Abstract
In arid regions, agricultural production is critically challenged by water scarcity, elevated temperatures, and high resource dependency. This study assesses an integrated water-energy-food (WEF) nexus approach tailored for small-scale farming to optimize resource use through innovative combinations of open-field, greenhouse, and agrivoltaic systems. Comparing typical farming practices (base case) with a WEF-enhanced scenario, we measured water and power consumption, crop yield, economic returns across three seasons, and conducted a comprehensive cost-benefit analysis. The WEF scenario demonstrated a 5.4% reduction in water use due to efficient irrigation techniques and produced all required power from solar energy. Crop production and profits were higher under the WEF scenario, in which the net profit per unit area was $1.1 greater. The utilization of a reverse osmosis desalination unit was pivotal in reducing water costs and enhancing economic viability. Notably, the study highlighted significant CO2 emission reductions with the WEF approach, underscoring its potential in climate change mitigation. By maximizing land use, diversifying crop types, and extending growing periods, the WEF nexus approach presents a viable solution for enhancing sustainability, profitability, and resource security in arid environments. This research offers crucial insights for stakeholders in optimizing agricultural production within the constraints of water and energy resources.
Keywords
Introduction
The Gulf Cooperation Council (GCC) member states face unique challenges due to their hot and dry summers, limited rainfall levels, high evapotranspiration rates, infertile soils, and limited groundwater resources with low annual recharge rates. Despite having one of the world’s lowest per capita freshwater values, the GCC is among the highest consumers of domestic water and energy and produces high CO2 emissions (World Bank, 2020). The GCC members rely mainly on their considerable reserves of oil and natural gas for their economic development and water desalinization (Alhajeri et al., 2018). However, several environmental and economic challenges occur due to fluctuations in oil and natural gas prices and the increasing demands for energy (Woertz, 2013).
The food demand in the GCC countries is met through imports, as groundwater resources are overexploited, with limited annual renewable groundwater, where the amount of the annual renewable groundwater is less than 500 m3/capita (Sherif et al., 2023). This is far less than the recognized water-scarcity threshold of 1,000 m3/capita-year (Abdolali et al., 2017). Hence, desalination of sea and brackish water is the primary source of potable water (Siddiqi & Anadon, 2011) but entails an energy- and cost-intensive process (Al-Fadhli et al., 2022, 2023; Wittholz et al., 2008), resulting in significant pollutant and greenhouse gas emissions (Alhajeri et al., 2022).
Kuwait, a GCC country, faces water scarcity and relies on desalination facilities to meet its freshwater demands. Brackish groundwater, with an average salinity level of 7,000 mg/L, is used for irrigation (Mukhopadhyay & Akber, 2018). Considering alternative sources of irrigation water, such as treated wastewater and desalinated brackish groundwater, the use of small-scale RO units has been explored in various countries, including the GCC region (Alotaibi et al., 2023; Burn et al., 2015; Zarzo et al., 2013). Small-scale desalination technology is an attractive option for sustaining agriculture, especially in arid environments, because it provides quality irrigation water throughout the year, regardless of the quality of the intake water. However, small-scale desalination technologies for agriculture face economic and environmental constraints, including high costs and increased salinity levels in groundwater (Burn et al., 2015; Molina, 2015). As elaborated by Burn et al. (2015), despite the advancements in desalination technology and membrane efficiency, the use of technology in the agricultural sector is still an expensive option. Moreover, the environmental impact of inland desalination is problematic because inland water is rejected when it exhibits a salinity level that is approximately three times that of the intake water. Most farmers return water (brine) to aquifers through deep injection via old wells or infiltration through prepared soil pits (Molina, 2015). This adds an extra cost to the environment because the groundwater salinity increases over time, and thus, the desalination costs increase.
In addition to water scarcity, GCC countries face challenges in achieving food security through conventional agriculture due to climatic and water availability constraints (Moussa et al., 2025). This has resulted in a shift toward food imports, which has raised concerns regarding water-energy-food (WEF) nexus trade-offs and cobenefits in countries with unsustainable groundwater resources (Dalin et al., 2017). Thus, understanding the WEF nexus is crucial, particularly in arid environments where these resources are scarce and vulnerable to crises (Ahmed et al., 2019). The concept of the WEF nexus has received little attention in the GCC region (Allan et al., 2015), probably due to the abundance of inexpensive energy (i.e. oil and natural gas), which obscures any shortage of other resources (Siderius et al., 2020).
Agrivoltaics, also known as solar sharing or dual land use, involves combining agricultural production with solar energy generation in the same plot. It encompasses the installation of photovoltaic (PV) panels above agricultural fields or their integration into greenhouse structures, allowing simultaneous crop cultivation and solar energy production. To integrate agrivoltaics into the WEF nexus model, it is necessary to assess the interactions and trade-offs between water, energy, and food systems. This involves evaluating the water requirements for crops in agrivoltaic systems, analyzing energy production and consumption related to solar panels, and assessing the economic viability of the integrated system. Furthermore, comprehensive assessments should consider environmental impacts such as carbon emissions and land-use changes.
Numerous studies have been conducted using modifications and with the application of energy and food (EF) in agricultural practices such as open-field, greenhouse, and agrivoltaic farming practices. Several studies (Allardyce et al., 2017; Hassanien et al., 2016; Roslan et al., 2018; Saleh et al., 2015; Vlontzos & Pardalos, 2017; Yano & Cossu, 2019; Weselek et al., 2021; Campana et al., 2021; Dinesh & Pearce, 2016; Gonocruz et al., 2022; Katsikogiannis et al., 2022; Kumpanalaisatit et al., 2022) have focused on combining solar energy with green houses to meet the energy requirements of greenhouse farming. Empirical and modeling studies indicate that agrivoltaics can moderate microclimate, lower irrigation demand, and increase combined food–energy output per unit land area—key WEF co-benefits relevant to this pilot (Barron-Gafford et al., 2019; Dinesh & Pearce, 2016). Modeling work shows that agrivoltaic shading can lower irrigation requirements with acceptable trade-offs in yield or crop cycle length (Elamri et al., 2018). Field evidence from a 2-year trial reports moderated microclimate and modest yield changes under AV for several crops, alongside gains in combined land productivity when energy is considered (Weselek et al., 2021). Very few studies exist that involve the combination of three farming practices, in situ desalination units and solar power utilization.
This study aimed to assess the environmental feasibility and economic viability of small-scale solar-powered reverse osmosis (RO) desalination for providing irrigation water at the farm level. Three agricultural practices, namely, open-field, greenhouse, and agrivoltaic methods, were compared to evaluate their net economic returns. These three agricultural practices were subsequently integrated and used as a model for the WEF nexus. The RO unit was powered by agrivoltaic solar panels and used to desalinate brackish groundwater, providing quality irrigation water for six major crops in different field plots. An economic analysis was conducted based on crop yields; water, energy, and input costs; and carbon emissions. The cost‒benefit analysis considered market prices for water and energy, among other factors. Detailed monitoring and recording of inputs (water, fertilizer, energy, and initial costs) and outputs (crop yields and carbon emissions) were conducted to support the cost‒benefit analysis. By quantifying the cobenefits and trade-offs of agrivoltaics within the WEF nexus, policy-makers and stakeholders can make informed decisions regarding resource management, energy production, and agricultural practices in arid environments. To summarize, this study’s objective is to evaluate, at farm scale, whether an on-farm RO + PV integrated WEF configuration (Scenario 2: Integrated WEF) can meet on-site water/energy demand and improve profit per m² relative to a sequential practice that uses one system per season (Scenario 1: Sequential)
This work is a field-scale pilot case study that evaluates the operational feasibility of integrating on-farm reverse osmosis desalination (RO) and solar photovoltaic (PV) supply with concurrent open-field, agrivoltaic, and greenhouse cultivation. The findings are reported as site-specific operational evidence, rather than as results from a replicated agronomic experiment or a comprehensive life-cycle/investment appraisal.
Methodology
This research was conducted on a farm located in the Wafra agricultural district southeast of Kuwait (28°30′ N, 48°10′ E). The study area represents an arid region characterized by predominantly calcareous loamy sand soil with a poor structure and low fertility levels. Soil and fertilizer samples were collected and analyzed for various parameters, including pH, specific conductance, total phosphorus (TP), total suspended solids (TSSs), and heavy metals. The soil and fertilizer analysis results indicated deficiencies in essential macro- and micronutrients required for optimal plant growth. As a result, additional plant nutrients must be supplemented at additional costs to maintain plant health and achieve optimum yield levels. Figure 1 shows the analysis of pure soil, fertilizer, and mixture of soil and fertilizer.
Chemical analysis of the soil and fertilizer in the field of the study.
System Design and Experimental Setup
The various farming methods used in this analysis were established as described below. Field observations spanned September 2022–August 2023, encompassing three cropping seasons: autumn (Season 1), spring (Season 2), and summer (Season 3).
Open-Field Farming (OF)
Open-field farming represents the conventional farming method implemented in an open environment without controlled parameters such as heating or cooling. Figure 2 shows the open farming system employing drip irrigation (Alhajeri et al., 2024). Crops are planted in different rows, and natural sunlight is utilized for crop growth. The growth rate of crops primarily depends on water consumption, nutrient availability (fertilizers), and sunlight, which vary according to the season.
Open-field farming.
Agrivoltaic Farming (AV)
Agrivoltaics maximize the land use efficiency by utilizing the same area for energy generation and agricultural production, which is particularly advantageous in arid regions where the land availability is limited (Jain et al., 2021). Additionally, the shading effect of solar panels in agrivoltaic systems reduces soil evaporation and water loss, potentially leading to water savings in agricultural irrigation in arid regions. Additionally, agrivoltaics can provide partial shading by solar panels that helps moderate extreme temperatures, alleviates water stress on plants, and creates a favorable microclimate, ultimately enhancing crop yields and quality.
Agrivoltaic farming is implemented in an open environment shaded by solar panels, as shown in Figure 3 (in which PV panels are installed above the field; Alhajeri et al., 2024). Solar panels provide shade, reducing the temperature for crops relative to open-field farming. The water requirement for crops depends on the amount of sunlight received through the panels. Solar panels generate solar energy, which is stored in batteries and used for satisfying the energy requirements such as water pumping and operation of air-conditioning systems in greenhouse farming. Average daily energy needs were met from on-site PV during the study period; however, when accounting for inverter and storage losses and gradual PV degradation, multi-day low-irradiance events can result in temporary shortfalls.
Agrivoltaic irrigation system.
Greenhouse Farming (GH)
A greenhouse system is an effective method for growing certain agricultural plants that cannot thrive in open fields under high temperatures (Hassan et al., 2022). Greenhouses regulate the light intensity, air temperature, moisture levels, and water consumption, creating optimal conditions for year-round plant growth. Typically, greenhouses are covered with materials such as glass or plastic that transmit light, which is essential for plant development and production (Saleh et al., 2015). However, greenhouse farming is energy intensive due to the use of air-conditioning systems for maintaining the required controlled temperature. Greenhouses provide a controlled environment that improves the yield conditions, increasing productivity by 10% to 20% (De Gelder et al., 2018). This type of farming is conducted in a closed environment with controlled temperatures using air-conditioning systems, as shown in Figure 4 (Alhajeri et al., 2024). Crops are planted in different rows, and drip irrigation is used. The water requirements for irrigation are lower due to the controlled environment. However, more water is consumed by the air-conditioning and temperature control systems.
Greenhouse irrigation system.
WEF nexus analysis of the farming systems was conducted including desalinated groundwater produced by small RO units, crop production with the three farming methods (OF, AV, and GH), and energy requirements for farming with renewable sources (solar panels of the AV method). To this end, three separate agricultural systems of 80 m2 each (5 m × 16 m) were developed. The same types of crops, including tomato, cauliflower, corn, cabbage, eggplant, broccoli, and strawberry, were planted in all three farming areas. Drip irrigation systems were used due to their efficiency. Groundwater was pumped and desalinated using a reverse osmosis unit with a capacity of 30,000 gal per day. The desalinated water was then distributed to three storage tanks and pumped into the farming areas according to the irrigation requirements of each field.
Irrigation Scheme and Cropping System
The field study was conducted over a year and covered three cropping seasons: autumn (season 1), spring (season 2), and summer (season 3). During the autumn season, the crops were planted on October 10, 2021, and harvested on January 10, 2022. The spring season included a planting date of March 1 and a harvest date of June 1, 2022. The summer season ranged from June to September. Each cropping season involved the cultivation of six crops (broccoli, corn, cabbage, tomato, eggplant, and strawberry) in individual areas with a 40 cm spacing between seedlings (Figures 2–4). Data on cropping patterns, irrigation frequency and depth, and planting and harvest dates were obtained from the records of the Department of Agriculture of Kuwait. All plots received the same amount of fertilizer and underwent similar maintenance procedures.
In this study, the following two scenarios were analyzed: (i) base case scenario and (ii) WEF scenario. The base case scenario reflects the farming practices commonly employed by farmers in arid regions. Open-field farming was performed during the first season (autumn), followed by greenhouse farming during the second season (spring) and third season (summer). Open-field farming is preferable during the first season due to its lower water and electricity consumption levels and moderate air temperatures during the autumn season relative to greenhouse farming, which is better suited for the subsequent seasons when the weather conditions necessitate temperature control due to the high ambient temperature. Under this scenario, the water and electricity consumed were sourced from the utility and grid according to government-set prices.
In contrast, the WEF scenario represents the integration of the open-field, greenhouse, and agrivoltaic farming methods. This approach combines open-field, agrivoltaic (farming under the shade of installed solar panels), and greenhouse farming practices during each season to evaluate the benefits and trade-offs compared to those of conventional farming methods (base case). Table 1 provides the criteria for each scenario in terms of the farming methods for each season.
Base Case and WEF Scenarios With the Various Farming Methods.
In the WEF case, nine lines of drip irrigation were installed in each area, with drippers placed 40 cm apart. Each area has an equal farming area of 80 m2.
Area 1 represents open-field conditions. Area 2 is an open field with agricultural practices implemented under the shade of installed solar panels (agrivoltaics). Area 3 represents an air-conditioned (AC) greenhouse.
Brackish groundwater was desalinated using a small-scale reverse osmosis unit with a capacity of 114 m3/day and a power requirement of 3.5 kWh. The energy needed to operate the RO desalination unit, AC units, and irrigation pumps was generated by the installed solar panels in the AV method. Solar-generated energy was stored using deep-cycle batteries.
The brackish water had a total dissolved salt (TDS) concentration of 7,000 mg/l, which was reduced to 270 to 300 mg/L after treatment. The desalinated water was stored in tanks for use in irrigation, cooling pads for the AC units, and cleaning of the solar panels. The overall system flows are depicted in Figure 5, which shows PV/inverter/battery supplying the RO high-pressure pump, irrigation pumps, and greenhouse ventilation, and RO permeate feeding irrigation to the OF, AV, and GH plots.
RO unit and schematic representation of the WEF.
During each cropping season, the initial irrigation cycle lasted 1 week and consisted of two irrigation sessions per day, with each session lasting 10 min, at an average irrigation rate of 2 L per hr (2 L/hr). Thus, the total water amount per crop per day was 0.67 L per day (or 4.7 L/week). Subsequently, the irrigation duration in weeks 2, 3, and 4 was increased to 20, 25, and 30 min, respectively, while the same irrigation rate was maintained as that in week 1. The irrigation timing remained constant at 25 min for the remainder of the cropping season, with two irrigation sessions per day. There were no significant rainfall events during the two seasons. The irrigation water used was desalinated water obtained from the small RO unit at the farm.
For benchmarking, the study reports a continuous 24/7 RO case as an upper-bound production scenario. In practice, RO dispatch is site-specific and will typically be solar-aligned with storage constraints and irrigation scheduling.
Parameters and Cost Analysis
To compare the two scenarios, multiple parameters were measured and recorded on hourly and daily bases throughout the whole season. These parameters included the temperature, irrigation water, water consumption for air-conditioning systems, and cleaning of solar panels (applicable to the WEF (AV) case). Additionally, the electricity consumption for the air-conditioning systems, water pumps, and RO unit was recorded.
To calculate the greenhouse gas (GHG) emissions for each farming method, the energy consumption was determined and multiplied by the corresponding emission factor. The emission factors used in this study were obtained from Al-Fadhli et al. (2023) and represent the carbon footprint per unit of electric energy produced, as listed in Table 2. The study does not perform a full LCA (e.g. embodied impacts, allocation decisions); emissions results are limited to operational values.
GHG Emission Factors.
A comprehensive cost‒benefit analysis was conducted for each cropping season and the combined seasons for both scenarios. The analysis considered all associated costs and returns involved in this study. The fixed investment costs encompassed expenses such as the costs of the RO desalination unit, photovoltaic panels, batteries, pumps, greenhouse systems, water meters, AC units, and drip irrigation systems. The operation costs included the costs of labor, seeds, fertilizer, maintenance, water and electricity for irrigation, AC cooling, and panel cleaning.
Economic returns were determined based on the crop yields and average crop sales price on the Kuwaiti market. A detailed breakdown of all the costs for each cropping season and for both scenarios is provided in Table 3.
Cost Breakdown of the Field Study.
The RO unit was operated for 3 hr per day throughout the three cropping seasons to produce desalinated water. However, the price of water was very high compared to the economic returns of the crops. This was expected due to the short duration of operation at the farm relative to the initial investment cost and size of the RO unit. As a result, an alternative scenario was explored, assuming 24-hr operation of the RO unit throughout the entire year, aiming to reduce the desalination costs. The cost‒benefit analysis was conducted using the computed water prices for both scenarios, considering each season individually and the combination of the two seasons. A discount rate of 10% and a lifetime of 10 years for the RO unit and 3 years for its membrane were assumed during the analysis. All computations were performed using the MS Excel package.
Overall, the cost‒benefit analysis considered various factors and costs associated with this study, allowing for comprehensive evaluation of the economic feasibility and potential returns of the different scenarios.
Results and Discussion
Water and Power Consumption Levels
The water and power consumption levels for scenario 1 (base case) and scenario 2 (WEF) are provided in Tables 4 and 5, respectively. In all farming practices, most of the water was utilized for irrigation purposes. Additional water was required for the operation of the AC systems in the greenhouse and for cleaning the PV panels used in AV farming.
Water Consumption for Scenarios 1 and 2.
Power Consumption for Scenarios 1 and 2.
As indicated in Table 3, more water is needed to clean the PV panels during seasons 2 and 3 in the WEF case due to the higher dust accumulation during these seasons. The total amount of water consumed in the base case is 5.4% greater than that in the WEF case (the water consumption is 9,330 gal lower in the WEF case than in the base case). This is mainly due to the large amount of water consumed by the air-conditioning systems during seasons 2 and 3 under the base case scenario, even though more water is needed for the irrigation requirements under the WEF scenario than under the base case scenario (approximately 14.4%).
This approach results in a significant reduction in the total water consumption, which could benefit farmers during drought seasons. The main reason for the high water consumption in the base case was that the entire cultivation was performed in greenhouses during two seasons (seasons 2 and 3), which required additional water for the air-conditioning systems. Note that additional water was needed under scenario 2 due to the need for water to clean the PV panels used in agrivoltaic farming. In general, the integrated WEF system reduced the water consumption compared to that in the base case during each individual season and overall. However, the percentage of the total water usage attributed to irrigation was lower in the base case than in the WEF case. This indicates that the overall WEF system was more water efficient in terms of the total water requirements for agricultural practices.
Power was needed to operate the greenhouse AC systems and the RO unit, and pumps were needed for the water supply. During season 1 in the base case, the power requirement was only for the pumps, as only OF farming was employed. Table 5 indicates that the power consumption due to AC system use was higher under scenario 1 than under the other scenarios because the entire farming process was performed in greenhouses during seasons 2 and 3. Additional power consumption was observed due to operation of the RO unit under scenario 2 for the desalination of brackish ground water. The total power consumption was 698 kWh higher in the WEF case than in the base case. This occurs because the RO unit in the WEF system consumes additional power for the supply of water.
Table 6 indicates that the water consumption per unit area is 38.9 gal less in the WEF case (scenario 2) than in the base case. The total water consumption for the 50,000 m2 farm is 1,943,750 gal lower in the WEF case than in the base case. This represents major water savings, especially in areas with limited water resources, such as arid regions. The power consumption per unit area is 2.9 kWh higher in the WEF case than in the base case. However, the overall energy savings resulting from water reduction may still outweigh the additional power consumption. The total power consumption for a 50,000 m2 farm is 145,378 kWh greater in the WEF case than in the base case. This is a significant increase in power consumption, but it is still lower than the total energy produced by the solar panels.
Comparison of the Water and Power Requirements Between Scenarios 1 and 2.
The results also demonstrated significant variations in GHG emissions among the three farming methods. The WEF scenario resulted in the lowest emissions, with 363 kg of CO2 emitted annually. In contrast, the base case farming scenario contributed considerably more to the GHG emissions, with a total of 2,892 kg of CO2 emitted per year.
The differences in emissions could be attributed to the energy sources utilized in each farming method. The base case scenario relies on traditional power sources, which results in higher CO2 emissions. In contrast, the WEF scenario, which incorporates agrivoltaic farming by integrating solar panels into agricultural practices, reduces the dependence on conventional power sources and has the potential to generate surplus energy, leading to lower GHG emissions.
PV configuration (panel tilt, height, row spacing, and transmittance) is crop- and site-specific; while this study reports observed performance under the installed layout here, crop-specific optimization will be examined in a dedicated follow-on study.
Crop Yield and Economic Returns
The crop yield in terms of the mass of crops grown under both scenarios during the 3 seasons was estimated. The selling price of each crop was considered per kg of crop grown, and the total estimated price was calculated for each crop. Table 7 shows the total production rates for each scenario during the three seasons, in addition to the difference between the two cases. The total highest production rate is observed under scenario 1 with only the OF and GH farming methods, which may be due to the highest production rate during season 1. Hence, the economic returns for scenario 1 were greater than those for scenario 2. The overall economic returns of open-field farming during season 1 were 16.4% and 23% greater than those of agrivoltaic and greenhouse farming, respectively.
Crop Yield and Profits for Scenarios 1 and 2.
Table 8 provides the crop yields and the respective economic returns for the three cropping seasons for all the fields under scenario 2. Under scenario 2, for the autumn cropping season (season 1), for example, open-field farming exhibited the highest total crop yield (321.2 kg) relative to agrivoltaic (268.7 kg) and greenhouse farming (216.9 kg). The yield of greenhouse farming was approximately 32% less than that of open-field farming. The higher yields of the OF and AV fields probably occur because they experienced more favorable weather conditions in terms of optimum temperatures, solar radiation, and wind dynamics during season 1. Agrivoltaic farming also involves an open field, but the exposure of agricultural areas to solar radiation due to the panels is spatiotemporally variable during the day, which is likely the reason for the lower yield in these areas than in the open field areas. Apparently, the greenhouse experienced the least favorable weather-related conditions during the mild winter season.
Crop Yield and Economic Returns in the WEF Case for Seasons 1, 2 and 3.
Eggplant, cabbage, and tomato yielded the highest economic returns among all the crops and across all the fields, as indicated in Table 7. This indicates that open-field agriculture is probably more profitable than the other two systems during the autumn season in Kuwait because of the availability of good quality irrigation water. Moreover, it requires minimal maintenance effort and energy. In terms of the crop type and yield, strawberry and broccoli exhibited the highest returns per unit mass (kg) in the local market for seasons 1 and 2. This indicates the importance of crop selection by farmers to maximize the returns to offset the high costs of desalinated water.
Regarding cropping during season 2, because of the unfavorable climatic conditions (the average temperature was approximately 40°C), only corn and eggplant survived in the open field. The agrivoltaic field performed better in terms of the number of grown crops, where only strawberry and cabbage did not survive. However, both fields (OF and AV) produced very low yields relative to the air-conditioned greenhouse. All the fields had lower yields and economic returns than those during the autumn cropping season. Obviously, climatic conditions were the limiting factor where protected agriculture is the only option under such harsh conditions. Even though the AC units were operated for 24 hr a day, the yield of the greenhouse was slightly lower than that during season 1.
Regarding cropping during season 3 (the summer season), only eggplant was grown within the entire farming area. This is due to the harsh climatic conditions and high temperatures, which do not provide favorable conditions for the growth of other crops. Hence, the entire farming area was utilized for growing eggplant.
The energy used for operating the AC units was generated by the solar panels. Protected agriculture in hot, dry environments requires excessive amounts of energy for cooling, which renders it an expensive option in arid regions. It is likely that importing agricultural products is more feasible for the GCC countries than extending the cropping season during the summertime. Moreover, this can reduce the stress on already depleted groundwater reservoirs. Extending the growing season in Kuwait would increase the salinity level of brackish water. However, this would come at a cost, which reduces the food security options.
Figure 6 shows a comparison of the economic returns of selling the crops of the 3 farming fields with respect to the season for scenario 2. The open and agrivoltaic fields performed relatively well during season 1 relative to season 2. The shade from the solar panels obviously allowed enhanced vegetative growth, which yielded slightly better returns than the open field (approximately 15.6%) during season 2.
Economic returns for the various farming methods with respect to the season under scenario 2.
Farmers in Kuwait should continue open-field agriculture in autumn and avoid it, except for animal fodder and date palms, during the summer cropping season. Agriculture in protected environments extends the growing season for seasons 2 and 3, which results in an increase in the irrigation water demand and places higher pressure on groundwater and energy resources. It should be noted that more irrigation water is needed in summer to compensate for the high evapotranspiration rates, that is, high crop water requirements. Crop diversification is also an option for increasing the economic returns during more favorable growing periods.
Economics of RO for Desalinated Water
The capacity of the RO unit is approximately 30,000 gallons/day, and its power requirement is 3.5 kWh. The desalination unit was operated for approximately 3 hr per day during the growing season to provide quality water for irrigation, AC systems in the greenhouse, and cleaning of the solar panels. This suggests that the unit produces approximately 3,700 gal per day during the growing season. Assuming that the lifetime of the unit is 10 years (if well maintained), the discount rate is 10%, and the net present value is zero, the price of desalinated water is US$ 0.008/gallons (approximately US$ 2.1/m3). This price is relatively high, especially when water is exclusively used for irrigation and low-return crops are grown.
The above price is comparable to that of water for the public in Kuwait (approximately US$ 2.0/m3), which indicates that desalinated water obtained from the public network is a more affordable option for farmers in this case. This value for water is expected because desalination technology is still considered an expensive option for agricultural purposes (Burn et al., 2015). Moreover, the unit is small and operated for a short period. Full utilization of the unit reduces the cost of produced water with respect to the initial investment cost. Therefore, the entire year was fully utilized by the unit. Even though this scenario seems nonrealistic, it provides insights into how to maximize the economic returns of grown crops irrigated with expensive desalinated water. Following the same assumptions, the price of water was reduced to US$ 0.0037/gallons (US$ 0.95/m3), which is obviously much lower than the current price of irrigation water. However, agriculture is still more expensive than that in other parts of the world. For example, the cost of desalination for agriculture in Spain, the world leader regarding this business, is approximately US$ 0.4/m3 (Jabri et al., 2019). Farmers in Spain use a central medium-sized RO desalination plant to irrigate the whole community in the region. The cost of desalination in Spain is further reduced by blending desalinated water with other sources of water, such as collected rainwater, flood water, and irrigation-return water. The plant is operated during low-tariff time slots to further reduce the desalination costs. Compliant brine management is essential and, as it lies beyond the scope of this pilot, it will be addressed in detail in a dedicated future study.
Water-Energy-Food Scenario Economic Analysis
Table 8 provides the water and power costs for scenarios 1 and 2. Scenario 1 has a higher water cost for irrigation, while scenario 2 has no water cost since the needed water is produced by the RO unit. Since all the power needed by the farming system is provided by the PV panels used in agrivoltaic farming, the power cost for pumps and AC systems under scenario 2 is 0. As a result, no electricity is bought from the power grid for farming.
Table 8 also shows an overall comparison of various factors for scenarios 1 and 2. The net profit for each scenario was calculated based on the overall fixed capital cost and overall operating and maintenance costs. The cost‒benefit analysis involved all associated costs and returns in this study. The analysis was conducted for each cropping season and for the combined seasons to estimate the costs/benefits for the entire year. The costs included the investment costs of the reverse osmosis (RO) desalination unit, photovoltaic panels, batteries, pumps, water meters, AC units, and drip irrigation systems for the three plots. The operation costs included labor, seed, maintenance, fertilizer and cleaning costs. The economic returns or sales prices of crops were determined from the crop yields and the average price of each crop in the Kuwaiti market.
The overall capital cost for scenario 2 is high due to the additional installation cost of PV panels and the RO unit. The sales cost of crops is high for scenario 1, where a larger number of crops are grown in the controlled environment of the greenhouse during seasons 1 and 2. However, the overall profit is high for scenario 2 due to the integration of agrivoltaic farming with the other two farming methods, which satisfies all the power requirements of the PV panels of AV farming without purchasing any power from the grid.
Under scenarios 1 and 2, the net profits per unit area are 5.0 and 6.1 USD, respectively. Therefore, a difference of 1.1$/m2 could significantly impact the farming profits across large areas. Farming with an integrated system of renewable energy and a solar-powered desalination unit could be more efficient than existing farming methods in arid regions.
As indicated in Table 9, the net profit under scenario 2 with WEF nexus application is $269 higher than that under scenario 1 (base case). This occurs because of the combination of water and power savings under scenario 2. The total net profit for a 50,000 m2 farm is $56,000 greater in the WEF case than in the base case. This leads to a significant increase in profit, which could make agrivoltaics a more attractive option for farmers.
Overall Comparison of Various Factors for Scenarios 1 and 2.
The above analysis explored the economic feasibility of desalination for agriculture in the arid environments of the GCC countries. It is likely that 1 year of field work is insufficient to fully evaluate the economic aspects of this subject, but it provides insights into the water-energy-food nexus. The economic aspects of small-scale desalination for agriculture could be improved if desalinated water is not used exclusively for irrigation but rather blended with regular groundwater and other sources of water, such as treated wastewater, to reduce the desalination costs. Farmers should grow crops with high economic returns in conjunction with the use of renewable energy and water recycling technologies such as hydroponic systems. The Spanish experience follows a cooperative approach, where farmers use a central, medium-size desalination plant with a high recovery rate (i.e. small amount of rejected water) and more efficient utilization of the available energy resources (Jabri et al., 2019). Moreover, farmers establish crop types and production rates to maximize the economic returns based on the available water resources in the region. Through their well-established cooperative societies, highly skilled farmers manage marketing chains for their products across Europe and the world to add more value to their consumed water from desalination plants.
Conclusion
In this study, the water-energy-food nexus for small-scale agricultural practices in Kuwait Province was evaluated using two scenarios: a base case based on current practices and a proposed WEF scenario integrating open-field, greenhouse, and agrivoltaic farming methods. The main findings indicated that the WEF scenario provides both economic and environmental benefits compared to conventional practices.
The total water consumption was slightly lower under the WEF scenario (by 5.4%), even though the irrigation requirements alone were lower by nearly 14% under the base case scenario. This represents a significant potential water savings, which is highly valuable in arid regions with limited water resources. The power consumption was also higher under the WEF scenario when operating the RO desalination unit and satisfying the energy needs. However, all power was generated by agrivoltaic solar panels, with no purchases from the grid. From an economic perspective, the WEF scenario resulted in $269 higher overall profits than those in the base case. On a per unit area basis, the net profits were $1.1 higher under the WEF scenario. Extrapolated across a 50,000 m2 farm, this difference could amount to more than $56,000 in additional annual profits. Moreover, while the water desalination costs remained relatively high, full utilization of the RO unit helped reduce the costs, improving the economic viability. Adoption feasibility is influenced by local electricity/water tariffs, input and crop prices, and subsidy structures; we briefly note this context here and will address it in greater depth in a dedicated follow-on study.
The integrated WEF approach could also help diversify crops and extend the growing season. While the yields varied with the farming methods and seasons, the returns were maximized through crop selection. The shading provided by the agrivoltaics panels, in particular, enhanced the yields during hot seasons relative to open fields.
It should be noted that under scenario 2, farmers would incur high environmental costs resulting from the disposal of large amounts of rejected water of extreme salinity from in situ RO units on farms that are too far from the sea. The arid environment of the GCC countries poses many environmental challenges to sustain agriculture in the region, such as high evapotranspiration rates, nonuniform distributions of water resources, and deterioration in the groundwater quality. Therefore, proper management of alternative sources of water based on environmental and economic aspects should be a priority for all concerned stakeholders in the region.
In conclusion, the WEF scenario provides a more sustainable model for agricultural practices given the arid climate in Kuwait through optimized resource use. With further refinements to reduce desalination costs, an integrated small-scale approach shows high potential to improve both farm profits and water-energy security in the long run. The findings provide valuable insights for stakeholders on enhancing food and water security through renewable energy and nexus-based solutions.
This single-site study used one plot per configuration; therefore, results should not be interpreted as statistically replicated nor generalized without caution. Outcomes reflect local conditions and may be influenced by soil heterogeneity, microclimate, and edge effects that were not controlled within this pilot. Confirmatory evidence should come from larger, replicated trials and/or modeling studies that explicitly address these sources of variability.
Footnotes
Author Contributions
[F.A.]: Conceptualization, Methodology, Supervision; [N.A.]: Conceptualization; Investigation, Data curation; Methodology, Resources, Project administration [M.G.]: Formal analysis, Visualization; [S.A.]: Conceptualization; [M.E.]: Methodology, Supervision; [All authors]: Writing—review & editing, and final approval of the manuscript.
Funding
The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The authors would like to thank Kuwait Foundation for the Advancement of Sciences (KFAS) for their funding of this work under project code: CN19-35EM-05. The authors would like to thank the facilities of the National Unit for Environmental Research and Services (NUERS) at Kuwait University for analyzing the samples.
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.