Low Temperature Geothermal Resource Assessment for Membrane Distillation Desalination in the United States

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6 Scopus Citations

Abstract

Substantial drought and declines in potable groundwater in the United States over the last decade have decreased the availability of fresh water. Desalination of saline water such as brackish surface or groundwater, seawater, brines co-produced from oil and gas operations, industrial wastewater, blow-down water from power plant cooling towers, and agriculture drainage water can reduce the volume of water that requires disposal while providing a source of high-quality fresh water for industrial or commercial use. Membrane distillation (MD) is a developing technology that uses low-temperature thermal energy for desalination. Geothermal heat can be an ideal thermal-energy source for MD desalination technology, with a target average cost of 1/m3 to 2/m3 for desalinated water depending on the cost of heat. Three different cases were analyzed to estimate levelized cost of heat (LCOH) for integration of MD desalination technology with low-grade geothermal heat: (1) residual heat from injection brine at a geothermal power plant, (2) heat from existing under-utilized low-temperature wells, and (3) drilling new wells for low-temperature resources. The Central and Western United States have important low-temperature (<90°C) geothermal resource potential with wide geographic distribution, but these resources are highly under-utilized because they are inefficient for power production. According to the U.S. Geological Survey, there are 1,075 identified low-temperature hydrothermal systems, 55 low-temperature sedimentary systems and 248 identified medium-to high-temperature geothermal systems in the United States. The estimated total beneficial heat potential from identified low-temperature hydrothermal geothermal systems and residual beneficial heat from mediumto high-temperature systems is estimated as 36,300 MWth, which could theoretically produce 1.4 to 7 million m3/day of potable water, depending on desalination efficiency.

Original languageAmerican English
Pages129-140
Number of pages12
StatePublished - 2016
EventGeothermal Resources Council 2016 Annual Meeting - Geothermal Energy Here and Now: Sustainable, Clean, Flexible, GRC 2016 - Sacramento, United States
Duration: 23 Oct 201626 Oct 2016

Conference

ConferenceGeothermal Resources Council 2016 Annual Meeting - Geothermal Energy Here and Now: Sustainable, Clean, Flexible, GRC 2016
Country/TerritoryUnited States
CitySacramento
Period23/10/1626/10/16

Bibliographical note

See NREL/CP-6A20-66657 for preprint

NREL Publication Number

  • NREL/CP-6A20-68516

Keywords

  • Desalination
  • Direct-use
  • Low temperature
  • Membrane distillation

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