At the national level, these scarce water resources are centrally managed by the \u201cMinistry of Agriculture, Hydraulic Resources and Fisheries\u201d. This institute is represented at the regional level by 24 \u201cagricultural development regional offices\u201d. At local level, \u201cGroupements de D\u00e9veloppement Agricole\u201d (GDA) are tasked with managing irrigation and drinking water systems in rural areas.<\/span><\/p>\n In Gab\u00e8s Governorate, which is located in the SE of Tunisia, the water situation is dire. In terms of rainfall, the average annual precipitation is 158 mm for Gab\u00e8s watershed with extremely dry years dipping to a low of 4.5 mm (<\/span>Jemai et al 2016<\/span><\/a>). Moreover, medium and long-term climate forecasting models derived from historic precipitation data show that dry episodes are slowly taking prevalence over rainy fronts (<\/span>Jemai et al 2018<\/span><\/a>).\u00a0<\/span><\/p>\n With an irrigated agricultural area of approximately 7\u00a0262 ha, and a flourishing agricultural sector, this climate reality threatens the economy of this governorate. Also, given the fact that the annual agricultural water usage reached 156.5 million m<\/span>3<\/span> in 2019, with rainfall waters paling by comparison (15.61 million m<\/span>3<\/span>) (<\/span>PEBD 2019<\/span><\/a>), non-conventional water resources became essential for sustaining agricultural activities (surficial and deep groundwater, treated wastewater). In fact, water pumped from deep aquifers, which is characterized by a relatively high salinity (2.5 to 5 g\/l) (<\/span>PEBD 2019<\/span><\/a>), represents most of the groundwater used in this governorate (<\/span>Beyrem et al 2015<\/span><\/a>).<\/span><\/p>\n To exploit such brackish waters for irrigation, desalination is required to reduce their salinity to usable levels (1.5 g\/l or less). Because of this, Tunisia adopted desalination since 1983, with more than 120 operational stations as of date. 86 % of the latter desalinate water using the reverse osmosis (RO) process (<\/span>IRESA-GIZ project 2017<\/span><\/a>). However, 50% of their output provides drinking water for urban populations in the South according to the same report. In addition, given the dependency of Tunisia\u2019s energy sector on thermal power generation (97%) according to <\/span>official numbers<\/span><\/a>, the fluctuating cost of natural gas required to generate electricity for the RO process may hinder the economic sustainability of desalination stations. Furthermore, more desalinisation units require more fuel and thus emit more CO<\/span>2<\/span>, which further contributes to the current climate change trends.\u00a0 Therefore, greener, decentralized and autonomous solutions are required to meet the agricultural water demand in Southern Tunisia.<\/span>\u00a0 <\/span><\/i><\/p>\n <\/p>\n Objectives<\/b><\/p>\n Gesellschaft f\u00fcr Internationale Zusammenarbeit <\/span><\/i>(GIZ) and <\/span>L\u2019Agence de promotion des investissements agricoles<\/span><\/i> (APIA) built a small-scale and autonomous desalination station in an agricultural farm in Gab\u00e8s governorate with the following aims in mind:<\/span><\/p>\n <\/p>\n Adaptation measures implemented in the case<\/b><\/p>\n Improvement of irrigation efficiency<\/span><\/p>\n Renewable desalination by RO<\/span><\/p>\n Agricultural management and plant selection<\/span><\/p>\n <\/p>\n Solutions<\/b><\/p>\n In Tunisia, multiple brackish water desalination units are operational. In Gab\u00e8s, the existing desalination plant produces 8 500 m<\/span>3<\/span>\/day through the RO process. However, the energy required for its operation is provided by the National Company of Electricity and Gaz (STGE) (<\/span>SONEDE 2015<\/span><\/a>). Therefore, it is mostly non-renewable energy, the price of which depends on the natural gaz market and other external factors to maintain a manageable cost of electricity. In addition, the current output of the station, which provides drinking water to the urban populations of the governorate, is just a fraction of its initial production rate in 1995 (34\u00a0000 m<\/span>3<\/span>) because of maintenance issues and the lack of sustainable raw water resources (<\/span>SONEDE 2015<\/span><\/a>). Therefore, questions arise regarding the sustainability and maintenance cost of big centralized desalination units. This lead authorities and different actors in the agricultural sector to begin the search for decentralized, sustainable and autonomous water desalination solutions.\u00a0<\/span><\/p>\n Taking the above issues into account, a renewable small-scale desalination unit (area = 108 m<\/span>2<\/span>) was considered for testing in El B\u00e9ji farm (42 ha), which is located 14 km South of Gab\u00e8s city. The basic premise of the test is the use of low-cost photovoltaic panels to power a small RO desalination unit. In addition to being fully autonomous and renewable, the electricity generated at the farm produces zero CO<\/span>2<\/span> emissions. Furthermore, the climate setting of the Tunisian South is ideal for such technology given the high solar radiation levels in the area. However, the latter is also responsible for high evapotranspiration levels, which increases plant water use. In the light of this, the water use efficiency was enhanced through constructing a drip irrigation system coupled with greenhouse shade nets to protect plants from the hot sun of the South. Finally, a plant selection thought process was followed to pick the most economically profitable and water efficient plants, thus ensuring good water valuation.\u00a0<\/span><\/p>\n The operational scheme of the station according to <\/span>GIZ (2019<\/span><\/a>), is similar to that of big RO plants. Nevertheless, instead of a diesel generator, the RO unit in El B\u00e9ji farm is equipped with photovoltaic panels that produce 13.5 KWc and are connected to a low-voltage distribution system. The latter nominal power figure is deemed sufficient to purify enough water for irrigating a 2ha greenhouse field. The plant variety selected in the experiment is comprised of piper (0.5ha), strawberries (0.25 ha), tomatoes (0.25 ha) and melon (1 ha), with an average daily water usage of 48m<\/span>3 <\/span>(1.4 KWh\/m<\/span>3<\/span>).\u00a0 To meet this demand, a small RO system is used, which produces on average 48m<\/span>3<\/span>\/day of purified water (0.5g\/l salinity). As for the RO reject, a daily debit of 32m<\/span>3<\/span> of brine solution (5 to 6 g\/l) is expected, most of which will be utilized to irrigate a 1 ha Alfalfa field (a plant characterized by its high salt tolerance). A lesser portion is planned to join the natural water drainage system through an existing 1.5 km drainage canal. The raw and purified waters are stored in 80m<\/span>3<\/span> and 40m<\/span>3<\/span> tanks respectively.\u00a0<\/span><\/p>\n In economic terms, this project required a significant initial investment of 301 500 TND (approximately 97\u00a0000 USD). These funds are used to purchase a full RO system with two storage basins (96\u00a0600 TND), photovoltaic panels with a nominal capacity of 13.5 KWc (45\u00a0500 TND) and greenhouse tunnels to cover 2 ha (159 400 TND). With a negligeable appraisal cost of 1840 DNT and approximately 1 third (34 %) of the upfront investment being subsidized by the APIA, the time to revenue is estimated at 4 years, given the average projected yearly revenue of 76\u00a0000 DNT (approximately 25\u00a0000 UD).\u00a0<\/span><\/p>\n <\/i>The success of this experiment will provide hard data for investors, thus promoting renewable and greener agricultural technology. In fact, for a country like Tunisia, the mass adoption of such desalination techniques will reduce the carbon foot print of its agricultural sector, which occupies the fourth place in terms of greenhouse emissions (<\/span>RIN-GES 2022<\/span><\/a>). For instance, the desalination of water for irrigating the 2 ha in the above experiment requires 24 528 kW-year of electricity, which translates to 14\u00a0226 kg of CO<\/span>2<\/span> emissions considering the average CO<\/span>2<\/span> emission factor of 0.58 kg\/KW in Tunisia (<\/span>U4E 2019<\/span><\/a>). In addition, the widespread use of renewable electricity options will help the country reduce its dependency on fossil fuel electricity, which are mostly imported from other countries. <\/span><\/p>\n <\/p>\n Leader of the initiative and key partners<\/b><\/p>\n The leader of El B\u00e9ji farm renewable desalination project is the deutsche <\/span>Gesellschaft f\u00fcr Internationale Zusammenarbeit<\/span><\/a> (GIZ), which is active in Tunisia since 1970. It is currently working on behalf of the German Government and the European Union (EU) that fund most of its operations. Due to its regular participation in local and regional development projects within Tunisia\u2019s borders, an office was established in Tunis in 1999 to ensure a closer and more efficient follow-up of GIZ activities. The involvement of this institute in Tunisian development projects became more relevant after the Arab Spring events (2011) due to the lack of economic dynamism and the high unemployment rate (15%) that characterize the current transitional period.\u00a0<\/span><\/p>\n Given the challenging water situation in Tunisia, the priority areas of GIZ cooperation include but are not limited to: (i) sustainable economic development and employment promotion, (ii) regional development, local governance and democracy and (iii) protection and management of water and natural resources. As such, the focus of GIZ on environmental governance including water management issues and their long work experience in the Maghreb setting ensures a smooth and savvy management of the financial and administrative risks associated with local development projects. In addition, GIZ is a well-known actor in the region with an established network of partners across North Africa, which grants it a good operational flexibility in the Maghreb region.\u00a0<\/span><\/p>\n <\/p>\n The Tunisian government, is also a partner in this pilot farm project and is represented by two institutions. The main one is <\/span>l\u2019Agence de Promotion des Investissements Agricoles<\/span><\/a> (APIA), which is tasked with promoting private investment in the agricultural sector across Tunisia. To achieve its goals, this governmental agency provides financial, technical and legal support to Tunisian farmers. That being the case, the agency is heavily invested in innovative agricultural projects. The secondary governmental partner in El B\u00e9ji project is <\/span>l\u2019Agence Nationale pour la Ma\u00eetrise de l’Energie<\/span><\/a> (ANME), which is entrusted by the Tunisian government with designing and implementing the state’s energy management policy. Therefore, ANME explores multiple power generation technologies to promote sustainable and renewable energy generation practices in the country.\u00a0<\/span><\/p>\n However, the key stakeholders<\/span> on the long run are the Tunisian farmers of the South, represented by the owners of El B\u00e9ji farm, who are directly impacted by the success of this initiative.<\/span><\/p>\n <\/p>\n Stakeholder participation<\/b><\/p>\n Being the main stakeholder of the project, GIZ is behind the conceptualization and funding of this pilot experiment. However, to study the feasibility of the project, they consulted with <\/span>KHAZEN Consulting<\/span><\/i> cabinet who produced hard data regarding the financial, environmental and technical aspects of the experiment.\u00a0 In addition, this cabinet assisted in communicating the project\u2019s ideas to the wider public (e.g.\u00a0 <\/span>GIZ 2019<\/span><\/a>).\u00a0<\/span><\/p>\n Nevertheless, the significant financial contribution of the <\/span>Fonds Tunisien de l\u2019Investissement<\/span><\/a> (FIT), which was received through the APIA and ANME, helped cover a third of the project\u2019s cost. This was essential in reducing the time to revenue of the project, thus encouraging its adoption by the farm\u2019s owners. In fact, the latter stakeholder\u2019s role is key to success since they trusted GIZ and their partners with managing a significant portion of their farm. Their risk tolerance and wiliness to explore uncharted territories was pivotal for providing a significant and representative testing ground of the proposed solution.<\/span><\/p>\n <\/p>\n Success and limiting factors<\/b><\/p>\n Considering the innovativeness of the project and its target audience, the main success factor for this initiative was its profitability. More precisely, the time to revenue and the maintenance cost. The APIA subsidies received by the project leader help improve the former performance parameter by reducing the time to revenue from 6 to 4 years. However, the cost of building the desalination station is considered high in the Tunisian setting, which may constitute one of the main limiting factors that hinder the mass adoption of the proposed solution by the south Tunisian agricultural community. That being so, high value crops (HVC) products were selected to increase the economic value of desalinated water. For this reason, replicating this model for low-value crop may be challenging. Still, this limitation can be overcome in the coming years thanks to the increasing affordability of photovoltaic solar panels and the enhanced efficiency of modern RO systems. In fact, the combined effect of both trends will reduce the cost of each m<\/span>3<\/span> of desalinated water. In addition, a financial mechanism is needed to promote this technology to the private sector, especially small-scale farmers. Such a mechanism can be provided by regional, national and international agricultural banks that must be enticed to propose low-interest financial solutions to small farms.<\/span><\/p>\n Although El B\u00e9ji farm experiment is progressing according to plan as of 2024, a sudden decrease of the selling price of the crop output may constitute a significant risk to the profitability of the project. To tackle this issue, multiple export markets may be considered as a substitute for managing price volatility.\u00a0<\/span><\/p>\n Finally, a good promotion of the project\u2019s idea and its economic feasibility is essential for mobilizing all actors involved in the Tunisian agricultural sector. To do so, multiple channels may be used such as electronic and print media outlets, short documentaries, promotion in agricultural salons, poster promotion in multiple economic and agricultural conferences and raising awareness through governmental and non-governmental outlets.<\/span> It is worth noting that a couple of press publications (<\/span>Univers News<\/span><\/a> and <\/span>African Manager<\/span><\/a>) have already shared news of El B\u00e9ji farm renewable desalination project and its objectives. However, more advertisement is needed to effectively market the project\u2019s idea to the public at large.\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/p>\n From a legal stand point, multiple questions arise regarding the environmental impact of this technology.\u00a0 The RO reject waters in particular are of central importance from a regulator\u2019s point of view on account of their high salinity. Also, the disposal and recycling of solar panels is not regulated in Tunisia as of data, which may cause issues down the road given the hazardous and high toxicity potential of expired panels (<\/span>Kwak et al 2020<\/span><\/a>). Such aspects must be considered before popularizing the technology across the country. <\/span><\/p>\n <\/p>\n Costs and benefits<\/b><\/p>\n El B\u00e9ji Farm renewable desalination project provides a blueprint for green and sustainable agriculture in an arid Mediterranean setting. The success of this project will also allow reducing the carbon footprint of the agricultural sector, which occupies fourth place in Tunisia and second place worldwide in terms of CO<\/span>2<\/span> emissions. In economic terms, this project required a significant initial investment of 301 500 TND (approximately 97\u00a0000 USD). These funds are used to purchase a full RO system with two storage basins (96\u00a0600 TND), photovoltaic panels with a nominal capacity of 13.5 KWc (45\u00a0500 TND) and greenhouse tunnels to cover 2 ha (159 400 TND). With a negligeable appraisal cost of 1840 DNT and approximately 1 third (34 %) of the upfront investment being subsidized by the APIA, the time to revenue is estimated at 4 years, given the average projected yearly revenue of 76\u00a0000 DNT (approximately 25\u00a0000 UD). Therefore, the 97\u00a0000 USD invested by the GIZ and the FIT through the APIA, is a reasonable cost for promoting climate-friendly prosperity.\u00a0<\/span><\/p>\n In fact, Tunisia is one of the most vulnerable countries to climate change, which requires a national-scale strategy for adapting to the current dry climate trend. Consequently, the increasing affordability of solar photovoltaic units will help to meet the energy demand of small desalination units. In fact, the flexibility offered by the latter solution is a significant advantage compared to big centralized desalination plants that require a couple of years to build, only to stay operational for a decade or two at maximum.\u00a0 Moreover, the adoption of this technology can help democratize water desalination through providing a flexible free-market solution to respond to the increasing demand on non-conventional water resources. <\/span><\/p>\n <\/p>\n Implementation time and lifetime<\/b><\/p>\n The final results of the feasibility analyses were communicated in December 2019 while the operation of the desalination unit began in June 2022. This accounts for a one-and-a-half-year period from conceptualization to inauguration. Considering the typical 25 to 40 years useful life of photovoltaic solar panels and the 10 to 15 years lifespan for the RO system, a conservative estimation of the project\u2019s life duration without additional investment is set around 10 years.\u00a0 However, the main objective of promoting renewable technology to the wider agricultural community requires more time and may necessitate one to two additional decades.\u00a0<\/span><\/p>\n Given the above estimations and the average CO<\/span>2<\/span> emission factor of Tunisia (0.58 kg\/KW), and a ten-year operational period, the current project will eliminate 145 tons of projected CO<\/span>2<\/span> emissions by 2032 that would have been emitted through thermal electricity generation. Such results in a small 2 ha field inspire hope for the adoption of renewable agriculture practices in the Maghreb region. <\/span><\/p>\n <\/p>\n Keywords<\/b><\/p>\n Southern Tunisia, Renewable desalination, Photovoltaic panels, Reverse Osmosis, Sustainable agriculture, Climate change adaptation. <\/span><\/p>\n <\/p>\n Contacts<\/b><\/p>\n Mr Amin Chtioui (<\/span>amin.chtioui@giz.de<\/span><\/a>), Head of the project \u2018Renforcement du March\u00e9 Solaire (RMS)\u2019.<\/span><\/p>\n GIZ-Bureau Tunisie – Rue Le Grand Boulevard de la Corniche Immeuble le Grand Boulevard Cit\u00e9 les Pins, 1053 Berges du Lac II de Tunis\u00a0; +216 71 967-220\u00a0; +216 71 967-227<\/span><\/p>\n giz-tunesien@giz.de<\/span><\/a>\u00a0<\/span><\/p>\n We are thankful to Ali Bounab who helped with the preparation of this case study.<\/span><\/i><\/p>\n <\/p>\n Map<\/b><\/p>\n <\/p>\n Pictures<\/b><\/p>\n Functional scheme of the Reverse Osmisis desalination unit in El B\u00e9ji farm<\/b><\/p>\n This sketch\/scheme explains in detail how the desalination station operates and provides relevant technical specifications to facilitate replication elsewhere.\u00a0\u00a0\u00a0<\/span><\/p>\n Source: <\/span>Gesellschaft f\u00fcr Internationale Zusammenarbeit<\/span><\/a>, 2019. Roundtable session<\/span><\/p>\n <\/p>\n Cash flow forecast chart for El B\u00e9ji farm project\u00a0<\/b><\/p>\n This histogram helps promote the project\u2019s idea to investors through providing an insight into its cash flow forecast given stable market conditions as well as its projected time to profit.\u00a0\u00a0<\/span><\/p>\n\n
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