Solar-driven humidification dehumidification desalination for potable use in Haiti

Abstract

Worldwide water scarcity, especially in the developing world, provides the impetus for utilizing inexpensive desalination technologies on a wider scale to contribute to freshwater supply. Small-scale desalination technologies, such as solar-driven humidification dehumidification (HDH), are needed to help provide clean drinking water to people living in coastal areas. This thesis explores the question of whether the fills used in the humidifier of the HDH system, which allow for increased contact area between the water and air streams, can be made of locally available materials such as charcoal, bamboo, and louffa found in Haiti. It also addresses how the institutional, economic, social and technological barriers to successful deployment of renewable energy (RE) desalination technologies such as HDH can be overcome. Charcoal, louffa and bamboo custom fills were experimentally tested in a benchtop cooling tower to determine their suitability for use in the humidifier of a HDH system. The fills' transfer characteristics and pressure drop data were obtained and analyzed to determine the overall fill performance in terms of fan power consumption. The lower the fan power consumption required by the fill, the better the fill performance. The performances of the custom fills were compared with each other and with two commercial thin film fills. The louffa fill performed the best among the custom fills, having power consumption 2.9 and 4.4 times less than the charcoal and bamboo fills, respectively. The louffa fill is therefore recommended for use in the humidifier. To help overcome the barriers facing RE desalination policy and implementation, several strategies are recommended: a decentralized regulatory system for water supply, public-private financial arrangements and supporting policies; market analysis of prospective RE desalination systems, targeted R&D to make improved system components and a community platform for the various stakeholders to work together. Most importantly, the general public must be engaged throughout the entire process to foster transparency, community trust and public acceptance of the desalination technology.