A better solution: (Intentional) Integrated Systems for Energy Water Nexus

For managing challenges at the energy-water nexus, we need to move from an interconnected world to an integrated world.  

For an interconnected world, energy depends on water and water depends on energy. There are some advantages from this approach. 

For example, water can be used to enhance energy systems. Water cooling improves the performance of thermal power plants, water can be used to improve growth rates of energy crops, and water can be used to enhance oil and gas extraction via hydraulic fracturing of shale formations. 

Going the other way around, energy can be used to improve the quality and reliability of water systems through pumping, heating and treating water to get it to our desired location with the preferred composition.

Although this is good news, there's also significant downside to interconnections. 

Energy-water interconnections are mostly ad hoc, implemented in a singular way to achieve particular outcomes rather than according to a high-level master plan.   Overall, this creates interdependencies and cross-sectoral vulnerabilities that can be difficult to manage.  

Because of this makeshift interconnectedness, a constraint in one resource becomes a constraint in the other. Water shortages can cause energy problems.  A lack of water cooling can cause power plants to turn off or dial back, and scarcity causes some regions to ban the use of freshwater for hydraulic fracturing of oil and gas wells.  Energy shortages can cause water problems; without the energy to pump and treat water, our taps would go dry.  

To solve these risks and vulnerabilities, we need to go from today’s accidental situation, where energy and water are interconnected, to a better system, where energy and water are purposely integrated. Whereas interconnection is accidental and risky, integration is intentional and improves performance overall.

For an integrated system, water improves the energy sector while energy improves the water sector. With clever integrated engineering, we can solve multiple problems simultaneously.  

Examples of integrated systems

Here are two examples: 1) using renewable electricity to treat and desalt water, and 2) using flared gas to treat wastewater at shale production sites. 

In places like parched West Texas, there is an ocean of brackish (i.e., slightly salty) water under our feet in vast aquifers.

Aboveground there is an abundance of sunshine and lots of wind.  Wind and solar are challenging for grid operators because of their variability.  Desalination of the brackish groundwater is challenging because of its energy and carbon intensity. 

But, we can put these together to create a better solution.  

Using a brackish desalination plant as a variable load for wind and solar—meaning the water plant’s operation is dialed up and down to match the available power—mitigates the challenges of wind and solar because the power would be dedicated to water treatment. And, wind and solar plants, whose fuels are free and zero-carbon, reduce the energy use and carbon footprint of desalination.  With integrated design, both solve each other’s problems.

In the Eagle Ford Shale and Bakken Shale formations, there is a renaissance of oil and gas production underway. While this boom offers many positive benefits, it also requires substantial volumes of freshwater for fracking, generates significant wastewater from the production process, and has triggered an epidemic of gas flaring.  

In today’s conventional operations, all three environmental impacts happen simultaneously. But, with integrated design, the flared gas can be used to treat the wastewater for re-use at the next well thus dramatically reducing the need for additional freshwater competition, eliminating the need for wastewater disposal, and improving the quality of the water. In this case, energy and water are helping each other out rather than exacerbating their worst features.

By consciously moving from (accidental) interconnected systems to (intentional) integrated systems, we can use the nexus of energy and water to achieve cross-cutting solutions, rather than cross-sectoral collapse.  

Note: The Cynthia and George Mitchell Foundation funded several research projects under Dr. Webber's direction on this specific issue.

 

As Deputy Director of the Energy Institute, Co-Director of the Clean Energy Incubator, Josey Centennial Fellow in Energy Resources, and Associate Professor of Mechanical Engineering, Dr. Michael E. Webber trains the next generation of energy leaders at the University of Texas at Austin through research and education at the convergence of engineering, policy, and commercialization.  His Energy at the Movies is currently in national syndication on PBS television, and his massive open online course (MOOC) “Energy 101” closed with record results in December. Dr. Webber holds a B.S. and B.A. from The University of Texas at Austin and M.S. and Ph.D. in mechanical engineering from Stanford University. For more information, follow Twitter @MichaelEWebber.

 

The views expressed by contributors to the Cynthia and George Mitchell Foundation's blogging initiative, "Achieving a Sustainable Texas," are those of the authors and do not necessarily represent the views of the foundation. 

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