permaculture

[venaurafarm <venaurafarm@bellsouth.net>]

On 11/24/2012 11:09 AM, Lawrence London wrote:
> http://www.rexresearch.com/airwells/airwells.htm
>
> *Air Wells, Fog Fences & Dew Ponds*
>
> *Methods for Recovery of Atmospheric Humidity*
>
> by
>
> *Robert A. Nelson*

http://science.slashdot.org/story/12/11/23/0235229/water-bottle-fills-itself-from-the-air?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+slashdot%2FeqWf+%28Slashdot%3A+Slashdot%29

"The Namib Desert Beetle generates water from water vapor via its shell, 
which has alternating hydrophilic and hydrophobic bumps which channel 
water droplets into its mouth. Scientists at MIT developed a 
self-filling water bottle using this technology, and have announced a 
contest for the best design of a countertop water-from-air generator."

<>

http://astounde.com/water-bottle-harvests-water-from-air/

Water Bottle Harvests Water From Air

Written by Mike Awada on November 22, 2012. Posted in Gadgets, Science, 
Social, Technology	

namib-beetle-harvests-water-from-air

There are nearly four quadrillion gallons of water in the air, yet 
people all over the world are still thirsty. Scientists have been 
working to break into this untapped resource for over a decade, and are 
making some incredible breakthroughs.

Progress in this field has been made by studying the survival mechanisms 
of an insect living in one of the most hostile regions on the planet.

The Namib Desert, located on the Southwest African coast, has sands 
reaching temperatures upwards of 140 °F. Here, there is less than 1/2″ 
of rainfall per year, yet the Namib Desert Beetle manages to survive 
each and every year.

Stenocara Solution

National Geographic describes the Namib Desert Beetle, also known as the 
stenocara, as a desert MacGyver. The stenocara is equipped with an armor 
like shell covered with bumps. The peak of each bump is hydrophilic, 
meaning that it attracts water. The slopes and valleys in between bumps 
are hydrophobic, meaning they repel water.

The Namib Desert Beetle climbs atop a desert hill in the morning as a 
fog sweeps over the land. The stenocara angles its body into the wind 
and miniscule water droplets from the fog stick to the hydrophilic peaks 
and gradually form droplets. Once enough water has accumulated, the 
droplets roll effortlessly down the hydrophobic slopes directly into the 
insect’s mouth, sustaining its life in the normally inhospitable 
environment.

Researchers are mimicking this natural trait to develop a bevy of 
important water harvesting platforms, including tent covers and roof 
tiles several times more effective at capturing H2O than the next most 
effective method. In the near future, it looks as if we’ll have water 
bottles that can capture drinkable water from the air as well.

NBD Nano: Self-Refilling Water Bottle

A company called NBD Nano is implementing this technology originally 
found only in nature into water bottles, with the hope that they’ll 
continually fill themselves while you’re on the go. In an interview with 
Public Radio International, we learn that the conceptual self-filling 
bottle can operate using a rechargeable battery or solar cell to 
speed-up accumulation and filter the water.

NBD Nano co-founder Deckard Sorensen wants this green technology 
available in all walks of life; installing it on people, cars, homes and 
anything else you can imagine. Sorensen believes that in a climate with 
75% humidity, his device can harvest “three liters per square meter per 
hour”.

“We see this being applicable to anything from marathon runners to 
people in third-world countries, because we realize that water is such a 
large issue in the world today, and we want to try to alleviate those 
problems with a cost-efficient solution.”

Global Implications

While the invention is certainly fascinating for the first world 
consumer, perhaps the most important use of this technology will be for 
the billion plus people who live without access to clean, drinkable 
water everyday.

NBD Nano hopes to have the self-refilling water bottle to market in 
2014. How do you think we should use the technology?

<>

Comment:

This is not new technology. This solution is wrapped into a different 
format, and uses slightly more advanced materials than what is already 
in use:

http://www.oas.org/DSD/publications/Unit/oea59e/ch12.htm

1.3 Fog harvesting

This innovative technology is based on the fact that water can be 
collected from fogs under favorable climatic conditions. Fogs are 
defined as a mass of water vapor condensed into small water droplets at, 
or just above, the Earth's surface. The small water droplets present in 
the fog precipitate when they come in contact with objects. The frequent 
fogs that occur in the arid coastal areas of Peru and Chile are 
traditionally known as camanchacas. These fogs have the potential to 
provide an alternative source of freshwater in this otherwise dry region 
if harvested through the use of simple and low-cost collection systems 
known as fog collectors. Present research suggests that fog collectors 
work best in coastal areas where the water can be harvested as the fog 
moves inland driven by the wind. However, the technology could also 
potentially supply water for multiple uses in mountainous areas should 
the water present in stratocumulus clouds, at altitudes of approximately 
400 m to 1 200 m, be harvested.

Technical Description

Full-scale fog collectors are simple, flat, rectangular nets of nylon 
supported by a post at either end and arranged perpendicular to the 
direction of the prevailing wind. The one used in a pilot-scale project 
in the El Tofo region of Chile consisted of a single 2 m by 24 m panel 
with a surface area of 48 m2. Alternatively, the collectors may be more 
complex structures, made up of a series of such collection panels joined 
together. The number and size of the modules chosen will depend on local 
topography and the quality of the materials used in the panels. 
Multiple-unit systems have the advantage of a lower cost per unit of 
water produced, and the number of panels in use can be changed as 
climatic conditions and demand for water vary.

The surface of fog collectors is usually made of fine-mesh nylon or 
polypropylene netting, e.g., "shade cloth," locally available in Chile 
under the brand name Raschel. Raschel netting (made of flat, black 
polypropylene filaments, 1.0 mm wide and 0.1 mm thick, in a triangular 
weave) can be produced in varying mesh densities. After testing the 
efficiency of various mesh densities, the fog collectors used at El Tofo 
were equipped with Raschel netting providing 35% coverage, mounted in 
double layers. This proportion of polypropylene-surface-to-opening 
extracts about 30% of the water from the fog passing through the nets.

As water collects on the net, the droplets join to form larger drops 
that fall under the influence of gravity into a trough or gutter at the 
bottom of the panel, from which it is conveyed to a storage tank or 
cistern. The collector itself is completely passive, and the water is 
conveyed to the storage system by gravity. If site topography permits, 
the stored water can also be conveyed by gravity to the point of use. 
The storage and distribution system usually consists of a plastic 
channel or PVC pipe approximately 110 mm in diameter which can be 
connected to a 20 nun to 25 nun diameter water hose for conveyance to 
the storage site/point of use. Storage is usually in a closed concrete 
cistern. A 30 m3 underground cistern is used in the zone of Antofagasta 
in northern Chile. The most common type of fog collector is shown in 
Figure 6.

Storage facilities should be provided for at least 50% of the expected 
maximum daily volume of water consumed. However, because the fog 
phenomenon is not perfectly regular from day to day, it may be necessary 
to store additional water to meet demands on days when no fog water is 
collected. Chlorination of storage tanks may be necessary if the water 
is used for drinking or cooking purposes.

Extent of Use

Fog harvesting has been investigated for more than thirty years and has 
been implemented successfully in the mountainous coastal areas of Chile 
(see case study in Part C, Chapter 5), Ecuador, Mexico, and Peru. 
Because of a similar climate and mountainous conditions, this technology 
also can be implemented in other regions as shown in Figure 7.

Figure 6: Section of a Typical Flat, Rectangular Nylon Mesh Fog 
Collector. The water is collected in a 200 l drum.

    Source: G. Soto Alvarez, National Forestry Corporation (CONAF), 
Antofagasta, Chile.

In Chile, the National Forestry Corporation (CONAF), the Catholic 
University of the North, and the Catholic University of Chile are 
implementing the technology in several regions, including El Toro, Los 
Nidos, Cerro Moreno, Travesía, San Jorge, and Pan de Azúcar. The results 
of the several experiments conducted in the northern coastal mountain 
region indicate the feasibility and applicability of this technology for 
supplying good-quality water for a variety of purposes, including 
potable water and water for commercial, industrial, agricultural, and 
environmental uses. These experiments were conducted between 1967 and 
1988 at altitudes ranging from 530 m to 948 m using different types of 
fog water collectors. The different types of neblinometers and fog 
collectors resulted in different water yields under the same climatic 
conditions and geographic location. A neblinometer or fog collector with 
a screen containing a double Raschel (30%) mesh was the most successful 
and the one that is currently recommended.

In Peru, the National Meteorological and Hydrological Service (SENAMHI) 
has been cooperating with the Estratus Company since the 1960s in 
implementing the technology in the following areas: Lachay, Pasamayo, 
Cerro Campana, Atiquipa, Cerro Orara (Ventinilla-Ancón), Cerro Colorado 
(Villa María de Triunfo), and Cahuide Recreational Park (Ate-Vitarte), 
and in southern Ecuador the Center for Alternative Social Research 
(CISA) is beginning to work in the National Park of Machalilla on Cerro 
La Gotera using the Chilean installations as models.

Operation and Maintenance

Operating this technology is very simple after once the fog collection 
system and associated facilities are properly installed. Training of 
personnel to operate the system might not be necessary if the users 
participate in the development and installation of the required 
equipment. A very important factor in the successful use of this 
technology is the establishment of a routine quality control program. 
This program should address both the fog collection system and the 
possible contamination of the harvested water, and include the following 
tasks:

    · Inspection of cable tensions. Loss of proper cable tension can 
result in water loss by failing to capture the harvested water in the 
receiving system. It can also cause structural damage to the collector 
panels.

    · Inspection of cable fasteners. Loose fasteners in the collection 
structure can cause the system to collapse and/or be destroyed.

    · Inspection of horizontal mesh net tensions. Loose nets will lead 
to a loss of harvesting efficiency and can also break easily.

    · Maintenance of mesh nets. After prolonged use, the nets may tear. 
Tears should be repaired immediately to avoid having to replace the 
entire panel. Algae can also grow on the surface of the mesh net after 
one or two years of use, accumulating dust, which will cloud the 
collected water and cause offensive taste and odor problems. The mesh 
net should be cleaned with a soft plastic brush as soon as algal growth 
is detected.

    · Maintenance of collector drains. A screen should be installed at 
the end of the receiving trough to trap undesirable materials (insects, 
plants, and other debris) and prevent contamination of water in the 
storage tank. This screen should be inspected and cleaned periodically.

    · Maintenance of pipelines and pressure outlets. Pipelines should 
be kept as clean as possible to prevent accumulation of sediments and 
decomposition of organic matter. Openings along the pipes should be 
built to facilitate flushing or partial cleaning of the system. 
Likewise, pressure outlets should be inspected and cleaned frequently to 
avoid accumulation of sediments. Openings in the system must be 
protected against possible entry of insects and other contaminants.

    · Maintenance of cisterns and storage tanks. Tanks must be cleaned 
periodically with a solution of concentrated calcium chloride to prevent 
the accumulation of fungi and bacteria on the walls.

    · Monitoring of dissolved chlorine. A decrease in the concentration 
of chlorine in potable water is a good indicator of possible growth of 
microorganisms. Monitoring of the dissolved chlorine will help to 
prevent the development of bacterial problems.

Figure 7: Locations Where Fog Harvesting Has Been or Can Be Implemented.

    Source: W. Canto Vera, et al. 1993. Fog Water Collection System. 
IDRC, Ottawa, Canada.

Level of Involvement

In applying this technology, it is strongly recommended that the end 
users folly participate in the construction of the project. Community 
participation will help to reduce the labor cost of building the fog 
harvesting system, provide the community with operation and maintenance 
experience, and develop a sense of community ownership and 
responsibility for the success of the project. Government subsidies, 
particularly in the initial stages, might be necessary to reduce the 
cost of constructing and installing the facilities. A cost-sharing 
approach could be adopted so that the end users will pay for the 
pipeline and operating costs, with the government or an external agency 
assuming the cost of providing storage and distribution to homes.

Costs

Actual costs of fog harvesting systems vary from location to location. 
In a project in the region of Antofagasta, Chile, the installation cost 
of a fog collector was estimated to be $90/m2 of mesh, while, in another 
project in northern Chile, the cost of a 48 m2 fog collector was 
approximately $378 ($225 in materials, $63 in labor, and $39 in 
incidentals). This latter system produced a yield of 3.0 l/m2 of 
mesh/day. The cost of a fog harvesting project constructed in the 
village of Chungungo, Chile, is shown in Table 2. The most expensive 
item in this system is the pipeline that carries the water from the fog 
collection panel to the storage tank located in the village.

Maintenance and operating costs are relatively low compared to other 
technologies. In the project in Antofagasta, the operation and 
maintenance cost was estimated at $600/year. This cost is significantly 
less than that of the Chungungo project: operating costs in that project 
were estimated at $4 740, and maintenance costs at $7 590 (resulting in 
a total cost of $12 330/year).

Both the capital costs and the operating and maintenance costs are 
affected by the efficiency of the collection system, the length of the 
pipeline that carries the water from the collection panels to the 
storage areas, and the size of the storage tank. For example, the unit 
cost for a system with an efficiency of 2.0 l/n^/day was estimated to be 
$4.80/1 0001. If the efficiency was improved to 5.0 l/m2/day, then the 
unit cost would be reduced to $1.90/1 0001. In the Antofagasta project, 
the unit cost of production was estimated at $1.41/1000 l with a 
production of 2.5 l/m2/day.

Table 2 Capital Investment Cost and Life Span of Fog Water Collection 
System Components

Component
        

Cost ($)
        

%of Total Cost
        

Life Span (Years)

Collection
        

27680
        

22.7
        

12

Main pipeline
        

43787
        

35.9
        

20

Storage (100m3 tank)
        

15632
        

12.8
        

20

Treatment
        

2037
        

1.7
        

10

Distribution
        

32806
        

26.9
        

20

TOTAL
        

121 942
        

100.0
        


    Source: Soto Alvarez, Q. National Forestry Corporation, 
Antofagasta, Chile.

Effectiveness of the Technology

Experimental projects conducted in Chile indicate that it is possible to 
harvest between 5.3 l/m2/day and 13.4 l/m2/day depending on the 
location, season, and type of collection system used. At El Tofo, Chile, 
during the period between 1987 and 1990, an average fog harvest of 3.0 
l/n^/day was obtained using 50 fog collectors made with Raschel mesh 
netting. Fog harvesting efficiencies were found to be highest during the 
spring and summer months, and lowest during the winter months. The 
average water collection rates during the fog seasons in Chile and Peru 
were 3.0 and 9.0 l/m2/day, respectively; the lengths of the fog seasons 
were 365 and 210 days, respectively. While this seems to indicate that 
higher rates are obtained during shorter fog seasons, the practical 
implications are that a shorter fog season will require large storage 
facilities in order to ensure a supply of water during non-fog periods. 
Thus, a minimum fog season duration of half a year might serve as a 
guideline when considering the feasibility of using this technology for 
water supply purposes; however, a detailed economic analysis to 
determine the minimum duration of the fog season that would make this 
technology cost-effective should be made. In general, fog harvesting has 
been found more efficient and more cost-effective in arid regions than 
other conventional systems.

Suitability

In order to implement a fog harvesting program, the potential for 
extracting water from fogs first must be investigated. The following 
factors affect the volume of water that can be extracted from fogs and 
the frequency with which the water can be harvested:

    · Frequency of fog occurrence, which is a function of atmospheric 
pressure and circulation, oceanic water temperature, and the presence of 
thermal inversions.

    · Fog water content, which is a function of altitude, seasons and 
terrain features.

    · Design of fog water collection system, which is a function of 
wind velocity and direction, topographic conditions, and the materials 
used in the construction of the fog collector.

The occurrence of fogs can be assessed from reports compiled by 
government meteorological agencies. To be successful, this technology 
should be located in regions where favorable climatic conditions exist. 
Since fogs/clouds are carried to the harvesting site by the wind, the 
interaction of the topography and the wind will be influential in 
determining the success of the site chosen. The following factors should 
be considered in selecting an appropriate site for fog harvesting:

    Global Wind Patterns: Persistent winds from one direction are ideal 
for fog collection. The high-pressure area in the eastern part of the 
South Pacific Ocean produces onshore, southwest winds in northern Chile 
for most of the year and southerly winds along the coast of Peru.

    Topography: It is necessary to have sufficient topographic relief 
to intercept the fogs/clouds; examples, on a continental scale, include 
the coastal mountains of Chile, Peru, and Ecuador, and, on a local 
scale, isolated hills or coastal dunes.

    Relief in the surrounding areas: It is important that there be no 
major obstacle to the wind within a few kilometers upwind of the site. 
In arid coastal regions, the presence of an inland depression or basin 
that heats up during the day can be advantageous, as the localized low 
pressure area thus created can enhance the sea breeze and increase the 
wind speed at which marine cloud decks flow over the collection devices.

    Altitude: The thickness of the stratocumulus clouds and the height 
of their bases will vary with location. A desirable working altitude is 
at two-thirds of the cloud thickness above the base. This portion of the 
cloud will normally have the highest liquid water content. In Chile and 
Peru, the working altitudes range from 400 m to 1 000 m above sea level.

    Orientation of the topographic features: It is important that the 
longitudinal axis of the mountain range, hills, or dune system be 
approximately perpendicular to the direction of the wind bringing the 
clouds from the ocean. The clouds will flow over the ridge lines and 
through passes, with the fog often dissipating on the downwind side.

    Distance from the coastline: 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. In 
these cases, the distance to the coastline is irrelevant. However, areas 
of high relief near the coastline are generally preferred sites for fog 
harvesting.

    Space for collectors: Ridge lines and the upwind edges of 
flat-topped mountains are good fog harvesting sites. When long fog water 
collectors are used, they should be placed at intervals of about 4.0 m 
to allow the wind to blow around the collectors.

    Crestline and upwind locations: Slightly lower-altitude upwind 
locations are acceptable, as are constant-altitude locations on a flat 
terrain. But locations behind a ridge or hill, especially where the wind 
is flowing downslope, should be avoided.

Prior to implementing a fog water harvesting program, a pilot-scale 
assessment of the collection system proposed for use and the water 
content of the fog at the proposed harvesting site should be undertaken. 
Low cost and low maintenance measurement devices to measure the liquid 
water content of fog, called neblinometers, have been developed at the 
Catholic University of Chile (Carvajal, 1982). Figure 8 illustrates four 
different types of neblinometers: (a) a pluviograph with a perforated 
cylinder; (b) a cylinder with a nylon mesh screen; (c) multiple mesh 
screens made of nylon or polypropylene mesh; and (d) a single mesh 
screen made of nylon or polypropylene mesh. The devices capture water 
droplets present in the fog on nylon filaments that are mounted in an 
iron frame. The original neblinometer had an area of 0.25 m2 made up of 
a panel with a length and width of 0.5 m, and fitted with a screen 
having a warp of 180 nylon threads 0.4 mm in diameter. The iron frame 
was 1.0 cm in diameter and was supported on a 2.0 m iron pole. These 
simple devices can be left in the field for more than a year without 
maintenance and can be easily modified to collect fog water samples for 
chemical analysis.

In pilot projects, use of a neblinometer with single or multiple panels 
having a width and length of one meter, fitted with fine-mesh nylon or 
polypropylene netting is recommended. It should be equipped with an 
anemometer to measure wind velocity and a vane to measure wind 
direction. The neblinometer can be connected to a data logger so that 
data can be made available in computer-compatible formats.

Advantages

    · A fog collection system can be easily built or assembled on site. 
Installation and connection of the collection panels is quick and 
simple. Assembly is not labor intensive and requires little skill.

    · No energy is needed to operate the system or transport the water.

    · Maintenance and repair requirements are generally minimal.

    · Capital investment and other costs are low in comparison with 
those of conventional sources of potable water supply used, especially 
in mountainous regions.

    · The technology can provide environmental benefits when used in 
national parks in mountainous areas, or as an inexpensive source of 
water supply for reforestation projects.

    · It has the potential to create viable communities in inhospitable 
environments and to improve the quality of life for people in 
mountainous rural communities.

    · The water quality is better than from existing water sources used 
for agriculture and domestic purposes.

Disadvantages

    · This technology might represent a significant investment risk 
unless a pilot project is first carried out to quantify the potential 
rate and yield that can be anticipated from the fog harvesting rate and 
the seasonably of the fog of the area under consideration.

    · Community participation in the process of developing and 
operating the technology in order to reduce installation and operating 
and maintenance costs is necessary.

    · If the harvesting area is not close to the point of use, the 
installation of the pipeline needed to deliver the water can be very 
costly in areas of high topographic relief.

    · The technology is very sensitive to changes in climatic 
conditions which could affect the water content and frequency of 
occurrence of fogs; a backup water supply to be used during periods of 
unfavorable climatic conditions is recommended.

    · In some coastal regions (e.g., in Paposo, Chile), fog water has 
failed to meet drinking water quality standards because of 
concentrations of chlorine, nitrate, and some minerals.

    · Caution is required to minimize impacts on the landscape and the 
flora and fauna of the region during the construction of the fog 
harvesting equipment and the storage and distribution facilities.

Figure 8: Types of Neblinometers.

    Source: G. Soto Alvarez, National Forestry Corporation, 
Antofagasta, Chile.

Cultural Acceptability

This technology has been accepted by communities in the mountainous 
areas of Chile and Peru. However, some skepticism has been expressed 
regarding its applicability to other regions. It remains a localized 
water supply option, dependent on local climatic conditions.

Future Development of the Technology

To improve fog harvesting technology, design improvements are necessary 
to increase the efficiency of the fog collectors. New, more durable 
materials should be developed. The storage and distribution systems 
needs to be made more cost-effective. An information and community 
education program should be established prior to the implementation of 
this technology.

Information Sources

Contacts

Guido Soto A., Waldo Canto V., and Alejandro Cruzet, Corporación 
Nacional Forestal (CONAF), IV Región, Cordovez 281, La Serena, Chile. 
Tel. (56-51)22-6090/22-4306/21-3565. Fax (56-51)21-5073.

Hector Correa C., Corporación Nacional Forestal (CONAF), III Región, 
Avda. Atacama 898, Copiapo, Chile. Tel. (56-52)21-2571. Fax (5 6-5 
2)21-25 71.

Roberta Espejo Guasp, Profesor, Departamento de Física, Facultad de 
Ciencias, Universidad Católica del Norte, Av. Angamos 0610, Casilla de 
Correo 1280, Antofagasta, Chile. Tel. (56-55)24-1148, anexos 211/287. 
Fax (56-55)24-1724/24-1756, E-mail: respejo@ocompa.cecum.ucn.cl.

Pilar Cereceda T., Instituto de Geografia, Universidad Católica de 
Chile, Casilla 306, Correo 22, Santiago, Chile. Tel./Fax (56-2)552-6028.

Derek Webb, Coordinador del Proyecto CIID/IDRC, Universidad Católica de 
Chile, Casilla 106, Correo 22, Santiago, Chile. Tel/Fax (56-2)233-7414.

Christian Gischler, Consultant, Alvaro Casanova 294-B2A, La Reina, 
Casilla 206, Correo 12, Santiago, Chile. Tel. (56-2)273-1433.

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