt (kg cucumbers -1 ) Week nr. nr. 7.8% more fruits 4.3% more fruit weight Clear Diffuse Diffuse light II yield cucumber Greenhouse climate - leaf temp, sunny days head High in the crop Low in the crop Control *Control 2*Low haze 2*High haze Haze % 3% 7% Transmission 83% 83% 8% Low haze High haze Crop growth - leaves Leaf development (#/wk) LAI (m2/m2) SLA (cm2/g) Control Low haze High haze Production time of flowering to fruit harvest Wk (days) Wk (days) Control Low haze High haze

4 Crop growth photosynthesis capacity Production overview 35 Net photosynthesis, (µmol m -2 s -1 ) High haze - high High hazelow Control-high Control-low Spring crop 28 Autumn crop 28 Reference Low haze High haze Kg/m % +9.2% Nr/m % +5.2% Kg/m % +9.7% Nr/m % +6.1% Licht intensity (µmol PAR m -2 s -1 ) Conclusions Diffuse light is positive because Changed light penetration in crop Diffuse light is absorbed more by middle leaf layers of cucumber Higher photosynthesis in those leaf layers Higher yield Milder greenhouse climate on sunny days Lower head temperature during high irradiation 1% light = 1% growth rule has to be re-defined Optimum diffusing properties have to be found Potplants Results - Light distribution Results: Light distribution potplants 4

5 Results: Crop temperature Results: Photosynthesis four potplants Time Crop temerperature Time Crop temerperature Photosynthesis [µmol m -2 s -1 ] Diffuse 2 Clear Light intensity [µmol m -2 s -1 ] Results: Growth chrysanthemum Results: Growth ficus Conclusions Diffuse light is positive because Changed light distribution in crop Diffuse light is absorbed better than direct light Higher photosynthesis under diffuse light Lower crop temperature (chrysanthemum) Higher growth rate Lower light transmission of covering material negative in winter choose material without light loss Measurement method 5

6 Measurement method Δ-5% inside PAR [mol m -2 dag -1 ] 6 y =.777x R² = y =.72x R² = Δ-5% 2 1 Clear North Diffuse North outside Measurement method Transmission for hemispherical light τ h and haze η to characterise diffuse materials inside PAR [mol m -2 day -1 ] 6 y =.775x R² = y =.746x R² = Δ-3% Clear South Diffuse South outside Δ-3% Perpendicular and hemipherical light transmission of diffuse and clear covering Measurements of daily PAR integral in- and outside experimental greenhouses with diffuse and clear covering Apr.-Sep. 26 in NL Measurement method Conclusion Transmission perpendicular (NEN 2675) not relevant! Measure Transmission hemispherical and Haze! Reference clear greenhouse glass: 82-83% = τ hemispherical Measurement tolerances ~.5% Transmission hemispherical vs. Haze Covering materials low transmission -5% less light high haze high transmission low haze Still tolerable? What is better? Price? 6

7 Transmission hemispherical Haze Different diffusing structures Effect of coating More light by 1 or 2 layers coating Same haze Higher costs Effect of basic glass Spectrum coating More light by low-iron basic glass Higher costs More PAR by coating Higher production Spectrum changed by GG, minor chnages by CS and SC Effect on crop? 7

8 Spectrum diffuse Transmission under different angles Hortifuse bloemen Hortifuse groente a Hortifuse groente b Vetrasol 53 Vetrasol 53 AR-AR V&V glas AR-AR Brisa Prismatic Prototype a AR-AR Conclusions Covering vs. Screen Roof materials with higher haze increase production (if light loss low!) high light losses are negative in winter Chose right material for crop Measure transmission hemispherical & haze Compare material prizes Few standard materials available a lot of prototypes development going fast Already good materials available Covering Screen Advantage in summer Advantage in spring/autumn ++ + Advantage in winter -/o + Controllable -/o + Light intensity on crop level o/+ >-15% e.g. Cucumber: no screens necessary with diffuse covering e.g. Potplants: diffuse screens in combination with (high) shading Screens Temporary coatings 8

9 Het mysterie diffuus glas Diffuus glas is alleen positief in zomer laat minder licht door NEE NEE zorgt ervoor dat ik meer moet stoken vervuilt sneller??? NEE Wageningen UR Glastuinbouw Innovations in Horticulture Wageningen UR Special thanks for my collegues Tom Dueck, Jan Janse et al. Effect condensation on transmissivity transmissie nat polycarbonaat 16 mm antidrop.5.4 polycarbonaat 16 mm diffuus structuur in diffuus structuur uit standard enkel glas standard dubbel glas hydrofob AR enkel hydrofob AR dubbel transmissie droog AR enkel Anti drip works (life time) No effect when surface is structured Hydrofob or hydrofoil (not shown) 9