Adam Bross Melissa LoeperDarryl Brown Sujata PalSonike Hendricks Casey SpenserBrian Jennings

Dew Harvesting

The Problem

The United States has the luxury of being a very water-rich nation with a sufficient infrastructure to transport that water. As a result, many Americans do not give a second thought about the quality of the water being supplied to their homes, whether or not there will be water for them to use on a daily basis or if the water contains water-borne diseases or parasites. The thought of having to travel long distances to retrieve the water necessary for daily life is completely foreign and absurd. However, for many people around the world, this is not the case and obtaining drinkable freshwater free of contaminants, diseases and parasites is a difficult task, if not an impossible one. In addition, because of an increasing global population and changing environmental factors, a global freshwater shortage appears to be looming on the horizon.

A 2003 article from USA Today reported that a United Nations report stated, “More than half of humanity will be living with water shortages… within 50 years because of a worldwide water crisis…” According to 10 facts about water scarcity assembled by the World Health Organization, “By 2025 nearly 2 billion people will be living in countries or regions with absolute water shortages, where water resources per person fall below the recommended level of 500 cubic meters per year.” As of February 2009, the world population is estimated to be around 6.76 billion people. This means that within the next 20 years approximately one-third of the world population will be living in absolute water shortage conditions. Halifa Drammeh, the coordinator of water policies of the United Nations Environmental Programme was quoted saying, “Tens of millions of people don’t have access to safe water. It is indeed a crisis.” As for the regions of the world most affected by this crisis, water resources economist Chuck Howe of the University of Colorado in Boulder said, “About 90% of the severe problems are in developing nations…” Numerous other reports over the past few years all point to the fact that freshwater shortages are a huge global problem already and, if unchanged, are likely to get worse.

Possible Solution

In researching possible solutions to this problem, our group came across a product called the Watercone. This is a recently new product not even on the market yet. Figure 1 includes pictures of the Watercone and a brief explanation of how it works. This device is used to purify water using only sunlight. Although this product presents a low-tech environmentally friendly way to purify water, it does not address the problem of water scarcity.

Upon further investigation our group discovered an article about the International Organization for Dew Utilization. It was then that the concept of dew collection and utilization became the focus of our group. Extracting dew and moisture out of the air appears to be a viable solution to water scarcity in many parts of the world affected by freshwater shortages.

The concept of dew collection is certainly not new, dating as far back as ancient China. Although it is not a new concept, few systems for collecting dew exist. There were basically two that our group

came upon in our research. One system involves a roof structure that would collect the dew. The dew then runs off into a gutter system leading to a storage tank. A second system we came upon was a project by two Israeli architects. Their design had an inverted pyramid-shaped canopy supported by poles. The dew would collect on the canopy, run down the slope of the canopy into a collection drum in the center.

The focus of our group is to create a design that would be suitable for use in developing countries where freshwater scarcity is a major problem. With this in mind, the group decided that a roof structure design would not be the best solution. Many people in developing countries may not even have a shelter that would be able to support a roof design. As far as the inverted pyramid design, this design took up an area of 10m2. People in developing countries tend to live in relatively crowded conditions in which large open spaces may not be available.

If this system is to be used for applications in developing countries, there are also other requirements that the system must meet. One of these is that all water surfaces must be sealed off from insects. The reason for this is that in some of the parts of the world where water scarcity is a problem, malaria and other diseases carried by mosquitoes and other insects are also a problem. Our design needs to ensure that water sources do not provide a breeding ground for disease-carrying insects.

Our design would use a dew collecting structure that would take up as little ground area as possible. The collected dew would run into a gutter system which would carry the dew to a purification system. The water would then be purified and would run into a storage tank.

Summary Description

The problem that is being addressed is the lack of clean freshwater in areas such as North Africa and the Middle East. The system that our group has designed would address the clean water scarcity by collecting water and purifying it. This water system utilizes dew collection, which is a viable process in these areas.

Our group has developed a system composed of two basic steps. Figure 2 is a rough sketch of what our system will look like. The first step is the collection of dew. A nylon tarp is used and is set up vertically between two poles, much like a volleyball net. The nylon material that our group will use is 200 Denier Uncoated Solarmax. This fabric is breathable, water repellent, ultraviolet resistant, and allows for dew droplets to run easily into a gutter system. A gutter system will be directly below the nylon material. Mosquito netting will be stretched over the open area of the gutter to prevent insects from entering into the collection system. The water will be able to drip through the netting into the gutter and flow into a tube that will deliver the water to our version of the Watercone. All tubing joints will be sealed with waterproof sealer which will completely isolate the collected water from insects. Our version of the Watercone is the second major component to this system and acts as a purifier. A technical drawing of this is provided in figure 3. Any dirt or impurities picked up from the nylon tarp or the gutter system will be separated from the clean water as the sun’s energy evaporates the collected dew. The cone allows for the sun’s rays to penetrate through the clear plastic upper shell. The water will evaporate, condense on the inside of the clear plastic and run into the outer collection trough. The water in the trough will be pure, clean, drinkable water. The outer trough will be drained into a collection tank where the pure water can be stored and used when needed. To prevent the potentially contaminated water from overflowing into the clean collection trough and into the collection container, a drainage tube will be

placed up through the base of our version of the Watercone. The height of the tube will be lower than the height of the wall separating the potentially contaminated water from the pure water so that if the potentially contaminated water level reaches the height of the drainage tube the water will flow out into a separate collection bin where it can later be poured back into the gutter. The overflow bin will also be sealed off from insects.

This system is unique because it both collects and purifies water “from thin air”. Prior solutions collect dew water but do not purify it. By incorporating the water cone, our product not only collects dew, but takes it to the next level by completely cleansing it of impurities. By setting up our dew collector vertically, our design is able to eliminate a lot of ground space occupied our system. This allows for instillation to be possible in more areas. In addition, our design does not require any prior structures, such as a roof, so that it can be a practical solution to many families in a variety of living conditions. This is very important to us because helping as many people as possible is a main goal of ours.

References

1. "Dew Harvesting |." Rainwater Harvesting Guide. 24 Feb. 2009 <http://www.rain-barrel.net/dew-harvesting.html>.

2. "Dew Harvesting." Tim Tyler's Home Page. 23 Feb. 2009 <http://timtyler.org/dew_harvesting>.

3. International Organization For Dew Utilization. 24 Feb. 2009 <http://www.opur.u-bordeaux.fr/>.

4. Kokic, Marko. "Ten Facts About Water Scarcity." World Health Organization. 25 Feb. 2009 <http://www.who.int/features/factfiles/water/en/index.html>.

5. Vergano, Dan (2003, January, 26). Water shortages will leave world in dire straits. USA Today, Retrieved February 25, 2009, from http://www.usatoday.com/news/nation/2003-01-26-water-usat_x.htm

6. "Watercone&reg; The Product." Watercone&reg; News. 22 Feb. 2009 <http://www.watercone.com/product.html>.

7. "World population -." Wikipedia, the free encyclopedia. 25 Feb. 2009 <http://en.wikipedia.org/wiki/World_population>.

1.Pour salty / brackish Water into pan. Then float the Watercone(r) on top. The black pan absorbs the sunlight and heats up the water to support evaporation.

2.The evaporated Water condensates in the form of droplets on the inner wall of the cone. These droplets trickle down the inner wall into a circular trough at the inner base of the cone.

3.By unscrewing the cap at the tip of the cone and turning the cone upside down, one can empty the potable Water gathered in the trough directly into a drinking device.

Figure 1

Figure 2

Figure 3

SYSTEM FLOW CHART

Atmospheric moisture condenses as dew on the nylon mesh surface. Stage 1

The dew on the nylon mesh runs into a collection gutter. Stage 2

Water from the collection gutter flows into the evaporation pan through a transfer hose. Stage 3

Solar radiation heats the water in the evaporation pan and evaporates into the cone’s atmosphere.

Stage 4

TECHNICAL DRWAINGS – Solar Purification System

TECHNICAL DRWAINGS – Dew Collection System