Research History and Functional Systems of Fog Water Harvesting

Abstract

Water is among the top five global risks in terms of impacts translated through socio-economic and environmental challenges, influencing people's wellbeing. The situation is grim in water-scarce countries, which need to think and act beyond conventional water resources and tap unconventional water supplies to narrow the gap between water demand and supply. Among unconventional water resources, water embedded in fog is increasingly seen as a source of potable water in dry areas where fog is intense and prevalent. Although a low maintenance option and a green technology to supply freshwater, the potential to collect water from air through fog harvesting is by far under-explored. Based on the comprehensive analysis of fog water collection's research history since 1980, this study reveals that recent years have witnessed a sharp increase in research related to technological developments in fog collection systems. Also, there is an increased focus on associated policy and institutional aspects, economics, environmental dimensions, capacity building, community participation, and gender mainstreaming. In addition to research, fog water collection practice has also increased over time with emerging examples worldwide, notably from Canary Islands, Chile, Colombia, Eritrea, Ethiopia, Guatemala, Israel, Morocco, Namibia, Oman, Peru, and South Africa. The functional systems of fog water collection demonstrate community engagement, women empowerment, enhanced capacity and training, and active participation of local institutions as the key drivers for effective fog collection systems to provide a sustainable supply of freshwater to the associated communities.

Bioinspired Asymmetric Surface Property of Functionalized Mesh to Maximize the Efficiency of Fog Harvesting

“…At ground level, air contains suspended water droplets (1–50 mm in diameter), and is usually recognized as fog [1] . Continued formation and accumulation of these droplets leads to the formation of a massive amount of humid air that is considered a valuable source of fresh water, especially in recent decades where scarcity of fresh water has largely increased throughout the world [2] . Therefore, harvesting of water from fog is an extremely promising and low‐cost technology for drinking water, crop irrigation, livestock beverages and forest restoration, especially in arid areas [3] .…”

“…This is a green technology, and fog harvesting is also an environmentally friendly intervention that does not rely on energy consumption and has no adverse environmental effects. Moreover, no adverse effects of fog water collection have been reported on the environment [2] . Ideal FWCs are required to have high water uptake, low energy consumption for water release, fast water capture/release, high cycling stability, and low cost [12] .…”

“…[1] Continued formation and accumulation of these droplets leads to the formation of a massive amount of humid air that is considered a valuable source of fresh water, especially in recent decades where scarcity of fresh water has largely increased throughout the world. [2] Therefore, harvesting of water from fog is an extremely promising and low-cost technology for drinking water, crop irrigation, livestock beverages and forest restoration, especially in arid areas. [3] Natural species, such as Namib desert beetles, [4] spider silky webs, [5] and desert grass and cactus plants, have highly effective water collection capabilities from fog.…”

“…[10b,11] Scientists have developed fog water collectors (FWCs) in the form of vertical meshes to intercept the fog droplet stream, producing suspended water droplets collision and coalescence. [2] This is a green technology, and fog harvesting is also an environmentally friendly intervention that does not rely on energy consumption and has no adverse environmental effects. Moreover, no adverse effects of fog water collection have been reported on the environment.…”

CFD simulation of updrafts initiated by a vertically directed jet fed by the heat of water vapor condensation

“…These systems, depending on the fog duration and water content, can produce from 2 to 20 L of water per day for each sq. m. of mesh 8 .…”