GREENHOUSE BASED DESALINATION FOR SUSTAINABLE AGRICULTURE IN DESERT CLIMATE

MOHAMED NOUR1, ASHRAF GHANEM1, MARTIN BUCHHOLZ2, AND AHMED NASSAR1

1 Cairo University, Faculty of Engineering 2 Technical University of Berlin

OUTLINE • Background and motivation • Methodology • Greenhouse construction and operation • Results and discussions • Conclusions and final remarks

BACKGROUND • Water scarcity in Arab world • Fading of fresh groundwater resources

(fossil) • Over mining of ground water increasing

salinity • Sea water intrusion in coastal zones (Nile

delta) • Climate change – sea level rise – sea water

intrusion – increasing groundwater salinity

BACKGROUND • Direct irrigation with brackish water poses

limitations on the kind of crops to be cultivated and reduces crop yield

• All this water quantity/quality problems results in significant shortages in food supply and food security issues

• This provokes a fundamental change of water management including a more efficient use of limited freshwater resources and the use of unconventional water resources like sea- and brackish water

MOTIVATION Brackish groundwater resources of salinities in the range of 2000 to 10,000 ppm are widely available in the western desert areas and Sinai.

OPPORTUNITIES

• Horticultural production in closed environments: more and better food by the practice of CO2 accumulation , pesticide free plant

• The concept, known in the literature as the Watergy (Buchholz et al., 2005; Buchholz, 2000)

TDS ~ 0

Brackish

Mix and use for irrigation

CHALLENGES • Temperature and Humidity control in a

closed greenhouse • Promoting evaporative cooling • Water harvesting • Co2 assimilation for boosting crop yield • Cost reduction – local material and waste

recycle

OBJECTIVES • Advancing Watergy by:

– using brackish water in the greenhouse irrigation system

– utilizing very high salinity desiccant in the greenhouse heating/cooling system

– developing of cooling methods for closed greenhouses, that will allow the use under climatic conditions of Egypt and the Middle East

– enhancing the economic feasibility of the system by researching the use of local materials

METHODOLOGY

100 m2 closed greenhouse

INITIAL RESULTS • Focus on desalination capacity of the

proposed greenhouse. Other aspects including greenhouse cooling, horticulture diversity and material selection are described elsewhere.

• Initial results: condensed water within the greenhouse amounts to 2.5-3.8 L/m2/d.

• Design allows harvesting nearly 80% of this condensed water. Thus, collected fresh water amounted to 2-3 L/m2/d.

STUDIED SCENARIOS • Scenario 1: Cultivating cherry tomatoes in

a 20 greenhouse setup • Scenario 2: Cultivating cucumbers in a 20

greenhouse setup • Scenario 3: Cultivating bell peppers in a 20

greenhouse setup

Cropping Pattern (20 ha) Cherry tomatoes Bell peppers Cucumbers

Water consumption per cropping season (m3)

180,000 168,000 90,000

Condensed water recovery per cropping season (m3)

72,000 84,000 36,000

*Target irrigation water salinity for optimum yield

(mg/L) <1000 <960 <1600

Maximum salinity for brackish water supply – Proposed greenhouse

system (mg/L)

1700 2000 2700

Productivity – Proposed greenhouse system (% of

maximum yield) 100% 100% 100%

*Productivity – other typical greenhouses (% of

maximum yield) 90% 77% 77%

% Increase in productivity 10% 23% 23% % Water saving 40% 50% 40%

Cropping Pattern (20 ha) Cherry tomatoes Bell peppers Cucumbers

Water consumption per cropping season (m3)

180,000 168,000 90,000

Condensed water recovery per cropping season (m3)

72,000 84,000 36,000

*Target irrigation water salinity for optimum yield

(mg/L) <1000 <960 <1600

Irrigation water salinity (mg/L)

3000 3000 3000

Proposed greenhouse modified salinity (mg/L)

1800 1500 1800

*Productivity – Proposed greenhouse system (% of

maximum yield) 92% 88% 96%

*Productivity – other typical greenhouses (% of

maximum yield) 72% 55% 71%

% Increase in productivity 20% 33% 25% % Water saving 40% 50% 40%

Sour

ce w

ater

TDS

= 3

000

mg/

L

CONCLUSIONS AND FINAL REMARKS • Joint effort between CU and TU-Berlin to develop

technologies for sustainable pesticide free agriculture using brackish water in an integrated desalination horticulture solar greenhouse.

• Watergy can save in irrigation water 40% for tomatoes and cucumbers and 50% for bell peppers.

• Maximum crop yield can be achieved at extended upper salinity levels: from 1000 to 1700 mg/L for cherry tomatoes; from 960 to 2000 mg/L for Bell Peppers; and from 1600 to 2700 mg/L for cucumbers.

CONCLUSIONS AND FINAL REMARKS • Under a possible scenario of increasing

groundwater salinity to 3000 mg/L from excessive mining and possible sea level rise, the proposed greenhouse can serve in increasing crop yield by: 20%, 33%, and 25% for cherry tomatoes, Bell Peppers, and Cucumbers, respectively. Coupled with irrigation water saving of 40% for tomatoes and cucumbers and 50% for bell peppers.

• The proposed technology not only provides water saving and increase in crop yield under brackish water conditions but also provide organic pesticide free produce.

ACKNOWLEDGMENT • ICDEMOS 2014

Thank You!!!!!!!!!!!!!!!

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