Abstract This paper focuses on the energy-water nexus, aiming at developing novel systems producing simultaneously energy and water. This work investigates two solar polygeneration plants for the production of thermal and cooling energy, electricity, and desalinated water for two small Mediterranean islands. In this case, seawater and solar energy are largely available, whereas freshwater is scarce and extremely expensive. The work also aims to compare different technologies included in the polygeneration systems. In particular, the first plant is based on concentrating photovoltaic/thermal solar collectors, producing electric and thermal energy. The thermal energy is used to produce space heating, domestic hot water and space cooling by means a single-stage Lithium Bromide/Water absorption chiller. An electric auxiliary chiller is also included. A multi-effect distillation unit is included for freshwater production supplied by the concentrating photovoltaic/thermal collectors solar energy and an auxiliary biomass-fired heater. In the second plant, a photovoltaic field is coupled with electric driven technologies, such as heat pumps for space heating, cooling and domestic hot water production and a reverse osmosis unit. The solar electrical energy excess is delivered to the grid. The third polygeneration plant includes the same components as the first layout but it is equipped with a reverse osmosis unit. Two main case studies, Favignana and Salina islands (South Italy) are selected. The heating, cooling and electric hourly loads of some buildings located in both investigated weather zones are calculated in detail. In particular, space heating and cooling loads are calculated by means of the Type 56 of TRNSYS (version 17), coupled to the Google SketchUp TRNSYS3d plug-in. The buildings geometry, envelope, windows, lighting, machineries heat gains schedule, as well as the buildings users’ occupation and activity are simulated by means of the Type 56. TRNSYS is also used to accurately model all of the plant components. The work also includes comprehensive energy, environmental and economic analyses to maximize the plants profitability, evaluated by considering both operating and capital costs. Sensitivity analyses aiming at establishing the optimal values of the most important design parameters are also performed. The developed plants achieve important savings in terms of carbon dioxide emissions due to the use of renewable energy sources and the high efficiency of the included technologies. The best economic indexes are obtained for the layout using electricity-driven technologies, resulting in very profitable operation with a payback period of about 6.2 years.

中文翻译：

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水能关系：地中海小岛多联产系统的热经济学分析

摘要 本文关注能源-水的关系，旨在开发同时生产能源和水的新型系统。这项工作调查了两个太阳能多发电厂，用于为两个地中海小岛生产热能和冷却能、电力和淡化水。在这种情况下，海水和太阳能大量可用，而淡水稀缺且极其昂贵。这项工作还旨在比较多联产系统中包含的不同技术。特别是，第一个工厂基于聚光光伏/热太阳能收集器，生产电能和热能。热能通过单级溴化锂/吸水式制冷机用于生产空间供暖、生活热水和空间冷却。还包括一个电动辅助冷却器。包括一个多效蒸馏装置，用于由聚光光伏/集热器太阳能和辅助生物质燃烧加热器提供的淡水生产。在第二个工厂中，光伏领域与电力驱动技术相结合，例如用于空间加热、冷却和生活热水生产的热泵以及反渗透装置。多余的太阳能被输送到电网。第三个多联发电厂包括与第一个布局相同的组件，但配备了反渗透装置。选择了两个主要案例研究，法维尼亚纳和萨利纳群岛（意大利南部）。详细计算了位于两个调查天气区的一些建筑物的供暖、制冷和电力小时负荷。特别是，空间加热和冷却负荷通过 TRNSYS 的 Type 56（版本 17）与 Google SketchUp TRNSYS3d 插件耦合计算。建筑物的几何形状、围护结构、窗户、照明、机械热增益计划以及建筑物用户的职业和活动均通过 Type 56 进行模拟。TRNSYS 还用于对所有工厂组件进行精确建模。这项工作还包括综合能源、环境和经济分析，以最大限度地提高工厂的盈利能力，并通过考虑运营和资本成本进行评估。敏感性分析旨在确定最重要的设计参数的最佳值。由于使用可再生能源和所含技术的高效率，已开发的工厂在二氧化碳排放方面取得了重要的节省。采用电力驱动技术的布局获得了最佳的经济指标，产生了非常有利可图的运营，投资回收期约为6.2年。