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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. Fontina Petrakopoulou would like to thank the Spanish Min- istry of Science, Innovation and Universities and the Universi- dad Carlos III de Madrid (Ramón y Cajal Programme, RYC-2016- 20971).

The first-ever SO2 emission concentration standards for Indian coal-power plants were notified on December 7, 2015. In light of the new stringent standards, this paper conducts a techno-economic policy evaluation of SO2 abatement options by building a system-wide marginal abatement cost curve (MACC) for India. An abatement cost model is developed, to estimate retrofit costs for three end-of-process (EOP) SO2 abatement technologies. A system-wide SO2 MACC is derived based on cost optimal allocation of EOP abatement technology to each boiler. Compliance with the new stricter emission standards is evaluated at 75 % pollution reduction (≈ 4600 kt-SO2 reductions per year). Compliance with the new standard corresponds to a marginal abatement cost of INR 23,500 per ton of SO2 (≈USD 368.50 per ton of SO2) and total system-wide abatement cost of INR 75 billion (≈USD 1.2 billion) per year. Reduction in pollution is estimated to save 46,000 lives per year at the cost of about INR 1.63 million per life per year. Sensitivity analysis of the MAC curve shows that plant capacity utilization has the most significant impact on total lifetime compliance costs followed by equipment fixed cost, sorbent cost, and water cost in that order.

The solar still is one of the best choices for obtaining fresh water, in small scale demands which covering the demand for remote arid regions which do not have enough power source to distill water or infrastructure to deliver fresh water. In this study, experimental investigation of tubular solar still (TSS) is presented. Two different models were constructed with different water basin absorber shapes; flat plate (TSS-FP) and semi circular corrugated surface (TSS-SC). Those two models were tested at same climatic conditions of 6 October City, Giza, Egypt (Latitude of 29.9381° N, Longitude of 30.9140° E). The TSS thermal, exergic and economic performance and productivity for the two models were studied and discussed. The TSS water production rate by using semi circular corrugated surface was about 4.3 L/m2 with enhancement by 26.47% rather than using a flat absorber with augmentation in thermal and exergy efficiencies about 25.9% and 23.7% respectively. The water cost of the TSS-SC was 0.0067 US$/L with reduction about 20.77% less than TSS-FP.

Contamination of water bodies by acid mine drainage (AMD) from mining industries is affecting global freshwater availability, especially in arid zones like northern Chile. A real AMD from a contaminated Chilean river was used in this study. This work aimed to evaluate an economic projection of a Forward Osmosis–Membrane Distillation (FO-MD) process versus a Forward Osmosis–Reverse Osmosis (FO-RO) for an AMD treatment. FO-MD continuous assays (12 h) were performed using AMD solution as feed and NaCl as draw solution, achieving an initial flux of 25 LMH with FO and a stable flux around 10 LMH for MD. Different FO-MD economic models were developed using steam and thermal-fluid as heat-source. The cost assessment showed that thermal-fluid FO-MD has a payback period of 1.8 years with a water cost of 3.36 $/m3 while FO-RO's investment return was one year with a water cost of 1.47 $/m3. A Monte Carlo modeling results identified the membrane cost and the thermal energy expense as the elements with the highest impact on the economic indicators. Nevertheless, the economic assessment revealed that if waste-heat is available, the FO-MD operation cost would be lower than FO-RO's (1.29 $/m3), even with today's high FO/MD membrane cost.

It is reported in the literature that Electrodialysis Desalination (ED) is the most efficient for groundwater ( 9.5 ppt. The net recovery ratio for the hybrid ED-RO plant is 87.5% when ED and RO plants operate at a recovery ratio of 75% and 50%, respectively. For typical conditions and brackish water salinity of 5 ppt, ED-RO shows an outstanding performance of 0.731 kWh/m3 for energy consumption and 0.370 $/m3 for water cost. These values are better than those of standalone RO and ED plants.

Predictive modeling and sensing based approaches to scheduling irrigation are increasingly being adopted by commercial nurseries due to their potential to automate irrigation and improve crop production. This study had two overarching objectives: first, to compare the irrigation scheduling performance of a substrate moisture sensing approach to that of a three-dimensional predictive transpiration modeling approach in five tree species grown in a containerized pot-in-pot production system. For comparison we measured tree growth (crown leaf area and stem caliper), volume of water applied and irrigation application efficiency (Ae) for each method. The predictive method (i.e., a linked photosynthesis-stomatal conductance (An-gs) scheme) applied 18–56% more water than the sensing-based method in four species and 6% less in the fifth. Mean Ae was 80.1 and 89.5% for predictive and sensing-based treatments, respectively. Across species, predictive scheduling yielded 19–53% greater leaf area and 3.4–11% more caliper growth than sensing-based scheduling. Our second objective was to determine if the accuracy of the An-gs scheme could be retained while using generalized multi-species means for key physiological input parameters instead of species-specific values. We found the accuracy of transpiration estimates to largely depend upon two parameters—g0: the minimum gs, and g1: the marginal water cost per unit of carbon gain. When just these two parameters were characterized on a species-specific basis, transpiration estimates were within 10% error >65% of the time and within 20% error >95% of the time. We conclude that the predictive transpiration modeling approach to scheduling irrigation was a superior method for producing greater tree growth but at the cost of greater water use and slightly lower Ae. Furthermore, species-specific parameterization of g0 and g1 in the An-gs scheme are critical to accurate species-specific transpiration estimates, whereas most other physiology parameters may be generalized—circumventing the need for comprehensive An-gs parameterization.

The paper examines the factors that determine the residential water demand level in the city of Kozani located in the NW part of Greece. Based on an 8-year (2005-12) detailed sample of residential water demand time panel data, the values of price and income water demand elasticity are estimated, and the influence of socio-economic and demographic characteristics, as well as climate conditions, on water use levels and trends are analysed. The overall objective is to estimate and record the overall response of consumption to the increased water price due to the full water cost principle adopted.

In this paper, a ship lock scheduling problem is investigated. Ships arrive randomly over time, and the instantaneous arrival rates are allowed to vary both temporally and stochastically in an arbitrary manner. A data-driven approach is applied to a single ship lock scheduling, which is a typical optimizing and decision-making problem. The objective is to minimize the operation costs and other costs(e.g. water cost, electricity cost, and staff welfare cost) by selecting an appropriate slot number during a planned period. The convergence of data-driven approach is discussed from three aspects: the convergence of ant colony optimization algorithm, the convergence of the proposed algorithm, and the error between the historical ship data and the current arrival ship data. The research findings are beneficial for the convergence analysis of data-driven theory and the management of waterway transportation.

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.

The competitiveness of nuclear desalination in the western region of Saudi Arabia was studied. A forecast of water demand between the years 2000 and 2025 was established as part of the input data required for the DEEP computer code. Several options of energy sources such as PWR (600 MWe), SPWR (160 MWth), PHWR (450 MWe), HR (200 MWth) and GT (125 MWe and 175 MWe) were investigated in conjunction with different desalination technologies such as RO, MSF, MED and the hybrid MED-RO. The total plant output, specific electricity investment cost, specific water investment cost, levelized power cost, average daily production, net saleable power and levelized water cost are presented for all cases. Two scenarios were investigated; the first assumed no interest and discount rates and the second assumed interest and discount rates equal to 4%, 8% and 12%. The first scenario assumed that the water utility continues under the control of the government while the second assumed that the water utility will be privatized.

This paper considers the economics of using photovoltaic (PV) technology for developing remote areas. “East Owienat” in Upper Egypt is the chosen region: there, the feasibility of using PV systems for the pumping of ground water in comparison with using diesel units, taking into consideration the different parameters affecting the costs and the present value of both systems, is considered. The study proved that PV-battery systems can be used efficiently for water pumping at East Owienat: the cost of the water unit pumped by PV systems is much less than that pumped using diesel systems, and the water cost is more sensitive to PV cells’ prices than their life-time periods.

This paper presents the main concepts and deliverables of the BOOT structure. It also summarizes current and foreseen BOOT desalination projects, which indicate their increasing role in the water desalination market. Finally, this paper includes a comparison of the life-cycle costs of three recent similar BOOT projects (Larnaca in Cyprus, Tampa Bay in Florida, and Trinidad) and identifies those parameters which have the most significant impact on the life-cycle water cost.

The success or failure of most medium and large plants in the region not only depends on efficient design, construction quality etc, but considerably depends on their operation and maintenance. Though most RO plants have state of art equipment and employ latest technology they lag behind substantially in specific areas of handson experience of their operation personnel due to which certain critical aspects get neglected and overlooked. This vital area inspite of being critically important, is probably the least appreciated. It is this most critical aspect which probably forms the weakest link in the chain and in most cases negatively impacts the RO plants in the Middle Eastern region. This paper attempts to outline several of such important O&M factors based on practical result oriented experience and underlines the benefits such experience contributes to the RO plants performance, availability and consequently to its total water cost.

The use of gas-fired backup heaters of poor efficiency or with a standing pilot imposes high penalties on solar hot water systems. With good backup heaters thermally coupled to the solar tank, large savings in fossil fuel can be obtained by building systems larger than optimum, at only slight increases in hot water cost.

The role of economic and social influences on water intake in humans was explored in two experiments. In the first experiment, the effect of water cost (as defined as the amount of effort required to acquire water) on prandial drinking was studied by manipulating water position during an ad libitum meal: water was available either on the dining table, about 20 feet from the table, or approximately 40 feet away. Subjects drank significantly more when the water was on the table than in the other conditions; but a linear relationship between cost (distance) and intake was not observed. In the second experiment, the effects of water cost and a social model on drinking were assessed in a similar paradigm. Increasing effort required to obtain water significantly reduced prandial water intake, and the presence of a social model increased water intake. Although some interesting trends emerged, no significant interactions between social and economic factors were found. These experiments demonstrate that environmental factors can significantly affect facultative drinking in humans.

The conventional pretreatment method is widely used to treat surface seawater feed for the seawater reverse osmosis (SWRO) process; however, this method is cumbersome and costly and has many drawbacks that lead to higher product water cost by RO desalination technology. This paper outlines the experience gained from 65 months of operation of a surface seawater conventional pretreatment system at the Doha Reverse Osmosis Plant (DROP) in Kuwait. The paper describes the pretreatment system used, problems and drawbacks encountered during the course of operation, namely: instability of Silt Density Index (SDI) value, high rate of chemical consumption, high rate of water consumption for backwashing and high energy consumption, and gives an economic assessment for the pretreatment system. The economic analysis shows that the cost for the conventional pretreatment system acounts for 26.7% of the total capital investment cost for a 4,546 m 3 /d two-stage spiral-wound (SW) RO system, similar to the one used at DROP. A 30% saving in unit product water cost could be achieved if a beachwell intake pretreatment system is used instead of the conventional pretreatment system.

The development and production of fresh water by reverse osmosis from the Arabian Gulf requires several considerations. Apart from those such as minimizing energy consumption, improved membrane performance, increased recovery and salt rejection, and increased chlorine resistance, materials selection and corrosion resistance make a significant contribution to the reduction in the product water cost. The state of the art for selection of appropriate corrosion resistance alloys for a specific enviromnent is not sufficiently advanced to make the choices for a specific environment obvious. It still remains necessary to perform laboratory and plant testing of candidate alloys to establish those alloys that may be suitable for use in a specific plant environment. Results of laboratory and plant testing of a number of candidate construction materials for the various components and pipings are described.

As a means to minimize or eliminate brine disposal problems, high recovery RO must be accompanied by pre- or post-treatment to avoid scale precipitation, almost entirely by CaSO4. All such methods will add to water cost. However, rigorous comparison must be made with the costs and constraints of brine disposal at recoveries low enough not to require these treatments. Such examination is invariably and totally site-specific. Prior to detailed design of any large RO facility, it is always prudent to invest in a pilot plant testing program, whereby membrane performance under varying recovery and flux may be evaluated on the raw feed to be used at full scale. Because of the even tighter design limits imposed at high recovery, pilot tests of combined membrane and treatment processes are absolutely essential.

Working with the population of the city does not just involve campaigns — it is a long-term, on-going process and it is a dialogue. It is not enough simply to tell people what to do. You have to come back all the time and show the results. It is a long process of learning and changing attitudes. The campaigns directed towards households and other consumer groups have been successful so far. Stockholm Water also intends to allocate considerable further resources to this type of activity. A changed attitude to environmental questions at consumer level is essential for the future work on water improvement. Finally, water and waste treatment for clean and healthy water cost a lot of money. One of the most important reasons for getting the inhabitants of the city involved in the work is to make them understand that a good environment requires financial sacrifices. People are prepared to make these sacrifices, if they feel the specified goal to be sufficiently meaningful and important. When we have increased charges in Stockholm, we have been careful to give an account of what the money is to be used for and how it will affect our drinking water, our health, our archipelago and the opportunities for swimming and fishing. Since Stockholm Water has started providing this information, complaints about increased charges have almost completely ceased. We regard that as a further measure of success for our work with the citizens of Stockholm. We are now working together with the water authorities in Riga to try out our ideas on water quality policies in a rather different environment.

Cogeneration power/desalting plants offer economic advantages over single-purpose plants. These advantages are derived from more efficient utilization of fuel and savings in capital investment costs of common components. The allocation of capital investment and operational costs could become a complex issue and a source of dispute. Two basic cost allocation methods have been established. These are the credit and available energy (exergy) methods. While most previous published studies have adopted the credit method, relatively very few have tackled the available energy method. Although the available energy method will typically predict power and water cost values from totally impartial standpoint, it has the disadvantage of being complex. This paper aims to preliminary examine the technoeconomics of large power/desalting cogeneration plants. Methods for the allocation of capital investment costs of different systems and operational costs will be established. Power generation and water production units costs are determined and related to the mode of operation. Sensitivity analysis with respect to systems lifetime, interest rate and fuel prices is also provided.

The use of the MSF process in seawater desalination is broad because of simplicity and reliability and an improvement of this process has been proven in the use of the fluidized bed heat exchanger. The choice of most economical gain ratio of a multi-stage flash evaporator is very dependent on energy cost, i.e. steam-and electricity cost. Because of lower investment and electricity costs the MSF/FBE has always lower product water cost than the MSF with equal gain ratio.

Solar distillation is a free energy operation, however low its efficiency because of low incident radiation. It requires a larger installation area for water production than other conventional desalination processes. Nevertheless it remains the best solution for remote areas and small communities where other water supply systems are not available. An overview is given of the economics of conventional solar distillation plants and on modern trends to combine collection of solar radiation with conventional desalination processes. A short description is also given of the influence of the investment cost on the product water cost.

In order to reduce the production cost of small capacity distilling plants, it is more effective to use a simple process and a simple evaporator mechanism than to take up some means of reducing the heat transfer area. In addition, ease of operation and trouble free operation are important factors in minimizing the water cost. We have developed the Reheat Type Distilling Plant for the purpose of satisfying these requirements, that is low cost, easy and trouble free operation. This paper cites the principle, process and mechanism of the evaporator.

It has been realised that the storage of water to be used during emergency cases will not be sufficient to meet water demand if emergency cases lasted for an unexpected period. This lead to the idea of having small mobile Reverse Osmosis desalination units installed at various sites in Kuwait and to serve essential communities such as hospitals and army camps. Consequently, the authors set specifications for the supply of thirteen Skid Mounted Mobile Brackish Water Reverse Osmosis units of capacity 250,000 IGPD, each. The units are identical in all aspects and utilizing low pressure membranes. This paper describes the operation, maintenance, performance and unit water cost of one of the units during one year continuous operation.

The effect of cell thickness and flow velocity on product water cost was investigated in order to obtain data for optimizing electrodialysis membrane stacks in water desalination. The calculations were carried out by means of a computer program; the experimental data were obtained from the determination of limiting current densities. The results indicate that a reduction of cell thickness to approximately 0.2 mm with a corresponding flow velocity of 0.13–0.17 m/s yields a cost minimum. However, this minimum cannot be identified exactly. Moreover it would be difficult to manufacture adequate sealing frames and to obtain a homogeneous flow distribution in such cells simultaneously. For industrial membrane stacks applied to water desalination, a cell thickness of 0.4–0.6 mm and a flow velocity of about 0.1 m/s seem to be the economically most reasonable design criteria.

The first seawater desalination plant by electrodialysis in the world started its operation in September, 1974 at Noshima island of Hofu city, Yamaguchi Prefecture, Japan. The capacity of the plant is 120 m3/day and the plant has been supplying fresh water from the sea for the 800 inhabitants of the island. Batchwise operation is utilized to simplify the process because of its relatively small capacity, but the operation is fully automatic to supply fresh water continuously using a storage of proper capacity. The water cost is relatively high but lower than that of conventional distillation processes of the same capacity.

An experimental RO seawater system has been in operation for two years at Eilat on the Red-Sea shore. Simplified seawater pretreatment, comprising only sand filtration and acid dosing was applied. Hollow fiber and spiral wound membranes were tested. Evaluation of pretreatment effectiveness and comparative membrane performances are reported. Investment and water cost analysis of a 4,000 m 3 /day RO seawater desalting system under various operating conditions is given. The analysis is based on the results of experimental site operation, current technology development and updated industrial quotations. The resulting water production cost from a one-stage system, adequate to produce desalted water acceptable for local drinking water standards, is approximately $ 1.1/m 3 .

This paper presents a short review of solar distillation followed by a description of conventional distillation methods and associated energy consumption. The paper then presents a system where solar energy is used to generate steam to drive a multieffect distillation plant. The system is optimized on the basis of minimum water cost . The analysis shows that enhancement of heat-transfer coefficients in the distillation section and increasing steam temperature from solar boiler result in lower water cost as well as increase the output per unit area of solar collectors. This study shows that a solar boiler producing saturated steam at 60 C in combination with an evaporator-condenser, developed and tested at this Laboratory, resulted in minimum water costs ranging from $1.40 to $3.70 per m3 for brackish water feed and $2.15 to $4.70 per m3 for seawater feed. At these conditions, the daily productivity per unit area of solar collectors ranged from 45 to 130 liters per m2. This study also shows that when the steam temperature was increased from 60 C to 88 C . the minimum water cost decreased from $2.15/m3 to $1.37/m3 for brackish water feed and from $3.60/m3 to $2.05/m3 for seawater feed. Also, at these conditions, the daily productivity per unit area of solar collector increased to 288 l/m2 for brackish water feed and to 151 l/m2 for seawater feed. These predicted values for the daily productivity are as much as seventy times the average productivity of simple solar stills at the assumed value of solar insolation.

An Idea to use a cement concrete as an evaporator shell material of a desalting plant is expected to lead to reduction of product water cost, as well as realization of durable and maintenance-free evaporator shell. p]Based upon the above idea, series of fundamental researches had been carried out on the subject such as resistivity of concrete exposed to hot sea water and hot distilled water, and changes of concrete properties exposed to an elevated temperature, which were followed by the studies on structural problems related to thermal stresses and air permeability of concrete evaporator shell. As the results of the research, the study using Test Plant with concrete evaporator shell modules was started in order to solve problems which would be encountered on the way of design, construction and operation of the plant, obtaining many Know-Hows and Experiences which lead to the design, construction and operation of the 100,000 m3/day Test Module Plant.

This paper considers distillation systems where all the plant's thermal energy requirements are provided by solar energy. Fairly small capacity plants are considered operating in remote arid regions. Such systems consist of solar collectors and thermal storage coupled to a distillation plant. Each of these aspects is considered as well as the type of control strategy to be used. Using a dynamic computer simulation model, two solar-driven systems are considered: one using flat-plate collectors and a 76°C MEE desalination plant, the other using evacuated tubular collectors and a 95°C MEE plant. Various combinations of collector area and thermal storage volume are considered, and optimal values determined for each case. For the particular example chosen (lOOm3/day, located at 23 1 2 °S) the flat-plate collector system was superior at current prices, giving an overall water cost of $5.82/m3 versus $7.34 for the second system. Both these costs are considerably less than water costs from conventional solar stills.

The current and the near-term thermal converters and the long-range fast breeders for seawater desalination are analyzed based on the fundamental principles, present technology and future development of nuclear reactors. By using the available data of light-water reactors, the trends of current and near-term thermal converters and long-range fast breeders are predicted and discussed. The unit plant cost, and the total nuclear power cost (consisting mainly of the fixed charge, the fuel cycle cost and the operating, maintenance cost) versus the cumulative and the net plant capacity (or reactor size) are respectively shown by curves. The first and the equilibrium core costs and the plant thermal efficiency versus the cumulative plant capacity are illustrated. The comparison of water cost versus net plant capacity and plant load factor for the single-purpose and the multipurpose nuclear desalting plants are also given. The feasibility and development of nuclear agro-industrial complexes and the vertical tube evaporators for desalting seawater technology are briefly discussed.

Multi-stage flash distillation and multiple effect boiling distillation are not entirely different processes, but the two ends of a continuum. The defining variable in the continuum is the rate of brine circulation relative to distillate product. The multi-stage flash “end” is characterised by morphological simplicity as compared with the MEB end which is morphologically complex. This simplicity is obtained at the cost only of increased circulation, i.e. pumping power. No water cost improvement is obtainable from the MEB system except by increasing performance ratio well beyond that achieved by multi-stage flash up to date. Multi-stage flash systems can be designed to give higher performance ratios also, and it is to this end that effort should be directed with greater acumen All argument for reversion to the MEB system is based on the assumption that in the VTE film boiling embodiment assured high heat transfer coefficients can be obtained and maintained in practice.