SIEM REAP HAS A
YEARLY WATER DEFICIT OF
300 MILLION CUBIC METERS
THE PROBLEM
PROBLEM: The tourism boom and an increasing population in Siem Reap, Cambodia have resulted in water shortages, forcing the authorities to tap into the groundwater, dangerously lowering the water table. To compensate for the province’s ongoing development and water shortages, the Siem Reap Water Supply Authority draws about 27,900 cubic meters of groundwater per day for domestic use. Groundwater levels are further impacted by hotels and other businesses, many of whom have sunk thousands of illegal private wells and pumps across the city to meet their water needs. In Siem Reap, the groundwater is about five meters below the ground surface, and therefore easy to access. This illegal use of water threatens the stability of the temples and towers of Angkor.
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In addition to the tourist use of water, residents in Siem Reap Province also want access to water. Most rural school children do not have access to clean drinking water at school. We want to change that. We are hopeful that by finding a safer water source for school children and other rural communities that we can help the people of Siem Reap have access to clean water without lowering the water table.
OUR SOLUTION
SOLAR-POWERED
WATER VAPOR
EXTRACTOR
Our project is called AWE. This stands for Atmospheric Water Extractor as we developed a method of extracting water vapor from the humid air of Siem Reap, Cambodia (and Doral, Florida where we live and have tested AWE). After building several different passive water collectors, we realized that none produced sufficient water. We then experimented with Peltier modules to create condensation and that too resulted in insufficient water extraction. Undeterred, we studied how dehumidifiers work and what makes the water they produce undrinkable. We set about taking what we could from the guts of a commercial dehumidifier, added food-safe hoses and a gravity-fed water purification system that we built to create an amazing system that can collect 15-20 gallons of clean drinking water per day using solar power. We have a two-stage platform. On the top stage is a fan that draws in humid air through an antimicrobial mesh air filter. The air passes over cold copper coils in which a coolant (R-410A) is circulated. R-410A is a zeotropic/near azeotropic mixture of difluoromethane and pentafluoroethane. It is non-ozone depleting. Because the air is cooled well below its dew point, the water condenses on the surface of the coils and adjacent hydrophobic mesh panel and then drips into a collection point. The collection point has a food-grade hose that carries the water down to the filtration system on the bottom platform.
Our gravity-fed purification system is comprised of two recycled five-gallon water bottles. In the top bottle, we drilled three holes and installed three Black Berkey purification elements. These elements have a compact matrix containing millions of microscopic pores and are capable of filtering out 99.9% of viruses, pathogenic bacteria, heavy metals, pesticides, e-Coli, etc. By using three filters we are able to filter three gallons of water per hour and can filter 6,000 gallons of water before they need to be replaced.
Also, located on the bottom platform is the R-410A compressor. R-410A is a zeotropic/near azeotropic mixture of difluoromethane and pentafluoroethane. The compressor is what expands and compresses the refrigerant (R-410A).
Finally, we have a solar powered generator. Solar panels are plugged directly into the generator. It has a Lithium-Ion battery with a peak capacity of 1,100 W continuous for one hour, an AC Inverter (pure sine wave, 1500W continuous capacity). The AWE system is solar powered using two 350W solar panels. It can extract more than one gallon of water per hour, yielding between 15 and 20 gallons of water per day using only solar power.
AWE is easy to install and requires little maintenance beyond changing filters as needed. We strived to use parts that we know will be locally available.