Episode 33: Atmospheric Water Harvesting

Lisa Peña (LP): The world needs free flowing, clean, water. But drought and pollution jeopardize our water sources. An SwRI team is taking on these threats, tapping into a solution called atmospheric water harvesting, and finding new ways to clean up contaminants. We're discussing their groundbreaking research next, on this episode of Technology Today.

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We live with technology, science, engineering, and the results of innovative research every day. Now let's understand it better. You're listening to the Technology Today podcast presented by Southwest Research Institute.

Hello, and welcome to Technology Today. I'm Lisa Peña. Our guest today is SwRI engineer and program manager, Kevin Supak. He leads a research team with two main goals, to find ways to augment sources of water, and to clean up existing water sources. The team is exploring atmospheric water harvesting, a method of pulling water from the air. And they're also looking at new ways to decontaminate water to make it safe for drinking. Their findings could help communities around the world dealing with water shortages. Thanks for joining us, Kevin.

Kevin Supak (KS): Thanks for having me, Lisa. This is an honor to talk to you.

LP: Let's talk about the problem first. Many of us just turn on our taps, and clean running water appears. But we're fortunate. We know here in the U.S., and around the world, community's experience drought, and clean water shortages. In fact, the Western US is going through a drought right now. So how extensive is the need globally for clean, readily available, drinking water?

KS: You're absolutely right, Lisa. We're very fortunate, here in the U.S., that most of us can go to our taps, open up a faucet, and get clean running water, that is extremely safe to drink. But that's not the case around the world. The United Nations currently estimates that over 25% of humanity lacks access to clean water. Most of these people are in Asia. And this figure can even double during periods of drought, when we have seasonal droughts that occur around the world.

And there's all kinds of sanitation issues that we see around the world, where they can contaminate our water sources too. And you mentioned as well, these problems are starting to show up here in the U.S. too. Our increasing population, and drought, and lack of snowfall, have really affected Lake Mead, which is a major water source for the Western part of the United States. And it's at its lowest level that it's been in since the Hoover Dam was constructed. I think this is really significant.

We're also all really familiar with the lead contamination issue that occurred in Flint, Michigan, that we're still trying to solve, related to our aging infrastructure here in the U.S. So, not only is it climate change, it's aging infrastructure. But the world's population is just increasingly, every year, putting pressure on our water resources.
 

Courtesy of SwRI

SwRI researchers are using these silica gel beads as part of a low-cost, large-scale method to harvest water molecules from the air. As they expel moisture, they turn from blue to pink.

LP: So at any given time, 25% to even up to 50% of the population is without the precious resource of water. Is that correct?

KS: That's correct. It's actually a really scary number when you look at it like that. I saw a really interesting video that was put together by some folks in Hollywood, it's on Netflix, is called Brave Blue World. This is a visual look at how big this problem really is. And I really would encourage everybody to show this to their children, and to just share it, and watch it. Because it is a real problem and it's only getting worse.

LP: OK. That's a really clear picture of the problem we're facing. But your team is looking at ways to tap into atmospheric water as a water source. You're also researching solutions to clean up existing water sources. I want to go into now, what was your inspiration to begin this type of water research? How did you decide to direct your expertise and resources toward the need for water?

KS: Yeah, that's a great question. And it's one that I feel personally compelled when I see some of the issues that are going on in our environment, I want to take action. That's what I would like to do. I feel a personal connection to wanting to improve the problems I see around me. And the problem really started a couple of years ago. I was driving into work one day, and this is during peak summer, people are watering their lawns a lot. And I was driving down the street, and almost like every 10th house, I swear, had a broken sprinkler head, and it's just spewing water into our streets. And water's pouring down the road, I'm driving through it like it's a little creek bed. And it really frustrated me to see that, especially during peak drought.

And because I know and understand the relationship between water and energy, we talked about how many people lack access to clean water, and I went and talked to my director about it. And we got to working together, and looking at what we could do, using our fluid mechanics knowledge, to solve some of the world's problems related to water. And so we started interacting with industry, and finding out all the problems that we need to solve. And we started to build a great team here at Southwest, that incorporates our experts in hydrology, and chemistry, and material science, and fluids, and heat transfer. And we've put together a really great team that is looking to solve these problems.
 

Courtesy of SwRI

SwRI Engineer and Program Manager Kevin Supak leads a research team exploring atmospheric water harvesting. Their technology, currently in development, is expected to be about the size of a mini fridge and capable of producing a gallon of water every day.

LP: All right, so that takes us to atmospheric water harvesting, which is what your team is working on. And it's exactly what it sounds like, harvesting water from the air around you. Wow. Pulling it from the atmosphere to use for drinking, washing hands, whatever you need. Who knew that was possible? So how does that work?

KS: So there's water vapor in the air around us all the time. And water vapor is even in arid environments, even in the desert. And we can tap into it, by condensing this water. We're all very familiar with these processes. We see them. We see dew in the morning on our windshields on our car, rain events that occur. These are all natural ways that we can get water out of the atmosphere.

But you know we've also all probably enjoyed a cold beverage on a hot day, a humid day. Or maybe even at our grandma's house, how we forgot to put a coaster under a cold beverage, and we left a water ring around it. We are directly condensing water out of the atmosphere there. And we all may not know this, or maybe a lot do, but the air conditioners in our home today are atmospheric water harvesters. They are doing that, day in and day out. Air conditioners in your home can produce on the order of like 5 to 10 gallons a day of water, any given day, that we could use to help flush toilets, maybe to help water plants in our yard.

And commercial companies have taken this type of technology, and they're actually offering atmospheric water harvesting to communities in the US, and communities around the world. Where people are using this technology to help bring clean water to areas that may not have had it before. Well the big challenge with a refrigeration based system, so having cold coils that condense water, is that when the humidity level gets so low, like in an arid environment, like a desert, it basically renders these units inoperable. You have to drive the temperature so low that they don't work anymore, they don't produce water.

And so what we're looking at is a second form of atmospheric water harvesting. And that's actually using a desiccant material to directly absorb water vapor, in it's gaseous form, into these materials. And we're all familiar with desiccants, just like we're familiar with air conditioners. Desiccants are in our daily lives, like rice, or the silica gel packets that you see in the equipment that you buy, or in shoes that you buy too.

I think we've all had a chance, even some unnamed people in my house, who have dropped their phone in water. And they read online, you can put your phone in a bag of rice and it'll absorb all the water. And that's true, it does. We're all familiar with desiccants and atmospheric water harvesting technology. And what we want to do is, we want to augment the existing systems that we have in order to absorb water at all humidity levels, basically, in arid environments or humid environments. And that's really the goal of this research.

LP: So you are working with a particular desiccant. Can you spell desiccant for us?

KS: Desiccant. D-E-S-I-C-C-A-N-T.

LP: OK, so that's a desiccant. And we're all familiar with all the examples you named there. I guess I've never thought of gathering that water, let's say, from the dew or the cold drinks. And being able to use so much of it that you can wash your hands, or take a drink of it. So that's really neat. That's amazing technology there. So you're working with a particular desiccant, you talked about silica. And that seems to be your preferred desiccant to study. What is it about silica that works so well for this method?

KS: So silica is one of the most prevalent materials in the Earth's crust, And we use it every day. You see it in forms of sand, it can be processed, it's from quartz. And it's just really readily available. There's a lot of commercial companies that make it. And like I said before, you see it in the silica gel packets when you buy equipment. And that's really attractive from the standpoint, that if we want to start gathering more water from the atmosphere, we need to do it in a cost effective manner.

Now there are other materials out there that researchers are working on that are called metal organic frameworks, or MOFs for short. And these are engineered materials that are desiccants, just like silica is, and just like rice is. Except they're engineered to absorb a lot more water per the unit mass that we make it. But these materials are costing thousands of dollars per pound. I mean, they have high performance, but it comes at a cost. So there's always an engineering balance between performance and cost. There may be a couple of markets here. But right now we're focusing on silica gel, because we believe cost is a driving factor here.

LP: OK. So silica gel, you're talking about those packets in our shoe boxes, as you said. What does this process look like, this technology? What is the size? Would this work as a unit that can be placed anywhere to retrieve water from the air?

KS: Yes it could be placed anywhere. We could place it in arid environments, like relative humidity's in the 20% to 30% range, which is typical of a desert, to very humid environments, as well. And the novelty we're employing here, is what's called a fluidized bed. And that's a fancy term for saying we're flowing air over small pellets, small pieces of this material. And it's essentially levitating in the air. And it's allowing that water vapor to get trapped more easily into those little pellets. Then we will then heat those pellets, after all the water vapor is absorbed. And then we'll take it through a temperature swing, just like an air conditioner would, to condense that water out.

We think that a unit that can produce about a gallon of water, per day in the desert areas, would probably be about the size of a large mini fridge. We've all seen those in our dorm rooms, or in our garages, and these are those mini fridges that are about that midsize range. That's about the size we think it's going to be.

LP: So is it just like a cube of silica that you're looking at putting out there? Or is there more to it than just the material?

KS: We actually have a great video that I encourage our listeners to look at. Our YouTube video that shows how the air moves over these particles. These particles sit in a couple of different tubes. One of them would be a tube that we flow humid air, or air from the atmosphere over these particles to absorb the water. And the other tube would be where we would move those particles over to it. That would be the heated tube, where we're removing that water vapor from there, to more easily condense it.

LP: All right. We'll definitely put that video on the Episode 33, episode page. So our listeners can check that out. So in what scenarios would atmospheric water harvesting be most useful?

KS: I think one of the things I need to do, real quick, is address the elephant in the room here. It takes a fair amount of energy, and it's a fairly complicated process for this refrigerator sized unit, a mini-fridge sized unit, to condense a gallon of water in the desert. One of your listeners may be hearing it and saying, wow, that's pretty complicated just for a gallon of water. And I would absolutely say, that's right. This type of technology would never replace our typical sources of water, like groundwater, and aquifers, and things like.

But there are scenarios where we need to make water, where that infrastructure isn't there. And the Department of Defense is really interested in this technology because moving water around to the front lines of a battlefield is actually a really logistical challenge. And if you could free up some trucking to move other equipment, and make water directly at the battlefield, that would be a huge, huge gain for our soldiers on the front lines.

Another area is disaster relief. And when hurricanes strike, or earthquakes strikes, or tsunamis, or other natural disasters, a lot of times our water sources get contaminated. Or maybe there's no electrical power there, to be able to provide water. And so if you had an atmospheric water harvester with you, you could start producing water for people directly from the air around you.

In another area, I talked about this earlier in the interview here, is the home user. And that's homes all over the world. Atmospheric water harvesting is actually already reaching impoverished communities. And these are the refrigeration based methods. But like I mentioned earlier, they only operate over a narrow range of humidity. If we can use our technology, the absorbance based technology, and pair it with these refrigeration based methods, we can greatly enhance the amount of water that they can produce every day.

LP: Because your technology can work even in the desert, as you're saying.

KS: That's right.

LP: Does it require a power source?

KS: That's a great question. And absolutely, yes, every form of water requires some type of power. So today, most of our water gets pumped out of the ground, or from a river, to different areas. And so this pumping power. To condense water from the air, you actually need more power than you do to convey it around. And that's because we have to change it from a gas form to a liquid form.

The Earth does this for us daily, almost, with day and night cycles. And there are atmospheric water harvesting researchers out, there that are using the daytime heating to heat these components, and the nighttime cold humid air and absorbing water. But those cycles are obviously really long and they don't produce as much water. So you do need power. And, as I mentioned earlier, this technology won't replace traditional water, the amount of water you can use. So it definitely needs power and you need a fair amount of this absorbent material to make the water potable.

LP: So you also mentioned that in some of the communities in need, that atmospheric water harvesting is already being used. And that's more the refrigeration method. So how long has atmospheric water harvesting been looked at as a solution? And is it getting results? At least the refrigeration method that's being used right now.

KS: Yeah. And there's a couple of really great examples. And one of those is highlighted in that Brave Blue World documentary I talked about earlier. There are some communities in Africa, that have home based units, where they're able to provide drinking water to their people that usually have to walk miles to go to a creek bed and get water. It's really impressive, really amazing.

And I would say that, to answer your question, in the past 20 years, people have been taking this more seriously, in terms of refrigeration based atmospheric water harvesting. And there are companies that have gone to Flint, Michigan, to provide drinking water for people that are being affected by the lead contamination crisis, with their atmospheric water harvesting units. This is the refrigeration based ones again. And this same group actually went to Puerto Rico, after Hurricane Maria, and helped provide atmospheric water harvested water for this community. So the short answer is, it's been around for a long time. Air conditioners have been around for a long time. But using them as potable water is probably the past 20 years, or so.

LP: OK, and just to clarify, as we've been talking about, there are two kinds of atmospheric water harvesting. Which is the refrigeration based method, and the method using desiccants, which is the method you are studying, which is not as widespread.

KS: Definitely, not.

LP: So your team is looking at this method, because it's a little bit simpler, it's a little bit more flexible. So what stage of research are you in? And how long could it be until your method can be deployed where needed most?

KS: So the stage we're at right now is, that we are taking some of the fundamentals that universities have done, when they've looked at some of these high surface area materials to absorb water. And there's a couple of different cycles that I mentioned earlier, like maybe using the day and night cycles to help make water. And what we're trying to do is put this in practical form, put it in so that we can take it on a pathway to commercialization.

And we're currently at, what we call, the benchtop scale. Which means that we're making water on the milliliters per day, kind of production. Just to vet out all the different pieces of absorbent based atmospheric water harvesting system, which is the fluidized bed that I mentioned earlier. Making sure we understand the variables, and how we can scale that process to something that's usable. Something that can make like five liters of water, a little over a gallon of water a day, for an individual use.

And we are currently designing that system right now, and we expect that system to be operating before the year end. So we can collect some critical data and take this data to maybe some commercialization partners, or to work with the military, or others to start deploying this technology.

LP: OK, so we've touched on this a little bit already, but what are the limitations of water harvesting?

KS: So the limitations of, as mentioned earlier, the current water harvesting techniques, which is refrigeration based, is you need a high humidity environment for them to be effective. We're trying to greatly expand the humidity window to be able to operate in an arid environment, or in a humid environment, or couple that together.

But we've talked about power, you still need power to make water in these scenarios. And that can come in the form of solar cells or solar heating. It can come from day/night cycles. But sometimes you just need water. And maybe you just need to plug this into the wall, get electricity. Or you run an engine, like a diesel engine or something, and you have a generator there that can provide electricity for you. And I will say as well, somebody reached out to me recently, and like has anybody ever studied, if you start absorbing all this water and providing water from the atmosphere, are you going to affect the climate? And that's a very valid question.

And I'll answer it with, we have traditional water sources that we're never going to replace. And it would take an exorbitant amount of energy, I mean a ton of energy, to take all the water in the atmosphere, which is currently estimated to be more than the amount of rivers that we have in the world, and start condensing that. So we definitely don't want to get to the point where we're condensing enough water from the atmosphere that we're affecting rain and snow fall, and things like that. So that's the biggest limitations I see right now.

LP: So there's a definite balance of tracking these units and making sure that it's not overdone. But when needed, It's a great solution, it sounds like.

KS: Absolutely. It's intended to augment sources when you don't have them. Or it's intended to augment disaster relief teams, and maybe even really remote communities that just don't have access to clean water.

LP: It's a lifeline, I would think, for those communities.

KS: Absolutely. Water is life. And I think it is very precious.

LP: So aside from water harvesting, you're also looking at ways to clean existing water sources, to make these sources safe for drinking. First, what type of water sources are you looking at cleaning up?

KS: I think most folks are familiar with that there's a lot of desalination that's going on in the world. And so seawater is an obvious source of water that we could tap into. We can't drink that right away, you know we've got salt in it, we've got other dissolved minerals in there. Brackish water is another term that's used, that we are currently in San Antonio doing. There's a plant here that's making 10 million gallons a day of water. Where they're pumping water from what's called a brackish water reservoir. And this is kind of a mixture between seawater and fresh water. And our local utility is currently doing that. Like many other utilities here in the US, they're going into these unconventional sources.

And there's another area that's growing in research attention. And this is wastewater from different processes. This is wastewater that's coming from industries. From cooling towers that we have, like our thermoelectric plants, that when we make electricity they use a lot of water. Industrial processes, as I mentioned. Agriculture is a big area as well. So these are all sources that we're looking at in order to provide augmentation to our existing groundwater and river sources.

LP: So your goal would be to clean up this water, again to make it safe for drinking. What methods are you exploring to decontaminate water?

KS: So I mentioned earlier that, most of the cost in moving water from an aquifer to your home, is in the pumping cost. And there's a little bit of cost associated with chlorinating water, and things like that. But most of the energy is in that pump itself. Well these other methods, these unconventional methods, they require a lot more pumping power, they require a lot more treatment to be able to make them potable. So it's really the energy needed to bring these unconventional sources of water to potable levels. And it's really astronomical when you look at how much energy it takes to do this.

And so what we're looking at is different treatments and post-treatments, that you could do to reduce the amount of energy needed to desalinate water. We're looking at extending the components of these systems. So that they have to go fewer time between cleanings, and basically extend the overall lifetime of these plants. And another area that we're really looking at, and this is of growing concern in the United States and around the world, is, I mentioned industrial processes and the waste that come off there, it's the growing amount of forever chemicals that are in our process. A forever chemical is a chemical that doesn't naturally break down in our water supply, like many other compounds do.

And these chemicals have the names, people may have seen him in the news, called PFAS, P-F-A-S, and PFOAs. These are chemicals that come from us making non-stick cookware, making things like stain guards. They're even in the plastics, and other repellent materials, that repel oil and water in the take out food that we order. It's really alarming how much humanity is starting to affect our groundwater. I saw a really disturbing article the other day that we're even finding these chemicals in breast milk. I think that should send red flags up everywhere for people that we need to start taking better care of the precious resource we have of water.

So, what we're doing, we're looking at developing more efficient methods. We need to reduce the amount of energy needed to clean this water. We need to reduce the amount of energy to make these unconventional sources of water competitive with the traditional water sources that we have. They may even be in the form of home sized units, too. Maybe the individual consumer might want to buy some of this technology at their home, if these problems can't be addressed at the municipal level.

LP: So that's what you're doing right now. You're researching ways to take out these chemicals. So when you say a unit at your home, are you thinking something under the sink that you just turn on your tap and it cleans? Which exists with reverse osmosis systems. But it would be like a step up from that, I'm guessing.

KS: Right. Reverse osmosis can remove a lot of contaminants from the water, but there are some contaminants that it can't remove. So we're looking at ways to efficiently do this. There are standard methods for getting these forever chemicals out, but they're really energy intensive. Some municipalities are starting to deploy these in heavily contaminated areas. These are areas like in Arizona, and Minnesota, and North Carolina, where these plants were making these kinds of chemicals. Or at military bases, where firefighting foams were used to help train firefighters. These chemicals are leaching into our water sources there.

We think that there could be a municipal level technology, where we can provide some more efficient ways of destroying these compounds. There could also be a home sized unit too. Like I said, we put together a team, we're brainstorming all these different ideas on how to address these really critical problems.

LP: So again, two parts to your research here. One, the water harvesting, which we discussed in depth. And then the cleaning up our water sources, which is research that is just beginning, but the results could be phenomenal. And it could really help again a lot of communities around the world.

So you are taking on a huge global issue of this clean water shortage issue. And your team's research has the potential to improve lives, as we said. And I'm sure that's encouragement to continue your work, but what is your motivation? What drives you to continue this research?

KS: That's a great question. And I'll try to stay off my soapbox as much as I can, as I answer it. I have a feeling I have a personal responsibility to take action here. And when I see a problem, I want to address it. We're very fortunate that we live in a world where, for the most part, we have clean air to breathe, and fresh water to drink. As I mentioned earlier, water is life. And you can't function without it. We all have a part in this.

I don't want to ignore the problems of today, and have our future generations, maybe my great grandkids, or even my grandkids, look back on our time and say, these guys knew about all these problems, and they did nothing about it? I mean, why didn't you do anything about it? I don't want our descendants to look back at us and say, they ignored these problems.

I want our future generations to have a world where they don't have to use atmospheric water harvesting just to get clean water to drink. I don't want a world like that. We have the technology to solve these problems today. We just need more people, more governments, more commercial companies, to start adopting these technologies.

LP: Can we help with this problem at home through water conservation? Is there another way we can help with this huge global issue?

KS: And that's a great question, because we can all help in this area. I recently read an article, I've talked a lot about, hey go read this, go watch this video, I get really excited about this topic. I realize people probably don't have the time to go read all these things, but there was a really interesting article the other time written in The Economist magazine, called Thirsty Planet. And this article really opened my eyes. I read this a couple of years ago. About how big the water problem is in our planet, how much contamination we have in other countries, and how this is just a growing issue as we increase our population.

This quote really stuck out, in there, that this author had in there. It says, the best way to solve the world's water woes is to use less of it. And I think that's where it really drives home. Is that, if we started using less water in our daily lives, we will help the problem for future generations. And the easiest way to do that, if you remember we mentioned earlier, that agricultural use is a very high consumer of water. We irrigate a lot of crops. We irrigate a lot of things that we grow in areas that are arid and that need the water to grow our food. If we were really cognizant about minimizing our food waste, that actually would make a really big difference. Especially in some of the high water use materials or high water use food.

And unfortunately, I'm not sure if you're a chocolate lover, Lisa. Chocolate is at the top of the list.

LP: Yeah, I said it in the last episode.

KS: Yeah. Chocolate is at the top of the list, unfortunately. And that's really bad because I love Snickers bars. And I'm not telling people, stop eating chocolate. I'm just saying, let's be cognizant of the food waste that we use. Buy what you need. Don't overbuy. Because agricultural uses over 80% of our water consumption here in the U.S. So that's big numbers. So if you can make a difference there, you actually impact the world much better than replacing your toilet with a low flush one. Which you should do anyway. But agriculture use is a big driver.

Beef and cotton are other two big categories too. So if you can minimize those areas, buying new clothes less often, and maybe minimizing meat consumption. Again I'm not trying to tell people to change your lifestyles from like, don't eat meat. I'm saying, be cognizant that these different areas use a lot of water. Awareness is big.

LP: Awareness is a huge difference. Yeah, I wouldn't have connected those dots myself. So thank you for bringing that to light. Food waste, buying clothes all the time, all that stuff can help our water...

KS: Even electrical use. Like I mentioned earlier, power plants need water to cool. We have a lot of waste heat in power plants. Water is everywhere. There's this thing called the energy-water nexus that we study. This is a term that everything is connected between energy and water in our world. And we all can make a difference by just being good stewards of using water and energy wisely.

LP: We've covered so much and you've really given us some great ways to make a difference in our daily lives. But what would you say is the big takeaway today for our listeners? What would you like us to remember about your research and our water resources?

KS: I think the biggest takeaway that I would say is, use this knowledge, and talk to your children about it. Don't take for granted that we can go to a faucet, and turn on, and clean water comes out. Water that keeps us alive. I mean that's such a blessing to have. We live in communities that have water infrastructure that make sure that our health is of utmost concern.

And just remember that there's a substantial amount of energy related to water and food growth, and the electricity that we use. And try to be good stewards of that. And while we are doing some really groundbreaking research at SwRI, to help look at unconventional sources of water, it's never going to replace our traditional ones. The amount of water that we pump from traditional sources just cannot even compete with some of these other non-traditional sources, like desalination and atmospheric water harvesting. So let's take care of the resources that we have and just enjoy what's been given to us.

LP: Such great lessons for us today. One family can make a difference. One person can make a difference with this global problem. And you and your team are really living up to the SwRI mission of developing solutions that benefit humanity. And I can see humanity is really going to benefit from your work. So a big thank you to you and your team for taking on this issue and looking for the solutions to this huge problem. I think I speak for our listeners, we look forward to the results of your research. And no doubt we will see more clean water flowing because of your work. Thank you for joining us, Kevin.

KS: Thank you very much for your time, Lisa.

And thank you to our listeners for learning along with us today. You can hear all of our Technology Today episodes and see photos and complete transcripts at podcast.swri.org. Remember to share our podcast and subscribe on your favorite podcast platform.

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Ian McKinney and Bryan Ortiz are the podcast audio engineers and editors. I am producer and host, Lisa Peña.

Thanks for listening.

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