Greening the greenhouse: general considerations

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Greening the greenhousegeneral considerations
Gerard Bot Wageningen UR Greenhouse
Horticulture
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Trends in European Horticulture
Introduction
Increase of scale partner in the market chain
Improved control crop growth factors production
quality quantity
Year round crop production labour market
Licence to deliver
Sustainability CPC, water, materials, energy
bottleneck energy consumption
Licence to produce
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Energy consumption in European greenhouses
1900 MJm-2 (45 l oil m-2)
1500 MJm-2 (35 l oil m-2)
Amsterdam
500 MJm-2 (12 l oil m-2)
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Yield in European greenhouses
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Introduction
objectives for Northern and Southern regions
Year round - maximize solar radiation (crop
production!) - minimize energy consumption
Hot periods - energy efficient cooling to
reduce high temperatures
Of course grower needs - profitable crop
production
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Greening the greenhouse energy saving
From a systems point of view

• properties low heat loss greenhouse cover
  insulation

combined with high light transmission
crop production solar energy in

• control climate settings and control strategy
• temperature humidity CO2
• winter heating and ventilation summer
  efficient cooling

• conversion of primary energy to heat
• the engine of the greenhouse
• boiler, cogeneration, heat pump, fuel cell,

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Properties cover insulation and energy
consumption
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properties plus energy friendly control
100
Rel. Econs ()
80
60
boiler
40
20
0
0
1
2
3
4
5
6
k (W/m2K)
about 20 improvement possible maintaining
optimal crop production
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Also changing the engine
100
100
25
COP4
75
100
25 work (electricity) needs 60 primary energy so
40 energy saving
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properties, control and other engine
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Properties Reduction of energy losses insulation

• Decreasing k-value (W/m2K)
• Thermal screens
• Double or triple cover (glass, plastic film)
• Gas filled space between glass layers
• Vacuum space between glass layers
• Reduction of thermal radiation loss
• Low TIR emission coatings

Bottleneck Light transmission
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Properties improved light transmission

• cleaning!

• anti-reflection coating 6

• geometry of the material
• V structure material
• Micro V surface

Principle multiple reflection increases light
transmission
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Energy friendly control

• aim optimal crop production

• grower holds the control-wheel

• estimated risks with humidity control

• crop dependent

• crop oriented research

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Engine heat pump and energy reservoir

• contains sufficient amount of energy in winter

• to be filled in summer exploiting excess solar
  energy

• Large capacity,
• 10 l oil eq per m2
• 10 m3 water/m2 with ?T 10K or 2000 kg PCM
  /m2

• Physically only possible in the soil
• Aquifer or VSHE

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Aquifer Summer period excess heat
emptying cold aquifer (greenhouse is
cooled) filling warm aquifer
heat exchanger
7 oC
17 oC
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emptying warm aquifer greenhouse is heated
filling cold aquifer
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Seasonal storage

• Aquifer 2 wells at different temperature
• specific geological conditions

not available at TLR

• Vertical Soil Heat Exchanger
• passive storage via boreholes

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Generating electricity

• Electricity plant 100 fuel energy in,
• 42 electric energy, useful
• 48 reject heat, lost

• By exploiting reject heat
• 30 energy (CO2) saving

• Bottleneck centralised electr production

decentralise ep local exploitation reject heat
greenhouses Holland 2000MW installed 40 of
greenhouse area
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Conclusions

• Greenhouse horticulture is vigorous in
• N-W Europe

• Energy is bottleneck in sustainability

• Energy saving via greenhouse properties,
• climate control and energy conversion

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Conclusions

• Greenhouse properties - insulation
• - light transmission

• Climate control interaction T and RH control
• growers tool to control production
• crop dependent quantity and quality
• growers try to avoid risks (disease control)

• Energy conversion
• - boiler with condensor
• - heat pump/seasonal storage
• - cogeneration

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Thank you for your attention
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• Introduction
• Sustainable greenhouses
• Seasonal energy storage
• To be realised
• conclusions

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• Energy demand?

• demand for energy carriers
• like oil, gas, coal, etc??

• in principle demand for

- mechanical work, both at fixed locations
and mobile
- heat for processing and climate
conditioning
- lighting (included in mech work)
- communication/info-tainment (same)
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Demand for mechanicalwork versus heat?

• energy demand in various sectors

Estimation Mech Work Units (MWU) and Heat
Units (HU)

• MWU HU
• transport 20 (efficiency 25) 5 -
• industry 40
• (28 raw materialsheatgt100oC) 8
  (electr) 4
• domestic 20 4 (electr) 16
• remainder 20 7 (electr) 13
• total excl transport 19 (electr) 33

First step to sustainability energy saving
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Generating electricity

• Electricity plant 100 fuel energy in,
• 42 electric energy, usefull
• 48 reject heat, lost

• By exploiting reject heat
• 30 energy (CO2) saving

• Bottleneck centralised el production

decentralise ep local exploitation reject heat
19 units electricity covers 19 units heat
greenhouses Holland 2000MW installed 40 of
greenhouse area
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Heat Pump
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Energy targets (Netherlands 2020 greenhouses
without fossil fuel)
target 2020 (0)
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Greening the Greenhouse April 2, 2008