Water and energy supply systems are essential parts of the infrastructure on islands. For small islands that are far from continents, water shortage is usually the main constraint on economic and social development. In order to maintain island water security, desalination plants are built to supply fresh water. The plants need a great deal of energy, which increases demand for energy and the cost of transportation. Thus, it is necessary to design a new island system driven by renewable energy. This study investigated the existing type of water and energy supply systems in some typical islands of the world, and analyzed their advantages and disadvantages. The energy supply systems can be classified into three categories: imported conventional energy supply system (ICESS); imported conventional energy & renewable energy supply system (ICE&RESS); and integrated energy supply system (IESS). Water supply systems can also be classified into three categories: imported water supply system (ImWSS); imported water and unconventional water supply system (IW&UWSS); and integrated water supply system (InWSS). The nexus of energy and water is very complicated on islands. This paper presents a framework for an interconnected energy and water system on an island. The new framework reveals a roadmap from “full input of energy & water (FIEW)” through “semi-input of energy & water (SIEW)” to “zero input of energy & water (ZIEW)”, which leads an island's energy and water resources to become gradually independent from the mainland. The new framework also reduces transportation costs and carbon emissions. The proposed framework is applied to the Maldives to aid design of a renewable energy-driven water supply system. The characteristics and mutual adaptability of three types of renewable energy (solar, wind, and biomass energy) and water supply systems is discussed. The results show that a ZIEW system can be realized in the Maldives with a reduction in the cost of renewable energy. ZIEW system has great potential for application in island regions in the future.

水和能源供应系统是岛屿基础设施的重要组成部分。对于远离大陆的小岛来说，缺水通常是经济和社会发展的主要制约因素。为了维持岛屿的水安全，建造了海水淡化厂来供应淡水。这些工厂需要大量能源，从而增加了能源需求和运输成本。因此，有必要设计一种由可再生能源驱动的新的岛状系统。这项研究调查了世界上一些典型岛屿上现有的水和能源供应系统类型，并分析了它们的优缺点。能源供应系统可分为三类：进口的常规能源供应系统（ICESS）；进口的传统能源供应系统。进口常规能源和可再生能源供应系统（ICE＆RESS）；和综合能源供应系统（IESS）。供水系统也可以分为三类：进口供水系统（ImWSS）；进口供水系统（ImWSS）。进口水和非常规供水系统（IW＆UWSS）；和集成供水系统（InWSS）。能源和水的关系在岛屿上非常复杂。本文提出了一个岛上能源和水系统互连的框架。新框架揭示了从“能源和水的完全输入（FIEW）”到“能源和水的半输入（SIEW）”到“能源和水的零输入（ZIEW）”的路线图，该路线图引导了岛上的能源和水资源逐渐脱离大陆。新框架还降低了运输成本和碳排放。拟议的框架已应用于马尔代夫，以协助设计可再生能源驱动的供水系统。讨论了三种可再生能源（太阳能，风能和生物质能）和供水系统的特性和相互适应性。结果表明，可以在马尔代夫实现ZIEW系统，同时降低可再生能源的成本。ZIEW系统在未来的海岛地区中具有巨大的应用潜力。