University of Nevada Creates New Solar Pond Distillation System
Ecosystems of terminus lakes worldwide can benefit from a new arrangement being developed at the University of Nevada, Reno, to desalinize water utilizing a differentiated low-priced solar pond and proprietary membrane distilment arrangement powered by renewable energy.
“These lakes — hundreds worldwide — such as the Great Salt Lake, the Salton Sea, the Aral Sea and Walker Lake here in Nevada, see a decline in water levels and an increase in salinity from both human and natural processes,” Francisco Suarez, a doctoral student in hydrological sciences at the University, said.
Suarez is developing an artificial salt-gradient stratification procedure that traps solar heat at the bottom of the solar pond and utilizes the accumulated energy to power the membrane distillate system recently patented by the University. The arrangement is configured to help sustain the ecosystems of these closed-basin regions where there is no efflux for the water and a high evaporation rate, leaving a high concentration of minerals and salts.
The hot brine in the lower storage district of the pond, which can reach temperatures greater than 195 degrees Fahrenheit, may then be utilized instantly for heating, thermal desalination, or for other low-temperature thermal applications.
“Our model results show that in a two-week period, the temperature in the bottom of the solar pond increased from 68 to 126 degrees Fahrenheit and, even though the insulating layer is being eroded by double-diffusive convection, the solar pond remained stable,” Suarez explained.
The process has been extremely successful in the lab in a small-scale experiment using a 400-gallon tank, where dissolved solids and precise fiber-optic temperature sensing are being used to track the process as it desalinates the water. The next step for Suarez and the research group is to build a pilot-project, demonstration-scale, low-temperature desalination scheme in an open environment.
The price to run the arrangement is negligible because it uses the renewable energy of the sun, trapped as heat in the bottom, to power most of the system.
This can operate 24 hours a day using the stored energy. Very little electrical energy would be used. For every surface acre of solar pond we can make three acre-feet of freshwater in about one year.
The major advantages of this system are that renewable energy is used, the system is low maintenance and the stratification procedure that helps drive the process uses the salts from the lake itself.
Hydrologist Tyler said the procedure could serve as one constituent of a salinity management program and, coupled with other remediation efforts, could desalinate Walker Lake enough to make it a safe marine habitat.
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