Energy consumption in desalinating produced water from shale oil and gas extraction

• Published in: Desalination Vol. 366; pp. 94 - 112
• Main Authors: Thiel, Gregory P., Tow, Emily W., Banchik, Leonardo D., Chung, Hyung Won, Lienhard, John H.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2015
• Subjects: Desalination; Distillation; Energy efficiency; Evaporative; Extraction; Frack water; High salinity; Hydraulic fracturing; Membranes; Natural gas; Produced water remediation; Reverse osmosis; Salinity; High salinity; Energy efficiency; Frack water; Produced water remediation; Hydraulic fracturing
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2014.12.038

On-site treatment and reuse is an increasingly preferred option for produced water management in unconventional oil and gas extraction. This paper analyzes and compares the energetics of several desalination technologies at the high salinities and diverse compositions commonly encountered in produced water from shale formations to guide technology selection and to inform further system development. Produced water properties are modeled using Pitzer's equations, and emphasis is placed on how these properties drive differences in system thermodynamics at salinities significantly above the oceanic range. Models of mechanical vapor compression, multi-effect distillation, forward osmosis, humidification–dehumidification, membrane distillation, and a hypothetical high pressure reverse osmosis system show that for a fixed brine salinity, evaporative system energetics tend to be less sensitive to changes in feed salinity. Consequently, second law efficiencies of evaporative systems tend to be higher when treating typical produced waters to near-saturation than when treating seawater. In addition, if realized for high-salinity produced waters, reverse osmosis has the potential to achieve very high efficiencies. The results suggest a different energetic paradigm in comparing membrane and evaporative systems for high salinity wastewater treatment than has been commonly accepted for lower salinity water. •Several desalination systems were modeled at high salinity.•The effect of salinity on desalination system energy consumption was analyzed.•The least energy required to desalinate produced water is much higher than seawater.•Evaporative systems analyzed tended to have higher efficiencies at higher salinity.•If realized, high salinity reverse osmosis could provide significant energy savings.