FAQ – Frequently asked questions
Here you will find answers to frequently asked questions about our CloudFisher projects.
What is fog?
In our context, fog describes the phenomenon of small water droplets (1 to 40 micrometers in diameter) dispersed in the air. Fog is a type of cloud that touches the ground or mountains. Fog can be very dense and reduce visibility to well under a kilometer.
What does fog collection generally mean?
Fog collection is the process of obtaining water from fog. To do this, large wire mesh nets, known as fog nets, are placed vertically at points where the wind drives the fog. The water remains in the mesh fibers, collects and drips into a collection and piping system.
What are the necessary conditions for fog collection?
The prerequisites for fog collection are fog and wind. Dew and humid air alone are not enough to collect water. Whether the local conditions are suitable for fog collection must be determined by scientific assessment and by pilot tests with a small test collector. There are validated methods.
What is fog water collected for?
The main purpose of fog water harvesting today is to supplement drinking water supplies. Beyond that, the water can also be used for irrigation, planting, livestock breeding and agriculture. A number of current projects include agricultural aspects, but closing gaps in drinking water supply is the most important application. Another positive effect is the general reduction in the consumption of polluted water resources.
How does a simple fog collector work?
Simple fog collectors use a very light and affordable net that is attached between two masts. The collector is easy to construct and comparatively cheap. It collects a moderate amount of fog water. Unfortunately, this technology is very susceptible to being destroyed by wind – which is quite common in mountainous regions where fog collection works best. Furthermore, aspects such as food quality and damage caused by strong sunlight are often underestimated in very simple and cheap designs.
What is special about the WaterFoundation’s CloudFisher fog collector?
The CloudFisher is characterized by its net composition and quality, as well as by the stable collector construction (frame, grid, water channels). The CloudFisher is more efficient and has a more sustainable design, while simple collectors are easier to construct and cheaper.
How are fog nets typically arranged?
Since wind and fog are the prerequisites for fog collection, fog nets are usually arranged on the windward slopes of mountains, where they are directly aligned with sustained winds. Orientation is a key factor, with a 30° deviation from the wind direction resulting in a 25% lower yield. To create less wind obstruction, it makes sense to spread a number of collectors over a given area, rather than placing large collectors too close to each other.
How much water can be collected?
Collector yield varies greatly depending on local conditions and the time of year. The average annual yield of simple collectors is around 5 liters per square meter, while the CloudFisher average in Morocco, for example, is more than 20 liters per square meter per foggy day. The daily yield per plant depends on the technology used, the weather conditions and the size of the fog collectors. Since the quality of the water droplet density, etc. varies greatly, pilot studies are required.
Is electricity needed for fog collection?
No electricity is required for fog collection. Fog collection is a passive technology that combines weather conditions (wind) and physics (gravity).
What are the first steps in starting a fog collection project?
After ensuring a favorable environment (people in need, administration, regulations, commitment of beneficiaries; even better: community involvement, etc.), the feasibility of fog collection in the desired area must be examined. To do this, climatic conditions must be measured and small test collectors must be installed first.
Is the collected water clean and drinkable?
Yes, it is safe because atmospheric water is normally free of bacteria and contaminants. In all existing projects, the fog water has met WHO drinking water standards. As with all other water sources and systems, the pipes and storage facilities must be cleaned regularly. In addition, contamination, e.g. from bird droppings, must be prevented.
Can you collect rainwater?
Yes, fog collectors can also collect rain – when the rain comes with wind and falls at a suitable angle.
What is the average cost of a fog collection project?
The costs for a project vary greatly and depend on the technology chosen, as well as on the size and the required performance.
Where can I buy the materials needed for a fog collector?
The main suppliers of fog nets are FogQuest (simple nets) and aqualonis GmbH (CloudFisher type). For more information, please visit their websites (www.fogquest.org and www.aqualonis.com).
Is fog collection sustainable?
As long as the fog collectors are properly maintained and the systems are kept clean, fog collection can be a very sustainable solution. In particular, the CloudFisher nets can be operated for many years. In addition, fog collection has no harmful effects on the environment and can promote socio-economic factors such as female labor force participation and education by saving time.
Is it possible to provide enough water for a city?
No, because the water demand in cities is far too high for a fog collection system. The system is very well suited for remote mountain communities and smaller villages.
