guadalagara Frank Kempkes 2 pdf - WUR

9/3/2009

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Frank Kempkes

Semi�closed greenhouse:

Pro's and Con's in relation to climate, crop management and systems

Frank KempkesTheo Gieling, Jouke Campen, Marcel Raaphorst

Frank Kempkes

Presentation guide

� Greenhouse growing: Goals & Means� Define goals of your crop cycle� What can we do to control and improve our climate and crop

growth� Heating � Improve CO2 level (do we have a CO2 source?)

� quality of CO2 more important when greenhouse becomes more closed

� Dehumidify� Reduce heat load� Cool � how (last option because expensive solution)

� Climate distribution inside the greenhouse� Air distribution� Conclusions

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Frank Kempkes

Greenhouse growing: Goals & Means

Holland� Top production, High quality� More niche than bulk products� High return on investment

expected 66666666666666666666666666666666666666666666666666666666666666666666666666� Electricity, CO2, Gas heating,

heat/cold storage, mild climate� High investment opportunities� High education level of staff� High tech equipment is commonly

used (high ridge glasshouses, computer control,

Mexico� average production?, fair quality?� More bulk than niche? � Lower investment � lower return

66666666666666666666666666666666666666666666666666666666666666666666666666666� Electricity? CO2? Gas heating?

heat/cold storage? Climate?� …. investment opportunity?� education level?� High tech equipment is commonly

used (high ridge glasshouses, computer control?

� Systems we apply are based on our local situation.� Systems can’t be copied but have to be adapted to the local situation

Frank Kempkes

Define goals of your production system

� High production � control of greenhouse climate

� Good quality � no blossom end rot (tomato) & more than one branch and flower (Phalaenopsis)

� On time delivery �flowers and pot plants

� Decrease risk of diseases

� Environmental goals� Water scarcity � more crop per drop

� Energy � CO2 footprint

� No run6off of nutrients into the environment

� Crop protection

But this isn’t a matter of just a button on our climate controller or buying a growing system. So don’t shop but combine in such a way that you find the best solution for the local situation

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Frank Kempkes

Dutch situation

� High production costs

� Quality � 90% export, Quantity � 70 kg·m 62 (tomato)

� On time delivery � Phalaenopsis: flower induction needs cooling

� Environmental goals:

� No water scarcity, but strong regulations by government

� Energy � agreement to reduce energy use

� Nutrients � strong regulations on closed growing systems by government

� Crop protection � flowers and pot plants zero tolerance for export

By closing the greenhouse: year round control of climate increase of production (CO2 effect), reduction of energy use, reduces inlet of insects via the windows.

Some examples: Euro � Nuevo Peso x 16

� Land Euro 50 – 100 Euro /m2

� Greenhouse structure 50 – 100 Euro /m2

� Equipment as artificial light, boilers, irrigation, aquifers, heat pump, heat exchangers, screens 20 – 200 Euro /m2

� Very high investments

Running costs � Energy 10 – 25 Euro /m2

� Labor 10 – 20 Euro /man hour

Frank Kempkes

Climate differences (Holland vs. Mexico

20o north, altitude 1500 m

53o north, altitude 65 6 25 m

global radiation 0.36 MJ/cm2 (1400 sun h)

global radiation ±0.9 MJ/cm2 (2800 sun h)

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Frank Kempkes






Frank Kempkes






daily based heat / cold demand balance

seasonal based heat / cold demand balance

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Frank Kempkes

32 oCThe variable

temperature

Why cooling the greenhouse ? optimal growing point

Frank Kempkes

32 oC25 oCThe variable

temperature


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Frank Kempkes

32 oC25 oC18 oCThe variable

temperature


Frank Kempkes


temperature


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Frank Kempkes


temperature


This CO2 effect can “ only “ be achieved by reduction of ventilation

� Do you have CO2 ? If not keep the vents opened

Frank Kempkes

What is limiting? Heat or cold demandsun radiation (MJ/m2.month)

0

200

400

600

800

0.0 5.0 10.0 15.0 20.0 25.0 30.0mean temperature (oC)

J D

July

sprin

g

autu

mnholland

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Frank Kempkes


0

200

400

600

800


J D

July

sprin

g

autu

mn

too low radiation CoolingHeating

holland

Frank Kempkes


0

200

400

600

800


J D

July

sprin

g

autu

mn

too low radiation CoolingHeating

holland

almeria

ensenada

puebla

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Frank Kempkes

Environmental goals: Water demand

kg fresh product per m 3 water

0

50

100

150

200

250

300

Israel &Spain, field

Spain,unheated

plastic"parral"

Israel,unheated

glass

Spain,unheated"parral",

regulatedventilation

Holland,climate-

controlledglass, CO2enrichment

Holland, asat left, withre-use of

drain water

Dutch"closed"

greenhouse

growing system

tomato

sweet pepper

2

increasing control of production factors

Frank Kempkes

Heat and cold demand Holland

� without heating no tomato crop from October – March

� half of March – half of September requires ventilation due to energy overload � seasonal heat/cold storage

� March – November requires energy to dehumidify

� More cold then heat demand (depends on closing factor: closed / semi closed

� Phalaenopsis (warm phase 27oC � year round heating; cold phase 20oC � without cooling between April and October not enough flowers and branches)

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Frank Kempkes

Heat and cool demand Mexico

� Huge variation in climate zones � no general solution

� Regions with huge difference between minimum (heating) and maximum temperature (cooling)

� No seasonal heat / cold storage required � balance daily heat & cold demand

� More cold then heat demand � reduce heat load

� Dehumidification (how ?)

Frank Kempkes

Heat and cool demand: seasonal

� Seasonal storage

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Frank Kempkes


Heating

heatpump

gasengine

warm well cold well

35 °C49 °C45 °C

5 °C

7 °C14 °C

� Heating in winter & store cold

Frank Kempkes


Heat extraction

Heat exchanger

warm well cold well

18 °C

8 °C16 °C

� Recharging the storage system in summer by cooling

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Frank Kempkes


� Lots of equipment

� Difficult to manage

� High investments (at least ±100 Euro/m2 � 1800 nuevo Peso)

Frank Kempkes

Heat and cold demand: daily

� First try to reduce heat load with conventional means, because this is often cheaper then active cooling

If this way of heat reduction is not sufficient:

� Which cold source is available to me?� Cooling tower possible (cold nights?)

� Heat pump � needs electricity (if available, then expensive)

� Is cold only used to cool or also for dehumidification?

� What does the heating system look like (water pipes, air heat exchanger)?

� Economy: Financial balance

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Frank Kempkes

wavelength

ener

gy

700400 2500 nm

UV NIR(Near InfraRed) = 50% of energy

A cover with high NIR reflectivity would reduce thermal load by 50% without reducing assimilation

0

The “ideal” cover has different properties in the PAR, NIR and TIR ranges !!

Reduction of heat load Radiative properties of the cover

Frank Kempkes

photosynthesis / growth

absorption

transmissiongreenhouse covering

UV PAR NIR

UV PAR heat

Τoutside

Τcrop ⇑

Τinside ⇑

Global radiation

increasing temperature

ventilators open“heat stress”

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Frank Kempkes

photosynthesis / growth

absorption

UV PAR NIR

UV PAR

heat

Τoutside

Τcrop ↓

Τinside ↓

Global radiation

Vents can be kept closedfor a longer period

Reflection by NIR6filter

transmission greenhouse covering CΟ2 ⇑

Frank Kempkes

BUT:

� Contribution of NIR to the heat load is smaller than we expect because of high NIR reflection of the crop (45 %) where PAR reflection is small (5%)

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Frank Kempkes

� Screens � Reduce transmission � transmission of greenhouse x transmission of screens

screen = 0.75 x 0.8 = 0.6 � Pick your choice from a large number of available screens� Most screens are multi6functional: both for shading and isolation purposes� Keep in mind that especially multi6functional screens reduce ventilation capacity� Photo6selective screen materials are available (expensive and questionable

functioning)� Screens on the outside of the greenhouse are more effective than inside the

greenhouse

� photo selective coatings (chalk/ white wash) reduce NIR (in or on6top6of greenhouse)� Cost6effective� Flexible (part of, or whole greenhouse)� Changes Direct Radiation into Diffuse Radiation� Once applied, not easily removed� Almost never the ideal solution

Reduce heat load: pro’s & con’s of screens and coatings

Frank Kempkes

� Roof sprinklers or water screen (big difference)� Pro’s

• Evaporation of water uses heat from greenhouse roof, thus cooling the greenhouse air• Roof temperature reaches dew6point temperature (at the cost of large amounts of water)• Temperature of sprinkler water less important than one may expect

(Keep in mind the difference between evaporative heat and specific heat) • With roof sprinklers allow energy to be harvested;

� Con’s• increases RH of the greenhouse air• reduces ventilation capacity• increases slightly humidity of the outside air entering the greenhouse

!!! high use of water !!!

� Humidification of the greenhouse air (evaporative cooling) � increase of ventilation efficiency� good (clean) water required� keep your crop dry (short running time, high pressure, high greenhouse ridge)

Reduce heat load: pro’s & con’s (roof) sprinklers

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Frank Kempkes

Ways of cooling: how to apply cold in the greenhouse

Frank Kempkes

Ways of cooling : Apply cold from below using air ducts

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Frank Kempkes

Ways of cooling: apply cold from below by decentral units

Frank Kempkes

Ways of cooling: apply cold from above by decentral units

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Frank Kempkes

Tomato: some results of closed versus open systems

� Temperature profile differs

Closed �

Open �

� Growers try to reduce this difference

15

20

25Gesloten kas maand gemiddelden 01-Jun-2008 30-Jun-2008

Tijd (uren)

T(°C)

T boven Etmaal: 20.4 °CT midden Etmaal: 20.7 °CT onder Etmaal: 20.2 °C

4 8 12 16 2015

20

25Open kas maand gemiddelden 01-Jun-2008 30-Jun-2008

Tijd (uren)

T(°C)

T boven Etmaal: 20.2 °CT midden Etmaal: 20.5 °CT onder Etmaal: 20.8 °C

T top day avg. 20.4 oCT mid day avg. 20.7 oCT low day avg. 20.2 oC

Open greenhouse cyclemean June 2008

T top day avg. 20.4 oCT mid day avg. 20.5 oCT low day avg. 20.8 oC

Closed greenhouse cyclemean June 2008

Time (hours)

Frank Kempkes

Company 1 Company 2

Company 3 Company 4

T top closedT mid closedT low closedT top openT mid openT low open

Effect of cooling on greenhouse climateTemperature cycle6average month of June

Company 1l below & above

Company 2p below

Company 3t below

Company 4g above

� Absolute Temp. difference open and closed 1 & 3

� Temp. under 2 & 3 low

� Top cooler (company 4) novertical temperature gradient

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Frank Kempkes

Company 1 Company 2

Company 4

VD top closedVD mid closedVD low closedVD top openVD mid openVD low open

Company 3

Company 1l below & above

Company 2p below

Company 3t below

Company 4g above

� During daytime more humid in closed greenhouse

� Start of cooling (vents are more closed)

Effect of cooling on greenhouse climateHumidity cycle6average during July 2008

Frank Kempkes

Effect of cooling on greenhouse climateCO2 effect

Company 1 below & above

Company 2 below

Company 3 below

Company 4 above

� Variability open and closed is subject to change

� Company 4 despite small cooling capacity reasonable differences in CO2

� Differences are smaller than expected !

company company

company company

Closed

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Effect of cooling on greenhouse climateCO2 effect in practice

Calculated and realized production increase (%)

Calculation takes into account that during high radiation effect is largest

Realized production differs from calculated due to diseases, deficiencies, predators and crop treatment

~ 85.84~ 012.83

~ 104.82~ 43.41

realizedcalculatedgrower

Production increase (%)2008

Frank Kempkes

Interaction between cooling and climate Cooling from above

Wire less

Temp. &

Humidity

Sensors

Network

At 3 heights

Cool unit

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Frank Kempkes

Interaction between cooling and climatecooling from above

510

1520

510

1520

5

10

15

20

Temperatuur [oC] 25-Jul-2008 - 01-Aug-2008

510

1520

510

1520

5

10

15

20

vpd [g/m3]

23

23.5

24

24.5

25

3.5

4

4.5

5

5.5

6

� The influence of the cooler is seen in the temperature profile

Temperature and humidity measured at 3 heights in the crop

(at substrate level, ripening truss and top of plant)

Arrows show position and air flow direction of cool units

Frank Kempkes

Interaction between cooling and climateTemperature with air duct (company 2)

•

� Temperature distribution good below the crop during cooling

-80 -60 -40 -20 0 20 40 60 8020.5

21

21.5

22

22.5

23

23.5[oC]

[locatie]

van: 02-Mar-2008 09:00:00 tot: 02-Mar-2008 12:00:00

ondermiddenboven

TopMiddleLow

Middle of greenhouse Side wallSide wall

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Frank Kempkes

Interaction between cooling and climateTemperature with air duct (company 2)

•

� Temperature distribution uneven during heating

-80 -60 -40 -20 0 20 40 60 8015.5

16

16.5

17

17.5

18

18.5[oC]

[locatie]

van: 05-Mar-2008 21:00:00 tot: 06-Mar-2008

ondermiddenboven

TopMiddleLow

Middle of greenhouse Side wallSide wall

Frank Kempkes

Interaction between cooling and climate example of air distribution (Theory)

Bedrijf 1 onder & boven

Bedrijf 2 onder

Good equal distribution of air through the table in theory

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Frank Kempkes

Interaction between cooling and climate example of air distribution (practice)

Inhomogeneous distribution through or even beside the table

Frank Kempkes

Conclusions (1)

� Cooling from below creates a vertical gradient in temperature and humidity in opposite direction compared to natural ventilated greenhouse� If differences are too high

� lower fruit temperatures will result � ripening time will increase � increase of fruit load � overall result: decrease of production

� Despite the systems, climate is still not homogenous (horizontal and vertical)

� Influence of the conditioning systems on the climate is minimized when windows are opened

� Only apply cooling from above when air is spread by fans

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Frank Kempkes

Conclusions (2)

� Potential production increase (CO2 effect) lags behind by

� Lower fruit temperature (unbalanced plants)

� Increase of CO2 smaller than expected

� Diseases show up at some companies

� During summer quality of Phalaenopsis will increase (more branches and flowers)

� Air ducts increase energy consumption

� During heating air ducts will just cause trouble

� The way growers use the system is subject to changes (we are still all learning)

� The control of the systems is still mainly manual

Frank Kempkes

Conclusions (3)

� What do these Dutch conclusions mean for the Mexican situation ?

� Closed system only beneficial when CO2 enriched inside the greenhouse

� Closed system should be designed for day6night cycles rather than winter6summer cycles

� Closed system are beneficial to decrease disease pressure in the greenhouse

� Closed system increases the water use efficiency considerably� beneficial in areas with water scarcity

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Frank Kempkes

Gracias

por su atención

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guadalagara Frank Kempkes 2 pdf - WUR