In countries such as Saudi Arabia and the United Arab Emirates, water is scarce as rainfall is minimal. Growers in the Gulf Region rely on groundwater for evaporative cooling and irrigation. This source of water is running out and growers are deciding to end production. The governments of the Kingdom of Saudi Arabia and the United Arab Emirates want to create new possibilities for horticulture in the region by developing more sustainable and water-efficient technique

Campen, J.B.

English

Wageningen Yield 

20 www.HortiWorld.nlFlowerTECH 2009, vol. 12/no. 6
In the Gulf Region, water used for agriculture is usu-ally extracted from deep groundwater sources. 
However, this resource is start-
ing to be depleted as a result of 
extensive use, and the quality 
of the water is decreasing dur-
ing this process. This has result-
ed in the decision by several 
vegetable and cut flower grow-
ers to stop their production 
due to poor water quality.
By applying reverse osmosis, 
sea water can become an alter-
native resource. This method to 
produce fresh water is already 
applied more extensively for 
domestic use. The salty water is 
pumped through a membrane 
that filters out the minerals. A 
cubic meter of water can be 
produced at a cost of about 
US$ 1.75; 70% of which results 
from energy costs. Using treat-
ed waste water for food pro-
duction is not considered an 
option in this region. This 
water is mainly used for irriga-
tion in parks and forests. 
Protected horticulture in this 
region primarily uses water for 
evaporative cooling. Pad and 
fan systems provide a moderate 
greenhouse climate due to the 
low relative humidity and are 
used extensively for this reason. 
However, as a result of the high 
outdoor temperature in combi-
nation with high levels of solar 
radiation, the water use of 
these systems is high. With 
water resources running out, 
alternative systems need to be 
developed.
Closed greenhouse
An alternative system that can 
be applied to reduce water use 
in Saudi Arabia and the United 
Arab Emirates can be mechani-
cal greenhouse cooling. This 
concept is often referred to as a 
‘closed greenhouse’ and has 
been developed and tested in 
the Netherlands in the last few 
years. A closed greenhouse is 
sealed off from the outside in 
terms of air exchange, and air 
treatment units control the 
humidity and temperature 
inside the greenhouse. 
The air treatment units are 
installed above and below the 
crop to provide the optimal cli-
mate. No vents are installed in 
the greenhouse cover. Since 
there is no interaction with the 
outside air, CO2 levels can be 
maintained at very high levels 
thus increasing production. 
Furthermore, the climate can 
be controlled precisely and pes-
ticides are not used. 
As the greenhouse is closed, 
all the water put into the sys-
tem remains in the system, so 
only the water put into the 
plants coming out of the green-
house has to be supplied. 
These benefits come at a price: 
the investment and operational 
costs. However, since the heat 
from the solar radiation enter-
ing the greenhouse has to be 
removed by the cooling system, 
the electricity use of this system 
forms a substantial part of the 
operational costs.
The main advantage of a 
closed greenhouse is that it 
drastically reduces water con-
sumption. This advantage has 
to compensate for the technol-
ogy being costly and energy 
consuming. On request of the 
authorities in the Gulf Region, 
an inventory study has been 
made by researchers from 
Wageningen University. The 
Dutch Ministry of Agriculture, 
Nature and Food Quality has 
been funding the project.
Comparison 
The economics of the closed 
In countries such as Saudi Arabia and the United 
Arab Emirates, water is scarce as rainfall is mini-
mal. Growers in the Gulf Region rely on ground-
water for evaporative cooling and irrigation. This 
source of water is running out and growers are 
deciding to end production. The governments of 
the Kingdom of Saudi Arabia and the United 
Arab Emirates want to create new possibilities for 
horticulture in the region by developing more sus-
tainable and water-efficient techniques.
By Jouke Campen, Wageningen UR Greenhouse Horticulture,                              
the Netherlands, Jouke.campen@wur.nl
Prospects for Gulf Region 
with closed greenhouse
Figure 1: Gross income per square meter of greenhouse as a function 
of tomato price in the Gulf Region.
Greenhouse
21www.HortiWorld.nl FlowerTECH 2009, vol. 12/no. 6
system have been compared 
with that of the traditional 
greenhouse operated using a 
pad and fan. The investment 
and operational costs have 
been estimated for both sys-
tems in the climate of the Gulf 
Region. Figure 1 shows the 
gross income per square meter 
of greenhouse as a function of 
tomato price. The lines repre-
sent values for the current pad 
and fan system and a closed 
greenhouse using different 
ways to raise CO2 levels. 
CO2 enrichment can be done 
by burning natural gas or by 
dosing pure CO2. Burning nat-
ural gas for CO2 is more eco-
nomical than applying pure 
CO2. The production of CO2 by 
burning natural gas can be 
combined with production of 
electricity using cogeneration. 
From the Figure it can be con-
cluded that, with the assump-
tions made, the closed green-
house is more economical than 
the traditional greenhouse 
operated by a pad and fan sys-
tem. The high operational and 
investment costs are compen-
sated by the increase in yield in 
the closed greenhouse due to 
the optimal climate and CO2 
enrichment. So, an economi-
cally feasible greenhouse that 
uses a minimal amount of 
water seems possible for the 
Gulf Region.
The closed greenhouse system 
has not yet been demonstrated 
in the harsh climate of the Gulf 
Region. The authorities in the 
Gulf Region, the Dutch 
Ministry of Agriculture, Nature 
and Food Quality and 
Wageningen University aim to 
develop a demonstration centre 
to see whether the technology 
can also be used successfully in 
this region. Training, commu-
nication, demonstration and 
research will be the centre’s 
main focus. n
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Prospects for Gulf Region with closed greenhouse

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