A guide to your fog collecting project
Environmental and topographical conditions
Each project begins with a study to determine whether conditions on site are suitable for fog harvesting. Discussions with the local population about fog frequency are the basis for our analysis. When a foggy area is found, one begins with the collection of meteorological data on wind speeds and directions, relative humidity and temperature, precipitation and amounts of accumulated water. These findings are used to decide whether the location is appropriate for a large fog water production system.
How fog collectors work
Fog and wind are necessary for the fog collector to work.
We have to differentiate between drizzle, dew and fog.
Wind drives the fog into the vertically suspended nets. The droplets are caught in the mesh and merge into larger drops, which then fall into the collecting trough below. From there the fog water is piped into a reservoir.
The amounts yielded per fog-day differ according to region and season. In Morocco, for example, we collect an average of 22 litres per square metre on a fog day. With 31 CloudFisher Pro, this corresponds to a water volume of 37,000 litres per fog day.
A fog collector is also a very good rain collector. This is because wind-blown rain always falls at an angle on the nets.
Fog is simply a cloud that touches the ground. It is formed when warm, damp air cools. When this happens, millions of tiny water droplets from 1 to 40 micrometres (μm) in diameter are formed. This is called condensation.
Fog is very common both in coastal regions and mountainous areas. There are many high-elevation continental locations with frequent fog cover resulting from either the transport of upwind clouds or the formation of orographic clouds (i.e. clouds that develop in response to the forced lifting of air by the earth's topography). In such cases the distance to the coastline is irrelevant. However, areas of higher elevation near the coastline are generally preferred sites for fog harvesting.
Hills must have an altitude at which clouds can be intercepted. Priority should be given to windward sites. Distance from sources of humidity such as the ocean is important. The shorter the distance, the less chance of dissipation or evaporation.
Persistent winds such as trade winds from one direction are ideal for fog collection. Conditions are suitable if they move clouds from the ocean to the continent. It is important that there are no major obstacles to the wind within a few kilometres upwind of the site. Ideal wind speed for fog harvesting is 4 to 10 m/s.
Optimal orientation to the wind
Find the right position
Together with a local partner, we will do an evaluation with several small fog collectors (net surface: 1m²) to see how much water is available and in which season. The yield quantities can be measured with meteorological instruments or an empirical measurement, such as a water canister and a measuring rod. If the yield is an average of 6 litres or more, expansion to a large plant is worthwhile.
A deviant orientation only of 30° degrees means 25% less water yield.
Fog collector model
Your choice of CloudFisher model depends on the application area.
The CloudFisher Pro is suitable for the extraction of larger amounts of water, such as for villages, agriculture and industrial use. It requires concrete foundations, which makes it extremely stable against strong winds.
The CloudFisher Mini is mainly designed for domestic users and as a test collector. It is also suitable for temporary projects such as afforestation, since it does not need concrete foundations and can be easily repositioned.
aqualonis offers consultation from evaluation to installation.
During the evaluation phase, we usually work together with meteorological institutes and universities. Our goal is to create a scientific basis that justifies expansion to a CloudFisher system. Our expert consultation during the installation ranges from two-week training courses to full-service project support.
Sample countries with yield quantities
Source: Correggiari et al., 2015