Integration of thermal energy and seawater desalination

Energy and freshwater shortage are the bottlenecks restricting China's economic development. The integration of energy utilization system and seawater desalination is considered as an innovative technology enabling efficient simultaneous use of middle or low temperature thermal energy and supply freshwater. Three feasible approaches to integrate seawater desalination with energy utilization system are presented in this paper, including combinations of the desalination process with a Combined Cooling Heating & Power system (CCHP), a power plant, or a solar thermal utilization system. In addition, the feasibility and advantages of a seawater desalination system combined with a power plant are described. The findings indicate that combining seawater desalination with industrial processes is a feasible and promising way to solve the problems of the lack of freshwater and low efficient use of low temperature thermal energy in coastland areas.     

一种新型太阳能、风能联合海水淡化装置

淡水资源短缺已成为一个世界性问题,我国也不例外.为了加大淡水供应,一条现实的途径就是充分利用我国丰富的海水资源,以及西北内陆地区的苦咸水(统称海水)进行淡化.提出了一种海水淡化装置,该装置利用温室效应原理和风能致热原理,可充分利用太阳能与风能进行海水淡化.与现有海水淡化装置相比该装置具有利用清洁能源、对环境无污染、适应性强、性价比高等特点.理论计算结果表明,该装置每小时产水量约为普通盘式太阳能海水淡化装置在晴天工作时的2倍.     

小型太阳能海水淡化装置

基于空气增湿-除湿海水淡化技术,采用热海水与空气逆流对喷的空气加湿器,设计了结合太阳能集热器的小型太阳能海水淡化系统。试验结果表明,该结构的空气加湿器具有很好的加湿效果,出口空气相对湿度可达到98%以上。当喷水温度为60℃、空气流量为11.8 L/s时,该小型海水淡化装置产水率可达3.42 kg/h。     

可再生能源对海岛旅游业发展的影响和在海水淡化中的应用

介绍了可再生能源在海岛旅游、海水淡化中的应用，同时介绍了克里特岛上可再生能源、节能和岛屿的可持续性发展有机结合的成功案例。最后指出了可再生能源和能效措施将可确保全世界岛屿长期持续的发展。     

海水淡化技术的研究进展

淡水资源的紧缺已成为一个世界性问题。我国水资源匮乏,海水淡化包括西北地区的苦咸水淡化,将成为解决我国沿海地区和岛屿、华北和西北部分干旱地区等缺水问题的重要手段。海水淡化技术在国外已得到广泛应用,在我国也日趋重视。分析了海水淡化不同技术的原理、特点及其应用情况,指出与热力发电厂余热利用相结合的多效蒸馏法、多级闪蒸法将体现其明显的经济性,而且可在掌握系统技术的基础上,开发相应的成套设备。     

Solar and wind opportunities for water desalination in the Arab regions

Despite the abundance of renewable energy resources in the Arab region, the use of solar thermal, solar photovoltaics, and wind is still in its technological and economic infancy. Great potential exists, but economic constraints have impeded more rapid growth for many applications. These technologies have certainly advanced technically over the last quarter century to the point where they should now be considered clean-energy alternatives to fossil fuels. For the Arab countries and many other regions of the world, potable water is becoming as critical a commodity as electricity. As renewable energy technologies advance and environmental concerns rise, these technologies are becoming more interesting partners for powering water desalination projects. We evaluate the current potential and viability of solar and wind, emphasizing the strict mandate for accurate, reliable site-specific resource data. Water desalination can be achieved through either thermal energy (using phase-change processes) or electricity (driving membrane processes), and these sources are best matched to the particular desalination technology. Desalination using solar thermal can be accomplished by multistage flash distillation, multi-effect distillation, vapor compression, freeze separation, and solar still methods. Concentrating solar power offers the best match to large-scale plants that require both high-temperature fluids and electricity. Solar and wind electricity can be effective energy sources for reverse osmosis, electrodialysis, and ultra- and nano-filtration. All these water desalination processes have special operational and high energy requirements that put additional requisites on the use of solar and wind to power these applications. We summarize the characteristics of the various desalination technologies. The effective match of solar thermal, solar photovoltaics, and wind to each of these is discussed in detail. An economic analysis is provided that incorporates energy consumption, water production levels, and environmental benefits in its model. Finally, the expected evolution of the renewable technologies over the near- to mid-term is discussed with the implications for desalination applications over these timeframes.     

Assessment of a stand-alone gradual capacity reverse osmosis desalination plant to adapt to wind power availability: A case study

Desalination driven by renewable energies is an interesting technology in isolated coastal areas. Its feasibility and reliability are guaranteed by innumerable designs implemented and experiences carried out, mainly focused on small capacity systems. However, only mature and efficient technologies are suitable for medium or large scale desalination. In the case of seawater desalination, wind-powered reverse osmosis is the most efficient, mature and cost-effective technology. This paper assesses the most suitable design for seawater reverse osmosis desalination driven by off-grid wind energy systems. A high innovative design based on gradual capacity with nominal production of 1000 m³/d is compared to a conventional fixed capacity desalination plant. Due to the intermittent wind resource, the gradual capacity desalination plant is able to fit the available energy and maximize the annual water production.     

The status and prospects for the gasification in the County of Split and Dalmatia

In order to establish a reliable and environmentally friendly power supply system for the County of Split and Dalmatia, a brief account of the geographic and demographic characteristics, economic structure and consumption of energy and resources of the region are given in this paper. On the basis of the analysis of energy consumption in the County, this study weighs the prospects of gas in achieving a reliable energy supply with preserving the environment. The model of a gas supply for the County has been defined with regard to the present stage of development of the gas supply system in the Republic of Croatia as well as to the energy consumption and characteristics of its parts.     

Proposal and analysis of a dual-purpose system integrating a chemically recuperated gas turbine cycle with thermal seawater desalination

A novel cogeneration system is proposed for power generation and seawater desalination. It combines the CRGT (chemically recuperated gas turbine) with the MED-TVC (multi-effect thermal vapor compression desalination) system. The CRGT contains a MSR (methane-steam reformer). The produced syngas includes plenty of steam and hydrogen, so the working medium flow increases and NO_x emissions can achieve 1 ppm low. However, the water consumption is large, ∼23 t/d water per MW power output. To solve this problem and produce water for sale, MED-TVC is introduced, driven by exhaust heat. Such a dual-purpose plant was analyzed to investigate its performance and parameter selection, and compared with four conventional cogeneration systems with the same methane input. Some main results are following: In the base case of the CRGT with a TIT of 1308 °C and a compression ratio of 15, the MED-TVC with 9 effects, the specific work output, performance ratio and CRGT-consumed water ratio are 491.5 kJ/kg, 11.3 and 18.2%, respectively. Compared with the backpressure ST (steam turbine)/CC (combined cycle) plus MED/MSF (multistage flash), the CRGT + MED has better thermal performance, lower product cost and shorter payback period, which indicates the CRGT + MED dual-purpose system is a feasible and attractive choice for power and water cogeneration.     

低温多效蒸发海水淡化装置的计算分析

建立了多效蒸发海水淡化装置计算模型,对串流、并流和并叉流三种不同工艺流程下的低温多效蒸发海水淡化系统进行了计算和分析。计算结果显示,对于给定的多效蒸发海水淡化装置,提高加热蒸汽温度,可大大提高装置的淡化水量,同时对加热蒸汽的需求量也增大,但造水比随加热蒸汽温度的升高呈减小趋势;就三种工艺流程而言,并叉流具有较好的热利用率。     

一种连续式冷冻法海水淡化方法及其特性分析

给出了一种基于界面渐进原理的连续式冷冻法海水淡化新方法,该方法具有易于大规模连续生产、淡化水中的含盐量易于控制、制取淡化水的能源消耗低等特点。在对其工作过程进行简要介绍的基础上,计算分析了该方法的主要特性指标吨水能耗比,并对下一步需开展的工作进行了探讨。     

Techno-economic assessment of green hydrogen and ammonia production from wind and solar energy in Iran

This paper presents a comprehensive technical and economic assessment of potential green hydrogen and ammonia production plants in different locations in Iran with strong wind and solar resources. The study was organized in five steps. First, regarding the wind density and solar PV potential data, three locations in Iran were chosen with the highest wind power, solar radiation, and a combination of both wind/solar energy. All these locations are inland spots, but since the produced ammonia is planned to be exported, it must be transported to the export harbor in the South of Iran. For comparison, a base case was also considered next to the export harbor with normal solar and wind potential, but no distance from the export harbor. In the second step, a similar large-scale hydrogen production facility with proton exchange membrane electrolyzers was modeled for all these locations using the HOMER Pro simulation platform. In the next step, the produced hydrogen and the nitrogen obtained from an air separation unit are supplied to a Haber-Bosch process to synthesize ammonia as a hydrogen carrier. Since water electrolysis requires a considerable amount of water with specific quality and because Iran suffers from water scarcity, this paper, unlike many similar research studies, addresses the challenges associated with the water supply system in the hydrogen production process. In this regard, in the fourth step of this study, it is assumed that seawater from the nearest sea is treated in a desalination plant and sent to the site locations. Finally, since this study intends to evaluate the possibility of green hydrogen export from Iran, a detailed piping model for the transportation of water, hydrogen, and ammonia from/to the production site and the export harbor is created in the last step, which considers the real routs using satellite images, and takes into account all pump/compression stations required to transport these media. This study provides a realistic cost of green hydrogen/ammonia production in Iran, which is ready to be exported, considering all related processes involved in the hydrogen supply chain.     

Effect of feed pressure on the performance of the photovoltaic powered reverse osmosis seawater desalination system

This paper describes the potential of the development of a seawater desalination system that combines the technologies of reverse osmosis (RO) and photovoltaic (PV) to deliver 100 m³/day of sweet water. Silicon cells are chosen for the PV array and the polyamide thin-film composite seawater Filmtec membranes are selected for the RO system. The software ROSA is adopted to study the influences of the feed pressure on the performance of the system. It is found that as the feed pressure increases, the specific energy of the plant decreases but the percentage of recovery increases.     

Potentials of wind energy development for water desalination in Jordan

The potential of the development of water desalination using wind energy in Jordan was studied. Eleven wind solar sites were considered. The results show that these sites can be divided, in terms of the yearly total amount of desalinated water, into three categories. One is considered favourable, which includes Ras Muneef, Mafraq, and Aqaba. Their water production adds up to about 75% of all water produced from all 11 sites combined. Others are considered to be promising (about 24% in total), which include H-5, Irbid, and Ma'an. The rest of sites considered are found to be very poor, which include H-4, Amman, Queen Alia Airport, Shoubak, and Deiralla, with traces of water produced (less than 1%). © 1998 John Wiley & Sons, Ltd.     

Critical aspects in the development of anodes for use in seawater electrolysis

The global water crisis limits the full implementation of purified water electrolysis across the world. Thus, seawater electrolysis has been identified as a powerful option to meet the requirements for sustainable production of green hydrogen without the constraint of using pure water. As in pure water electrolysis, seawater electrolysis research has been oriented to produce a durable, electrocatalytic, and selective anode.Even though seawater electrolysis was proposed for the first time in 1980, the research found on this topic grew exponentially in the last few years. Nevertheless, researchers do not give a clear insight about the impact that important variables have in the process of seawater electrolysis and, in particular, the anodic process. In this work, an in-depth literature review on articles reporting the development of various anode materials and the conditions in which they have been tested was carried out. The conclusions reveal a need to standardize some parameters for testing the anodes, such as simulated seawater composition, pH of the solution, the method through which parasitic reactions are measured and the choice of secondary reactions to be considered in the process. A standardization of these parameters will allow researchers to compare results, which in turn will allow collaborative work towards the goal of finding a feasible process for seawater electrolysis.     

Performance and development of PV - plant for water pumping and desalination for remote area in Saudi Arabia

PV plant for water pumping and desalination in remote area has been implemented; the plant was the first of its kind in Saudi Arabia. The design of PV plant was based on the specification of the site, the depth and quality of water, the daily water quantity produced and the autonomy period of the plant during cloudy conditions as well as other local climatic conditions. The plant has two main PV separate systems, first, PV water pumping system which is characterized by storing the water in two storage tanks and without electric energy storage, second, PV system for the operation of the reverse osmosis unit (water desalination), this system is characterized by the storage of electric energy (batteries). The storage batteries are used to supply the required electric power to the equipment in the plant, during night and cloudy weather. The batteries capacity is designed to be sufficient for 5 days autonomy. In order to make the operation and maintenance of the PV plant highly reliable, the design is based on the selection of equipment which are commonly available in the local market. The head of the submersible pump is 50 m from surface level, and the amount of water production from Reverse Osmosis Unit is about 600 liters per hour. The total installed PV capacity for pumping system is 980 Wp, and for desalination system is 10. 89 kWp.     

Design and simulation of water-cooled dehumidifier for HDH desalination plant

Condensers are widely used in thermal applications to transfer the maximum heat between the working fluids and change the phase of vapor. In basic thermal-based humidification–dehumidification (HDH) desalination, a condenser is used as a water-cooled dehumidifier for improving freshwater production within the minimum area. In this thermal-based HDH system, desalinated water production is the major output. The simulation tool is used to analyze the thermohydraulic performance of a water-cooled dehumidifier. In this thermohydraulic analysis, variables, like, airflow rate, tube diameter, and longitudinal pitch are thoroughly investigated to identify the optimum parameters for improving the performance of the water-cooled dehumidifier. The obtained results indicate that the heat transfer area and performance index are increased when the airflow rate and tube diameter change. But at 8 and 10 mm tube diameter, the surface area and performance index are contradictory in nature while longitudinal pitch varies from 30 to 45 mm. At 12.5 mm tube diameter, surface area and performance index decrease gradually but the certain period of pitch limit performance increases markedly. In addition, the yield of HDH desalination has been investigated. When the mass flow rate changed from 100 to 500 kg/h, it was 0.667–3.32 L/h.     

LiBr吸收式空调与海水淡化联合运行装置工艺流程的研究

将LiBr吸收式空调排放出的废热应用于多效蒸馏法 (MED)海水淡化工艺流程是海水淡化领域一个全新的设计概念。本文对这种联合运行的热力循环进行了描述和论证 ,并用一算例证明此工艺流程在技术上是可行的。该装置利用LiBr冷水机组排出的废热加热预处理后的海水。本文给出算例中的理论计算值可供设计做参考     

The impact of different grid regulatory scenarios on the development of renewable energy on islands: A comparative study and improvement proposals

Electricity generation costs are typically higher on islands than in mainland regions, primarily due to the costs associated with conventional primary energy transportation. However, at the same time, islands are commonly granted with significant renewable energy potential in terms of wind, solar radiation and marine energy, among others, varying by case.This article is focused on the impact that the grid regulatory framework has had on several islands from both the technical and economical points of view, with respect to renewable energy development. A comparison among the studied islands is carried out. Additionally, the possible differences between each island (or archipelago) and the rest of the corresponding country on the mainland are analysed to determine to what extent the peculiarities of the islands have been taken into account in the regulations.Our objective is to analyse whether the renewable energy developments on certain islands have taken place because of certain favourable scenarios or by promoting specific actuations, which could be applicable on other islands to promote similar developments. As a result of the study, strategic key ideas are identified to increase the renewable energy percentage of the electricity generation and energy consumption mix on islands.     

Optimal design of fossil-solar hybrid thermal desalination for saline agricultural drainage water reuse

Ultra-high recovery solar thermal desalination of agricultural drainage water is presented as one solution to the historic extreme drought and long-standing salt accumulation problems facing California's fertile Central Valley region. Building on the results obtained from a recent pilot demonstration of a novel solar thermal desalination system, a techno-economic analysis is presented using an existing agricultural region as a case study. Three strategies are considered: continue retiring farmland as crop productivity wanes in future years, desalinate saline drainage water with a novel distillation process using natural gas as the fuel source, and desalinate using natural gas and solar as a hybrid energy source. The study is cast as a parametric optimization problem taking into account natural gas costs and water purchase contract pricing. The results show that with projections of the long-term effects and cost of salt accumulation in the region, solar thermal desalination is economically favorable over both the alternative of doing nothing (retire farmland) as well as implementing conventional (non-renewable) thermal desalination. Most importantly, the results indicate that solar thermal desalination is an economically-viable solution that can increase the sustainability of farming in the region and create a new, sustainable, scalable source of additional freshwater.