An Integrated Approach to Water-Energy Nexus in Shale-Gas Production

Abstract

ABSTRACT-Shale gas production is associated with significant usage of fresh water and discharge of wastewater. Consequently, there is a necessity to create the proper management strategies for water resources in shale gas production and to integrate conventional energy sources (e.g., shale gas) with renewables (e.g., solar energy). The objective of this study is to develop a design framework for integrating water and energy systems including multiple energy sources, cogeneration process, and desalination technologies in treating wastewater and providing fresh water for shale gas production. Solar energy is included to provide thermal power directly to a multi-effect distillation plant (MED) exclusively (to be more feasible economically) or indirect supply through a thermal energy storage system. Thus, MED is driven by direct or indirect solar energy, and excess or direct cogeneration process heat. The proposed thermal energy storage along with the fossil fuel boiler will allow for the dual-purpose system to operate at steady-state by managing the dynamic variability of solar energy. Additionally, electric production is considered to supply a reverse osmosis plant (RO) without connecting to the local electric grid. A multiperiod mixed integer nonlinear program (MINLP) is developed and applied to discretize operation period to track the diurnal fluctuations of solar energy. The solution of the optimization program determines the optimal mix of solar energy, thermal storage, and fossil fuel to attain the maximum annual profit of the entire system. A case study is solved for water treatment and energy management for Eagle Ford Basin in Texas.

An enterprise control methodology for the techno-economic assessment of the energy water nexus

“…No multi-stage flash desalination units were included in this study. The reader is referred to several works that have treated this subject in detail [7,81,[81][82][83][84][85][86][87][88][89][90][91][92].…”

“…To illustrate, a recent study estimates that water withdrawals by electricity generating facilities in 2010 constituted 45% of the overall freshwater withdrawals in the United States with approximately 2% of that water being consumed as a result [4]. In addition to cooling purposes, large quantities of water are utilized in the extraction of raw fuels for electricity generation [7,8]. A recent study reported that the water consumption (in liters per gigajoule -L/GJ) for worldwide production of carbon-based and nuclear fuels is as follows: 1) traditional oil (3-7 L/GJ); 2) oil from oil sands (70-1800 L/GJ); 3) conventional natural gas (minimal water use); 4) shale gas (36-54 L/GJ); 5) coal (5-70 L/GJ); and 6) uranium (4-22 L/GJ) [8].…”

“…As a consequence of decarbonization and low gas prices, a lot of new natural gas power plants are being installed to replace the retired coal and oil generation facilities [23]. However, natural gas production withdraws and consumes significant amounts of water (≈ 1000m 3 -30000m 3 per shale well per year [7]) and hence, cannot be ignored within the context of renewable energy integration [7,[24][25][26][27][28][29]. To meet the required CO 2 emission reductions, natural gas production is projected to grow by 44% between 2011 and 2040 [30].…”

Models and hierarchical methodologies for evaluating solar energy availability under different sky conditions toward enhancing concentrating solar collectors use: Texas as a case study

“…3 [87], which represents one of the significant Fig. 1 A hierarchical methodology of predicting DNI hotspots in the United States due to various activities of water-energy-food nexus [88] such as shale oil and gas production [89][90][91], agricultural production [92,93], etc. The solar data for San Antonio is obtained from the National Solar Radiation Data Base (NSRDB) between 1991 and 2010 are: hourly global solar irradiance, hourly direct solar irradiance, hourly diffuse solar irradiance, hourly solar incidence angle, hourly dry bulk temperature, hourly wet bulk temperature, and relative humidity.…”