Come Rain or Shine

Water Desalination: Barriers and Opportunities

October 06, 2021 USDA Southwest Climate Hub & DOI Southwest Climate Adaptation Science Center Season 2 Episode 12
Come Rain or Shine
Water Desalination: Barriers and Opportunities
Show Notes Transcript

This month we take a closer look at desalination of brackish groundwater and/or seawater as a potential solution to augment water supply in the arid southwest. We are joined by Dr. Sam Fernald, Director of the New Mexico State University Water Resources Research Institute, and Dr. Pei Xu researcher and professor in the Department of Civil Engineering at New Mexico State University, who share their current research and thoughts on the future of this technology. Episode art courtesy of Pixabay.

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Welcome to Come Rain or Shine, podcast of the USDA Southwest Climate Hub and the USGS Southwest Climate Adaptation Science Center or Southwest CASC. I'm Sarah LeRoy, science applications and communications coordinator for the Southwest CASC. And I'm Emile Elias, director of the Southwest Climate Hub.

 Here we highlight stories to share the most recent advances in climate science, weather and climate adaptation and innovative practices to support resilient landscapes and communities. We believe that sharing some of the most innovative forward thinking and creative climate science and adaptation will strengthen our collective ability to respond to even the most challenging impacts of climate change in one of the hottest and driest regions of the world.

[00:00:54] Emile Elias: A few months ago, a member of our Come Rain or Shine podcast team asked about desalination as a solution to water scarcity in the arid west. If you're tracking the news, then you likely know that this year is the first year of curtailment on the Colorado river, which means that some irrigators must leave their fields fallow.

Creative solutions and coping with water scarcity are critical in the Southwestern United States. Today, we take a deeper look at the opportunities and challenges for desalination. Desal is the process of producing drinkable water from seawater or brackish water by removing salts. There are different technologies to remove salt from water, with reverse osmosis being the predominant technology for desalination providing about 60% of global installed capacity.

Thermal desalination accounts for another 35%. Today, we'll hear from two experts, exploring the barriers and opportunities for desalination in New Mexico and across the arid and semi-arid Southwest. Sam Fernald is a professor of watershed management and the director of the New Mexico Water Resources Research Institute, which funds research conducted by faculty and students from universities across New Mexico, to address water problems critical to New Mexico and the Southwest.

The Institute also participates in joint efforts to solve water related problems along the U S-Mexico border. Dr. Fernald researches socio-hydrology, surface water, groundwater interactions, and integrated human and natural systems. Pei Xu is a professor in the department of civil and environmental engineering at New Mexico State University and the director of the environmental lab for innovative technologies.

Her research focuses on water reuse, desalination, membrane processes, nanomaterials and produced water treatment. The goal of her research is to address critical water shortage challenges in arid and semi-arid region. Welcome Sam and Pei before we get started, can each of you give us a little bit of background on your work as it relates to water desalination?

And we'll start with you, Sam. 

[00:03:14] Sam Fernald: Thank you, Emile. I'm a professor of hydrology, but also work at our water Institute where we really conduct research to improve water management and one of the opportunities for desalination taking the salt out of water is adding to the water budget in scarce regions.

Of course, our inflow is low and variable from precipitation, snow runoff, groundwater use. And that's the case in New Mexico and throughout the Western US. So we've really looked at desalination as a way to augment the water budget. And our Institute has funded multiple research projects with support from the Bureau of Reclamation and the State of New Mexico and other federal agencies, such as the US Geological Survey and the US Department of Agriculture to look at ways to find alternative water supplies.

So we've done a lot with treatment technology to look at ways to use the renewable energy, to figure out different membranes, to use different source waters with different chemistry, all to basically add more water, taking this salty in our case often groundwater because we're in the, we're not on the coast, we're in the interior west and making that usable waters.

And, we've got a lot of work with the system, the human system that uses the water. For example, we did some studies where we, there was a lot of interest in a community water supply that would use desalination, but our research showed that really, it was the industry that needed the desalination, not the community.

And that's borne out in the fact that it's now the industry that's pushing desalination. So. That's just an overview, even with advanced agricultural techniques such as closed system agriculture, basically glorified greenhouses, we're finding that we can economically use desalination to add to the water budget for all the water uses across the spectrum.

[00:05:32] Emile Elias: Great. Thanks, Sam. Yeah, it's really important. Important technology here in our arid and dry regions. Pei, can you give us a little bit of background about your work as it relates to water desalination? 

[00:05:44] Pei Xu: Yes. So I would be happy to introduce the research work we are doing at New Mexico State University. I am a professor in environmental engineering and the research director for the New Mexico Produce Water Research consortium.

My research focuses on basic and applied research on water quality, water reuse, desalination membrane processes, and the renewable energy powered water treatment and the desalination systems. The goal is to significantly reduce the treatment costs and energy demand of the desalination. And we do fundamental research to develop cost effective, innovative membranes.

So the desalination technologies can be environmental friendly and affordable. And we also come back to pilot scale testing of the technologies that we developed to England lab. So the industry could adapt to these technologies for industrial applications and also for commercialization.

Basically the goal of my research is to develop cost effective and the environmental friendly desalination technologies. So non-traditional water supplies such as brackish water, produce water, desalination concentrate, industrial, and the municipal wastewater could become reliable water sources to address the challenge of water scarcity and climate change.

In addition to this, I want to add on, that's the, some efforts that we have not to touch on. For example led by Sam, we have been collaborating with Bureau of Reclamation Desalination Technologies. And in addition, we are also working with a new organization called the NAWI, the National Alliance for Water Innovation.

That is a energy water desalination hub founded by DOE. It is over a hundred million dollars investigation. So that is led by Lawrence Berkeley National Lab with Oak Ridge National Lab and the National Renewable Energy Lab. So NMSU is a founding member of NAWI, another one is RenewIt. RenewIt stand for the re-inventing the nation's urban water infrastructure.

So it's includes the desalination water use technologies that is a 10 years program founded by the National Science Foundation Engineering Research Center. That is the first water center founded by the prestigious Engineer Research Center. So it is led by Stanford university, UC Berkeley, Colorado School of Mines and NMSU.

And I think right now there a lot of efforts ongoing to enhance the sustainability of desalination technologies. Sam is a lead on the cooperative agreements. So besides the cooperative agreement between New Mexico State University and the Bureau of Reclamation, we also work very closely with Reclamation through unsolicited research programs like a Pitch to Pilot, and the desalination and the water purification program to test the new technologies for desalination and the pilots testing of those technologies in the Bureau of Reclamation research facility and the in water utilities. 

[00:09:36] Sam Fernald: Absolutely. So we had a cooperative agreement with Reclamation.

It was actually linked back to the original funding that paved the way for the Brackish Groundwater National Desalination research facility. That's in Alamogordo, New Mexico. The Water Institute was one of the kind of instigators of that whole effort as long with, along with College of Engineering at NMSU and the fundings led to some great groundbreaking technology. We have some new patents, like a brand new, a new company, I think. I think Reza has a company, not sure, but he's done a lot with his technology. And the neat thing is too, the traditional solar still, which has been around ever since, they tell you, if you get lost in the desert to make a little solar still with a piece of a tarp and a rock. That's advanced to the point where we may be seeing some really effective, just simple solar desalination.

So if you go to that link, you can see some of that research and we're actually renewing that project to have ongoing collaboration with Reclamation and New Mexico State University and the National Research facility. So that's going to continue. That's looking optimistic, that will continue into the future and we'll fund more research of the, along the lines of what we were talking about.

[00:11:11] Pei Xu: I think we're very fortunate to receive a significant funding from a Bureau of Reclamation on desalination. So I hope, one day we will really make the desalination widely implemented as a viable solution.

[00:11:27] Emile Elias: Thank you. That's really exciting thinking about making these technologies cost effective and environmentally friendly, and it leads into my next question.

So there's a wide range of technologies from these small systems in people's homes, reverse osmosis to some major desalination plants. And so, thinking about being cost-effective and environmentally friendly. Sam, can you tell us about some places in the United States where we have these large scale desalination plants and where that's currently being used to contribute to water supply?

[00:12:06] Sam Fernald: Absolutely. So the most prevalent location is on the coast where there's a huge supply the ocean and it's easy to get rid of concentrate which is, after you've taken out the fresh water you have left behind the sludge that's basically very high concentration of salts. And so we see a lot of desalination along arid region coasts that's in this country and around the world.

And so we also are starting to see more inland brackish desal. In fact, in New Mexico, we have the, if I get it right, the Brackish Groundwater National Desalination Research facility. That's operated by the Bureau of Reclamation, but really collaborates with many public and private agencies, researchers, and companies to figure out ways to treat water that isn't on the coast. And we're starting to see that there's the El Paso has the largest operational inland desal, but we're starting to see it in some of the smaller towns and a lot of interest throughout the west. So that's the profile, a lot of the bigger plants along the coast with a few starting to show up in the in-land west.

[00:13:28] Emile Elias: Great. Thanks, Sam. I always think about these plants as being along the coast, and so it's exciting to hear that more and more are being used to treat brackish water inland. Pei, one of the things we often hear about as a potential barrier to using this process more widely is the high cost involved. And you mentioned your research looking at both cost-effective and environmentally friendly technologies.

Can you give us some insight into what makes desalination so expensive? 

[00:14:00] Pei Xu: The high cost of desalination, primarily due to the higher salinity in brackish water and the seawater. Reverse osmosis is a primary desalination technology that uses a semi-permeable membrane that allows the passage of water molecules, but not to the majority of dissolved salts, organics, bacteria, and pathogens. But because the salinity of the water is high, so it has high osmotic pressure. We need high hydraulic pressure to push the water through the reverse osmosis membrane. This applied hydraulic pressure must be greater than the naturally occurring osmotic pressure in order to allow pure water through while rejecting a majority of contaminants.

Therefore the energy cost are higher for desalination as compared to conventional treatment of a fresh water. In addition, the saline water may contain minerals and organics that will scale and the foul membranes, when they become more and more concentrated, when we recover more water from the brackish water or sea water.

So we need the proper pre-treatment to reduce membrane fouling and scaling. Membrane fouling and the scaling can reduce the membrane lifetime, and also increase the energy consumption of desalination systems. Besides, we also need appropriate disposal of the concentrate. We call it brine or reject, that's laden with the salts and other contaminants. The concentrate disposal is a significant challenge and can be costly for desalination. So for our research and also right now many efforts have been put together to reduce the cost through a affordable, environmental friendly, concentrated disposal options, and reduce the membrane fouling and the scaling, and also develop new desalination technologies to reduce the treatment costs. 

[00:16:26] Sarah LeRoy: Thanks Pei. It's great to hear that there's new technologies coming on board to really make this desalination affordable. So thinking about the barriers to desalination, one of them that we came across in our research is that it requires a lot of energy, which of course, we know a lot of our energy right now comes from fossil fuels.

And so if we bring on more desalination, that means more fossil fuel consumption, contributing to climate change. And so I wondered if you had any thoughts on this topic. Pei? 

[00:16:59] Pei Xu: Right, yes. Desalination technology is energy intensive and we have been working on to reduce the energy demand by using the renewable energy, such as solar thermal energy and a solar PV system to power the desalination technologies. One example is to use the solar thermal to power the membrane desalination system. That can utilize the solar thermal energy and there's a membrane system to generate the distillate that is very pure. And we are also working on smaller desalination systems, such as the solar still.

It is very simple, easy to operate and completely using the solar energy to generate the water for household use. 

[00:17:50] Sarah LeRoy: That's great! Very hopeful. And so it makes me feel much better about the quote unquote barriers of desalination. It seems like they're just barriers are going away and it's becoming much more cost efficient and energy efficient.

And so Sam are there other considerations that might be less obvious, but still important to keep in mind when thinking about desalination. For example, does it impact coastal ecosystems?

[00:18:18] Sam Fernald: That's a great question. And yes, in fact, the concentrate as Pei just described has chemicals that can be toxic, especially if they're concentrated in a place where there's a diverse ecosystem, that's perceptible.

So the location and pattern of delivering the brine back to the ocean's really important, so that there's not a negative environmental impact. It's also interesting. We have done some system modeling of a couple of human natural systems looking at not only the hydrology and water quality, but also the community structure.

And it's really important to keep in mind. There are basically community equity and accessibility issues that can be either improved or negatively impacted. If you don't take into account the community you're serving when you set up your desalination, but I would say still cost concentrate disposal.

The one's Pei mentioned are still the biggest limitations. 

[00:19:28] Emile Elias: Great. Thanks, sam. And it's interesting, we're thinking about this in the Southwestern United States, because that's where we're located. We know there are some areas of the world such as Israel that already rely heavily on desalination for their domestic water supply.

Are there lessons we can learn from places where desalination is more commonplace?

[00:19:50] Sam Fernald: So basically, I think one of the things that I've learned, just talking to people, I haven't visited the sites, but it's encouraging to me that they have basically augmented their water supply with desalination and then it's helped their, the range of water uses. So, in the Western US, and we just compare the cost of desalination with our existing water supplies, it seems exorbitant to try and use it for things like agriculture. But when you look at Israel where they do have highly efficient crops and also, or closed system agriculture, and they add to their available water budget using desal, it's really encouraging me for the longterm profile of desal in the Western US where as we get more and more efficient costs go down, water scarcity is potentially increasing. It may and seems likely to be a bigger and bigger part of our water budget. 

[00:20:58] Pei Xu: I agree with Sam. Actually, the water scarcity is a global problem and the desalination has been widely implemented in other areas of the world such as Israel. There are new desalination technologies, innovative configurations developed to reduce a cost and energy demand.

For example, the Israeli company, Desalitech developed closed circuit reverse osmosis to reduce the membrane fouling and scaling and improve water recovery. The US water industry has worked with such companies for testing their technologies and implementing them in the United States. At New Mexico State University, we also collaborate with the other entities, such as in Israel to learn the lessons. For example, as Sam mentioned to use the desalinated water for agriculture irrigation, and also new sensors used to make the water use more efficiently. 

[00:22:10] Emile Elias: Great. Thanks, Pei. In August, water levels in Lake Mead dropped to the point where the federal government declared a water shortage for the first time ever, reducing Colorado river water allocations in Arizona, Nevada, and Mexico.

What are the barriers, and we've already talked about these a bit in terms of the cost and also disposing of the brine and also opportunities and including that increased efficiency and looking to other areas of the world for desal from brackish and ocean water to address our supply shortages in the Southwest.

So I feel like you've already hit on some of these barriers and opportunities, but are there other barriers or opportunities you'd like to mention. And we'll start with Pei. 

[00:22:56] Pei Xu: I think you know, for the large municipalities, it is easier to implement the desalination technologies, but for the rural areas and the small communities, they may face even more challenges to receive clean, safe water supply using alternative water sources, such as brackish water, ocean water, waste water.

And I think the challenge right now is to develop again, I said so many times, the cost effective technologies and that is affordable to these small communities, rural areas. And we also need to find sustainable, environmental friendly approach to dispose the concentrate, because otherwise this concentrate may cause an environmental issues.

I also want to add on desalination is a multidisciplinary research. It involves environmental engineering and this like a solar desalination was developed with the mechanical engineering faculty. And we also collaborate with chemical engineering and the electrical engineers. So I feel, this involves a lot of effort through the collaborative research.

I'm an engineer. So I'm fully aware of all the challenges, even though I work on desalination right now for almost 20 years and I feel that we are working on all the challenges to bring environmental sustainability to desalination. For example, their high cost to energy demand, the greenhouse gas emissions that's, and the brine management.

That is what we are working on right now.

[00:24:50] Emile Elias: Great. Thank you. Thinking about those small communities and rural areas, that's really important as we advance the technologies. Sam, is there anything you'd like to add in terms of the barriers and opportunities for desal in the Southwest?

[00:25:04] Sam Fernald: I think an opportunity is an integrated system approach to finding cost effective, environmentally friendly, socially desired locations for adding desalination to the water that's from desalination to the water budget. So for example we have, we did modeling with the approach called system dynamics that quantifies some of the relationships between the things we've been talking about treating water technology, but also even things like community perception and health and characteristics of the aquifer and the hydrogeology. And if you put all this together, some interesting patterns emerge and we're working with other universities in New Mexico, of course, New Mexico State University, New Mexico Tech, University of New Mexico to, and also Reclamation to bring these together in a translatable modeling format, that then becomes the decision tool to show how to implement desalination in different environments. For example, going to the Navajo Nation, there's a separate set of uses source water technology that requires a separate and customized approach to desalination going to Southeast New Mexico.

With produced water from the oil and gas industry, there's a unique set of circumstances that makes desalination cost effective. So, and even really interestingly, going across the border to Mexico, there's opportunities to have concentrate disposal and some great places in Mexico and water treatment in the U S and have a binational desalination facility and our system modeling is helping us make some of the decisions that would be needed to implement these creative solutions.

[00:27:14] Sarah LeRoy: Thanks, Sam. So we always like to end our podcast on a hopeful note and, listening to you both talk about the opportunities related to desalination really does make me hopeful. But I'd like to ask each of you now, as you think about water resources and the technologies that are available to us, is there anything in particular that makes you hopeful for the future?

So Pei, why don't we start with you?

[00:27:38] Pei Xu: I think the cost of treating fresh water supplies will increase. Especially the fresh water resources are very limited. I'm very hopeful that the advances in desalination technologies could provide opportunities to utilize non traditional water such as brackish water and ocean water to augment diminishing fresh water supply and to meet growing water needs. We are working hard to develop affordable and environmental friendly technologies to enhance the sustainability and the resilience of desalination systems. I totally agree with Sam that we are now taking a system level approach to consider not only the technical and the economic perspective of technologies, but also considering societal environmental public health and the environmental justice of desalination technologies.

[00:28:44] Sarah LeRoy: Sam, what about you? What makes you hopeful for the future? 

[00:28:48] Sam Fernald: I've mentioned some of the hope I have in our approaches. What occurs to me is the change in per capita water consumption and municipalities. And if you look over time in the US, many cities have gone below a hundred gallons per capita. In Europe, many cities have gone below a hundred liters per capita. So. There's more and more efficient municipal water years. And as I described for agriculture, if you can add some water to your water budget and have efficient agriculture, then that can really be cost effective. And I think that's true for municipalities also that over we will have, especially in places with access to brackish water, whether it's an underground aquifer or a coastal location.

I think that where water has a high value, desalination has great a great future. And I think it's, it'll hopefully have a cascading effects that impact the environment positively. With what's happened in the Southwest is with over extraction of freshwater aquifers we've seen drying of rivers and stressed riparian areas, stressed aquatic ecosystems.

If we can use some of the brackish resources for a water supply and free up some of the water that's coursing through our natural river systems then we can have healthy hydrology along with fully supplied municipal areas. So I think these big system approaches will become more common in the future.

And I think it's exciting to think how we can bring these together for healthy cities and economies and the environment.

[00:30:58] Sarah LeRoy: Thanks, Sam. Excellent. Well, we'd like to let you have some time for any last thoughts before we wrap up. So Sam, any last thoughts from you? 

[00:31:09] Sam Fernald: What occurs to me is that with desalination, there's a lot of effort that goes into turning salty water into usable water and fresh water.

And I think the, what goes along with that is increased appreciation and care for our water resources. So a kind of a beneficial side effect of this greater awareness of desalination may be an increased awareness of the preciousness of our water resources. And better management overall, because we've found also where communities are more involved in their water management all the way from the watershed to the, municipal water treatment to then there's a more efficient and better integrated management.

So I think that may be a beneficial side effect of this whole emphasis on desalination. 

[00:32:21] Sarah LeRoy: Pei, any last thoughts?

[00:32:23] Pei Xu: So the Southwest regions, we are sitting on a large amount of brackish water aquifer, and the brackish water desalination is less expensive as compared to the ocean desalination and the Sam Potable Water Use project.

I think a brackish water desalination may become a viable solution to address water scarcity and climate change. 

[00:32:54] Emile Elias: Thank you so much Pei Xu and Sam Fernald. Thank you so much for the work you're doing. It's really exciting to hear about how these technologies are advancing, what some of these opportunities might be and how it's really shifting our opportunities and water scarcity challenges in the Southwest.

So thank you for doing this work. I'm excited to see where it goes in the future. So we'll check in with you again, and it's just really, I'm hopeful because of your work that you're doing and that there are some opportunities to provide water in this water scarce region. 

[00:33:35] Pei Xu: Sarah, Emile, thank you so much for the invitation.

[00:33:39] Sam Fernald: Thanks again. Appreciate the chance to talk about. 

[00:33:44] Emile Elias: Thanks for listening to Come Rain or Shine, podcast of the USDA Southwest Climate Hub and the USGS Southwest CASC. If you liked this podcast, don't forget to rate or review it and subscribe for more great episodes. A special thanks to our production crew, Skye Aney and Reanna Burnett.

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