Geothermal desalination

Geothermal desalination is an proven process under development for the production of fresh water using heat energy. Claimed benefits of this method of desalination are that it requires less maintenance than reverse osmosis membranes and that the primary energy input is from geothermal heat, which is a low-environmental-impact source of energy.

Around 1995, several entrepreneurs came together with an idea to use geothermal water directly as a source for desalination. About 1998 several individuals began working with evaporation/condensation air loop desalination about 1998. The experiment was moderately successful and a proof of concept, proving that geothermal waters could be used as process water to produce potable water in 2001. In 2003 Professor Ronald A. Newcomb, formerly working on the process with Autek LLC, now at San Diego State University International Consortium for Advanced Technologies and Security or “ICATS” began to work to enhance the process of using geothermal energy for the purpose of desalination. The University explains that the device is owned by World Wide Assets LLC and Strident Ltd. and that geothermal energy is a primary energy source.

In 2005 some testing was done in a fifth 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 five prototypes and three 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-half acre foot (600 m³) of water per day. Salt 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 to adjust.

SDSU ICATS continues to develop different devices for the same purpose with the goal of making desalination an environmentally friendly process.