New covering materials – how far can we go in energy saving? A look into the future

1. New covering materials – how far can we go in energy saving?A look into the future Seminar 23rd of October 2012, Gjennestad, Norwegen Silke Hemming

2. Background Convection and radiation from cover 1500 MJ Total energy in: 4000 MJ Total by ventilation: 2300 MJ (Sensible and Latent heat by ventilation, leakage and dehumidfication) 2400 MJ Inside Photosynthesis: 50 MJ Total energy loss: 3950 MJ Boiler or CHP 1600 MJ Soil150 MJ

3. Background Total energy in: 4000 MJ 2400 MJ Inside Photosynthesis: 50 MJ Boiler or CHP 1600 MJ

4. Energy input by solar radiation • Importance of PAR • Rule of thumb: 1% more light means 1% higher yield Crop Yield increase at 1% more lightLettuce 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

5. 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

6. Energy input by solar radiation • Filtering out NIR radiation Effects: • Lower greenhouse temperature • Reduction in transpiration • Less humidity control needed • No effect on crop production In summer: • Reduction heat load • More efficient use of CO2 In winter: • More energy needed Source: Kempkes et al., 2008

7. Background Convection and radiation from cover 1500 MJ Total by ventilation: 2300 MJ (Sensible and Latent heat by ventilation, leakage and dehumidfication) Photosynthesis: 50 MJ Total energy loss: 3950 MJ Soil150 MJ

8. Reduction of energy losses • Double covering materials • High insulation = less convection losses • Specific coatings (low-e) = less radiation losses

9. 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...)

10. Innovative energy saving coverings

11. 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

12. 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

13. 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

14. Diffuse glass Low diffusion 27% High diffusion74% Reference clear

15. 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)

16. 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

17. AR glass • Spectral transmission of glass with different anti-reflection coatings from three different producers (SA, CS, GG) • Increase of PAR by AR coating  Higher crop production • Changed spectrum • Possibilities for cooling • Possibilities for energy saving with double materials More PAR Cooling Hemming et al., Greensys 2009

18. Low iron and AR glass Light transmission of different greenhouse glasses (producer CS) with anti-reflection (AR) coatings and/or low-iron treatment

19. AR and low-e glass Light transmission and energy saving of different greenhouse glasses (producer GG) with anti-reflection (AR) and/or low-emission (LOWe) coatings

20. 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 !

21. 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

22. 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

23. Venlow Energy Greenhouse – double glass Mohammadkhani et al., 2011

24. Venlow Energy Greenhouse – energy use Kempkes et al., 2011

25. VenlowEnergy Greenhouse – tomato yield Janse et al., 2011

26. A look into the future V-grooves • New surface structures on covering materials • Micro V surface • Micro pyramides • Micro moth-eye • Principle: multiple reflection increase light transmission? Micro pyramides Micro pyramides Gieling et al.

27. 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

28. 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.