Extraction of Water from Extraction of Water from AirAir

Sarah WatsonSarah WatsonDepartment of Chemical Department of Chemical

EngineeringEngineeringUniversity of Texas at AustinUniversity of Texas at Austin

Major ConceptsMajor Concepts

• Water: 3% by mass of air Water: 3% by mass of air 4% by volume 4% by volume

• Absolute humidityAbsolute humidity• Relative humidityRelative humidity

Method 1: Direct ExtractionMethod 1: Direct Extraction

• Air pumped into a Air pumped into a chiller where chiller where sensible heat is sensible heat is removedremoved

• Air lowered to Air lowered to dew point and dew point and water condenseswater condenses

Method 2: DesiccantMethod 2: Desiccant

• Create vapor Create vapor pressure gradientpressure gradient

• Attract water Attract water moleculesmolecules

• Liquid or SolidLiquid or Solid

Method 3: ConvectionMethod 3: Convection

• Transfer of heat by the circulation or Transfer of heat by the circulation or movement of the heated parts of a movement of the heated parts of a liquid or gas liquid or gas

• Very tall Very tall towers are towers are usedused

Power SourcesPower Sources

EfficiencyEfficiency• Daily capacityDaily capacity (L/day)= (L/day)= Airflow (m^3/s) x 86400s/day x absolute Airflow (m^3/s) x 86400s/day x absolute

humidity (g/m^3)X 1/1000 L/g x ηhumidity (g/m^3)X 1/1000 L/g x η• ηη= =

____amount of water extracted per unit amount of water extracted per unit time_______time_______

Total moisture content of air processed per unit timeTotal moisture content of air processed per unit timeMethod Capacity (L/day)

reverse osmosis desalination 284,000-45,000,000

cooled surface atmospheric extraction 5,860,000

solid desiccant extraction 100,000,000

liquid desiccant extraction 1,700,000

convection-based extraction 31,000,000

QUESTIONS?QUESTIONS?

ReferencesReferences1. Barlow, M. (2007). 1. Barlow, M. (2007). Blue CovenantBlue Covenant. The New Press. . The New Press. 2. Ferret, G. (2003, November 2). 2. Ferret, G. (2003, November 2). Water shortages threaten AfricaWater shortages threaten Africa [Scientists and [Scientists and

researchers meeting in the Kenyan capital, Nairobi, have warned of the growing threat researchers meeting in the Kenyan capital, Nairobi, have warned of the growing threat posed by water shortages across Africa. ]. Retrieved November 16, 2008, from BBC posed by water shortages across Africa. ]. Retrieved November 16, 2008, from BBC News Web site: http://news.bbc.co.uk/ 1/ hi/ sci/ tech/ 3235829.stmNews Web site: http://news.bbc.co.uk/ 1/ hi/ sci/ tech/ 3235829.stm

3. Festel, D. G. (n.d.). 3. Festel, D. G. (n.d.). Drinking Water Extraction from AirDrinking Water Extraction from Air. Retrieved November 19, 2008, . Retrieved November 19, 2008, from Festel Capital Web site: http://www.festel.org/ Water_from_Air.pdffrom Festel Capital Web site: http://www.festel.org/ Water_from_Air.pdf

4. Kirby, A. (2003, March 5). 4. Kirby, A. (2003, March 5). UN warns of future water crisisUN warns of future water crisis [The world’s water crisis is so [The world’s water crisis is so severe it could take almost 30 years to eradicate hunger, the United Nations says.]. severe it could take almost 30 years to eradicate hunger, the United Nations says.]. Retrieved November 16, 2008, from http://news.bbc.co.uk/ 2/ hi/ science/ nature/ Retrieved November 16, 2008, from http://news.bbc.co.uk/ 2/ hi/ science/ nature/ 2818615.stm2818615.stm

5. Kloosterman, K. (2008, November 3). 5. Kloosterman, K. (2008, November 3). Israeli startup EWA squeezes drinking water from Israeli startup EWA squeezes drinking water from thin airthin air. Retrieved November 16, 2008, from Israel Ministry of Foreign Affairs Web site: . Retrieved November 16, 2008, from Israel Ministry of Foreign Affairs Web site: http://www.mfa.gov.il/ MFA/ Israel+beyond+politics/ EWA-squeezes-drinking-water-from-http://www.mfa.gov.il/ MFA/ Israel+beyond+politics/ EWA-squeezes-drinking-water-from-air-3-Nov-2008.htmair-3-Nov-2008.htm

6. Royse, D. (2006, September 29). 6. Royse, D. (2006, September 29). Air alchemy: Can humidity solve post hurricane drinking Air alchemy: Can humidity solve post hurricane drinking water problem?water problem? Retrieved November 19, 2008, from http://www.usatoday.com/ tech/ Retrieved November 19, 2008, from http://www.usatoday.com/ tech/ news/ techinnovations/ 2006-09-29-air-water-machines_x.htmnews/ techinnovations/ 2006-09-29-air-water-machines_x.htm

7. Scrivani, A., & Bardi, U. (n.d.). A study of the use of solar concentrating plants for the 7. Scrivani, A., & Bardi, U. (n.d.). A study of the use of solar concentrating plants for the atmospheric water vapour extraction from ambient air in the Middle East and Northern atmospheric water vapour extraction from ambient air in the Middle East and Northern Africa [Electronic version]. Africa [Electronic version]. DesalinationDesalination, 592-599., 592-599.

8. Wahlgren, R. V. (2000, April). Atmospheric Water Vapour Processor Designs for Potable 8. Wahlgren, R. V. (2000, April). Atmospheric Water Vapour Processor Designs for Potable Water Production:: A Review. Water Production:: A Review. PergamonPergamon, 1-22., 1-22.

Images: Google ImagesImages: Google Images