Lourdes García-Rodríguez

Seawater desalination driven by renewable energies: a review

This paper deals with seawater desalination systems driven by renewable energies. A review of pilot plants and perspectives of development is presented. There are many reasons why the use of renewable energies in seawater desalination is suitable, especially for remote areas where conventional energy supply and skilled workers are not usually available. Nevertheless, desalination systems driven by renewable energies are scarce and they tend to have a limited capacity.

Economic analysis of wind-powered desalination

Abstract Wind-powered desalination is one of the most promising uses of renewable energies for seawater desalination. The influence of the main parameters on the levelized cost of fresh water was analyzed: climatic conditions, nominal power of the wind turbine, salt concentration of seawater or brackish water, design arrangement, operating conditions, plant capacity, cost of reverse osmosis modules and cost of wind turbines. In addition, the competitiveness of wind power vs. conventional energy in reverse osmosis plants was studied. Results obtained are useful, not only to quantify the influence of the parameter studied, but also to system design and to evaluate the economic perspectives of this technology.

Comparison of solar thermal technologies for applications in seawater desalination

This paper deals with a global analysis of the use of solar energy in seawater distillation under Spanish climatic conditions. Static solar technologies as well as one-axis sun tracking were compared. Different temperature ranges of the thermal energy supply required for a desalination process were considered. At each temperature range, suitable solar collectors were compared in some aspects as: (1) fresh water production from a given desalination plant; (2) attainable fresh water production if a heat pump is coupled to the solar desalination system; (3) area of solar collector required for equivalent energy production. Results showed that direct steam generation (DSG) parabolic troughs are a promising technology for solar-assisted seawater desalination.

Exergy analysis of the SOL-14 plant (Plataforma Solar de Almería, Spain)☆

Abstract In July, 1988, the first start-up of a solar multi-effect distillation system took place at the Plataforma Solar de Almeria, a solar research centre located in southeastern Spain, near Almeria. The plant, known as “Sol-14”, is still in operation. The plant was built and connected to the previous existing solar facilities as a result of a Spanish—German project, which consisted of two phases. The main purpose of Phase I was to study the reliability and feasibility of solar desalination. The objective of Phase II was the design and implementation of those improvements that could make solar thermal desalination more competitive. The initial vacuum system was replaced, and a double-effect absorption heat pump was coupled to the MED plant that was already installed. This solar desalination system was thermodynamically analyzed in order to propose possible improvements of the system. This study complements previous sensitivity analyses of the Sol-14 plant. Further thermoeconomic evaluation of these suggestions, which are out of the scope of this paper, will permit optimization of the system.

Perspectives of solar-assisted seawater distillation

Abstract The use of solar energy in thermal desalination processes is one of the most promising applications of renewable energies to seawater desalination. A solar distillation system may consist of two separated devices—the solar collector and the distiller—or of one integrated system. The first case is an indirect solar desalination process, and the second one is a direct solar desalination. This paper deals with indirect solar desalination and its perspectives in the future. First, a summary of existing plants was given. Second, different technologies were compared. Finally, the possible improvements of thermal solar and seawater distillation technologies were considered in order to analyze the perspectives of the competitiveness of solar vs. conventional energy in seawater desalination.

Preliminary design and cost analysis of a solar distillation system

In this paper different solar systems of seawater distillation are proposed and economically analyzed. The solar collectors are parabolic trough ones in which brine circulates as thermal fluid. Steam is directly obtained from circulating brine. The solar collector field could be connected to condenser/preheater heat exchangers; nevertheless, the system would have a low performance ratio. In addition, the solar collectors could be coupled to multi-stage flash or multi-effect distillation systems to continue the evaporation of the remaining brine. The steam generated by the solar field would drive the distillation plant. The above systems are analyzed in comparison with other solar distillation ones as follows: a multi-effect distillation plant connected to a solar field in which steam is directly generated from fresh water, and a multi-stage flash plant that uses parabolic trough collectors as the brine heater. The specific cost of the product is evaluated for different climatic conditions, plant capacities, cost of the solar collectors, and costs of a conventional energy supply. Results obtained are useful in preliminary cost evaluation of the proposed solar distillation systems.

Thermoeconomic analysis of a solar parabolic trough collector distillation plant

Abstract Thermoeconomy, which is based on the Systems Theory and the Second Law of Thermodynamic, gives strategies for diagnoses and control of energetic systems (these are systems which consume great amounts of energy). In this paper a thermoeconomic analysis of a multi-stage flash and a multi-effect distillation plant coupled to a solar parabolic trough collector field have been made. The analysis was particularized to the climatic conditions of the Plataforma Solar de Almeria (PSA), a research centre in southeastern Spain, and could be generalized to coastal areas in southern Spain. Conclusions of this paper are useful for designing, for preliminary evaluation of distilled water cost, and for finding possible improvements in solar parabolic trough collector distillation plants. In addition, the importance of knowing in detail the climatic conditions (especially irradiant transients), for designing and for cost evaluation, is pointed out.

Design parameter selection for a distillation system coupled to a solar parabolic trough collector

In this paper a seawater multi-stage flash and a multi-effect distillation system, coupled to a solar parabolic trough collector (PTC) field, are considered. The influence on distilled water production of the main operation and design parameters was studied by thermodynamic analysis. The parameters analyzed define the solar field, the thermal storage and the desalination plant. Firstly, the orientation of the collector axis is determined by the axis azimuth and height. Secondly, the solar field is defined by the distances between rows and columns, the rows azimuth and the number of collectors as the inlet/outlet temperatures of the thermal fluid determine its operation. Finally, the main characteristics of the thermal storage and the desalination plant are the respective capacities and the desalination unit performance ratio and energy supply temperature. The analysis performed is useful not only for selection of the most suitable parameters to increase production, but also for prediction of the water production of a particular system and for water cost calculations. The place selected for this study was the Plataforma Solar de Almeria research center, located in southeastern Spain where a solar multi-effect distillation plant was installed in 1988. Results could be generalized to coastal areas in southern Spain.

Application of direct steam generation into a solar parabolic trough collector to multieffect distillation

Abstract In this paper, the application of the direct steam generation into a solar parabolic trough collector to multieffect distillation is proposed and economically evaluated. The thermal fluid of the solar field is pure water, which boils as circulating along the solar collectors. The steam generated drives a multieffect distillation unit. This solar distillation system is compared with multieffect plants connected to a conventional parabolic trough collector field, and with fossil fuel powered distillation plants. Different parameters are analysed, the plant capacity and performance ratio, the cost of conventional thermal energy, the cost of the solar collectors, and the annual average of the fresh water obtained per m 2 of solar collector. Results obtained are useful in finding the most suitable conditions in which solar energy could compete with conventional energies in solar desalination.

Conditions for economical benefits of the use of solar energy in multi-stage flash distillation

Abstract A solar assisted multi-stage flash (MSF) distillation system is economically compared with a conventional energy MSF plant. Moreover, the economical and climatic conditions that make competitive the use of solar energy in MSF plants vs. conventional energy are analyzed. The design arrangement of the solar distillation system considered consists of a solar parabolic trough collector field coupled to a conventional MSF plant. The solar field directly heats the brine until its top temperature. Therefore, the solar field acts as brine heater when solar energy is available. Nevertheless, the plant consumes conventional energy at nighttime. The parameters analyzed are the climatic conditions, which define the energy production and the average daily operation time of the solar field; the capacity and the performance ratio of the desalination plant; the cost of the solar collector, and the cost of conventional energy. It was concluded that the solarassisted distillation system described above could make possible the competitiveness of the use of solar energy in MSF distillation plants.