# Fog harvesting system

Fog harvesting system refers to the method of collecting water from fog using specialized structures and materials to capture and condense atmospheric moisture. This technique involves using mesh nets or other materials that allow fog droplets to condense and coalesce into larger droplets, which then drip into collection systems for use. Fog harvesting is particularly valuable in arid regions where conventional water sources are limited, providing a sustainable and low-cost method to supplement water supply. To address the water crisis and protect the global supply of water resources, fog collection emerges as a promising yet relatively unexplored solution. Fog harvesting is a simple and sustainable technology that can procure freshwater for afforestation, gardening, as well as serving as a source of drinking water for humans and animals. In regions where freshwater is scarce and fog is prevalent, establishing passive mesh systems for fog water collection is viable. These meshes are directly exposed to the atmosphere, with the fog being driven through them by the wind. Fog droplets deposit on the mesh, coalesce into larger droplets, and then flow into storage tanks. The rate of fog water collection varies by location, but operational projects typically average 4-10 liters per square meter per day.

## Principle

Fog harvesting systems work by using mesh nets or similar materials to capture fog droplets. These droplets condense on the mesh and accumulate, eventually dripping into collection troughs. This process leverages natural fog conditions and requires no external energy, making it a sustainable option for water collection. The basic principle involves three key steps:
* Capture: Fog droplets are intercepted by a mesh net, which serves as a condensation surface.
* Coalescence: The intercepted droplets merge into larger droplets due to the mesh’s hydrophilic properties.
* Collection: Gravity causes the larger droplets to flow down into a trough or basin where the water is collected for use.
In certain advanced systems, mesh materials are designed to maximize water capture efficiency by mimicking the microstructures found in nature, such as the Namib Desert beetle’s back or spider silk. These biomimetic designs enhance droplet adhesion and coalescence, leading to higher water yield.

## History

The practice of fog harvesting dates back to ancient civilizations. Early examples include the Incas, who used simple systems to collect dew and fog water for agriculture. Modern developments in fog harvesting began in the mid-20th century. In the 1980s, the Meteorological Service of Canada initiated substantial fog collection projects in Chile's Atacama Desert, one of the driest places on Earth. These projects demonstrated the feasibility of fog harvesting as a reliable water source.
Fog harvesting has since evolved, with large-scale projects being implemented globally. Notable projects include those in Morocco, where the Dar Si Hmad initiative has successfully used fog collection to provide water to rural communities in the Anti-Atlas Mountains. This project utilizes advanced mesh materials and has significantly improved local water availability.

## Components of a fog harvesting system

A typical fog harvesting system consists of:
* Frame: Supports the mesh and can be made from various materials including metal and bamboo.
* Mesh netting: The surface where condensation occurs, often treated with hydrophilic and hydrophobic coatings to optimize water collection.
* Trough or basin: Collects the water that drips from the mesh.

## Efficiency factors

The efficiency of fog harvesting systems depends on several factors, including:
* Mesh material and design
* Local climate and fog density
* Placement and orientation of the system relative to wind patterns.

## Recent advances and innovations

* Biomimetic materials and design innovations: Recent research has focused on developing advanced mesh materials inspired by nature. For instance, structures mimicking the Namib Desert beetle's back, spider silk, and cactus spines have shown promise in enhancing water collection efficiency.
* Hybrid systems for enhanced efficiency: Combining different fog harvesting technologies can significantly improve overall efficiency. Hybrid systems integrate traditional mesh designs with new materials and configurations to maximize water capture.
* Architectural integration and aesthetic considerations: Integrating fog harvesting systems into urban architecture is a growing trend. Buildings and public spaces can incorporate fog collectors into their design, enhancing both functionality and aesthetics. This approach not only provides water but also contributes to sustainable urban development.
* Scalability and community impact projects: Large-scale fog harvesting projects, such as those in Peru and Morocco, have demonstrated significant benefits for local communities. These projects not only provide a reliable water source but also support reforestation and ecosystem restoration efforts.

## Applications

Fog harvesting systems are beneficial in various contexts:
* Rural areas: Providing fresh water for drinking, agriculture, and reforestation in arid and semi-arid regions.
* Urban environments: Integrating into building designs and public spaces to supplement water supply and enhance sustainability.
* Community projects: Supporting local communities by providing a sustainable and reliable source of fresh water.

## Case studies

* Chile
Extensive fog harvesting projects in the Atacama Desert have demonstrated the viability of this technology for community water supply and agriculture. The projects, initiated by the Meteorological Service of Canada, have shown that even in one of the driest places on Earth, significant amounts of water can be collected from fog.
* Morocco
The Dar Si Hmad project in the Anti-Atlas Mountains has successfully implemented large-scale fog collection systems, significantly improving local water availability. This project uses advanced mesh materials to maximize water capture efficiency and supports the daily water needs of several communities.
* Peru
In the outskirts of Lima, fog nets have been used to collect water for residents of some of the city's poorest neighborhoods. These projects, spearheaded by non-profit organizations, have provided a sustainable water source in areas where traditional water infrastructure is lacking.
* Eritrea
In the highlands of Eritrea, fog harvesting projects have been implemented to address chronic water shortages. These systems have been particularly beneficial for remote communities, providing them with a reliable source of clean water.
* United Arab Emirates
Research and pilot projects in the UAE have focused on using fog harvesting to support water needs in coastal and mountainous regions. These initiatives aim to supplement traditional water sources and contribute to the country's water security strategy.

## Advantages and disadvantages
### Advantages

* Sustainable and low-maintenance: Fog harvesting systems rely on passive collection methods, which do not require external energy sources, making them environmentally friendly and easy to maintain.
* Suitable for remote and arid regions: These systems are particularly beneficial in areas where conventional water sources are limited or non-existent. Projects in the Atacama Desert and the Anti-Atlas Mountains have demonstrated their effectiveness.
* Reduces dependency on traditional water sources: By providing an alternative water source, fog harvesting reduces the strain on overexploited freshwater resources and helps in maintaining the ecological balance.
* Economic benefits: Installation and maintenance costs are relatively low compared to other water collection methods, making it an economically viable option for developing regions.

### Disadvantages

* Dependent on local climate conditions: The efficiency of fog harvesting systems is heavily dependent on the presence and consistency of fog. Regions without frequent fog cannot rely on this method as a stable water source.
* Potential for contamination: Collected water can be contaminated by dust, microorganisms, or pollutants in the atmosphere, necessitating additional filtration and purification processes to ensure safety for consumption.
* Variable collection rates: The amount of water collected can vary significantly based on factors such as mesh design, wind speed, and fog density. Operational projects typically average 4-10 liters per square meter per day, but this can fluctuate.
* Infrastructure and accessibility: While installation is relatively straightforward, setting up fog harvesting systems in remote or rugged terrains can pose logistical challenges and require significant initial investment.