Minimum energy requirements for desalination of brackish groundwater in the United States with comparison to international datasets

Yvana D Ahdab; Gregory P Thiel; J K Böhlke; Jennifer Stanton; John H Lienhard

doi:10.1016/j.watres.2018.04.015

Minimum energy requirements for desalination of brackish groundwater in the United States with comparison to international datasets

Water Res. 2018 Sep 15:141:387-404. doi: 10.1016/j.watres.2018.04.015. Epub 2018 Apr 12.

Authors

Yvana D Ahdab¹, Gregory P Thiel¹, J K Böhlke², Jennifer Stanton³, John H Lienhard⁴

Affiliations

¹ Rohsenow Kendall Heat Transfer Laboratory, Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, United States.
² U.S. Geological Survey, MS 431, 12201 Sunrise Valley Drive, Reston, VA 20192, United States.
³ U.S. Geological Survey, 10 Bearfoot Road, Northborough, MA 01532, United States.
⁴ Rohsenow Kendall Heat Transfer Laboratory, Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, United States. Electronic address: lienhard@mit.edu.

PMID: 29857319
DOI: 10.1016/j.watres.2018.04.015

Abstract

This paper uses chemical and physical data from a large 2017 U.S. Geological Survey groundwater dataset with wells in the U.S. and three smaller international groundwater datasets with wells primarily in Australia and Spain to carry out a comprehensive investigation of brackish groundwater composition in relation to minimum desalination energy costs. First, we compute the site-specific least work required for groundwater desalination. Least work of separation represents a baseline for specific energy consumption of desalination systems. We develop simplified equations based on the U.S. data for least work as a function of water recovery ratio and a proxy variable for composition, either total dissolved solids, specific conductance, molality or ionic strength. We show that the U.S. correlations for total dissolved solids and molality may be applied to the international datasets. We find that total molality can be used to calculate the least work of dilute solutions with very high accuracy. Then, we examine the effects of groundwater solute composition on minimum energy requirements, showing that separation requirements increase from calcium to sodium for cations and from sulfate to bicarbonate to chloride for anions, for any given TDS concentration. We study the geographic distribution of least work, total dissolved solids, and major ions concentration across the U.S. We determine areas with both low least work and high water stress in order to highlight regions holding potential for desalination to decrease the disparity between high water demand and low water supply. Finally, we discuss the implications of the USGS results on water resource planning, by comparing least work to the specific energy consumption of brackish water reverse osmosis plants and showing the scaling propensity of major electrolytes and silica in the U.S. groundwater samples.

Keywords: Brackish groundwater composition; Desalination; Energy requirements; Least work of separation; Saturation index.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Australia
Conservation of Energy Resources*
Groundwater / chemistry
Saline Waters*
Spain
Sulfates
United States
Water Purification / methods*

Substances

Sulfates