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

Abstract

Substantial drought and declines in potable groundwater in the United States over the last decade has increased the demand for 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 range 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 underutilized low-temperature wells, and (3) drilling new wells for low-temperature resources. The Central and Western United States have important low-temperature (<90 degrees C) geothermal resource potential with wide geographic distribution, but these resources are highly underutilized because they are inefficient for power production. According tomore » the USGS, 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 medium to 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.« less

Authors:
;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Geothermal Technologies Office (EE-4G)
OSTI Identifier:
1357950
Report Number(s):
NREL/CP-6A20-68516
DOE Contract Number:
AC36-08GO28308
Resource Type:
Conference
Resource Relation:
Conference: Presented at the Geothermal Resources Council Annual Meeting (GRC 2016), 23-26 October 2016, Sacramento, California
Country of Publication:
United States
Language:
English
Subject:
15 GEOTHERMAL ENERGY; 29 ENERGY PLANNING, POLICY, AND ECONOMY; low temperature; direct-use; desalination; membrane; distillation

Citation Formats

Akar, Sertac, and Turchi, Craig. Low Temperature Geothermal Resource Assessment for Membrane Distillation Desalination in the United States. United States: N. p., 2017. Web.
Akar, Sertac, & Turchi, Craig. Low Temperature Geothermal Resource Assessment for Membrane Distillation Desalination in the United States. United States.
Akar, Sertac, and Turchi, Craig. Mon . "Low Temperature Geothermal Resource Assessment for Membrane Distillation Desalination in the United States". United States. doi:.
@article{osti_1357950,
title = {Low Temperature Geothermal Resource Assessment for Membrane Distillation Desalination in the United States},
author = {Akar, Sertac and Turchi, Craig},
abstractNote = {Substantial drought and declines in potable groundwater in the United States over the last decade has increased the demand for 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 range 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 underutilized low-temperature wells, and (3) drilling new wells for low-temperature resources. The Central and Western United States have important low-temperature (<90 degrees C) geothermal resource potential with wide geographic distribution, but these resources are highly underutilized because they are inefficient for power production. According to the USGS, 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 medium to 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.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon May 01 00:00:00 EDT 2017},
month = {Mon May 01 00:00:00 EDT 2017}
}

Conference:
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  • Substantial drought and declines in potable groundwater in the United States over the last decade has increased the demand for 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 desalinationmore » technology, with a target range 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 underutilized low-temperature wells, and (3) drilling new wells for low-temperature resources. The Central and Western United States have important low-temperature (<90 degrees C) geothermal resource potential with wide geographic distribution, but these resources are highly underutilized because they are inefficient for power production. According to the USGS, 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 medium to 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.« less
  • The US Geological Survey is conducting the first quantitative assessment of low-temperature (less than 100/sup 0/C) geothermal reources in the United States. The survey has been aided in this task by the geothermal data-gathering programs of many state agencies and several private contractors supported by the State Coupled Geothermal Program of the US Department of Energy/Division of Geothermal Energy (DOE/DGE). The methodology being used in this assessment is summarized.
  • This joint project between the National Renewable Energy Laboratory and the Colorado School of Mines has examined the potential of using low-temperature geothermal resources for desalination. The temperature range in question is not well suited for electricity generation, but can be used for direct heating. Accordingly, the best integration approaches use thermal desalination technologies such as multi-effect distillation (MED) or membrane distillation (MD), rather than electric-driven technologies such as reverse osmosis (RO). The examination of different desalination technologies led to the selection of MD for pairing with geothermal energy. MD operates at near-ambient pressure and temperatures less than 100°C withmore » hydrophobic membranes. The technology is modular like RO, but the equipment costs are lower. The thermal energy demands of MD are higher than MED, but this is offset by an ability to run at lower temperatures and a low capital cost. Consequently, a geothermal-MD system could offer a low capital cost and, if paired with low-cost geothermal energy, a low operating cost. The target product water cost is $1.0 to $1.5 per cubic meter depending on system capacity and the cost of thermal energy.« less
  • The amount of thermal energy in high-temperature geothermal systems (>150/sup 0/C) in the United States has been calculated by estimating the temperature, area, and thickness of each identified system. These data, along with a general model for recoverability of geothermal energy and a calculation that takes account of the conversion of thermal energy to electricity, yield a resource estimate of 23,000 MW /SUB e/ for 30 years. The undiscovered component was estimated based on multipliers of the identified resource as either 72,000 or 127,000 MW /SUB e/ for 30 years depending on the model chosen for the distribution of undiscoveredmore » energy as a function of temperature.« less
  • The difficiencies of existing analyses of only geothermal gradient as a basic approach and as illustrated by three different gradient maps are demonstrated. Examples of approaches to evaluation in two different settings (Kansas and Oregon) are illustrated. Kansas is in the geologically stable Midcontinent where horizontal sedimentary rocks overlie a granitic and metamorphic basement. Oregon is in the geologically complex and young Cordillera. The significant data in Kansas include relatively widely spaced (10 to 20 km), vertically detailed, temperature-depth and thermal conductivity measurements and aquifer analyses (location, water quality and flow characteristics). It is possible to interpolate temperature values atmore » intermediate sites using well samples and logs to determine basement radioactivity and thermal conductivity and thus local heat flow and temperature. In Oregon, in the more complex geological provinces, assessment must proceed statistically or on a case by case basis. The important parameters are local geothermal gradients and heat flow, and aquifer conditions. Interpolated values between data points are not reliable because an individual data point has a lateral zone of significance of only about 1 to 5 km.« less