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This study assessed the economic sustainability and contribution of tomato farming ventures to Addis Ababa's resilience. Using a project-based evaluation method, the profitability of tomato production was analyzed with and without the cost of water. The results showed that including the cost of water, the venture had a negative net present value (NPV) of 30100 USD/hectare/annum, an internal rate of return (IRR) of 0.2%, a payback period (PBP) of over ten years, and a cost-benefit ratio (CBR) of 0.83. However, without the cost of water, the venture showed a subtle profit, with an NPV of 15100 USD/hectare/annum, an IRR of 21%, a PBP of 2.9 years, and a CBR of 1.02. Sensitivity analysis revealed that an increase in sales price and yield positively affected profitability, while an increase in operating cost had a negative effect. The study concluded that when water costs are considered, the tomato venture in Addis Ababa is not profitable or sustainable, and does not contribute to the city's resilience. However, without water cost accounting, the venture's contribution to the city's resilience is minimal. The study recommends policy interventions to enhance farmers' access to the market, establish agro-industries, and improve their bargaining power.

Social structure is based on the availability of the Water-Energy-Food Nexus. To cover these needs of society, several solutions of different scales of infrastructures coexist. The construction of infrastructure is capital-intensive; therefore, investment risk is always a consideration. In this paper, we try to evaluate the investment risk by interest rates (IR). We show that IR is a key indicator, which includes multiple parameters of prosperity expressing the political and economic status quo of the society. The selection of a particular scale influences the required capital and is thus one of the most critical decisions. Water supply infrastructure is one of the foundations of society, and the selection of the optimal scale of such infrastructure is often a great challenge in civil engineering. As a case study, we analyse three different scales of water supply infrastructures for the area of West Mani (Greece), i.e., dam, water ponds, and seawater desalination. We evaluate each case by the capital intensity by performing stochastic simulations of interest rates and identify the optimal solution as the one with the smallest median unit cost, in this case, the water ponds. In order to assess the impact of the development level of a country on the resulting unit cost stochastic properties we apply the optimal solution to various countries with different development levels and IR. We show that IR in the least developed countries, being generally higher and more variable, increases the unit cost, including its variability, which ultimately indicates higher investment risk.

Social structure is based on the availability of the Water-Energy-Food Nexus. To cover these needs of society, several solutions of different scales of infrastructures coexist. The construction of infrastructure is capital-intensive; therefore, investment risk is always a consideration. In this paper, we try to evaluate the investment risk by interest rates (IR). We show that IR is a key indicator, which includes multiple parameters of prosperity expressing the political and economic status quo of the society. The selection of a particular scale influences the required capital and is thus one of the most critical decisions. Water supply infrastructure is one of the foundations of society, and the selection of the optimal scale of such infrastructure is often a great challenge in civil engineering. As a case study, we analyse three different scales of water supply infrastructures for the area of West Mani (Greece), i.e., dam, water ponds, and seawater desalination. We evaluate each case by the capital intensity by performing stochastic simulations of interest rates and identify the optimal solution as the one with the smallest median unit cost, in this case, the water ponds. In order to assess the impact of the development level of a country on the resulting unit cost stochastic properties we apply the optimal solution to various countries with different development levels and IR. We show that IR in the least developed countries, being generally higher and more variable, increases the unit cost, including its variability, which ultimately indicates higher investment risk. [ABSTRACT FROM AUTHOR]

Seawater membrane distillation (SWMD) is a promising separation technology due to its ability to operate as a stand-alone desalination unit operation. This paper reviews approaches to improve laboratory-to-pilot-scale MD performance, which comprise operational strategies, module design, and specifically tailored membranes. A detailed comparison of SWMD and sea water reverse osmosis is presented to further analyze the critical shortcomings of SWMD. The unique features of SWMD, namely the ability to operate with extremely high salt rejection and at extreme feed concentration, highlight the SWMD potential to be operated under zero liquid discharge (ZLD) conditions, which results in the production of high-purity water and simultaneous salt recovery, as well as the elimination of the brine disposal cost. However, technical challenges, such as thermal energy requirements, inefficient heat transfer and integration, low water recovery factors, and lack of studies on real-case valuable-salt recovery, are impeding the commercialization of ZLD SWMD. This review highlights the possibility of applying selected strategies to push forward ZLD SWMD commercialization. Suggestions are projected to include intermittent removal of valuable salts, in-depth study on the robustness of novel membranes, module and configuration, utilization of a low-cost heat exchanger, and capital cost reduction in a renewable-energy-integrated SWMD plant. [ABSTRACT FROM AUTHOR]

Thermal power plants use large amounts of water, mainly for cooling purposes. Over a long operational period, power-plant cooling can have a large impact on the water source: elevated temperatures of return flows alter the local physical and chemical properties of the water (i.e., quality impact), while water consumption reduces the available water reserves for future and down-stream uses (i.e., Quantity impact). The vulnerability of the energy sector to water availability is an important problem and measures to confront or mitigate this challenge have not yet been adopted. Here, a novel, straightforward methodology to calculate the cost of water impact caused by coal and natural-gas (combined-cycle) plants with once-through and wet-recirculating cooling systems is developed. The goal is to internalize systemic costs related to water use impacts and thereby incentivize more sustainable energy generation practices. The impact is calculated here as a theoretical feedback on the plant’s operational costs, since altered water properties will eventually lead to malfunction or part-load operation. The main parameter affecting the cost of water impact is found to be the temperature rise of the cooling water in the condenser. In plants with once-through cooling systems, the quantity and quality impacts of water use are of a comparable magnitude. The cost of water impacts in facilities with wet-recirculating cooling systems, on the other hand, is determined only by their quantity impact on water resources. Overall, recirculating systems result in a significantly lower water cost when compared to once-through systems. Furthermore, an approximately three times higher cost of water impact is calculated for coal plants in comparison to natural gas plants, which clearly demonstrates the importance of operational efficiency on the water use of power plants.

The use of renewable energy for desalination started in the 1980s, in order to provide a sustainable water supply in windy/sunny areas with water shortages. Nevertheless, this initiative has been generally limited to the R&D field and prototypes, with few units operating under real conditions. The research tradition in this field carried out by the Canary Islands Institute of Technology, based on pilot facilities, resulted in wide expertise on practical issues, as well as a deep knowledge on the state of the art. This paper deals with the most relevant technical aspects to be considered in the optimal design and operation of wind/photovoltaic (PV)-powered reverse-osmosis (RO) systems, focusing on practical indications: appropriate pre-treatment, the use and selection of the RO energy recovery system (ERD), the selection of an energy storage system, key recommendations for the O&M actions in wind- and PV-powered RO systems (extracted from the experience of operating different units in remote locations (PV and RO) and coastal areas (wind and RO)), and an identification of the pros and cons of hybrid systems. A selection of economic data is given, indicating the main aspects of the minimization of the cost of water. Finally, the paper mentions the latest advances in the involved technologies. [ABSTRACT FROM AUTHOR]

Potable water scarcity is one of the major issues that has been affecting millions of lives. It became serious in underprivileged remote communities that are unable to afford conventional water supply and treatment systems. Passive solar desalination systems as a cost-effective option for water supply are becoming more feasible in remote areas. However, low water yield and poor reliability are the main deficiencies that need improvement. This article reviews recent studies conducted on performance improvement and water cost reduction of passive solar stills associated with new designs and modifications appropriate for remote areas to identify the most effective designs. The individual effect of each component's design on performance parameters (water yield, thermal efficiency, and unit water cost) has been reported and discussed. The design specifications and outcomes of studies were reviewed and presented in tables to give a broad view of activities in the area, and to provide future studies with data for validation purposes. This article shows knowledge gaps and opportunities for future research through a distinct classification of studies to shape a clear roadmap on the development of passive solar stills. The most effective designs of components with respect to their application in remote or disaster-stricken areas with no access to power infrastructure were determined. In addition, issues around the structural design complexity and operational reliability associated with new designs were presented. [ABSTRACT FROM AUTHOR]

In this study, we present a novel methodology to design and optimally operate a standalone winddriven reverse osmosis desalination plant to provide the required water production in face of fluctuating wind power. The methodology is applied to a plant with a capacity of 2,592 m3/h for a rural area in Saudi Arabia. The plant nominal size, operating conditions, and the number of wind turbines are determined through numerical simulations. The performance of the desalination plant is tested under fluctuating wind power using two different operation strategies that allow for better leverage of the generated wind power. It is found that the desalination system can provide the annual production capacity if the feed pressure is optimally adapted in response to the varying wind speed. Another successful strategy involves the optimal use of the plant vessels in face of fluctuating wind power. Both strategies are successful but necessitate the use of a control system to automatically adapt the feed pressure or the plant active vessels during wind power variations. Moreover, the economic analysis signified a water cost as low as 0.45 $/m³ for the studied plant. [ABSTRACT FROM AUTHOR]

An off-grid multi-generation model (solar photovoltaic, wind power, and diesel) has been used to assess the performance of a low scale (up to 250 m3/d) seawater reverse osmosis desalination plant with four different operating modes: fix, variable (180-250 m3/d), modular-fix (100 + 150 m3/d) and modular-variable operation (100 + 115-150 m3/d). The high-pressure pump and energy recovery system have been selected for each case according to the flow requirements; reverse osmosis membrane simulations have been made to know the power demand, product water flow and quality for the whole operating range of each option. The use of real solar and wind data allows to preliminarily assess the performance of the system. A specific battery charge/discharge strategy has been considered to take maximum advantage of wind and solar available energies. The most relevant technical and economic results have been presented, finding out the pros and cons of the different analyzed cases. A sensitivity analysis complements the study to identify the key parameter values addressed to achieve a minimum water cost under 2.2 €/m3. A new index is proposed to assess the performance of the whole system. [ABSTRACT FROM AUTHOR]

A technical and economic assessment has been made to simulate the operation of a wind energy-driven seawater reverse osmosis (SWRO) desalination plant (10,000 m³/d). Three different generation systems were compared: wind and batteries; wind and diesel; wind and photovoltaic (PV). In each case, two options of the SWRO plant were considered: variable operation high-pressure pump and modular plant consisting of three different trains operated independently. The ranges of power demand of said options are 81%-100% and 20%-100% of the nominal value, respectively. The energy lost, operation time, water production and water costs for each case were calculated, concluding design recommendations with the best technical and economic criteria. Water cost was identified in the range 1-1.35 €/m³, operation time under renewable energy supply can reach 75% of the year for modular reverse osmosis plant. A sensibility study for the water cost, for different parameters (capacity of batteries, diesel price, and PV power) was carried out for the different off-grid generation systems. [ABSTRACT FROM AUTHOR]

A technical and economic assessment of wind-powered seawater reverse osmosis (SWRO) systems is presented to identify the best combination of coupling between wind power and demanded power for a 5,000 m³/d SWRO unit. Three situations have been studied: Reference or Case 0) SWRO plant operating at the nominal point all of the time; Case 1) SWRO plant operating with variable power demand (up to 67% of the nominal point) by reducing the rotation speed of the high pressure pump, and Case 2) use of a modular SWRO plant, able to operate at four different values of power consumption by means of configuring two units of 1,250 m³/d and a unit of 2,500 m³/d. Power and fresh water production are calculated through a year based on experimental data of wind availability with time steps of 1 h. A comparative techno-economic analysis is performed to identify the best configurations along with recommendations on nominal values of desalination capacity and battery capacity in relation to the nominal power of the wind turbine installed. [ABSTRACT FROM AUTHOR]

The analysis of the costs and of the structure of tariffs for operators in the sector of water and sewage system in Romania are a real challenge. Through this analysis we can form an overview of the costs which may involve in the service of providing clean water and the sewage and wastewater treatment. The costs is analysed both in the cost structure at the enterprise level and in comparison with the income made from the activity (supply of drinking water or treatment of wastewater). In the article we study the cost structure at the level of sector of activity and the correlation between the tariff applied to water and sewer services and size of enterprise, number of employees, wage costs, maintenance and repair costs, energy cost and other variables. The correlations results helps us to make the first steps for the realization of an equation of the cost at the level of the sector of water and sewage system. Another correlation study will be between the applied tariff and the size of the investments made with european co-financing in the framework of the SOP Environment. Through this correlation we determine if the size of the tariffs applied in this sector correlate to the size of the investments made in the SOP Environment.

This study assessed the economic sustainability and contribution of tomato farming ventures to Addis Ababa's resilience. Using a project-based evaluation method, the profitability of tomato production was analyzed with and without the cost of water. The results showed that including the cost of water, the venture had a negative net present value (NPV) of 30100 USD/hectare/annum, an internal rate of return (IRR) of 0.2%, a payback period (PBP) of over ten years, and a cost-benefit ratio (CBR) of 0.83. However, without the cost of water, the venture showed a subtle profit, with an NPV of 15100 USD/hectare/annum, an IRR of 21%, a PBP of 2.9 years, and a CBR of 1.02. Sensitivity analysis revealed that an increase in sales price and yield positively affected profitability, while an increase in operating cost had a negative effect. The study concluded that when water costs are considered, the tomato venture in Addis Ababa is not profitable or sustainable, and does not contribute to the city's resilience. However, without water cost accounting, the venture's contribution to the city's resilience is minimal. The study recommends policy interventions to enhance farmers' access to the market, establish agro-industries, and improve their bargaining power., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors. Published by Elsevier Ltd.)

In this paper, nanofiltration (NF) was investigated as a suitable technology for defluoridating brackish groundwater. A comparison between NF and reverse osmosis (RO) was performed to evaluate which method is the best for removing fluorine from groundwater to produce drinking water. Although NF employs a membrane that requires a low amount of energy, both NF and RO have advantages and limitations. NF and RO have similar costs for desalinating brackish water, and thus both the membranes can be used for this aim, but we believe that this will change with the next generation of NF membranes. [ABSTRACT FROM AUTHOR]

This paper is focused on the development of technical and economical prospective of Karachi Nuclear Power Plant (KANUPP) in terms of various desalination technologies. During the first phase, an initial research contingency to desalination technologies already running at KANUPP was discussed and evaluated for economic assessment. In the next phase, mathematical model was developed for calculating various parameters of desalination technologies. During this step, simulation model from IAEA (International Atomic Energy Agency) named as DEEP & DE-TOP were used for calculating various desalination techniques including Reverse osmosis (RO), Multi effect desalination (MED), Multi stage desalination (MSF) and also for coupled technologies i.e., RO+MED and R0+MSF. Different parameters including capital/water cost and thermal desalination parameters were calculated for coupled desalination technologies for KANUPP. Number of stages for coupled KANUPP desalination plant in terms of experimental and computational analysis were carried out. The calculation shows that water cost for each coupled desalination technologies have varying trends. The objective of the research was to developed technical and economical viable model for coupled nuclear reactor desalination system. The research gives an indication to developed experimentally viable KANUPP desalination plant. [ABSTRACT FROM AUTHOR]

Information regarding domestic water consumption is vital, as the Kathmandu Valley will soon be implementing the Melamchi Water Supply Project; however, updated information on the current situation after the 2015 Gorkha Earthquake (GEQ) is still lacking. We investigated the dynamics of domestic water consumption pre- and post-GEQ. The piped water supply was short, and consumption varied widely across the Kathmandu Upatyaka Khanepani Limited (KUKL) branches and altitude. The reduction in piped, ground, and jar water consumption and the increase in tanker water consumption post-GEQ appeared to be due to the impact of the GEQ. However, the impact did not appear to be prominent on per capita water consumption, although it was reduced from 117 to 99 L post-GEQ. Piped, ground, and tanker water use were associated with an increase and jar water use was associated with a decrease in water consumption. Despite improvements in quantity, inequality in water consumption and inequity in affordability across wealth status was well established. This study suggests to KUKL the areas of priority where improvements to supply are required, and recommends an emphasis on resuming performance. Policy planners should consider the existing inequity in affordability, which is a major issue in the United Nations Sustainable Development Goals. [ABSTRACT FROM AUTHOR]

The availability of freshwater supplies to meet future demand is a growing concern. Water availability metrics are needed to inform future water development decisions. With the help of water managers, water availability was mapped for over 1300 watersheds throughout the 31 contiguous states in the eastern US complimenting a prior study of the west. The compiled set of water availability data is unique in that it considers multiple sources of water (fresh surface and groundwater, wastewater and brackish groundwater); accommodates institutional controls placed on water use; is accompanied by cost estimates to access, treat and convey each unique source of water; and is compared to projected future growth in consumptive water use to 2030. Although few administrative limits have been set on water availability in the east, water managers have identified 315 fresh surface water and 398 fresh groundwater basins (with 151 overlapping basins) as areas of concern (AOCs) where water supply challenges exist due to drought related concerns, environmental flows, groundwater overdraft, or salt water intrusion. This highlights a difference in management where AOCs are identified in the east which simply require additional permitting, while in the west strict administrative limits are established. Although the east is generally considered ‘water rich’ roughly a quarter of the basins were identified as AOCs; however, this is still in strong contrast to the west where 78% of the surface water basins are operating at or near their administrative limit. Little effort was noted on the part of eastern or western water managers to quantify non-fresh water resources.

The objective of this study is to include environmental impact in optimization of concentrated solar power plants previously limited to techno-economic analysis only. Performance of solar towers and parabolic trough collectors equipped with dry and wet cooling is numerically investigated at 10 min interval for three climatic zones. Based on electricity generation profiles pertinent to variation of design variables of solar multiple and thermal energy storage, the water usage is quantified techno-economically, considering water scarcity levels. Besides, five different potential impacts over lifecycle of concentrated solar and natural gas-based power plants are compared after unifying them into metric of net environmental impact avoided. Additionally, utilizing techno-economic solutions and eco-friendly solutions, multi-objective 'balanced' solution is proposed. It is found that levelized cost of water increases five-fold for areas with extreme water scarcity and is higher for trough than solar tower. Net environmental impact of troughs is higher and lower electricity generation causes the avoided impact to be higher than solar towers, when compared with natural gas-fired power plants. For eco-friendly solutions, solar multiple varies from 3.5 to 4 with thermal energy storage of 24 h. Dry-cooled solar towers with optimal solar multiple in range of 3–3.2 and thermal energy storage of 18.8–19.9 h are evaluated for pareto-optimality based 'balanced' solutions for all zones. These solutions offer minimum net levelized cost of electricity, alongside maximized electricity generation, huge return on invested capital and energy, and reducing environmental impact by over 94%. Lastly, semi-arid climates are found suitable for concentrated solar power plant installation. [Display omitted] • Dry-cooled systems give better plant output for solar tower and parabolic troughs. • Water footprint of solar tower is 1–1.5 times higher than parabolic troughs. • Water scarcity levels increase the levelized cost of water use manifold. • Global warming is most significant form of environmental impact for both plant types. • Dry-cooled solar towers offer optimality between low-cost and eco-friendly solutions. [ABSTRACT FROM AUTHOR]

This paper presents an overview of using solar energy in running desalination systems, called solar desalination. Solar energy can be converted directly to electric energy, which can operate electrically driven desalting systems such as reverse osmosis (RO), electrodialysis (ED), and mechanical vapor compression systems. Solar energy can also be converted to the thermal energy that can operate the mainly used thermally operated desalination system such as multistage flash (MSF), conventional multieffect (ME), and multieffect thermal vapor compression (ME-TVC), and emerging membrane distillation and humidification–dehumidification desalination systems. The thermal energy converted from solar energy can also be used to produce high-pressure steam running power plant producing electric power to operate mechanically driven desalting systems, and/or extracted steam at relatively low pressure to operate thermally driven desalting system. The main obstacle that hinders the use of solar desalination is the initial investment cost. This paper discusses the use of the solar desalination and calculates the investment cost to install solar desalination plants. These include photovoltaic (PV)-driven RO system, and thermally driven MSF and ME plants by steam directly generated by solar collectors, or by steam extracted from solar steam power plants operated by the concentrated solar collectors. The results revealed that PV-RO desalting system has the highest specific capital cost, among the considered systems, because the expensive storage of the electric energy in batteries, and the fact solar energy supply lasts about one third of the day. It showed also that using the thermally generated energy from concentrated solar collectors operating power plant is much cheaper than using this thermal energy when directly operating the desalination system. [ABSTRACT FROM PUBLISHER]

The treatment of wastewater and its further reuse is an essential part of an efficient rationalization of water within the field of Environmental Management Initiatives. Opting for the regeneration of this resource will lead to an important increase in water supply. Few studies have specifically calculated the economic costs of wastewater treatment and reuse using cost accounting and management techniques. In this paper, a cost management model is designed and adapted to the wastewater treatment process. The model quantifies, in economic terms, the change of water state from treated to regenerated water, favoring more efficient decision making regarding this resource. A practical application of this model was carried out at the Wastewater Treatment Plant of Santa Cruz de Tenerife (Canary Islands – Spain). The costs of the resources consumed by the treatment plant were calculated, as well as the costs for the different activities identified in treatment and reuse processes. As a result of our calculation process, it can be noted that the reuse of wastewater is an interesting option in terms of costs compared to other existing sources of water: surface water, underground water or desalination. [ABSTRACT FROM AUTHOR]

In this paper, research has been conducted on the floating type nuclear power plant named as ABV reactor which is designed for district heating, power, and sea water desalination by OKBM facility at Russia. This reactor was tested under different thermal loads during the designing phase, and three modules have been investigated. Theoretical calculations and simulation studies have been performed on these three modules having specifications as ABV-6M with 47MWth, ABV-6 with 38MWth, and ABV-3 with 18MWth.The results obtained from these modules have been calculated mathematically and verified by simulation. We have compared the originally derived data of ABV desalination system with our theoretical and simulation analysis. The results from two desalination techniques including RO and RO + MED have been calculated and are presented in this paper with details. The results obtained from both analysis show that the efficiency of ABV nuclear reactor desalination system increases with the decrease in corresponding water cost ratio. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Reverse osmosis (RO) has contributed to a large extent in positioning membrane desalination as one of the best available technologies to meet water demand in dry coastal areas. However, membrane desalination may still be perceived as an energy consuming and high cost desalination technology. Seawater Osmotic Dilution (SOD) may lower the energy consumption and the water cost by decreasing the salt content of seawater; and, at the same time SOD can become a sustainable technology that does not impact marine environments considering that less concentrated brines are discharged into the sea. The main objective of this study was the economical evaluation of SOD for the purpose of decreasing desalination costs. The authors have investigated the attractiveness and viability of SOD opportunities compared with standard RO membrane desalination. Three process configurations (desalination, desalination and reuse, SOD) were defined for a coastal area location, where the possibilities of water availability are limited to mainly the ocean. For each configuration, three different water production capacities (1.000, 10.000, and 25.000 m³/day) were studied and evaluated economically in terms of capital expenditure (CAPEX) and operational expenditure (OPEX). The results show that SOD can produce desalinated water with 27% energy reduction compared with seawater reverse osmosis desalination; and that operational costs of desalination can be reduced by 31%. Water volume balances of each configuration demonstrate that SOD has a high potential in dry coastal areas with limited availability of fresh water. For SOD with a commercial price of forward osmosis (FO) membranes at 30–60 US$/m² and a membrane flux of 7–14 L/m²-h, SOD becomes a viable technology for lowering costs of desalination, with payback times of less than 1.5 years when compared with desalination. [ABSTRACT FROM PUBLISHER]

The main two supply of potable water to Amman city are Zai water treatment plant (represent 60%) and Wadi Ma'in, Zara, and Mujib (WMZM) water treatment plant (represent 30%). WMZM receives raw water from three main sources originally flowing to the Dead Sea, now collected and conveyed to a raw water reservoir at the treatment plant to produce about 110,000m3/day. WMZM was commissioned in 2006 and still operating at the original design capacity. WMZM water treatment plant and its conveyance system are presently operated by Jordan Water Company-Miyahuna. This paper covers the plant description, original design parameters, and RO membrane performance after more than five years of operation. [ABSTRACT FROM AUTHOR]

Highlights: [•] We design the schematic diagram of solar desalination system with evacuated tube collectors. [•] Mathematical and economic models of the collector and desalination subsystem are proposed. [•] The method of desalination is low temperature multi effect distillation. [•] The cost constitution of solar desalination system is shown. [•] The water cost given appreciate the economic performance of the system. [Copyright &y& Elsevier]

Abstract: Membrane distillation (MD) has shown potential as a desalination process. As a thermally driven membrane technology which runs at relatively low pressure and can tolerate high salinity feed, MD may be useful for desalination under condition for which reverse osmosis is not a good option. However, improved energy utilization and reduced water production cost in MD systems remains an important technical challenge. In this paper, we examine how optimization of the heat and mass transfer properties of the MD membrane can raise water flux and reduce unit energy consumption. Numerical modeling tools and factorial analysis are used to examine the effect of five MD membrane characteristics: porosity, tortuosity, thermal conductivity, pore diameter, and thickness. The water production cost (in USD/m3 of purified water) is calculated as a function of these parameters for a small-scale, single-stage MD process driven by waste heat. Two MD configurations were considered: Direct Contact MD (DCMD) and Air Gap MD (AGMD). All five membrane properties examined were found to have a significant effect on water production cost, although the magnitude of this effect was greatly dependent on the MD configuration. [Copyright &y& Elsevier]

The paper presents part of the work that has been elaborated within the project entitled "Promotion of Renewable Energy Sources (RES) through Desalination", PRODES, IEE/07/781/ SI2.499059, Intelligent Energy EU Programme. Part of the project work is dedicated to the analysis of the energy and water framework in four target countries, that is, Greece, Italy, Portugal and Spain. The present paper is focused on the current situation of the energy and water in Greece as well as on the legislation and administrative framework for RES and Water Desalination. Energy tariffs and water costs from conventional or alternative resources are also presented. The output of this work includes recommendations for policy makers, suggestions on the improvement and acceleration of the procedures, and further progress of RE-Desalination in Greece. [ABSTRACT FROM AUTHOR]

The article presents a study which examined the exergy cost of water supply as well as technologies involved in water treatment. It obtained an index like the unit exergy cost (UEC) of different water-related technologies which is based on exergy analysis (EA). It mentioned that aside from their embedded energy-efficiency information, UEC values can used in the assessment of water costs.

This paper addresses the effect of the oil prices on the cost of low pressure heating steam for thermal desalination systems, electricity and desalinated water. Two methods of calculating the low pressure steam, and electricity are developed and compared with a typical power/ water cogeneration plant commissioned in 2009, by the King of Saudi Arabia. The first method is based on the calculation of the monetary cost of all streams of power cycle and charging the levelized capital and operating and maintenance costs based on exergy. The cost of bleeding steam is allocated based on the steam quality. In the second method we calculate the low pres- sure steam of the back pressure turbine based on equivalent cost of power loss due to the steam withdrawal for desalination plant. Visual Design and Simulation Program (VDSP) previously developed by the authors is used. The effect of a wide range of the oil price (5-100 $/bbl) is investigated. The results showed that the second method overestimates the electricity cost by 8% and underestimates the low pressure steam cost by 25% at oil price of 70 $/bbl. The results showed also that, the product water, electricity, and steam costs are significantly affected by the variation in oil price. The product water cost will be less than 1.0 $/m³ only if oil price is subsidized to near to 20 $/bbl. However, the water unit cost may jump to 4 $/m³ when the oil price increased to 100 $/bbl. [ABSTRACT FROM AUTHOR]

Approximately 85% of the water consumed in Chile is destined to agricultural irrigation and is managed by the users themselves. This study analyzed the price that irrigation water users pay to their Water User Associations (WUAs) to which they belong and the relationship of this price to the professional level and performance of the WUAs. The study included 24 WUAs: 10 River Administration Boards (JV) and 14 Irrigation Canal Associations (AC). The annual operational budget of each WUA, the price paid by users and the management capacities of the board of directors of each WUA were compared. The study also determined the relative value of user payments to WUAs as a proportion of total production costs of the main crops in each zone. The variability of user fees per irrigated hectare decreases when the irrigation area of the WUA is more than 10 000 ha, though this was not observed in JVs. The presence of technical-professional staff directly affects the development and growth of the WUAs. As well, the WUAs with a greater level of capacity development (NDC) have more board members with a higher education level and have lower rates of unpaid user fees. The price that users pay to the WUA by irrigated hectare represents less than 4.0% of the average total production cost of the main crops in the study area. Finally, no correlation was found between the prices that users pay and the average profitability of the main crops, or between price and the geographical location of the WUAs. [ABSTRACT FROM AUTHOR]

A battery is required in reverse osmosis powered by a photovoltaic system (PV-RO) to prevent inevitable dumping energy and to prolong the operating time of producing water simultaneously. However, the battery is expensive and has a short lifespan. To obtain a competitive water cost, a battery capacity should be as small as possible. This study presents a novel strategy to prevent dumping energy and minimize battery capacity. PV-RO system with battery (PV-RO-Battery) and seasonal water storage tank (SWST) is investigated and its water cost is analyzed. This strategy ensures that all of the daily energy produced by the PV system is used to produce water in less than 24 h, avoiding the accumulation of storing daily excessive energy. Excess daily water production over daily demand is stored in SWST and is supplied to the source of demand when the water production is less than demand. A comparison of a PV-RO-Battery system with and without SWST is also conducted. The reduction of water cost was from 10.21 $/m3 to 2.31 $/m3 and 36.96 $/m3 to 3.06 $/m3 for the constant and variable demand, respectively. It means that the water cost from the system with SWST is only 20.5% and 8.3% of the system without SWST. • Novel strategy in PV-RO-Battery system to fulfill the demand is presented. • The concept of seasonal water storage tank (SWST) is employed. • The resulted water cost is 20.5% of the system without SWST. • The required capacity of PV modules is only 33.2% of the battery-less PV-RO system. • The required capacity of RO unit is only 48.5% of the battery-less PV-RO system. [ABSTRACT FROM AUTHOR]

The present work proposes a stand-alone process for brackish water thermal desalination for the Brazilian semi-arid (BSA) region. The Multi-Effect Distillation (MED) is coupled with solar collectors, a thermal energy storage (TES) system, a biodigester for electricity generation and a brine reject valorization scheme. The TES provides the continuous production of freshwater using solar energy alone, unlike other studies in the literature. The brine recycling affords lower amounts of brine reject than that reported in the literature for MED plants. A detailed cash-flow analysis estimates the economic feasibility of the plant and a water sales price of US$ 4.95/m³ for a plant with a capacity of 72 m3/day. The results indicate that thermal desalination is a cost-effective and sustainable alternative to mitigate the water shortage in the BSA region. • Stand-alone MED plant coupled with thermosolar energy in Brazilian semi-arid. • Thermal energy storage system affords freshwater supply over the whole year. • Economic feasibility analysis estimates freshwater sales price at 4.95 US$/m3. • Brine recycling affords a reject of only 13% of the brackish water inlet. • Brine valorization scheme further provides biomass for electricity generation. [ABSTRACT FROM AUTHOR]

Abstract: Today, three billion people around the world have no access to clean drinking water and about 1.76 billion people live in areas already facing a high degree of water stress. This paper analyzes the cost-effectiveness of a stand alone small-scale renewable energy-powered seawater reverse osmosis (SWRO) system for developing countries. In this paper, we have introduced a new methodology; an energy optimization model which simulates hourly power production from renewable energy sources. Applying the model using the wind and solar radiation conditions for Eritrea, East Africa, we have computed hourly water production for a two-stage SWRO system with a capacity of 35m3/day. According to our results, specific energy consumption is about 2.33kWh/m3, which is a lower value than that achieved in most of the previous designs. The use of a booster pump, energy recovery turbine and an appropriate membrane, allows the specific energy consumption to be decreased by about 70% compared to less efficient design without these features. The energy recovery turbine results in a reduction in the water cost of about 41%. Our results show that a wind-powered system is the least cost and a PV-powered system the most expensive, with finished water costs of about 0.50 and 1.00$/m3, respectively. By international standards, for example, in China, these values are considered economically feasible. Detailed simulations of the RO system design, energy options, and power, water, and life-cycle costs are presented. [Copyright &y& Elsevier]

Abstract: This paper presents the technical characteristics as well as an economic comparison of two autonomous desalination systems. The first system concerns the laboratory experimental results of a direct coupled PV-SWRO desalination system without batteries equipped with a hydraulic energy recovery device of the Clark pump type. The PV system consists of 18 Arco-Solar monocristaline PV panels, with total peak power of 846 W. These panels are directly connected to a brushless DC motor of 510 W, powering a rotary vane pump as low pressure pump. The clark pump utilizes the high pressure brine to intensify the feed pressure to the RO desalination system. The desalination system has a capacity of 0.1 m3/h. The specific energy recovery of this system has been experimentally found to be in the range of 3.8–6 kWh/m3 depending on the feed water temperature and the feed water salinity. The second system is an organic solar Rankine system for RO desalination. The heat produced by the solar collectors’ field is transformed to mechanical power through an organic Rankine cycle process. The shaft power produced drives the high pressure pump of the RO unit, initiating the desalination process. The prototype system consists of vacuum tube solar collectors 90 m2, a Rankine engine of 100 kW and an RO unit of 0.3 m3/h. The energy recovery system of the RO unit consists of a pair of axial piston pumps (APP) manufactured by Danfoss. One of them operates reversely, as turbine, exploiting the hydraulic energy of the brine stream. The aim of the economic analysis is not only to estimate the cost of each system but also to compare them on the same basis, in order to allow a meaningful comparison. Hence, each system cost is determined having utilised the same economic assumptions like interest, operating expenses, etc. Moreover, these desalination systems can provide sufficient amounts of potable water for the local needs of a small island, like Thirasia, (Cyclades, Greece) at a cost as low as 7.77 ɛ/m3, very close to that of water hauling. [Copyright &y& Elsevier]

A new approach for evaluating water sustainability is introduced by comparing physical and economic sustainability. To achieve physical sustainability, water should be available in sufficient quantity and of good quality and used efficiently. The economic sustainability can be achieved by balancing between costs and values of water. The objectives of this study were to estimate the physical and economic sustainability of surface water in the Big Lost River, south–central Idaho. The study used a Bayesian network by building a graphical diagram of nodes representing all significant variables related with the sustainability, such as water demand, water quality, and the different costs and values of water. The study showed that the likelihood of the physical sustainability is less than that of the economic sustainability, which is attributed to the scarcity of water in the Big Lost River. [ABSTRACT FROM AUTHOR]

Abstract: The economic benefits of integrating seawater desalination with power plants are discussed, starting from the first principles of thermodynamics. The concepts of the “fuel-use performance ratio” and the “power loss” method are described in the context of their usage for thermal cycle evaluation and desalination process selection, both with conventional steam cycles and with combined cycle power plants. A thermo-economic model is introduced to evaluate water and power costs and rates of return in dual-purpose power/desalination applications. The future of integrated power and desalination plants is discussed with reference to the growing role of seawater reverse osmosis (SWRO) in the desalination arena. A case study is presented to evaluate the benefits of integrating SWRO with existing power/desalination plants in the Middle East. Subject to the assumptions of the study, it is concluded that repowering and retrofitting would result in a nearly three-fold increase in the power generating capacity and an over six-fold increase in the water output, without requiring any expansion of the seawater intake system. Based on natural gas fuel, the repowered plant would also result in a 70% increase in the fuel efficiency of the station and a drastic reduction in the cost of water production. For a privatization scenario, an economic analysis is used to show that attractive rates of return would be obtained if a developer were to purchase and refurbish the existing plant, selling the products on a build own and operate (BOO) basis. In preparation for this promising application, the need for pilot plant testing at existing power/desalination stations, together with research and development work in membrane technology for high temperature operation, is emphasized. [Copyright &y& Elsevier]

Abstract: The paper presents economic and socioeconomic factors that led to the decision to desalt brackish water on the Croatian islands. Capital and operating costs and water rates of the first reverse osmosis desalination plant were analysed after five years of operation. The positive and negative impact of the desalination plant on the environment is discussed, as well as its successful operation and effect on the wide range of use of desalination in Croatia. [Copyright &y& Elsevier]

Many regions of the world are facing formidable freshwater scarcity. Although there is substantial scope for economizing on the consumption of water without affecting its service level, the main response to water scarcity has been to increase the supply. To a large extent, this is done by transporting water from places where it is abundant to places where it is scarce. At a smaller scale and without a lot of public and political attention, people have started to tap into the sheer limitless resource of desalinated water. This study looks at the development of desalination and its costs over time. The unit costs of desalinated water for five main processes are evaluated, followed by regressions to analyze the main influencing factors to the costs. The unit costs for all processes have fallen considerably over the years. This study suggests that a cost of $1/m3 for seawater desalination and $0.6/m3 for brackish water would be feasible today. The costs will continue to decline in the future as technology progresses. In addition, a literature review on the costs of water transport is conducted in order to estimate the total cost of desalination and the transport of desalinated water to selected water stress cities. Transport costs range from a few cents per cubic meter to over a dollar. A 100 m vertical lift is about as costly as a 100 km horizontal transport ($0.05-0.06/m3). Transport makes desalinated water prohibitively expensive in highlands and continental interiors but not elsewhere. [ABSTRACT FROM AUTHOR]

Abstract: Water is an increasingly scarce resource and in many regions people are turning to new sources such as seawater and wastewater. Various membrane technology improvements in the last decade have led to a significant cost reduction in reverse osmosis (RO). This has triggered selection of seawater reverse osmosis (SWRO) technology for many large drinking water projects in the world. Since energy cost is the single largest factor in the cost of a seawater system (usually 20–30% of the total cost of water), it is an obvious target for cost reduction. Therefore new membrane developments have to focus on lower energy consumption. This requires the development of high productivity membrane elements and compatible design concepts that enable operation at lower pressure. This publication presents new products with higher flow (7500–9000 gpd at standard test conditions) and high rejection (99.70–99.75%) for the seawater desalination segment. The technical features of these products are explained and possible energy and other cost savings are calculated. It is shown that these products can be used across the entire seawater segment to reduce energy consumption down to levels of 2.0 kWh/m3 or to reduce the capital cost of the membrane stage by up to 30%. Field data for these new products is presented at the end and confirms both, performance of the presented new products, and significant capital and operational cost savings. [Copyright &y& Elsevier]

The greatest water consumption takes place during irrigation of arid and semiarid areas, therefore, water resource management is fundamental for sustainability. For correct management, several tools and decision-making systems are necessary while paying close attention to aspects such as profitability, water cost, etc. Water resources are scarce and some of them are of low quality. This extremely delicate situation occurs in some regions of the world and it explains increasing water cost. In Europe, the policies relating to water use (2000/60/EC) pay particular attention to the need of its protection and conservation. To ensure this, a large number of measures, including the establishment of prices which really correspond to their usage costs, have been set forth. Water subsidies are relatively important in all European countries. In this study, a specific methodology is applied to a Spanish semi-arid region. It is useful and easy to apply, not only by farmers, but also by water managers and politicians in charge of policy. The methodology also helps in the decision-making process about water cost in agriculture. In this area (Hydrogeological System 08.29, Spain), the resources are mainly underground water with a high variable cost and without any direct subsidies. This model allows us to analyse the effect of different water costs and to find the optimum strategy giving the maximum gross margin in line with water cost and its main determining factors (irrigation system, climatic variability, etc.).The methodology is based on the effect of irrigation on crop yield with its production function, integrating the effect of application efficiency. In this way, a relationship between gross margin and gross irrigation depth is obtained. Working with permanent irrigation systems and four crops (barley, garlic, maize and onion), the main conclusion is that the optimum gross irrigation depths are always fewer than those necessary for maximum crop yield and when irrigation depths are fewer water cost increases. Irrigation depths, which maximise the economic efficiency in the use of water (€ m−3), are fewer than those which maximise the gross margin; therefore, this aspect must be considered in irrigation scheduling. The results also show important differences among crops, depending on their water requirements and their economic profitability. [Copyright &y& Elsevier]

While the fuel cost has increased in the past years, the desalinated water demand has also increased sharply, especially in the deserted areas. The challenge is to be able to meet such future demand, minimizing the water production costs. The desalination concepts have evolved, achieving substantial progress: desalination thermal process is moving from MSF to MED, hybrids involving both thermal and membrane process are more and more implemented. Reduction in cost and the improved economics of desalination plants are essential elements for the development of communities. Energy, capital, and operating costs are key issues of water desalination economics. This will lead to an optimized process selection on a case by case approach: the choice will depend on the specific conditions prevailing on site, such as existing facilities, power and water demand increase, land availability, raw water quality of water to be produced, ratio between power and water production, ratio between thermal and membrane desalination. The presentation will focus on these various aspects of seawater desalination economics. [Copyright &y& Elsevier]

The paper describes the results of a feasibility study jointly promoted by Israel Electricity Corporation and Aster - Sowit Division (Italy) aimed at investigation of the possible integration of the low-temperature flash (LTF) desalination technology in existing IEC power stations. The LTF technology exploits the residual heat discharged by the cooling seawater for its distillation, with a dramatic reduction in steam consumption as compared to otherdistillation processes. A prototype LTF desalination unit has been operating at ENEL power station in Piombino, Italy since 1993, showing the industrial applicability of this technology. In the present study an improved LTF design, with long tube, multistage evaporator, has been applied to a typical IEC site located on the southern shore of the Mediterranean Sea. The study has been carried out both for small-scale units, devoted to boiler make-up production, and for a large plant able to produce the whole water supply for the site. The investigation has shown very interesting perspectives for such an application, with extremely low steam and electrical consumption and a very competitive cost of produced water. Other advantages of LTF technology are related to the extreme plant availability, to the high purity of produced distillate, to the absence of any chemicals consumption and environmental impact. [Copyright &y& Elsevier]

This detailed study was carried out for the determination of the water cost in small size RO desalination plants in remote areas. Data from desalination plants in three Greek islands were used for a period of three years. The actual expenses for these plants were examined thoroughly and as a result the real cost per cubic meter was estimated. An evaluation of the efficiency of two different energy recovery systems was conducted by using factual operating data. The introduction of new technologies, automation, data acquisition and remote operation can be used to reduce the labor and maintenance cost for small size RO desalination plants. The increase in labor productivity has proved to be the direct result of the introduction of a low cost SCADA system to the RO plant. [Copyright &y& Elsevier]

New demands for water can be satisfied through a variety of source options. In some basins surface and/or groundwater may be available through permitting with the state water management agency (termed unappropriated water), alternatively water might be purchased and transferred out of its current use to another (termed appropriated water), or non-traditional water sources can be captured and treated (e.g., wastewater). The relative availability and cost of each source are key factors in the development decision. Unfortunately, these measures are location dependent with no consistent or comparable set of data available for evaluating competing water sources. With the help of western water managers, water availability was mapped for over 1200 watersheds throughout the western US. Five water sources were individually examined, including unappropriated surface water, unappropriated groundwater, appropriated water, municipal wastewater and brackish groundwater. Also mapped was projected change in consumptive water use from 2010 to 2030. Associated costs to acquire, convey and treat the water, as necessary, for each of the five sources were estimated. These metrics were developed to support regional water planning and policy analysis with initial application to electric transmission planning in the western US.