Observation bysatellite
Advanced prediction
system of regional
water cycle
Rainfallradar

Research and Development to
Improve Desert Environments
and Create a Sustainable
Oasis Network

Meteorological- andenvironmental-observation

Promoting rainfall

Wastewater
Desert greening
treatment
by deep-rooted
system withseeding
air-conditioning
equipment

Atmospheric moisturecollection system

Seawater desalination
by solar energy
and biomass

MAKOTO HARADA* 1
WATARU KAWAMURA* 3

RYOHJI OHBA* 2
MASAHIKO NAGAI* 4

As economic development and urbanization have expanded in the Middle East, so too has desertification. Securing adequate water resources to support economic development and enhance urban environments is critical. Accordingly, adopting highly efficient energy-supply equipment and technologies for securing water resources, using water
effectively, and implementing desert greening or reforesting projects are important. Mitsubishi Heavy Industries,
Ltd. (MHI) aims to contribute to the stable and continuous economic development and environmental improvementof Middle Eastern countries and, in turn, to strengthen the energy security of Japan. Specifically, using its technologies and products, MHI proposes a scenario for creating a sustainable "oasis." This paper introduces some of MHI's
efforts to improve desert environments with the goal of creating such a sustainable desert oasis.
academic organizations, MHI has undertaken various
engineering studies related to global and regional climate change.
Such studies have revealed the possibility of greening the so-called coastal deserts, many of which exist in
western coastal areas of continents. In particular, theRed Sea coastal area of Saudi Arabia receives high-humidity air from the sea. Various simulations haveexamined the possibility of greening and have shown thatonce greening expands to a certain extent in this area,
there is a possibility that the newly established forests
could promote cloud formation and hence greater rainfall. Accordingly, the following hypothetical scenario is
proposed:
A greened area of a certain scale would be created ina suitable desert region.
An increase in rainfall would be spurred by interactions of vegetated land and the climate by which
forests promote cloud formation and subsequent precipitation.
The increased rainfall would increase the amount ofavailable water in the region, which in turn would
further encourage the expansion of greening.
Finally, a system would be created by which most of
the water would be supplied from water circulated
from the ocean to the atmosphere and then to thegreened lands. This cycle would minimize dependence
on supplemental water sources such as desalinizedseawater or deep subterranean water (non-rechargeable fossil water drawn from biostratigraphic aquifers
that exist several hundred meters to more than 1 km
below the ground surface).

1. Project Overview: Improving Desert Environments
1.1 Creating a sustainable oasis network
Middle Eastern countries continue to enjoy remarkable progress in economic development and urbanization.
However, desertification and a lack of water resources
are increasingly serious problems for which various solutions are being sought. To help these and other nations
that are suffering from water deficits, MHI is developing a scenario to create a sustainable oasis network.
Instead of applying conventional methods that requirelarge amounts of fossil fuels, which are also limited natural resources, and pursuing only short-term economic
efficiency, the scenario that MHI proposes here includes
new and dynamic methods for greening deserts and enhancing urban infrastructures. These methods
incorporate active acquisition of sustainable water resources and sustainable and renewable energy wherever
possible.
MHI hopes that this proposed scenario will help improve desert environments and promote stable andcontinuous economic development in the Middle East. It
is further hoped that the resulting economic and environmental benefits to the Middle East will help ensure
the Middle Eastern fossil fuel supply to, and subsequent
energy security of, Japan.

.
.
.
.

1.2 Scenario for creating an oasis network
MHI has participated in the Global Frontier Projectof the Ministry of Education, Culture, Sports, Science,
and Technology of Japan since 1999. As part of the
project, in collaboration with industry, government, and*1 Technology Planning Department, Technical Headquarters*2 Nagasaki Research & Development Center, Technical Headquarters*3 Takasago Research & Development Center, Technical Headquarters*4 Advanced Technology Research Center, Technical Headquarters

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This system would create a hydrological circulation
within which the artificially greened lands would increase the moisture content of the winds blowing fromcoastal areas to the mountains. In the mountains, themoisture contained in the winds would be converted toclouds that would then precipitate over the mountain
districts. The rainwater would replenish groundwaterlayers located in the comparatively shallow (approximately several meters deep) underground zones andsubsequently increase the amount of groundwater
Fig.1(Fig.1
Fig.1). The oasis MHI envisions would provide a comfortable living space, would be based on a verified,feasible scenario, would minimize the use of deep subt e r r a n e a n w a t e r, a n d w o u l d f o r m a s u s t a i n a b l ehydrological circulation system.
1.3 Procedure to verify the feasibility of the scenario
The feasibility of the scenario was verified as follows
Fig. 2(Fig.
2).

High temperatureand high humidity

Transpiration
MangroveforestHumid wind(1) Investigation of hydrological cycle mechanisms
First, to understand hydrological circulation at global and regional scales, hydrological circulation
mechanisms were investigated to identify the mostsuitable area for greening along the Red Sea coast of
Saudi Arabia and to estimate the size of the greenedarea required to increase rainfall amounts. These factors were examined using observational data andsimulations by the "Earth Simulator" supercomputer.
Section 2 introduces an example of this research.
(2) Acquiring sustainable water resources and desert
greening
To create the hydrological circulation mechanism
described above, engineering and agricultural analyses, combined with economic, social, and cultural
perspectives, are required. These interdisciplinary
fields were applied to examine methods for acquiring
sustainable water resources and desert greening.
Cloud
and rain

Formation of cloud

Mountain
district

Grassland
and forest
1.0

Red Sea

Recharging
underground water(shallow layer)

Humidification zone

Water efficiently using zone

Harvested water
Harvest zone

Fig. 1 Conceptual image of the water circulation system

Global meteorological analysis

Securing sustainable
water resources

Research of hydrologicalcirculation mechanisms incoastal areas of Saudi Arabia

Western Asia
meteorological analysis

Sustainable desert
greening

Review and evaluation from
economic, social, andcultural perspectives
Creating a sustainable oasis network

Fig. 2 Research procedures

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.
.

The following issues are important.
Identifying the best method presently available to secure a necessary amount of water.
(Securing sustainable water resources)
Identifying the best method to achieve efficient greening
Identifying the best method to reduce the amountof water required for greening(Sustainable greening of deserts)
Section 3 presents two approaches for securing sustainable water resources. An example of a technical study
related to sustainable desert greening is presented in
Section 4.
This study was performed as part of the Research
Project for Sustainable Coexistence of Humans, Nature,and the Earth entitled "Advanced Prediction System andCounter Measures of Global- and Meso-scale Water
Cycle" (Global Water Cycle Project: GWCP). Research forthis project is conducted in cooperation with the Japan
Agency for Marine-Earth Science and Technology(JAMSTEC), the National Research Institute for Earth
Science and Disaster Prevention, Kyoto University,
Tottori University, Sophia University, and various research institutes in Saudi Arabia (1).
The project began in 2001 and will continue until 2006
(years are based on the Japanese fiscal year). Over thelast 3 years, the MHI project team has nearly completed
research on the basic technology involved and has begun preparing the overall plan in parallel with on-siteverification tests initiated in 2005.

2. Hydrological Circulation Study
This section describes research on hydrological circulation processes ranging from global to local scales;
results will be applied to securing sustainable water resources and greening deserts in dry zones. The results
were obtained through numerical analyses using observational data of local weather, the latest weather
forecasting models, and a large-scale parallel
supercomputer, the Earth Simulator.
2.1 Analysis of global-scale meteorologicalphenomena
Recent research has revealed that global-scale meteorological and hydrological circulation changes are
driven by long-term changes in ocean surface temperature distributions. Figure 3 illustrates the influence ofchanges in the Pacific Ocean surface temperature (ElNino Southern Oscillation: ENSO) and Indian Ocean
surface temperature change (Indian Ocean Dipole: IOD)
on global total rainfall based on analyses of long-term
observation data. The figure reveals that total rainfall
in India decreases during summer when the ENSO isprevalent, and total rainfall in the Middle East and India increases when the IDO is prevalent.
Rainfall in the Red Sea coastal region of Saudi Arabia
is characterized by two climatic peaks. One peak iscaused by low atmospheric pressure arriving from over
the Mediterranean Sea during winter, while the otherpeak is caused by the Indian Ocean monsoon during sum4 The mechanism of this rainfall
mer, as shown in Fig. 4.
phenomenon in winter was first discovered during thisresearch and is referred to as the "Arabian Cyclone"(Yamagata et al., 2005) (2).

Composite for Pure ENSO Events cm/month70

Average monthly rainfall(1978 ~2001)

mm/month60(a) Impact of ENSO

50
40
30
20
10
0

Composite for Pure IOD Events cm/month

1

2

3

4

5

6

7

8

9

10 11

12

month
(a) City in mountain district (Abha)
70

Average monthly rainfall(1976 ~2001)

mm/month

60
50
40
30
20
10

(b) Impact of IOD

0

Fig. 3 Influence of Pacific Ocean surface temperature change(El Nino Southern Oscillation, ENSO) and Indian Ocean
surface temperature change (Indian Ocean Dipole; IOD)
on global rainfall based on meteorological observation
data (The gray area shows the increase in rainfall, thedotted lines show areas of decreased rainfall.)

1

2

3

4

5

6

7

8

9

10 11

12

month
(b) Coastal city (Gizan)
Fig. 4 Observed monthly average rainfall in a city in themountainous district (Abha) and a coastal city
(Gizan) along the Red Sea coast

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In summer and winter, rainfall increases in mountainous zones higher than 2 000 m in the Red Sea coastal
region. As shown in Fig. 55, natural forests and agricultural zones have formed in this region known as the"Asir." It is important to improve the accuracy of meteorological analyses by ongoing analyses and simulationsof meteorological phenomena at both global and regional
scales. Global climate trends such as global warming may
remarkably alter the global climate in the future andcan also greatly affect regional-scale climates.
2.2 Hydrological circulation mechanism of the Red
Sea coastal region of Saudi Arabia
Using the regional weather model, this study thenquantitatively verified the hypothesis that the greening
and afforestation of deserts along the Red Sea in Saudi
Arabia would increase the amount of water supplied tothe atmosphere, resulting in enhanced rainfall in themountainous zone.
For example, if a 75 x 150-km area of desert wereconverted to grassland, the grassland would then supply water vapor to the atmosphere. Increased
atmospheric water vapor could increase the water content in clouds over the mountainous zone by
Fig.6
approximately 20% [Fig.6
Fig.6(a)(b)]. Thus, the analysis
showed that there is a possibility that the amount of
rainfall could also increase by approximately 20%
Fig.6[Fig.6
Fig.6(c)(d)]. Current investigations are examining differences in the types of cultivated plants, vegetated area,(a) Natural forest at 3000m altitudeand number of years required to further clarify themechanism by which greening deserts could form clouds,
leading to greater rainfall.
To enhance rainfall in the mountainous zone, investigations of cloud-seeding techniques using numerous
balloons are planned in cooperation with Presidency ofMeteorology and Environment in Saudi Arabia, as shownin Fig. 7
7. In those experiments, the launched balloons
spray moisture-condensing agents in the air and clouds.
The U.S. National Center for Atmospheric Research(NCAR) is performing similar experiments using aircraftin the United Arab Emirates, Saudi Arabia, South Africa,and India. In China, similar technology was examined not
only to enhance rainfall but also to prevent hail and eliminate fog. It is anticipated that results from these studies
will be mutually beneficial and will assist with the Saudi
Arabian research project reported here.

(b) Agricultural zone at 2500m(a) Desert (max.: 0.59 g/kg)(b) Grassland (max.: 0.75 g/kg)(c) Desert (max.: 14.6 mm/hr)(d) Grassland (max.: 19.1 mm/hr)

Fig. 6 Numerical calculation of areas affected by desert-greening,
using a regional-scale meteorological modelFig. 5 Natural conditions at altitudes of approx. 2 500 m and 3 000 m

Balloon
Airplane(USA)

Observation by satellite
BalloonRainfall radar
Prediction of diffusionof condensation agent

Spraying
condensation
agent

Promotingrainfall

Radar reflection dishRocket(China)Parachute
GPS sonde

Water dam
ascending current

Equipment loadedwith rainfall p
promoter
BallastFig. 7 Technology used to promote rainfall by spraying a condensation agent from balloons (i.e., cloud seeding)

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Technical Review Vol. 42 No. 4 (Nov. 2005)4

source. As shown in Fig. 99, current experiments are investigating the use of both solar energy and biomass forseawater desalination.
As shown in Fig. 10
10, an experimental solar electric generating system (SEGS) power plant (354 MW) has alreadybeen built in the Mojave Desert of the U.S. In addition,
1, a number of large-scale experimenas shown in Table 1
tal solar thermal power plants are either currently underconstruction or in the planning stages in several othercountries. MHI manufactured the steam generators andturbines for the third, fourth, and fifth 90-MW plants built
as part of SEGS projects 20 years ago. These facilities arestill operating smoothly. Three types of solar collectors
are used in solar thermal power plants: the tower type,separate light-collecting (trough) type, and parabola type.
In this research, the trough type is being investigated fordesalination applications, because this type of collector
has long actual operating records and is suitable for lowtemperature (around 100 o C) steam generation. By
progressively depreciating capital costs, SEGS solar power
plants have reduced power generation costs to as low as 5cents/kWh. The average generation cost since the operations began 20 years ago is estimated to be approximately
Fig. 11)
8 cents/kWh. (Fig.
11

3. Securing Sustainable Water Resources
Rapid population growth in the arid Middle Eastern region has led to vast amounts of water being consumed forfood production. Much of the water used is pumped fromdeep, subterranean sources, the depletion of which is a serious concern. For example, in Saudi Arabia, approximately
90% of water use is related to greening efforts and agriculture. It is crucial to secure new water resources. This section
introduces two approaches for acquiring a sustainable water supply using natural energy as the major power source.
3.1 Seawater desalination using solar heat andbiomass waste
Compared to Japan, the Middle East receives more
Fig. 8than two times the annual amount of sunshine (Fig.
8).
Therefore, seawater desalination using solar energy wasinvestigated. An on-site survey also showed that a tremendous amount of biomass, such as leaves discarded
from date palm plantations, is also available as a power

Power generation cost(¢/kWh)14>3600
30003600
24003000
16002400
<1600

12
10
8
6
4
2

Fossil fuel-firing power-generation cost01980 1985 1990 1995 2000 2005 2010 2015 2020 2025

Fig. 8 Distribution of annual sunshine hours

Calendar year

Solar enegy

Evaporator

Steam turbine

MSF

Electric power
generator

RO

Fig. 11 Cost comparison between a fossil-fuel power plant
and the SEGS solar thermal power plant in the U.S.A.

(Daytime)(Nighttime)

Biomass

Table 1 Solar energy power plants worldwide

MSF: Multi-step flush typedesalination system
RO : Reverse osmosis membrane
type desalinization system

Country

Location

Output power
(MW)

Heat
collector

Operation
periodUSA

California(Solar 1)

10

Tower

1982 - 88

California(Solar 2)

10

Tower

1996 - 99

California(SEGS 3)354

Trough1982 - present

FrancePyrenees

2.5

Tower

1982

Spain

Almeria

1

Tower

1983

Sicily

1

Tower

1982

Specchia

12

TroughPlanned

Crete

50

Parabola

1998
Planned1981 - 1985

Fig. 9 Configuration of a desalination system using solar andbiomass as power sources

Italy

GreeceFig. 10 Solar electric generating system(SEGS) trough-type heat collector solar
thermal power plant with an output of
380 MW (Mohave Desert, CA, U.S.A)

IsraelRehobot

250

Tower

Japan

Nio

1

Tower

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Water production cost (cents/ton)

250
: RO
200

: MSF
: Average150
CDM (cents/ton)100

Desalination cost by
fossil fuel50
0Fossil fuel only
(Case 1)

Solar energy only
(Case 2)

Solar energy +biomass (Case 3)

Condensed water

Desalination method

Fig. 12 Cost comparison of seawater desalination by fossil fuel (Case 1), solar
energy (Case 2), and a combination of solar energy and biomass (Case 3)(Based on sunshine conditions in California and Saudi Arabia
and assuming a water-producing capacity of 40,000 tons/day.)A drawback of solar-powered desalination plants isthat they can only be continuously operated for approximately 8 hours per day. Accordingly, the cost ofdesalination is about three times that of fossil-fuel-powered desalination, as shown in Fig
Fig.. 12
12. One way toaddress this cost problem is to use biomass from biomass as a supplemental fuel. This method makes it possible
to increase the operating hours each day, so that costs
can be expected to decrease to those of fossil-fuel-powered desalination. Moreover, this method could beconsidered a Clean Development Mechanism (CDM) andcould thus earn CO2 emission credits.
3.2 Atmospheric moisture collection system
Because the relative humidity of the Red Sea coastal
area of Saudi Arabia exceeds 80% in summer, large
amounts of moisture are carried in the air. The annual
rate of air conditioner use is also high in this area, where
the average temperature often exceeds 30oC for 9 monthsof the year. This research team focused on these conditions and developed the "Atmospheric MoistureFig. 13
Collection System" (Fig.
13), using an MHI packaged air
conditioner (power consumption of 12.5 kW) to collectwater condensed from the air. The performance of theunit has been verified.
In the preliminary test carried out in Nagoya, Japan, in
2003, approximately 300 L of condensed water per day weresuccessfully collected under similar weather conditions tothose in Saudi Arabia. This test unit has now been transferred to the Water Research Center at King Abdul Aziz
University in Jeddah (KAAU). On-site verification tests
have begun and are expected to last for 1 year.
Because the unit is usually used as an ordinary air conditioner, the costs for producing water are essentially nil.
Hence, the unit can serve as an effective alternative source
for securing domestic-use water in urban areas. It is anticipated that the unit can collect approximately 100 L ofwater per day, based on the annual average, especially incities like Jeddah that are located along the coast.

Fig. 13 Atmospheric moisture-collecting systemusing a refrigerating air conditioner

4. Technology to Realize Sustainable Desert Greening
Saudi Arabia is facing a severe water crisis as rapid
population growth and increased food demands deplete
its deep subterranean water supplies. To solve this problem, new water resources and more efficient uses of
surface water, soil water (moisture contained in soil layers at a depth of several meters), and sewage waste watermust be developed.
The project described here focuses on the creation ofgreenbelts that can maintain sustainable plant and crop
production and provide a comfortable living environment.
Under examination are the efficient uses of soil and waste
water, both of which have been only negligibly utilized.
The research described in this section is currently underway as a joint project with the Arid Land ResearchCenter (ALRC) of Tottori University, Japan.
4.1 Cultivation of deep-rooted seedlings
In arid areas, the amount of water near the soil surface (several tens of cm) is generally insufficient forplant cultivation, due to large amounts of evaporation
and a lack of rainfall. However, in areas where water isrecharged by hydrological circulation, sufficientamounts of water are contained at depths from one toseveral meters below the soil surface. A new method
called "deep-rooted seedling cultivation" was developed
Fig
to use such deeper soil waters (Fig
Fig.. 1414). In this cultivation method, water contained in soil can be used directly
by seedlings developed to grow long roots (deep-rooted
seedlings).
From the viewpoint of preventing water depletion,
however, it is important that this water be replenishedperiodically with freshwater from sustainable, hydrological circulation in greening areas. It is thus essential
to select a proper site for deep-rooted seedling cultivation to retain a balance between water supply anddemand and to cultivate plants at a proper planting
density.
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Transpitation
Rainfall

Subsurface irrigation(effective use of swage water)
Cross section ofroot cylinder

Evaporation(small)Root cylinder

Irrigation
pipes

Irrigation
pipes
Culture medium
Root
Root cylinder
Subsurface
irrigation

Absorption of soil water
Deep rooted seeding

Longitudinal section oflower end part of root cylinder

Approximately 70% of surface
irrigation water can be reducedby this technology.
Approximately 60% of micro
irrigation can be reduced.

Irrigation water can be significantly reduced through theuse of rechargeable soil water

Fig. 14 Deep-rooted seedling cultivation method

CompostDry
Wastewater

Concentrated
sludgePre-treatment
equipment(for removing SS)

Utilization ofcooling energy
Freeze concentrationequipment

Air-conditioning
equipment

Recovery of exhaust heat
Sterilizer

Concentrated water

Processed water

For plant cultivation

Concentrated water-processing system

Fig. 15 Wastewater treatment system based on the freeze-concentration method

The effectiveness of the deep-rooted seedling method
has been verified using soybeans (an annual plant) andJapanese black pine (a perennial tree species) as model
plants. Soybeans with roots 95 cm long were successfully grown using this method, and it was confirmed thatthe soybeans had rooted normally.
The deep-rooting method was also confirmed using
Japanese black pine. The main, elongated root of the
deep-rooted black pine seedlings increased up to 2.5
times faster than by normal methods. In the future, onsite surveys will be conducted at a suitable site in Saudi
Arabia to confirm the suitability of the deep-rooted seedling method for date palm trees, a crop that is in highdemand in the region.
4.2 Plant cultivation using waste water
MHI is developing a sewage treatment system basedon the freeze-concentration method to promote the effective use of sewage waste water in Middle Easterncountries, where great demand for refrigeration is exFig. 15
pected (Fig.
15).
In this system, impurities are eliminated from ice

when water is frozen; therefore, this method can be used
to purify water. At the same time, the ice can be used asa cold energy source for air conditioners. The system has
been tested and verified in Japan, and the following results were obtained.
(1) A verification test using simulated sewage water similar to local sewage in Saudi Arabia demonstrated that
this system can produce water of suitable quality forplant cultivation.
Water conditions in inlet (equivalent to sewage):
Chemical oxygen demand (COD): 300 mg/L,
Suspended substance (SS): 120 mg/L;
Processed water qualities: COD < 10 mg/L,
SS < 5 mg/L
(2) Sewage water treatment costs can be reduced to as
low as approximately 50 yen/m3 by using cold energy
for air conditioning. However, because the cost of irrigation water is approximately 30 yen/m 3 or lower
in Saudi Arabia, additional research is currently attempting to improve the equipment and further reducethe cost of this processed water.
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5. Conclusions

Acknowledgements

MHI intends to conduct an on-site demonstration test
in Saudi Arabia in fiscal year 2005 (Japan), using the technologies verified thus far. The on-site demonstration will
be performed following detailed and frequent discussions
with local collaborators. Important factors include theneeds of local residents and the government, social planning documents, and large-scale hydrological circulation
trends. In addition, the present state of water resource
conservation and the influence of greening the desert environment will be evaluated. MHI aims to advance andclarify knowledge of hydrological circulation mechanisms
and to show that the presented scenario is highly feasible
through on-site observations, plant cultivation demonstrations, and completing the scenario for an artificial oasis.

The authors would like to extend their deepest appreciation to Dr. Adil Busknak, Chairman of Saudi Arabia
Busknak Co., Dr. Hiromasa Ueda, Director General of
the Acid Rain Research Center (Acid Deposition andOxidant Research Center (ADORC)) of the Japan Environmental Sanitation Center, Dr. Toshio Yamagata,
Program Director of the Japan Agency for Marine-Earth
Science and Technology, Dr. Tomonori Matsuura, (Section Chief - Senior Researcher) of the National ResearchInstitute for Earth Science and Disaster Prevention,
Professor Shinobu Inanaga of the Arid Land ResearchCenter of Tottori University, Professor Toru Okamura,
Professor of Law at Sophia University, and many others
for their kind cooperation and support.

Makoto Harada

Ryohji Ohba

Wataru Kawamura

Masahiko Nagai

References(1) Sustainable Coexistence of Human Nature and the Earth"Advanced Prediction System and Counter Measures of Regional- and Meso-scale Water Cycle", Report of Research
Progress in 2004, March (2005)(2) T. Yamagata et al., Diagnosis of troposphere moisture over
Saudi Arabia and influences of IOD and ENSO, Monthly
Weather Review, (to be accepted) 2005

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