3/7/2011
Ervaringen met diffuus licht in de kas
Programma Kas als Energiebron Eén integrale aanpak met 7 transitiepaden: www.energiek2020.nu
Groententelers Sint-Katelijne-Waver, België, 10 januari 2011
Energie besparen
Fossiele energie efficiënt inzetten
Duurzame energiebronnen
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
1 scherm andere setpoints ontvochtigen buitenlucht warmteterugwinning
3 schermen Een ander kasdek mijn kas? andereop setpoints ontvochtigen buitenlucht
HNT
diffuus
40
Totaal verbruik [m3 a.e./m2]
Gewasopbrengst [kg/m2] Energie efficiency [m3 a.e./kg]
40
25
25
6
6
26
26
75
75
79
0.53
0.35
0.33
100%
66%
62%
74-83%
Anti-reflectie glas
96%
89%
PMMA
89%
76%
ETFE
93%
86%
Een ander kasdek op mijn kas?
Demo in najaar in kas IDC, Bleiswijk
Warmte
Elektriciteit1) [kWh]
83%
90%
dubbel
Energieverbruik [m3/m2]
90%
Diffuus glas (!?!)
Conclusie
komkommer praktijk
Traditioneel glas
12 8
14
75
0.19
36%
Meer productie / hogere energie efficiency (diffuus, AR) Situatie nu: Isolatie door 1-3 schermen Æ 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 CO2 wordt punt van aandacht
1
3/7/2011
Diffuse light
Natural Light Conditions
Greenhouse covering materials are able to scatter light rays, transforming direct light into diffuse light
20% 70% 40%
40% 85% 60%
50%
0% Haze Breuer and Van de Braak (1989)
Materials & Methods
Cucumber
Results – Light in greenhouse
Results - Light interception cucumber
PAR [mol m-2 dag-1] 60
inside
April May 23 25rdth,, 2006 2006 May 3rd, 2006
y = 0.777x R² = 0.997
50 40
250 y = 0.720x R² = 0.996
30
Δ-5% Δ-3%
20 10 Clear North
Diffuse North
0 0
20
40 outside
60
3-5% less light under diffuse covering
80
Crop height [cm]
Clear/Diffuse, duplicated greenhouses Cucumber Controlled and logged climate (temperature, humidity, radiation, light, CO2, ventilation)
Clear Diffuse
200 150 100 Clear
50
Diffuse
0 0
20
40 60 Light interception [%]
80
100
2
3/7/2011
Results - Photosynthesis cucumber
Results - Yield cucumber
7.8% more fruits 4.3% more fruit weight
2 Average fruitweigt Number of fruits (# per m ) (kg cucumbers-1)
80 0.7 70 0.6 60 0.5 50 40 30
0.4
Clear Clear Diffuse Diffuse
0.3
20 0.2 10 0.1 0 0.0 18 18 2020
22 22
24 26 26 28 28 24 30
30 32
Week Weeknr. nr.
Diffuse light II – yield cucumber
Greenhouse climate - leaf temp, sunny days head
2*Control
2*Low haze
2*High haze
0%
30%
70%
Transmission 83%
83%
80%
Haze
Crop growth - leaves
Control
34.5
34.8
25.4
Low haze
32.8
34.4
24.7
High haze
32.4
33.7
24.6
Production – time of flowering to fruit harvest
Leaf development (#/wk) 6.1
LAI (m2/m2)
SLA (cm2/g)
4.6
344
Low haze
5.7
4.2
338
High haze
5.9
4.1
322
Control
High in Low in the crop the crop
Wk 19-21 (days)
Wk 24-26 (days)
Control
15.5
16.3
Low haze
15.2
15.9
High haze
14.6
15.9
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3/7/2011
Crop growth – photosynthesis capacity
Production – overview
30 High haze high
Net photosynthesis, (µmol m
-2
s -1)
35
25 20
Reference
High hazelow
15
Control-high
10 Control-low
5
Spring crop 2008 Autumn crop 2008
0 -5 0
200
400
600
800
1000
1200
Low haze
High haze
Kg/m2
+6.5%
+9.2%
Nr/m2
+3.5%
+5.2%
Kg/m2
+8.8%
+9.7%
Nr/m2
+5.3%
+6.1%
Licht intensity (µmol PAR m -2 s -1)
Conclusions
Diffuse light is positive because… z z z z z z
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
Potplants
1% light = 1% growth rule has to be re-defined Optimum diffusing properties have to be found
Results - Light distribution
Results: Light distribution potplants
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3/7/2011
Photosynthesis [µmol m-2 s-1]
Results: Photosynthesis four potplants
Time
Time
Results: Crop temperature
Crop temerperature
Crop temerperature
12 10 8 6 4 Diffuse
2
Clear
0 0
100
200
300
400
500
Light intensity [µmol m-2 s-1]
Results: Growth chrysanthemum
Results: Growth ficus
Conclusions
Diffuse light is positive because… z z z z z
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
Measurement method
Lower light transmission of covering material negative in winter Æ choose material without light loss
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3/7/2011
PAR [mol m-2 day-1] 60
Measurement method inside
Measurement method PAR [mol m-2 dag-1] 60
inside
Δ-5%
40
Δ-5%
20 10 Clear North
y = 0.746x R² = 0.997
30
Δ-3%
10 Clear South
0
Æ Transmission for hemispherical light τh and haze η to characterise diffuse materials
y = 0.720x R² = 0.996
30
40
20
y = 0.777x R² = 0.997
50
y = 0.775x R² = 0.995
50
0
Perpendicular and hemipherical light transmission of diffuse and clear covering
Measurement method
20
Diffuse South
40 outside
60
80
Diffuse North
0 0
20
40 outside
60
Δ-3%
80
Measurements of daily PAR integral in- and outside experimental greenhouses with diffuse and clear covering Apr.-Sep. 2006 in NL
Conclusion
Transmission perpendicular (NEN 2675) not relevant! Measure Transmission hemispherical and Haze! Reference clear greenhouse glass: 82-83% = τhemispherical Measurement tolerances ~ 0.5%
Transmission hemispherical vs. Haze -5% less light
low transmission
Still tolerable?
high haze high transmission
What is better?
Covering materials low haze
Price?
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3/7/2011
Transmission hemispherical
Haze
Different diffusing structures
Effect of coating
Effect of basic glass
More light by 1 or 2 layers coating Same haze Higher costs
Spectrum coating
More light by low-iron basic glass Higher costs
More PAR by coating Æ Higher production Spectrum changed by GG, minor chnages by CS and SC Æ Effect on crop?
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3/7/2011
Spectrum diffuse
Transmission under different angles 100
Hortifuse® bloemen
90
Hortifuse® groente a Hortifuse® groente b
80
Vetrasol 503
70
Vetrasol 503 AR-AR V&V glas AR-AR
60
Brisa
50
Prismatic Prototype a AR-AR
40 30 20 10 0 0
Conclusions
Roof materials with higher haze increase production (if light loss low!) Æ 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
10
20
30
40
50
60
70
80
90
Covering vs. Screen 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
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3/7/2011
Het mysterie diffuus glas
Diffuus glas …is alleen positief in zomer NEE …laat minder licht door NEE …zorgt ervoor dat ik meer moet stoken NEE …vervuilt sneller ???
Wageningen UR Glastuinbouw Innovations in Horticulture Special thanks for my collegues Tom Dueck, Jan Janse et al. © Wageningen UR
Effect condensation on transmissivity transmissie nat 0.9
diffuus structuur in AR enkel
0.8
diffuus structuur uit
0.6
hydrofob AR enkel
standard enkel glas
0.7
polycarbonaat 16 mm antidrop
standard dubbel glas
hydrofob AR dubbel
0.5
polycarbonaat 16 mm
Anti drip works (life time) No effect when surface is structured Hydrofob or hydrofoil (not shown)
0.4 0.4
0.5
0.6 0.7 transmissie droog
0.8
0.9
9
