Transcript PowerPoint-presentatie

New covering materials – how far can we
go in energy saving?
A look into the future
Silke Hemming
Seminar 23rd of October 2012, Gjennestad, Norwegen
Background
Convection and
radiation from cover
Total by ventilation:
1500 MJ
2300 MJ
(Sensible and Latent
heat by ventilation,
leakage and
dehumidfication)
Total energy loss:
3950 MJ
Total energy in:
4000 MJ
Inside 2400 MJ
Photosynthesis:
50 MJ
Boiler or CHP
Soil 150 MJ
1600 MJ
Background
Total energy in:
4000 MJ
Inside 2400 MJ
Photosynthesis:
50 MJ
Boiler or CHP
1600 MJ
Energy input by solar radiation
 Importance of PAR
 Rule of thumb: 1% more light means 1% higher yield
Crop
Yield increase
at 1% more light
Lettuce
0.8%
Radish
1%
Cucumber
0.7-1%
Tomato
0.7-1%
Rose
0.8-1%
Chrysanthemum
0.6%
Pointsettia
0.5-0.7%
Ficus benjamina
0.6%
Source: Marcelis et al., 2006
Energy input by solar radiation
=PAR+NIR
 More PAR by:
 Advanced covering material
●
●
●
●
Low iron glass (+1-2%)
New plastic films ETFE (+1-3%)
Modern coatings on glass, AR (+5-8%)
New surface structures (+5-8%)
 Lighter greenhouse construction (+1-5%)
 Less installations (+1-3%)
 Greenhouse orientation / shape
 Cleaning
Energy input by solar radiation
 Filtering out NIR radiation
In summer:
 Reduction heat load
 More efficient use of CO2
In winter:
 More energy needed
4
NIR transpiration [kg/m2/day]
Effects:
 Lower greenhouse temperature
 Reduction in transpiration
 Less humidity control needed
 No effect on crop production
3
2
1
0
0
1
2
3
4
2
reference transpiration [kg/m /day]
Source: Kempkes et al., 2008
Background
Convection and
radiation from cover
Total by ventilation:
1500 MJ
2300 MJ
(Sensible and Latent
heat by ventilation,
leakage and
dehumidfication)
Total energy loss:
3950 MJ
Photosynthesis:
50 MJ
Soil 150 MJ
Reduction of energy losses
 Double covering materials
 High insulation = less convection losses
 Specific coatings (low-e) = less radiation losses
Reduction of energy losses
Double covering materials
Humidity:
 Humidity is an increasing problem with increasing insulation
 Decrease of condensation from 100l/m2/yr to about 10l/m2/yr
 Search for alternative dehumidification system
Plant reactions:
 High light transmission necessary
 Less CO2 available
 Increase of crop temperature in top of plant
 New climate control strategies possible (temperature
integration, nbo minimum pipe...)
Innovative energy saving coverings
ETFE (F-Clean)
 Plastic film material
 Long lifetime (20 years)
 Lighttransmission 93% (86%)
clear film
 Lichttransmission 93% (82%)
diffuse film,
high diffusion 75%
 UV transparant
 Ca. 20% Energy saving
double materials
PMMA (Plexiglas Alltop)
 U-value 2.5 W/m2/K
 16 mm space
 Lighttransmission 91% UV transparant material
 Lighttranmission 86% Plexiglas Resist, UV-bloc material
 Ca. 25 energy saving
Glass with modern
surface treatments/coatings
 New covering materials with different
surface treatments/coatings
●
●
●
●
●
Diffuse structure  light scattering
Low-iron  increase light transmission (PAR)
Anti-reflection  increase light transmission (PAR)
NIR-reflection  decrease solar transmission (NIR)
Low-emission  decrease solar transmission (NIR),
decrease heat losses
 Single and double glass
 Effect on energy saving, greenhouse climate (temperature,
humidity, CO2), light transmission, crop response
Diffuse glass
Reference
clear
Low diffusion
27%
High diffusion
74%
Spring crop
2008 Kg/m2
+6.5%
+9.2%
Autumn crop
2008 Kg/m2
+8.8%
+9.7%
Diffuse glass - crop
 Diffuse light is positive because…
 Photosynthesis
● Horizontal light distribution more equally
(Hemming et al., 2006)
● Changed light penetration in crop vertically
(Hemming et al., 2007)
● Diffuse light is absorbed more by middle
leaf layers (Hemming et al., 2007; Dueck
et al. 2009, 2012)
● Higher photosynthesis in those leaf layers
(Hemming et al., 2006, 2007; Dueck et al.
2009, 2012)
● Higher dry matter in those leaves (Dueck
et al. 2012)
Diffuse glass - crop
 Diffuse light is positive because…

Stress:
● Lower crop temperature in upper leaves
during high irradiation, higher crop
temperature in lower leaves (Dueck et al.,
2009)

Morphology and Development
● More generative growth and faster fruit
development (Hemming et al., 2007;
Dueck et al. 2009, 2012)
● Higher yield, mainly due to heavier fruits
(Dueck et al. 2009, 2012)
● Faster development potplants (Hemming et
al., 2007)
 1% light ≠ 1% growth rule
AR glass

Spectral transmission of glass with different
anti-reflection coatings from three different producers
(SA, CS, GG)
More PAR
Cooling
• Increase of PAR by
AR coating
 Higher crop
production
• Changed spectrum
• Possibilities for
cooling
• Possibilities for
energy saving with
double materials
Hemming et al., Greensys 2009
Low iron and AR glass
Light transmission of different greenhouse glasses (producer CS)
with anti-reflection (AR) coatings and/or low-iron treatment
AR and low-e glass
Light transmission and energy saving of different greenhouse
glasses (producer GG) with anti-reflection (AR) and/or lowemission (LOWe) coatings
Modern coatings on glass – energy & CO2
 Year-round energy consumption and CO2 concentration under
different greenhouse glasses calculated by KASPRO, CO2 use
from boiler
energy saving
25%
33%
need for
external
CO2 !
Summary
 Increase light transmission covering
 more light  more production
 more energy  less fossil fuels needed
 Make light diffuse  more production
 Increase insulation by double coverings and low-e coatings
 use AR / low-iron  compensate light
 less energy needed
 higher humidity  dehumidification needed
 Less CO2 available  external CO2 needed
Venlow Energy Greenhouse
 Double glass
 Modern coatings: AR, low-e
 Low u-value
 Lighttransmission ~ single glass
 Energy saving tomato 50-60%
 New growing strategies!
Screen, active dehumidification with
heat regain, no minimumpipe,
temperatureintegration
Venlow Energy Greenhouse – double glass
tp
th
Single glass
AR-AR
98
91
Single glass
AR-Low-e
91
81
Double
AR-AR-Low-e-AR
89
80
Single glass
traditional
90
82
Mohammadkhani et al., 2011
Venlow Energy Greenhouse – energy use
m3
Energy saving
gas/year
(I)
(II)
VenlowEnergy
measured
VenlowEnergy
estimated
16.3
48%
54%
15.8
49%
56%
commercial(I)
31.2
commercial (II)
35.5
Kempkes et al., 2011
VenlowEnergy Greenhouse – tomato yield
Janse et al., 2011
A look into the future
 New surface
structures on
covering materials
● Micro V surface
● Micro pyramides
● Micro moth-eye
● Principle: multiple
V-grooves
Micro pyramides
reflection increase
light transmission?
Micro pyramides
Gieling et al.
Energy reduction tomato: how far can we go?
 Reference: 40 m3 g.e. per m2 per year
●
●
●
●
●
Later planting, shorter cultivation: 2.5 m3
Screening strategy: 1 m3
Double screen: 3.7 m3
Temperature integration: 3.2 m3
Humidity control: 2.5 m3
 Reduction by new growing strategies: 27 m3 g.e. per m2 per year
● Double glass with modern coatings: 12 m3
● Heat exchangers+heat pump+aquifer: replace 10 m3 gas
by solar energy, but use more electricity
 Total energy needed: 11 m3 g.e. per m2 per year
Source: Poot et al., 2011
& Kempkes, 2012
Takk skal du ha!
Special thanks to my
colleagues:
Vida Mohammadkhani,
Frank Kempkes, Feije de
Zwart, Tom Dueck, Jan
Janse, Eric Poot, Theo
Gieling, Gert-Jan
Swinkels et al.