Unit Cost Of Water Research Articles

English

A solar photovoltaic (PV) water pumping system was investigated to determine performance and economic viability. An in-built data logger was used to collect real time data on key performance parameters. Performance indicators were defined and determined, while economic viability was analyzed using life-cycle cost (LCC) method and these costs were compared with a diesel generator pumping system. Solar irradiance varied from 63 W/m2 to a peak of 857 W/m2, corresponding to a maximum power output of 11.75 kW. PV array efficiency of 12.1%, sub-system efficiency of 91.82% and overall efficiency of 5.14% were obtained, which are well comparable to the efficiencies reported elsewhere for similar systems. The LCC analysis showed a 20 year average unit water cost of 0.25 US $/m3 for solar PV system and 0.6 US $/m3 for diesel genset system. Solar PV system is found to be more cost effective and suitable for use over conventional sources. Key words: Photovoltaics, water pumping, life-cycle cost analysis, efficiency, unit water costs, diesel generator.

Comparing Pre-Paid Communal Water Metering and Delegated Management in Urban Poor Setting: Case Studies in Nakuru and Kisumu in Kenya

Water service providers face multiple challenges in their service provision. These challenges include high non-revenue water, low water coverage, many incidences of waterborne diseases, and high water bills, etc. This study set to assess how changes in water metering strategies can overcome these challenges. The study analyzed three water metering technologies for their suitability to improve service provision. The strategies were: conventional water metering where meter-readers collect readings for post-billing; community prepaid metering (CPM) where meters are preloaded with tokens; and delegated meter management (DMM) where service provision and billing is delegated to master operators. CPM and DMM were installed in an existing conventional network and data on commonly-used performance evaluation parameters collected through interviews, field-visits, and existing literature. The results portrayed CPM and DMM with positive improvements to the conventional metering. CPM had over 70% improvements in unit cost of water and time for water access. DMM had over 90% improvements in water coverage and non-revenue water. In general, the study found CPM with positive impacts on the cost of water, potable water, and time to fetching water while DMM had positive impacts on water coverage and non-revenue water. It’s recommended that the CPM and DMM models used in this study be cross-tested and more individual strengths be drawn.

Application of micellar-enhanced ultrafiltration in the pre-treatment of seawater for boron removal

In this research, micellar enhanced ultrafiltration (MEUF) is tested as a seawater pre-treatment before entering RO. The experimental tests were performed by means of monotubular ceramic membranes of 210kDa and 1kDa. Boron is removed from the water flow using sodium dodecyl sulphate as a surfactant. The synthetic solutions contain 5mg/L of boron and SDS concentrations are equal to 1.15g/L and 2.88g/L, under and above the critical micellar concentration, respectively.Experimental data showed that MUEF is efficient in removing boron, with best performances obtained at low pressure, with a low or null surfactant concentration for 1kDa membrane and a high surfactant concentration for 210kDa membrane. Moreover, experimental results have been used to perform a preliminary process analysis for a hypothetic sea-water desalination plant, with MEUF as a pretreatment for the RO section. The results showed that the MEUF guarantees a boron concentration after RO below the allowed threshold, by using a single step osmosis; moreover, in this way it was possible to reduce the energy consumption thus resulting in an appreciable reduction of carbon footprint as well as of the unit cost of water.

Optimal design of spacers in reverse osmosis

Spiral-wound membrane (SWM) modules are the most common membrane configuration utilized in reverse osmosis (RO) and nanofiltration. The enhancement of SWM module design, particularly in the geometric design of the feed spacer, can play a crucial role in the cost and the potential for wider application of these modules. The feed spacer influences the flux, pressure losses and fouling in the membrane process and consequently the product water unit cost. Despite the shift in the application of SWM modules of RO toward low salinity sources and the resulting higher sensitivity performance using these waters, the configuration and orientation of feed spacers have not significantly changed since the original design. A wider use of SWM modules, therefore, requires the adaptation of geometric parameters of the feed spacer to the water source. Improving the feed spacer's design according to the feed water type requires the knowledge of previous studies conducted in spacer-filled channels as well as further needed investigations in future. This paper reviews the role of the feed spacer in SWM modules and provides an overview of studies conducted in narrow spacer-filled channels to determine the effect of different geometric characteristics of the feed spacer on hydraulic conditions.

Energy, exergy and exergo-economic analysis of different water desalination technologies powered by Linear Fresnel solar field

The integration of Multi Effect Desalination (MED) unit with and without Thermal Vapor Compression (TVC) system into the Linear Fresnel Rankine Cycle (LFRC) was investigated for different seawater temperatures when it is located at the regions with different solar radiation levels. A comparison was made between the fresh water costs of the dual purpose LFRC/MED (or LFRC/MED/TVC) plants and the case when the MED and MED/TVC systems use direct steam of the LF solar field to produce fresh water (LF/MED & LF/MED/TVC). The water production costs of the described dual purpose plants were compared with that of the LFRC/Reverse Osmosis (RO) plant (LFRC/RO). An exergo-economic analysis was performed to determine the water unit costs of the plants. The results show that the fresh water costs of the LF/MED and LF/MED/TVC configurations are higher than that of the dual purpose plants. Also, it was shown that the fresh water cost is more affected by solar radiation level rather than seawater temperature of a region. It was also found that at fuel prices of 0.23$/m3, the water production costs of fuel based dual purpose plants would be equal to that of the plants with solar thermal source.

Experimental evaluation of a low pressure desalination system (NF-PV), without battery support, for application in sustainable agriculture in rural areas

Desalination driven by solar energy represents an appealing solution for agricultural irrigation in remote areas. In this work, a desalination system based on a photovoltaic-powered nanofiltration (NF-PV) membrane is studied. The experimental work explored the effect of the influent concentration and solar radiation on permeate production, energy consumption, recovery rate and quality of the permeate product. Four cases of different inlet conditions of influent concentrations were studied. In each set, the influent concentration was kept constant, varying only the irradiance along the solar day. In addition, a unit cost of permeated water was estimated. The maximum tested energy consumption was 1.55 Kwh m−3, with a concentration of 2,539 mg L−1 of total dissolved solids. The NF-PV system produces 2.16 to 4.8 m3 d−1, with a permeate water unit cost of 1.05–0.47 US$ m−3.

Proposal and performance assessment of novel combined ORC and HDD cogeneration systems

In this paper, four combined cogeneration systems including the Humidification-Dehumidification Desalination (HDD) and Organic Rankine Cycle (ORC) are investigated from thermodynamic and economic viewpoints. In the first scenario, the outlet water flow of ORC condenser enters the HDD directly as feed water. In the second scenario, the temperature of ORC condenser outlet water rises in a heat exchanger by the ORC evaporator heat source outlet flow before entering the HDD. In the third scenario, the ORC evaporator heat source outlet flow passes through a heat exchanger to heat the HDD feed water. The fourth scenario is a combination of scenarios (I) and (III) so that it contains both of them in one configuration. In all the scenarios the ORC waste heat either from its condenser or evaporator is utilized. Results show that the ORC with toluene produces more power and that scenarios (IV) and (II) produce more desalinated water compared to the other scenarios. It is also observed that, compared to seven working fluids, using n-heptane as a working fluid in these two scenarios results in the highest distilled water production rate. It is concluded that the least distilled water unit cost is achieved by the scenarios (I) and (II), respectively and that using n-heptane, among the other working fluids, brings about the least unit cost for produced distilled water.

Analiza kosztów nieużytkowania lub organiczenia wielkości poboru wody z zakładu uzdatniania wody Goczałkowice

Górnośląskie Przedsiębiorstwo Wodociągów (GPW S.A.) jest największym systemem zaopatrzenia w wodę w Polsce z 11 stacjami uzdatniania wody i 3 mln konsumentów. Jednak system ten jest stopniowo rozmontowywany. Lokalne przedsiębiorstwa wodno-kanalizacyjne rozbudowują własne ujęcia wody lub importują wodę z Czech, traktując system GPW S.A. tylko jako źródło rezerwowe. Jest to efekt wzrastających kosztów jednostkowych wody dostarczanej przez GPW S.A.Koszty te cześciowo są związane z utrzymywaniem zbiorników przeciwpowodziowych oraz dodatkowymipodatkami. Zakład Uzdatniania Wody Goczałkowice jest głównym, najnowocześniejszym i najtańszym producentem wody w systemie GPW S.A. Wobec tego całkowita rezygnacja z poboru wody z tego źródła jest mało realna. Jednakże ograniczenie poboru wody z zakładu Goczałkowice zmniejszyłoby konkurencyjność tej stacji w wyniku wzrostu średnich kosztów stałych. Bardziej racjonalne byłoby ograniczenie produkcji w innych stacjach uzdatniania wody. Ponadto, ze względu na spływ grawitacyjny, pobór wody z Soły przez zakład Goczałkowice jest bardziej opłacalny niż pobór z innych źródeł.

Techno-economic analysis of sustainable water management techniques - a case study of residential township in India

Technically efficient and economically viable methods of rooftop rainwater harvesting, greywater recycling and use of low flow devices for integrating in residential townships are identified. An integrated tool is developed for generating designs of identified techniques along with the estimates of capital costs required for installation and the total net present cost. It also calculates potential of water saving. A case study of a residential township in Nagpur, India has been presented. Unit cost and current net value of water using these techniques are calculated. Unit costs of water per cubic meter using rainwater harvesting, low flow devices and greywater recycling are found to be INR 230 (1USD = INR 55), INR 38 and INR 124 respectively. The current net value of water saved using rainwater harvesting; low flow devices and greywater recycling are INR 388,080 INR 162,437 and INR 70,560. Total cost of installation of these three techniques for the case study of residential township is INR 19,813,866, i.e., only 1.14% of the total cost of the project. This study enables prioritisation of practicing rainwater harvesting, use of low flow devices and greywater recycling for conservation of water as well as evaluation and allocation of the percentage of land area required for these techniques.

Technoeconomic study of a novel integrated thermal MSF–MED desalination technology

This work presents a novel integrated MSF–MED thermal desalination technology and its techno-economics as compared to conventional systems such as MSF-BR, MED-TVC, MSF-OT-LT and plain MED. The new integrated MSF–MED benefits from (i) high top brine temperature (TBT) of natural dilution seawater feed of the once through (MSF-OT), (ii) lower pumping power of long tube MSF-LT, and (iii) the low heating steam quality and cost of MED.The process calculation showed that the pumping power of the integrated MSF–MED is 58% lower than that of the traditional MSF-BR while it is 16%, lower than that of MED-TVC. The cost analysis showed that at subsidized oil price of 12$/bbl, the unit water cost of the integrated MSF–MED is 32% lower than that of MSF-BR and 21% lower than that of MED-TVC. The unit water cost of the integrated MSF–MED is the lowest value when the oil price is lower than 40$/bbl. This result showed the superiority of the integrated MSF–MED configuration for GCC countries since the oil price is generally subsidized. It also has a chance to utilize a diverse available energy such as waste heat and steam from backpressure or condensing turbine.

OPTIWAM: An Intelligent Tool for Optimizing Irrigation Water Management in Coupled Reservoir–Groundwater Systems

An approach based on a real coded Genetic Algorithm (GA) model was used to optimize water allocation from a coupled reservoir-groundwater system. The GA model considered five objectives: satisfying irrigation water demand, safeguarding water storage for the environment and fisheries, maximizing crop water productivity, protecting the downstream ecosystem against elevated soil salinity and hydromorphic issues, and reducing the unit cost of water. The model constraints are based on hydraulic and storage continuity requirements. The objectives and constraints were combined into a fitness function using a weighting factor and the penalty approaches. The decision variable was water allocation for irrigation demand from reservoir and groundwater. The irrigation water demands around the reservoir were estimated using the Food and Agriculture Organization (FAO) Penman-Monteith method in the water evaluation and planning (WEAP) software. The deterministic GA model was coded using Visual Basic 6 and a new tool for irrigation water management optimization (OPTIWAM) was developed. To validate the applicability of the deterministic model for the operation of coupled reservoir-groundwater systems, the Boura reservoir (in the center-west region of Burkina Faso) and the downstream irrigation area were used as a case study. Results show that the proposed methodology and the developed tool are effective and useful for determining optimal allocation of irrigation water. Furthermore, the methodology and tool can improve water resources management of coupled reservoir-groundwater systems.

Economic feasibility of large scale PV water pumping applications utilizing real field data for a case study in Jordan

Economic viability of photovoltaic, diesel and grid connected water pumping systems is investigated and compared for system capacities in the range 1500 m4/day to 100,000 m4/day. Actual performance data from installed systems are considered in calculating systems outputs for base case scenarios. Sensitivity analysis is carried out to generalize results for other locations and conditions. Several scenarios of the effect of variation electricity tariffs, components prices, diesel fuel prices, operation cost and interest rate on the output water unit cost (US$/1000m4) are investigated. Breakeven points of PV pumping systems are determined at certain input parameters.

Problems in seawater industrial desalination processes and potential sustainable solutions: a review

Seawater desalination has significantly developed towards membrane technology than phase change process during last decade. Seawater reverse osmosis (SWRO) in general is the most familiar process due to higher water recovery and lower energy consumption compared to other available desalination processes. Despite major advancements in SWRO technology, desalination industry is still facing significant amount of practical issues. Therefore, the potentials and problems faced by current SWRO industries and essential study areas are discussed in this review for the benefit of desalination industry. It is important to consider all the following five components in SWRO process i.e. (1) intake (2) pre-treatment (3) high pressure pumping (4) membrane separation (performance of membranes and brine disposal) and (5) product quality. Development of higher corrosion resistant piping materials or coating materials, valves, and pumps is believed to be in higher research demand. Furthermore, brine management, that includes brine disposal and resource recovery need further attention. Pre-treatment sludge management and reduced cleaning in place flush volume will reduce the capital costs associated with evaporation ponds and the maintenance costs associated with disposal and transportation reducing the unit cost of water.

Valuing flexibilities in the design of urban water management systems

Climate change and rapid urbanization requires decision-makers to develop a long-term forward assessment on sustainable urban water management projects. This is further complicated by the difficulties of assessing sustainable designs and various design scenarios from an economic standpoint. A conventional valuation approach for urban water management projects, like Discounted Cash Flow (DCF) analysis, fails to incorporate uncertainties, such as amount of rainfall, unit cost of water, and other uncertainties associated with future changes in technological domains. Such approach also fails to include the value of flexibility, which enables managers to adapt and reconfigure systems over time as uncertainty unfolds.This work describes an integrated framework to value investments in urban water management systems under uncertainty. It also extends the conventional DCF analysis through explicit considerations of flexibility in systems design and management. The approach incorporates flexibility as intelligent decision-making mechanisms that enable systems to avoid future downside risks and increase opportunities for upside gains over a range of possible futures.A water catchment area in Singapore was chosen to assess the value of a flexible extension of standard drainage canals and a flexible deployment of a novel water catchment technology based on green roofs and porous pavements. Results show that integrating uncertainty and flexibility explicitly into the decision-making process can reduce initial capital expenditure, improve value for investment, and enable decision-makers to learn more about system requirements during the lifetime of the project.

Mathematical Model and Numerical Experiment of Photovoltaic Water Pumping System

This paper presents the engineering analytical models of photovoltaic (PV) water pumping system from electronics theory, and some mathematical models of system components have been established. Studies have shown that the minimum unit water cost may not be reached only with the control strategy of maximum output power of the system. Therefore, system optimization is very necessary to reducing the capacity for every unit of pumped water, which is based on the design optimization theory and has shown its economics.

Comparative assessment of feasible options for delivery of potable water to remote coastal locations: North-West Egypt

Growing potable water demand associated with water shortage in remote coastal communities mandates identification and evaluation of viable water supply options. This paper addresses technical and financial analysis of water supply options in northwest Egypt as a typical remote coastal community on the Mediterranean. Water supply and energy availability are the main challenges hindering possible potential development schemes. Population reallocation programs being the core of any development plan should rely upon availability and accessibility of water and energy resources. The technically feasible proposed options for water supply scenarios to northwest Egypt comprise long-distance water transfer pipeline (LDWTP), large-scale desalination, or a combination of the two. Each option has been incorporated with a water reuse component and investigated for a daily capacity of 200,000 m3/d of fresh water. Since all the options are energy intensive in nature, they have been assessed from economic and energy standpoints. Thus, both conventional and small nuclear energy supply schemes have been considered. The estimated capital costs were $M 741.9, 260.0, and 634.5, while the unit water costs were $/m3 0.92, 0.73, and 0.81 for LDWTP, desalination and joint LDWTP/desalination options, respectively. The merits of cost-effectiveness, energy saving, technical reliability, and environmental aspects were manifested by the second proposed option.

Modeling of air-gap membrane distillation process: A theoretical and experimental study

A one dimensional (1-D) air gap membrane distillation (AGMD) model for flat sheet type modules has been developed. This model is based on mathematical equations that describe the heat and mass transfer mechanisms of a single-stage AGMD process. It can simulate AGMD modules in both co-current and counter-current flow regimes. The theoretical model was validated using AGMD experimental data obtained under different operating conditions and parameters. The predicted water vapor flux was compared to the flux measured at five different feed water temperatures, two different feed water salinities, three different air gap widths and two MD membranes with different average pore sizes. This comparison showed that the model flux predictions are strongly correlated with the experimental data, with model predictions being within +10% of the experimentally determined values. The model was then used to study and analyze the parameters that have significant effect on scaling-up the AGMD process such as the effect of increasing the membrane length, and feed and coolant flow rates. The model was also used to analyze the maximum thermal efficiency of the AGMD process by tracing changes in water production rate and the heat input to the process along the membrane length. This was used to understand the gain in both process production and thermal efficiency for different membrane surface areas and the resultant increases in process capital and water unit cost.

A cost perspective for long distance ore pipeline water and energy utilization. Part II: Effect of input parameter variability

The simultaneous efficient use of water and energy in long distance hydraulic transport of copper or iron concentrates in dynamic energy and/or water cost scenarios has been recently studied as an optimization problem (Ihle, Int. J. Miner. Process, 2012, submitted), including static input parameters of hydraulic interest, such as the specific gravity of solids, slurry particle size distribution and loose packing concentration. It is common that such variables fluctuate throughout the concentrate line operation, and thus the optimal estimated values in the light of the aforementioned optimization model. In the present paper, a continuation of the latter analysis including the effect of input parameter variability by means of a Monte Carlo analysis is proposed. Results show that, under a variety of unit water and energy cost scenarios, lack of process follow-up in front of relatively small variations of input parameters might cause important effects in optimal water and energy consumption, ultimately resulting in increased operational costs. By taking a copper concentrate long distance pipeline example case detailed in Ihle (2013b), present simulations reveal fluctuations on water and energy use close to 8% and 17%, respectively, whereas total costs may have variations up to 18%.

Technoeconomic analysis of once through long tube MSF process for high capacity desalination plants

This work presents a technoeconomic comparison between once through long tube (MSF-OT-LT) with atmospheric deaerator, and brine recycle cross tube (MSF-BR-CT) evaporators. The process design and cost analysis of 30 MIGD MSF-OT-LT evaporator is presented.The process calculations showed that for the same performance ratio, the heat transfer area of MSF-OT-LT is 34% lower than that of MSF-BR evaporator. This is due to the flashing range increase and higher heat transfer coefficient of MSF-OT-LT configuration. The pumping power of the MSF-OT-LT is 40% lower than that of MSF-BR-CT evaporator. This is due to lower friction loss in the tubes and due to remove brine recycle pump. A novel configuration of MSF-OT-LT is proposed in which the stages are arranged in a triple deck. The footprint decreases up to 57% in the large size project of 150 MIGD.For a large size project of 150 MIGD capacity, the unit water cost of the MSF-OT-LT configuration is 36% lower than that of the MSF-BR-CT. It can be concluded from this study that the MSF-OT-LT evaporator is a viable option for large scale capacity and a reliable technology for poor quality and high salinity sea water.

Exergoeconomic analysis and performance assessment of hydrogen and power production using different gasification systems

In this paper, we investigate three different gasifiers for hydrogen production, namely, downdraft gasifier (DG), circulating fluidized bed gasifier (CFBG) and plasma gasifier (PG) as taken from the literature under Cases 1–3, respectively. These cases are then modified for cogeneration of hydrogen and power. We use the specific exergy cost (SPECO) method to calculate exergy-related parameters and display cost flows for all streams and components. The case studies are selected from different countries. We study how flow rates of streams cost and hydrogen unit costs change if these facilities operate in Turkey. The process life time is considered 15years, and the inflation rate and energy inflation rate are taken from the Central Bank of the Republic of Turkey as 8.91% and 19.25% while unit energy, water and biomass costs are taken 31.38$/GJ, 4.59$/t and 35.42$/t for Turkey, respectively. The electric power requirements are calculated to be 0.0915, 12.53 and 23.26MWe for DG, CFBG and PG, respectively. In Cases 1–3, the electric power generated by the systems are 0.144MW, 1.17MW and 3.88MW, respectively and may be sold to the national grid with cost rates of 31.8$/h, 258.39$/h and 856.88$/h. In the systems, the hydrogen production rates and costs per unit mass are obtained to be 0.004kg/s, 0.521kg/s and 0.155kg/s and 1.16$/kg, 3.33$/kg and 2.45$/kg for the DG, the CFBG and the PG, respectively.