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Geothermal desalination

Geothermal desalination

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Geothermal desalination is a process under development for the production of fresh water
Fresh Water
Fresh Water is the debut album by Australian rock and blues singer Alison McCallum, released in 1972. Rare for an Australian artist at the time, it came in a gatefold sleeve...

 using heat energy
Geothermal power
Geothermal energy is thermal energy generated and stored in the Earth. Thermal energy is the energy that determines the temperature of matter. Earth's geothermal energy originates from the original formation of the planet and from radioactive decay of minerals...

. Claimed benefits of this method of desalination
Desalination, desalinization, or desalinisation refers to any of several processes that remove some amount of salt and other minerals from saline water...

 are that it requires less maintenance than reverse osmosis
Reverse osmosis
Reverse osmosis is a membrane technical filtration method that removes many types of large molecules and ions from solutions by applying pressure to the solution when it is on one side of a selective membrane. The result is that the solute is retained on the pressurized side of the membrane and...

 membranes and that the primary energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...

 input is from geothermal heat, which is a low-environmental-impact source of energy.

Around 1995, entrepreneur Douglas Firestone from Nevada
Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...

 came up with an idea to use geothermal water directly as a source for desalination. In 1998, several individuals began working with evaporation/condensation air loop water desalination. The experiment was successful and a proof of concept
Proof of concept
A proof of concept or a proof of principle is a realization of a certain method or idea to demonstrate its feasibility, or a demonstration in principle, whose purpose is to verify that some concept or theory that has the potential of being used...

, proving that geothermal waters could be used as process water to produce potable water in 2001.

In 2005 to 2009 some testing was done in a sixth prototype of a device referred to as a delta t device, a closed air loop, atmospheric pressure, evaporation condensation loop geothermally powered desalination device. The device used filtered sea water from Scripps Institute of Oceanography and reduced the salt concentration from 35,000 ppm to 51 ppm.

A total of six prototypes and six modifications demonstrated that, with process water approaching 210 degrees Fahrenheit (100 degrees Celsius) and a chill source about 35 °F (2 °C), a full-size device would produce about one acre foot (600 m³) of water per day. Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...

 concentration in the wastewater would only be about 10% above the level of the original water, thus, from, say, 35,000 to about 38,000 parts per million, well within the ability of osmoregulators
Osmoregulation is the active regulation of the osmotic pressure of an organism's fluids to maintain the homeostasis of the organism's water content; that is it keeps the organism's fluids from becoming too diluted or too concentrated. Osmotic pressure is a measure of the tendency of water to move...

to adjust.

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