The decarbonization of essential water supply infrastructure is a critical challenge for water-stressed and geographically constrained regions, particularly islands where both water and electricity systems are highly dependent on external or fossil-based resources. In Northern Cyprus, approximately 70% of domestic water demand is met through imported water via pipeline, while electricity generation relies predominantly on fuel oil, resulting in high greenhouse gas emissions and environmental burden. This study evaluates an integrated renewable energy-based supply system using a medium-scale concentrating solar power (CSP) plant with parabolic trough collectors coupled to thermal desalination. The proposed configuration is assessed as an alternative energy-driven infrastructure option for reducing dependence on imported water and fossil-based electricity. System performance was evaluated by estimating electricity and freshwater production under local climatic conditions, demonstrating that the proposed configuration can meet both the associated electrical energy requirements and domestic water demand in the selected region. A cradle-to-gate life cycle assessment (LCA) was conducted to quantify the environmental impacts of the integrated system and support sustainability-oriented decision-making. The LCA results identify residual fossil-based electricity, phosphoric acid consumption, and brine discharge as the main environmental hotspots. Overall, the findings show that CSP-driven desalination can provide a viable and more sustainable option for integrated energy and water supply in water-scarce coastal regions with high solar potential, highlighting its relevance for renewable energy integration, water-energy nexus planning, and resource-efficient infrastructure development.

DETECTIVE (Development of a novEl Tube-bundlE-CaviTy lInear receiVEr for CSP applications) is a project that aims at enhancing the overall performance of the current solar parabolic trough collectors. The proposed design focuses on improving such performance by substituting the traditional single metal absorber tube with a tubular bundle whose outer contour largely matches the outer circumference of the replaced tube. To assess the optical performance of the proposed receiver, a Monte Carlo ray tracing technique was employed by utilizing the SolTrace software. The effects of the two design parameters, such as cavity opening angle and cavity radius, on the overall optical behavior have been explored and the optimum design is determined with the maximum optical performance. The ray tracing data proved that the cavity-like space formed within the multi-tube arrangement results in a multi-reflection process between bundle tubes and could result in a higher ray absorption compared to the conventional design, leading to lower optical losses. The obtained numerical results indicated that an aperture angle of 60 degrees could provide the highest optical performance among the studied options. Considering the second parameter, the rise in the cavity radius is shown to increase the ray intersection inside the cavity, while the optical efficiency decreases. Finally, the most efficient design reaches an enhancement of 10% in optical efficiency if compared to the conventional PTC design.

Multi-Effect Distillation (MED) is a suitable solution for water desalination and brine concentration in a wide scale of applications. Its potential is even more relevant when they are powered by a variable energy source owing to its operational flexibility. This study introduces a comprehensive methodology for assessing the performance of MED processes, encompassing crucial aspects such as system configuration, instrumentation requirements, test procedure and evaluation criteria like performance metrics adequacy and uncertainty determination. The proposed methodology has been successfully implemented and validated at an experimental MED facility located at the Plataforma Solar de Almería (PSA, Spain). Through this research, valuable insights and guidelines are provided to achieve an accurate performance evaluation of MED systems in practical settings.

The pressing problems of water scarcity in many parts of the planet make water desalination one of the technological solutions for guaranteeing the fresh water supply. However, desalination processes require high energy consumption, mainly provided by fossil fuels. The integration of renewable energy sources into desalination processes is a promising option for decarbonizing the desalination sector. As most water-scarce regions with access to seawater frequently have high solar irradiation levels, it seems appropriate to exploit the sun to power the desalination process. This work presents the assessment of two integrated solar power and desalination systems regarding efficiency and water production. Two desalination processes (multi-effect distillation and reverse osmosis) are studied for potential coupling with the combined cycle of a central receiver solar plant to produce electricity and freshwater. In the case of the multi-effect distillation plant, it is integrated by replacing the Rankine cycle condenser of the combined cycle. In the case of the reverse osmosis plant, it is powered by the electricity generated from the combined cycle. For this comparison, the 21st of March has been considered as the design point and Almería (in the Southeast of Spain) as the plant location. The results show that the thermal cogeneration option renders a worse outcome (thermal efficiency of 50.2% for LT-MED case) than the decoupled generation of electricity and water (thermal efficiency of 53.3% for RO case), producing 18% less fresh water than the RO configuration (3831 m3/d vs. 4640 m3/d), due to the 6% penalty in the efficiency of the Rankine power cycle in the MED configuration as a result of increasing the condensation temperature from 42.6 °C to 70 °C.

Large market opportunities exist for solar powered Reverse Osmosis (RO) desalination technologies in fertile but arid areas with large solar and sea water resources. A challenge to realizing these markets is the variable nature of solar resources, which for the desalination plant can lead to high water costs due to low capacity factors (CF) and increased maintenance costs due to repeated start-ups and shut-downs. A potential solution is to power RO plants using both PV and CSP with Thermal Energy Storage (TES) with an aim to reduce shut-downs, and increase CF. In this study, three solar energy systems to power RO are considered: 1) PV only; 2) CSP with central receiver (CR) and TES; 3) PV and CSP with CR and TES. Two RO operational strategies are considered: 1) nominal load only; 2) variable load between minimal and nominal. The performance of these systems is simulated for Mersin, Turkey, using TMY data. The PV and CSP with TES system and variable RO operation achieved the levelized cost of water (LCOW) 1.92 USD m-3 with an RO CF of 60.8%.

There is interest for desalination technologies powered by solar energy as arid areas are typically bestowed with good solar potential. In response to a US DOE call for solar desalination analysis tools, we developed an open-source solar energy desalination analysis tool, sedat , for techno-economical evaluation of desalination technologies and selection of regions with the highest potential for using solar energy to power desalination plants. It is expected that this software will simplify the planning, design, and valuation of solar desalination systems in the U.S. and worldwide. Sedat uses Dash for integrating various layers of large volumes of GIS data with Python-based models of solar energy generation and desalination technologies. It derives time-series of energy generation and water production, with details of plant performance and suggestions for improving the solar-desalination coupling. This paper summarizes the various phases of the tool’s development, presents example results showing the potential, under multiple objectives, of solar desalination in parts of the U.S. southwest, and discusses method details that would be useful for future model development.

This work presents the dynamic modeling of a vertical multi-effect evaporator plant designed and manufactured for its installation at a commercial concentrating solar power (CSP) plant, within the framework of EU H2020 project SOLWARIS (Solving Water Issues for CSP plants). The model has been developed using Modelica computational language and implemented in Dymola® software environment. The results from the validation show a good agreement against the design data, obtaining relative errors lower than 5%. The dynamic response of the plant against external disturbances of the motive steam mass flow rate, feedwater mass flow rate and condenser pressure has been investigated. The main results reveal that increasing the motive steam flow rate by 5% produces a similar increment of the water recovered (5.2%), although the concentrate salinity is raised to an unsafe operation zone (106%) that could lead to scaling issues in the evaporators. The same effect occurs when the feedwater is decreased by 5% from its nominal value, causing a significant rise in the concentrate salinity (163%). In those cases, the simultaneous and proportional variation of the motive steam and feedwater mass flow rates allows maintaining the outlet concentrate salinity far from scale formation limits.

Since carbon-based fuels and freshwater sources are depleting rapidly, alternative renewable energy and water resources must be used for the growing world’s demand. In Northern Cyprus Island, about 70% of the water supply of the region comes from abroad via a pipeline, and the electricity is produced by burning fuel oil that places a high burden on the environment. As an alternative solution, a concentrating solar power plant using parabolic trough collectors coupled with desalination was designed for a selected area in the island for this study. Evaluation of the design was conducted by analyzing the performance by estimating the hourly thermal and electrical energy production and by LCA considering cradle to gate analysis. The results show that the proposed system could provide all the electrical demand and about 78% of the domestic water demand of the campus. LCA of the system revealed that electricity production from fuel oil, chemical usage (mainly phosphoric acid), and brine release to ocean are the system’s main environmental burdens. Overall results suggest that hybrid systems could be an alternative and sustainable approach for future water and electricity demand in regions where sufficient saline water and solar resources are present.

This research work presents the assessment of the impact of the solar irradiation, the distance from the coast, and the altitude of the location for a Concentrated Solar Power + Photovoltaic + Multi-Effect Distillation (CSP + PV + MED) plant for simultaneous power generation and seawater desalination. For that, a comparative analysis of the thermoeconomic cost of electricity and water (TCE and TCW) at different locations is carried out to determine the most competitive sites where this kind of cogeneration plant can be deployed. Also, multi-objective optimization is performed to assess the optimum sizing that allows reducing the costs. The study considers four Direct Normal Irradiation (DNI) levels (from 2000 to 3500 kWh/m2-yr), six distances from the sea (from 5 to 100 km), and six altitudes (from 20 to 1000 m.a.s.l.). The results show that solar irradiation has the most significant effect on the TCE and TCW, the distance to the sea affects the TCW considerably, and the altitude has a moderate impact despite its impact is substantially lower than the other two factors. Also, cost maps of the TCE and TCW giving insights about which locations have a higher potential for developing CSP + PV + MED plants are presented. From these maps, it has been found that the potential inland locations to reach TCE and TCW under 100 $/MWh and TCW 2 $/m3 should have high DNI (at least 300 kWh/m2-yr above the coast level), distances from the coast up to 60 km, and altitudes up to 750–1000 m.

This research work presents the assessment of the impact of the solar irradiation, the distance from the coast, and the altitude of the location for a Concentrated Solar Power + Photovoltaic + Multi-Effect Distillation (CSP + PV + MED) plant for simultaneous power generation and seawater desalination. For that, a comparative analysis of the thermoeconomic cost of electricity and water (TCE and TCW) at different locations is carried out to determine the most competitive sites where this kind of cogeneration plant can be deployed. Also, multi-objective optimization is performed to assess the optimum sizing that allows reducing the costs. The study considers four Direct Normal Irradiation (DNI) levels (from 2000 to 3500 kWh/m(2)-yr), six distances from the sea (from 5 to 100 km), and six altitudes (from 20 to 1000 m.a.s.l.). The results show that solar irradiation has the most significant effect on the TCE and TCW, the distance to the sea affects the TCW considerably, and the altitude has a moderate impact despite its impact is substantially lower than the other two factors. Also, cost maps of the TCE and TCW giving insights about which locations have a higher potential for developing CSP + PV + MED plants are presented. From these maps, it has been found that the potential inland locations to reach TCE and TCW under 100 $/MWh and TCW 2 $/m(3) should have high DNI (at least 300 kWh/m(2)-yr above the coast level), distances from the coast up to 60 km, and altitudes up to 750-1000 m.

The dual production of power and freshwater by the combination of Concentrating Solar Power (CSP) plants and desalination units, technology known as CSP + D, may help to solve the energy and water scarcity problems in arid and semi-arid regions. The lack of accurate annual analyses, crucial for the proper selection of the best CSP + D configuration, hampers the investment in this technology that has not been implemented on an industrial scale so far. This paper presents a simulation tool able to perform an annual assessment of power and freshwater production of CSP + D plants, based on a very accurate solar field model that uses time steps of 10 s. Three CSP + D configurations have been analyzed in two different locations, Abu Dhabi (UAE) and Almeria (Spain). Two of the three CSP + D configurations consider the multi-effect distillation (MED) technology for freshwater production, in low-temperature and thermocompression modes. The latter also accounts for the water and electricity demands for the selection of the best coupling arrangement. The annual results of the CSP + MED systems have been finally compared with those obtained from the third configuration, a Reverse Osmosis (RO) unit connected to a CSP plant. Results obtained indicate that, in both locations, the configuration leading to maximum water and electricity productions is CSP + RO (26% more of freshwater in Almeria and 10% more in Abu Dhabi). Only if the specific energy consumption of the RO process is above 5.4-5.6 kWh/m(3), the most optimum configuration would be CSP + MED at low temperature.

This study presents a performance analysis of a Concentrating Solar Power (CSP) plant coupled to a Multi-Effect Distillation (MEL)) unit with an Air-Cooled Condenser (ACC) as the MED last condenser (configuration named as MED-ACC) to evaluate the advantage of this integration in comparison to the typical once-through condenser (configuration named as MED-OTC). The analysis has been performed for Cnicero, Chile, which is located 100 km far from the coast and 1000 m above sea level. Thus, a seawater pumping system and energy recovery of the brine disposal are considered. The design of the MED-ACC plant has been carried out in terms of the ACC temperature limitations, and the simulation of both configurations has been performed on an hourly basis. Results obtained in the design show that configuration MED-ACC requires a lower number of effects than the MED-OTC configuration, which reduces the capacity and efficiency of the MED plant. A significant advantage of the former configuration is the reduction in the MED electric consumption with respect that of the latter configuration. Regarding annual performance results, it was found that the net electric output of the MED-ACC plant was 14% higher than the MED-OTC plant due to the seawater pumping consumption reduction, while the water production was 43% lower, despite the water capacity factor of both configurations remained similar.

This study presents a performance analysis of a Concentrating Solar Power (CSP) plant coupled to a Multi-Effect Distillation (MED) unit with an Air-Cooled Condenser (ACC) as the MED last condenser (configuration named as MED- ACC) to evaluate the advantage of this integration in comparison to the typical once-through condenser (configuration named as MED-OTC). The analysis has been performed for Crucero, Chile, which is located 100 km far from the coast and 1000 m above sea level. Thus, a seawater pumping system and energy recovery of the brine disposal are considered. The design of the MED-ACC plant has been carried out in terms of the ACC temperature limitations, and the simulation of both configurations has been performed on an hourly basis. Results obtained in the design show that configuration MED- ACC requires a lower number of effects than the MED-OTC configuration, which reduces the capacity and efficiency of the MED plant. A significant advantage of the former configuration is the reduction in the MED electric consumption with respect that of the latter configuration. Regarding annual performance results, it was found that the net electric output of the MED-ACC plant was 14% higher than the MED-OTC plant due to the seawater pumping consumption reduction, while the water production was 43% lower, despite the water capacity factor of both configurations remained similar.

A detailed annual performance and thermoeconomic analysis of a Concentrated Solar Power plant coupled to a Photovoltaic and a Multi-Effect Distillation plants (CSP + PV + MED) were performed using an extensive methodology based on an hourly simulation. The aim was to assess the impact of the PV integration into the CSP + PV plant and to evaluate the sizing of the plant in terms of the design parameters (PV plant size, solar multiple, Thermal Energy Storage capacity, and numbers of MED units) that allow achieving the lowest thermoeconomic electric and water costs (TCE and TCW). Results show that PV integration mainly increases the electric output but could increase the water production depending on the PV and CSP plants’ sizes. Moreover, the PV plant cost is mainly allocated to electricity, decreasing the TCE, while on the TCW it has a moderate impact. Finally, it was found that the PV plant and the CSP plant size has contradictory roles between the costs, where the minimum TCE is obtained for large PV plant with an undersized CSP plant and one MED unit, and the minimum TCW is obtained for small PV plant with an oversized CSP plant and a large MED plant (5 units).

The objective of this work was to simulate the behavior of an Organic Rankine Cycle (ORC) system with two expanders in series at off-design working conditions. The influence of both the intermediate pressure and the volumetric expansion ratio of the expanders on the off-design performance of the ORC was studied and the irreversibilities of the components were analyzed. The performance of the ORC with two expanders for two different designs was also discussed. The thermal efficiency reached using two expanders was higher than the obtained using only one. However, this increase conveyed an increase in the complexity of the design and control of the expanders. As an additional conclusion, it was found that the influence of the intermediate pressure is higher than that of the volume expansion ratio of each expander. The irreversibility of the first expander was mainly due to leaks. However, the performance of the second expander was particularly affected by the difference between the discharged pressure and the condensation pressure. The off-design analysis allowed the definition of a methodology to achieve the desired power with the maximum thermal efficiency, and the identification of the best actuation for the part load operation.

An exergy cost assessment of solar trigeneration plant to generate electricity, fresh-water, and heat is carried out in order to study the process of exergy cost formation, to determine the key components that contribute to the cost of each product, and to establish the best configuration in term of unit exergy cost. The solar trigeneration plants evaluated consist of a concentrated solar power (CSP), a multi-effect distillation plant, and a process heat module, in which the CSP plant is the prime mover. The methodology includes modeling and evaluating the performance of standalone and trigeneration plants using the symbolic exergoeconomic methodology. Results show that the best configuration, in terms of exergy cost, is when the multi-effect distillation plant replaces the power cycle condenser. Regarding the costs formation, the key components which could be improved in their design are: solar collectors, evaporator, re-heater, dissipative systems, and productive subsystems.

The operation of large-scale reverse osmosis units in combination with different solar power plants, both, Concentrating Solar Power (CSP) and Photovoltaics (PV) has been evaluated under variable load conditions. In the case of the Reverse Osmosis (RO) unit, configurations with and without an energy recovery device have been considered. In the case of the CSP plant, a thermal storage system with several capacities (8-14 h) covers the periods with low solar radiation and no storage has been taken into account for the PV plant due to the prohibitively high cost of batteries at large scale. Two scenarios and different strategies within each scenario have been proposed to adapt the operation of the RO unit at partial load in order to assure a stable operation. In the first scenario, the RO unit is represented as a whole unit with variable performance according to the power availability. In the second scenario, the RO unit is composed of 10 sub-units that are switched on/off depending on the power availability. The analysis has been done for a specific location in Algeria and the dynamic performance of the RO unit has been presented for each scenario, together with an economic analysis.

An exergy cost assessment of integrated solar multi-generation schemes, which includes cogeneration, trigeneration, and polygeneration schemes, for the joint production of electricity, fresh water, cooling, and process heat, is carried out. This evaluation process allows finding out the key equipment to improve the design, detect potential energy savings, and establish the best configurations of these schemes, in terms of unit exergy cost, total exergy cost, and exergy efficiency. The methodology includes modelling and evaluating the performance of solar multi-generation schemes and stand-alone systems, by applying the symbolic exergoeconomic methodology. The solar multi-generation schemes consider a concentrated solar power as the prime mover, which is coupled to a multi-effect distillation, an absorption refrigeration, and a process heat plant. Twenty-one configurations were investigated, twenty of them regarding solar multi-generation plants: eight of cogeneration, eight of trigeneration, four polygeneration schemes, and the other one considering stand-alone systems. This study reveals that the recommended configurations for the solar multigeneration schemes are those in which the desalination plant replaces the condenser of the power cycle, and the refrigeration plant, as well as the process heat module are coupled to turbine extractions. Furthermore, the main components contributing to the cost formation of electricity are, in this order, solar collectors, evaporator, and reheater. In the case of by-products generated, the main components are dissipative systems, solar collectors, and productive subsystems (multi effect distillation, refrigeration, and process heat plants). In consequence, they constitute the key equipment that could be improved. Finally, solar multi-generation schemes are more cost effective than stand-alone systems. For instance, the best option within the polygeneration schemes analyzed allowed reducing the unit exergy cost about 6.8%, 59.2%, 45.6%, and 32.2% for electricity, water, cooling, and process heat respectively. Therefore, solar multi-generation schemes are identified as a promising alternative for zones with high irradiation conditions and scarcity of water, where the CSP technology can be the prime mover.

This paper presents the experimental characterization of a double-effect absorption heat pump (DEAHP) using lithium bromide-water (LiBr-H2O) which recovers the low-energy latent heat from the last effect of a multi-effect distillation (MED) plant. The experimental facility is located at the Plataforma Solar de Almeria (PSA) and the test campaign has been performed with the aim to fmd the best operating strategies that minimize the energy consumption and maximize the energetic efficiency of the DEAHP-MED system taking also into account the distillate production of the MED unit. For this purpose, the impact of the variation of the input variables by which the DEAHP-MED system can be controlled (MED inlet hot water flow rate, MED inlet hot water temperature, the live steam flow rate and the DEAHP cooling water flow rate) on the coefficient of performance (COP), the performance ratio (PR) and on the total distillate production, has been analysed in two different coupling schemes between the DEAHP and the MED unit (indirect and direct). The results revealed that in direct mode, the rise in the live steam flow rate has the greatest impact on the distillate production and the increase of the MED inlet hot water flow rate and the DEAHP cooling flow rate on the COP. In the indirect mode, the rise in the MED inlet hot water temperature was the most influential in both parameters. The maximum COP, distillate production and PR was 2.08 +/- 0.34, 2.42 +/- 0.07 m(3)/h, and 18.53 +/- 1.94, respectively in the direct mode and 2.04 +/- 0.39, 1.92 +/- 0.11 m(3)/h, 16.67 +/- 3.42, respectively in the indirect mode. Moreover, empirical correlations that forecast the PR and the distillate production as a function of the COP were developed from the characterization results and were validated statistically by the coefficient of determination (R-2) and the adjusted R-2 (R-adj(2)).