Feasibility of Wind Power for Brackish Groundwater Desalination: A Case Study of the Energy-Water Nexus in Texas

Abstract

With dwindling water supplies and the impacts of climate change, many cities are turning to water sources previously considered unusable. One such source for inland cities is brackish groundwater. With prolonged drought throughout Texas, cities such as El Paso, Lubbock, and San Antonio are desalinating brackish groundwater to supplement existing water sources. Similar projects are under consideration elsewhere in Texas. While brackish groundwater contains fewer total dissolved solids than seawater, desalination of brackish groundwater is still an energy-intensive process. Brackish water desalination using reverse osmosis, the most common desalination membrane treatment process, consumes 20 to 40 times more energy than traditional surface water treatment using local water sources. This additional energy consumption leads to increased carbon emissions when using fossil fuel-generated electricity. As a result of concern over greenhouse gas emissions from additional energy consumption, some desalination plants are powered by wind-generated electricity. West Texas is a prime area for desalination of brackish groundwater using wind power, since both wind and brackish groundwater resources are abundant in the area. Most of the Texas Panhandle and Plains region has wind resource potential classified as Class 3 or higher. Additionally, brackish groundwater is found at depths less than 150 m in most of west Texas. This combination of wind and brackish groundwater resources presents opportunities for the production of alternative drinking water supplies without severe carbon emissions. Additionally, since membrane treatment is not required to operate continuously, desalination matches well with variable wind power. Implementing a brackish groundwater desalination project using wind-generated electricity requires economic feasibility, in addition to the geographic availability of the two resources. Using capital and operating cost data for wind turbines and desalination membranes, we conducted a thermoeconomic analysis for three parameters: 1) transmission and transport, 2) geographic proximity, and 3) aquifer volume. Our first parameter analyzes the cost effectiveness of tradeoffs between building infrastructure to transmit wind-generated electricity to the desalination facility versus pipelines to transport brackish groundwater to the wind turbines. Secondly, we estimate the maximum distance between the wind turbines and brackish groundwater at which desalination using wind power remains economically feasible. Finally, we estimate the minimum available brackish aquifer volume necessary to make such a project profitable. Our analysis illustrates a potential drinking water option for Texas (and other parts of the world with similar conditions) using renewable energy to treat previously unusable water. Harnessing these two resources in an economically efficient manner may help reduce future strain on the energy-water nexus.