Greening the greenhouse: general considerations Gerard Bot Wageningen UR Greenhouse Horticulture...

Greening the greenhouse:general considerations

Gerard Bot

Wageningen UR Greenhouse Horticulture

Greening the Greenhouse; April 2, 2008

Trends in European HorticultureIncrease of scale partner in the market chain


Introduction

Improved control crop growth factorsproduction : quality + quantity

Year round crop production: labour + market

Sustainability: CPC, water, materials, energybottleneck: energy consumption Licence to produce

Licence to deliver

Energy consumption in European greenhouses

1900 MJm-2

(45 l oil m-

2)

1500 MJm-2

(35 l oil m-

2)

500 MJm-2

(12 l oil m-

2)Greening the Greenhouse; April 2, 2008

Amsterdam

0

150

300

450

600

750

Cyprus

Spain

Egypt

Greece

Israel

Italy

Palestina

Average Mediteranean

Netherlands

Tomato Cucumber Sweet pepper

yield (ton/ha)


Yield in European greenhouses

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

Greening the greenhouse: energy saving properties: low heat loss:

greenhouse cover insulation

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, …

combined with high light transmission: crop production + solar energy in

From a systems point of view:

http://www.livingrainforest.org/about/ecosystems/giantwaterlily

coverk-value (W/m2K)

single glass 5.7

Double or 1+screen 3.0

triple or 2+screen 2.3

HR++* 1.6

Vacuum glas* 1.0

0

20

40

60

80

100

0 1 2 3 4 5 6

k (W/m2K)

Rel. Econs (%)

boiler

Properties: cover insulation and energy consumption


coverk-value (W/m2K)

single glass 5.7

Double or 1+screen 3.0

triple or 2+screen 2.3

HR++* 1.6

Vacuum glas* 1.0

0

20

40

60

80

100

0 1 2 3 4 5 6

k (W/m2K)

Rel. Econs (%)

boiler

properties plus energy friendly control

about 20 % improvement possible maintaining optimal crop production


heat-demand

energy in:

boiler

Also changing the “engine”

100

heat demandenergy in:

work

HeatPump

energy

reservoir

100

100

100

COP=4

25

75

25 work (electricity) needs 60 primary energy so 40% energy saving


properties, control and other “engine”

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


Properties: improved light transmission

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

anti-reflection coating: +6%

cleaning!

Principle: multiple reflection increases light transmission

25 mm

25 mmLexan ZigZagLexan ZigZagTMTM


Energy friendly control

aim: optimal crop production


grower holds the control-wheel

estimated risks with humidity control

crop dependent

crop oriented research

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 ΔT = 10K or 2000 kg PCM /m2

Physically only possible in the soil: Aquifer or VSHE

emptying cold aquifer (greenhouse is cooled)

filling warm aquifer

17 oC 7 oC

heat exchanger

Aquifer: Summer period: excess heat

Aquifer: Winter period

17 oC 7 oC

heat

pump

heat exchanger

emptying warm aquifer: greenhouse is heated filling cold aquifer

Seasonal storage

Aquifer: 2 wells at different temperature specific geological conditions

Vertical Soil Heat Exchanger: passive storage via boreholes

not available at TLR


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

greenhouses Holland 2000MW installed40% of greenhouse area

decentralise ep: local exploitation reject heat:


http://www.livingrainforest.org/about/human-needs/wildyam

Conclusions

Greenhouse horticulture is vigorous in N-W Europe


Energy is bottleneck in sustainability

Energy saving via greenhouse properties, climate control and energy conversion

Conclusions


Greenhouse properties: - insulation - light transmission

Climate control: interaction T and RH controlgrowers tool to control productioncrop dependent: quantity and qualitygrowers try to avoid risks (disease control)

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

http://www.livingrainforest.org/about/cultures/poisondartfrog


Thank you for your

attention


Introduction Sustainable greenhouses Seasonal energy storage To be realised conclusions


http://www.livingrainforest.org/about/cultures/poisondartfrog


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)


Demand for mechanicalwork versus heat?

energy demand in various sectors

MWU HU

• transport 20% (efficiency 25%) 5 -• industry 40% (28% raw materials+heat>100oC) 8 (electr) 4• domestic 20% 4 (electr) 16• remainder 20% 7 (electr) 13

total excl transport 19 (electr) 33

domestic ~ 20%

transport ~ 20%

industry~ 40%

remainder ~ 20%

Estimation:

Mech Work Units (MWU)

and Heat Units (HU)

First step to sustainability: energy savingGreening the Greenhouse; April 2, 2008

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

greenhouses Holland 2000MW installed40% of greenhouse area

decentralise ep: local exploitation reject heat: 19 units electricity covers 19 units heat



high

evaporatorlowcondensorhighCarnot T

TT )()(

5.0, cwithc carnotpraktical

Heat Pump:

Energy targets (Netherlands 2020: greenhouses

without fossil fuel)

1980 1990 2000 2010

20

40

60

80

100

target 2000 (50)

target 2010 (35)

2020

target 2020 (0)


Greening the greenhouse: general considerations Gerard Bot Wageningen UR Greenhouse Horticulture...

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Transcript of Greening the greenhouse: general considerations Gerard Bot Wageningen UR Greenhouse Horticulture...