Javier Uche

Thermoeconomic optimization of a dual-purpose power and desalination plant

Abstract The thermoeconomic optimization of an actual steam power plant coupled with a MSF desalination unit is reported. A global optimization of the whole system is performed based on separated local optimizations of different plant units. The local optimization procedure described herein requires fewer computing resources and deals with simpler mathematical problems than conventional optimization methods. On the other hand, the local optimization method requires a thermoeconomic model providing the exery and economic costs of all mass and energy flows of a plant, including those corresponding to fresh and electricity produced. This application can be very useful, either for the plant management in order to achieve a cost-effective operation, and for a better plant design. In the example given, approximately 11% of the total cost was saved according to the optimization results in the nominal operating conditions of the plant.

Comparison of heat transfer coefficient correlations for thermal desalination units

This paper presents several simulator models allowing studying the behavior of different types of thermal desalination plants [1]. Three types of evaporators have been distinguished in thermal desalination plants: horizontal falling film evaporators (HFF), vertical falling film evaporators (VFF) and vertical rising film evaporators (VRF). An in depth study of the correlations adopted to calculate the heat transfer coefficients (HTC) of the selected evaporator/condenser has been made, in order to predict the plant performance of dual-purpose plants. Once the sensitivity analysis of the possible HTC has been done, the selected HTC has been implemented in a complex simulation model of MSF and MED/VC/TVC desalination units. Validation (if possible) of the calculated HTC was also done with the real data encountered in the literature.

Hybrid desalting systems for avoiding water shortage in Spain

This paper presents the economic analysis of the Ebro River transfer (a total amount of 1.050 hm 3 /y) presented for the Spanish Government in his project for the National Hydrologic Plan and its alternative: drinking water obtained from desalination plants. In this paper is proved that the cost of the desalted water is similar to the transferred one, by using conventional reverse osmosis (RO) methods or hybrid methods combining thermal and membrane desalination processes. The sensitivity analysis of the desalting alternative is mainly restricted to the plant size and the energy prices (natural gas or electricity). The new concepts of the global cycle of non-conventional water resources (desalt, use and recycle) is also introduced in order to decrease the water cost for urban supply.

Software for the analysis of water and energy systems

Water and energy are crucial aspects strongly connected when dealing with the problem of augmenting fresh water resources. Surprisingly, in the scientific and technological community there is a marked lack of attention to the combined research of water and energy issues. The present paper outlines a development-oriented object program in the said direction, oriented to the integrated analysis of power and desalination plants, which would hopefully fill the gap in having user-friendly software in the form of building blocks as an appropriate framework for the analysis, synthesis and design of either individual or integrated systems for energy and water. Such an approach would transcend other traditional approaches for process integration and obviously prove of great help not only to designers but also to researchers, educators and students. For illustrative purposes, in order to show the scope of the software being developed, an example is presented in which two different operation conditions of a dual-purpose power and desalination plant are compared. In particular, the effect of the throttling part of the steam extracted to the desalination unit is analyzed, which significantly increases the cost of water and electricity produced.

Life cycle analysis of urban water cycle in two Spanish areas: Inland city and island area

Abstract In this paper, the results of the complete life-cycle assessment (LCA) analysis of the water cycle in two Spanish urban areas are presented. First case study was Zaragoza city (700,000 inhabitants), with enough surface water resources for drinking purpose. Second case was the Mancomunidad del Sureste, a highly populated and touristic area in a water-scarce island (Gran Canaria). Main objective of the paper was to show, from an environmental global perspective, which was the relative pollutant weights of the diverse water cycle stages in an urban area, in order to put the efforts in reducing the environmental penalties associated to the water cycle. Results showed that environmental load associated to energy consumed in dwelling uses (to produce hot sanitary water) exceeded by far the environmental impact provoked by water cycle infrastructures (water treatment plants, water supply and drainage networks, and wastewater treatment plants). Additionally, it is very important to remark that new water ...

Exergy as a guide to allocate environmental costs for implementing the Water Framework Directive in the Ebro River

Abstract The Physical Hydronomics (PH) methodology is a tool to properly calculate restoration cost of water resources (regarding to quality degradation of water as well as water quantity losses) in the framework of the Second Law of Thermodynamics. It is based on the exergy, a thermodynamic property that can be understood as the minimum energy needed to restore a resource from its reference environment. An opportunity that methodology brings up is the development of River exergy profiles which can be represented along the length of the river, for different periods and degradation statuses. Focusing on the Water Framework Directive milestones, the most relevant contribution which is presented here is the assessment of restoration cost among diverse water polluters from physicochemical parameters of the river. The case study which is developed is the Ebro basin, a very representative Mediterranean river in Spain. Figures shown that quality restoration costs, found in the agriculture user resulted to be the...

Batch ED fed by a PV unit: a reliable, flexible, and sustainable integration

Abstract Electrodialysis (ED) is a reliable technique to produce drinking water from brackish raw water sources. If the ED unit is fed by a photovoltaic (PV) generator, water production maybe also understood as sustainable. In this paper, the feasibility of a small and easily operating batch ED pilot plant powered by PV modules or by a rectifier (electrical grid connection) was studied in depth. First, a mathematical model was implemented in order to predict the batch ED-FV pilot plant behavior. Then, numerous tests were carried out at the experimental installation. Some relevant parameters were studied: the influence of NaCl concentration (600–10,000 ppm), the applied voltage (8–12 V), and the configuration of PV array, as well as environmental conditions. Different optimal operating conditions were investigated depending on the batch ED energy source: if the ED stack was fed by the rectifier, the lowest specific energy consumption or maximal production was followed. On the contrary, when it was fed by t...

DESALINATION AS A SUSTAINABLE SOURCE OF FRESH WATER PROVISION

This paper analyzes the potential role of desalination as a sustainable source of fresh water provision, starting from the present framework and considering the trends in the desalination technology. Several aspects have been reviewed: the state of the art of the technology, focusing the attention on the most widespread desalination technologies; the importance of desalination in the different regions of the World and the future trends; the economic costs of desalted water and the uses derived from those costs, the environmental charges provoked by desalination and their possible corrective measures to be undertaken; future improvements expected for desalination technology, and their economic consequences. Particular attention is focused to environmental issues and integration of desalination with other productive processes, particularly with energy production systems as a mean of dramatically reduce the environmental loads provoked by desalination systems.

A study of the application of the physical hydronomics methodology to assess environmental costs of European rivers

Purpose – The purpose of this paper is to check out the status of collected data in European water-related information tools, with the final aim of analyzing the cost to reach the good environmental status in European rivers, from recorded physical and chemical data, within the second law of thermodynamics. Design/methodology/approach – The study is especially focussed in an economical assessment to account for the environmental costs of water bodies according to the Water Framework Directive. The Catchments and Rivers Network System, the most important information tool in Europe nowadays, constitutes the support of this work. This study shows a methodology to estimate the cost to restore water bodies in energy terms with the help of an aggregated indicator, from physical and chemical characteristics of rivers. More over, energy results are converted later into an economic value. This work presents diverse case studies, starting from Garonne, Rhone, Rhine, Danube, Ebro and Seine rivers. Findings – Figures...

Assessment of Water Resources by Exergy Cost

This chapter presents the application of exergy analysis to water bodies focusing the attention on the assessment of the exergy cost. It comprises three different but clearly connected sections: exergy cost of water technologies, exergy value of the hydrological cycle and fundamentals, and application and results of the Physical Hydronomics methodology. The exergy cost is a key parameter to be included in any water analysis regarding exergy efficiency. It measures the goodness of the considered technological process when it is compared with the ideal one and it is used to translate the objective exergy measurements into economic figures. The unit exergy cost of water technologies is introduced both in the analysis of the exergy value of the natural hydrological cycle and in the calculation of water costs. In particular, Physical Hydronomics is defined as the application of the exergy analysis to the assessment of costs of water bodies and it has presented interesting results when considered in the European Water Framework Directive implementation for Spanish and European watersheds. The background and main results of these three mentioned issues are presented along this chapter.