Research Awards To Improve Water Desalination Methods

Upcoming Research Is Part of a Greater Effort To Make the Most of Every Water Resource

As concerns about water scarcity in the United States grow, desalination—which turns salt water into fresh water—could be the answer to providing new sources for drinking, irrigation, and other uses. Yet, the amount of energy needed to separate salt from water can be expensive and negatively impact the environment.

Thanks to two new funding awards, National Renewable Energy Laboratory (NREL) researchers will collaborate with other partners to improve the energy efficiency of desalination and water reuse technologies across the country. The awards are part of the $9M National Alliance for Water Innovation (NAWI) Pilot Program funded by the U.S. Department of Energy’s Industrial Efficiency and Decarbonization Office.

“From developing novel membranes that filter out undesirable residues to analyzing methods to decarbonize water and wastewater treatment, NREL is working at the forefront of providing cost-effective and sustainable alternative water sources to meet U.S. demand,” said Matt Ringer, NREL laboratory program manager.

NREL received two of the program’s awards, which will support researchers' efforts to make desalination devices more sustainable by finding better ways to treat their waste (in ways that can recapture useful chemicals) and ensuring they can run on renewable power.

Advanced Membrane Takes Desalination All the Way to Clean
The Low Salinity Inland Desalination Brine Treatment Using Scalable Next Generation Bipolar Membranes project, which is being led by NREL, is developing a next-generation membrane to improve the quality of desalinated water by filtering out salt water (or brine) and contaminants while also recovering substances that can be used for other purposes.

Reverse osmosis is a process that removes most contaminants from water by using pressure to push it through a semipermeable membrane, like a sieve, that collects waste brine. That waste brine—which can build up in large volumes from inland brackish (or somewhat salty) water desalination and wastewater recycling—is challenging to treat or discard. Current methods to treat it include thermal (heating) technologies that use a lot of energy and evaporation ponds that take up a lot of space. Disposing of it down deep wells means losing water.

Project partners will address these waste-treatment challenges to:

• Lower the cost of waste brine treatment
• Use significantly less energy compared to thermal approaches
• Recover 100% of the water while also removing contaminants such as heavy metals and hazardous chemicals.

“This work will directly address the challenges to inland brackish water desalination and wastewater recycling,” said Abhishek Roy, an NREL materials science researcher and the project lead. “By fabricating, piloting, and analyzing a next-generation membrane, the research team aims to lower the cost and increase the energy efficiency of desalination technology.”

The novel membrane technology—known as a bipolar membrane electrodialysis system—has the potential to desalinate brine while converting the dissolved substances into valuable acids and bases that have other uses, contributing to a circular economy.

The four project partners play different roles. NREL will conduct membrane and polymer synthesis and characterization, roll-to-roll synthesis, and device-scale modeling. The University of Texas at Austin will perform membrane system bench- and pilot-scale engineering and testing, GivePower will lead a reverse-osmosis pilot and membrane pilot system integration, and the Lawrence Berkeley National Laboratory will conduct life-cycle analyses.

Desalination Processes Need To Be Compatible With Electrification
The Optimizing Electric and Water Grid Coordination Under Technical, Operational, and Environmental Considerations project addresses both water and energy security. The project team is led by the Electric Power Research Institute, an independent, nonprofit energy R&D organization, and features research collaborators NREL, Colorado State University, and the Salt River Project.

During the two-year project, researchers will examine strategies to manage and coordinate water system operations with the electric grid to ensure desalination treatment processes are compatible with efforts to use renewable sources for electricity.

With extensive experience in water technology research and advanced modeling capabilities, NREL will conduct techno-economic modeling using the Water treatment Technoeconomic Assessment Platform (WaterTAP). An open-source, Python-based software package, WaterTAP was developed for NAWI by NREL, one of four national laboratories leading NAWI, a six-year, $110M energy-water desalination hub funded by the U.S. Department of Energy.

“This project will use multiple tools, models, and methods to assess and characterize the current conditions in desalination treatment and evaluate and compare long-term impacts and trade-offs when we’re considering costs, energy, and environment,” said Joshua Sperling, a researcher at NREL who is co-leading the laboratory’s team with fellow NREL researcher David Greene. “Water and electricity are both foundational to our lives and our economy. In an environment where decarbonization and resilience are a priority, NREL is evaluating water treatment options to move us to a net-zero-carbon economy.”

To inform NREL’s WaterTAP analysis, the other collaborators on the project will provide dynamic operational models and develop a digital version of the Salt River Project’s power and water system. Using a multimodel, multimethod approach, the researchers will be able to understand how operations could become more flexible to use more on-site renewable energy instead of electricity from the grid while also desalinating more water and increasing cooperative activities between water and energy utilities as they plan for climate uncertainty.

“Water treatment operators typically try to avoid rapid or significant changes at plants. This steady-state operation has historically been considered as being easier to manage and having energy advantages. NREL will use WaterTAP to explore whether a desalination plant can operate cost effectively with high quality under variable conditions with expanded use of renewable energy sources and battery storage,” Greene said.

“In addition,” he added, “if we can demonstrate that a large energy user like a desalination plant can vary its electric demand during high-energy-consumption periods without a negative impact on its water production goals, that could open new revenue streams for plants by providing a benefit that grid operators might be willing to pay for.”

Greene said that, through this project, NREL is building on NAWI’s initial investments in tools, baseline studies, and road-mapping frameworks by ensuring that WaterTAP is useful for real-world applications, technology integration, and economic and environmental analysis.

By considering the economic and environmental aspects of desalination and how technologies could improve water security and cost savings around electrification and the grid, these NAWI Pilot Program projects will help augment and diversify water resources to ensure availability, affordability, and access to water.

Learn more about NAWI and its efforts to secure an affordable, energy-efficient, and resilient water supply for the United States.

About The National Alliance for Water Innovation
The National Alliance for Water Innovation is a public–private partnership that brings together a world-class team of industry and academic partners to examine the critical technical barriers and research needed to radically lower the cost and energy of desalination. The alliance is led by the U.S. Department of Energy’s Lawrence Berkeley National Laboratory in collaboration with the National Energy Technology Laboratory, the National Renewable Energy Laboratory, and Oak Ridge National Laboratory and is funded by the U.S. Department of Energy’s Industrial Efficiency and Decarbonization Office.