Human Transcribed
Carlos Diaz-Marin:
We did experiments in two places. One was in the Atacama Desert, that's the driest desert in the world. And then we did also experiments in another region that is more in the mountains. That helped us probe a little bit the impact of these conditions and the limits of these devices across weathers. We found that things like humidity and things like the amount of sun irradiance that you have are going to be key.
Chai Nussbaumer:
You might be wondering what was today's guest testing in these contrasting locations?
Micah Schweizer:
The answer is a new affordable water production device that could make a significant difference worldwide.
Chai Nussbaumer:
In this episode, we'll talk to a scientist who won the 2026 METTLER TOLEDO Innovator Award for his breakthrough solar-powered solution.
Micah Schweizer:
We'll learn how this device works, who it could help, and get a closer look at how it was tested and developed.
Chai Nussbaumer:
I'm Chai Nussbaumer.
Micah Schweizer:
And I'm Micah Schweizer. This is Balancing the Future from Mettler Toledo.
Chai Nussbaumer:
On this show, we explore the world of science and technology and the solutions transforming our lives.
Carlos Diaz-Marin:
So my name is Carlos Daniel Diaz-Marin, and I'm an assistant professor in energy science and engineering at the Doerr School of Sustainability at Stanford University. We all have a sense of water being a problem and that problem not getting any better into the future. So right now, two billion people face water scarcity for at least one month of the year, and that's expected to become five billion people by 2050. So a lot of people are going to not have enough water to meet their needs. There's many places in the world where people have to walk maybe hours a day or a week to get water. And that, of course, is something that limits socioeconomic development of these people. So we are developing a technology that produces water from an unconventional source, which is moisture in the air. So we are developing these materials called hydroscopic hydrogels or hydrogels with salts that capture that humidity from the air, even in really dry conditions.
And then when you heat them up, they release that moisture back and you can then condense that water, essentially producing ultra pure water at the end of the cyclic process of capture and release. So we are making the materials, these hydrogels, and we're integrating these into devices. This has a few advantages. One is that you can produce water in principle anywhere in the world, as long as there's humidity. You don't need centralized infrastructure, so you don't need a big treatment plant and you don't need all the pipes to move the water because you can produce water essentially where you need it. And then this can be powered even by sunlight heating. So we've been building devices that take heat from the sun and use that to produce that water. So it can be powered by perhaps even wasted energy sources in some cases, which is exciting for us.
Chai Nussbaumer:
And if this device is widely adopted, who will benefit from it most likely?
Carlos Diaz-Marin:
Yeah. Two ways to imagine this. One would be the small scale household devices. There are many places, as I said, where people have to travel significant distances to procure water, like developing countries and developing regions like Africa, for example. And those places actually have to pay more for their water. So you could imagine that these devices would be a way for water production to happen onsite and to meet drinking water needs. The other approach would be thinking of how water intensive industrial sectors could offset some of their water demand. Data centers, there's a huge interest by many people at this moment.
And that would be great. Data centers right now consume water typically for their cooling. You could think of these devices as a way for them to not consume any water at all and maybe to even produce water for the communities that surround them. So you could imagine that right now you might have some pushback for data centers because of the water consumption. What if we actually did the opposite? And what if we had these data centers produce water for the communities? That, to me, seems something really wonderful both for these industries, but also for the communities around them.
Chai Nussbaumer:
And I know you just touched on data centers, but I will ask you, in recent years, data centers have been using large amounts of water. So how could your technology address this more specifically?
Carlos Diaz-Marin:
Yeah, right, so data centers consume water in a few parts. Producing power consumes water and cooling data centers requires water as well. All the electricity that is consumed at a data center, it's converted into heat and you have to dissipate that heat. So the typical way to do that is by evaporating water. In these data centers, you might have a cooling tower, for example. To do that, what we're imagining is almost the opposite. What if you use the heat from the data center to actually produce water from the air? That would solve that getting rid of the heat issue, but also then produce potentially water again for the data center or for the communities around the data center.
Chai Nussbaumer:
And so what are some other types of wasted energy?
Carlos Diaz-Marin:
Yeah, so I mean, what's exciting about this approach is that it uses heat at around 50 degrees C. That's very low temperature heat. So people typically call this waste heat because we typically just throw that to the atmosphere. So we can use something that is trash essentially to power these devices. And that is really exciting. Data centers, especially AI liquid cooled data centers are expected to have massive amounts of wasted energy. Industrial processes generate a lot of wasted. Potentially, hydrogen production also produces wasted energy. Power plants also produce wasted energy. So all of those low grade heat sources are potentially energy sources for these types of approaches.
Chai Nussbaumer:
Can you explain how your atmospheric water harvesting system works and how much energy is needed to power it?
Carlos Diaz-Marin:
So people have looked at atmospheric water harvesting for quite some time. There are basically three approaches that you can have to do this. And those depend on how much humidity you have. So on the highest end, the highest humidity, we have fogging devices. So these devices are meshes that capture fog as it goes through and captures those droplets and collects those droplets. So those are applied in places like Chile or California actually to produce water from fog. The second category, at intermediate humidities, are dewing devices or condensation devices. You've probably drank a cold beverage and you see water droplets condense outside that cold beverage, that condensation. So you can imagine having a cold surface and keeping that surface cold by a refrigeration cycle to condense water. Those devices, there's also companies that are commercializing those and those work at intermediate humidities. The problem to your energy question is that once you start going below 45% humidity or so, that energy consumption of those condensation devices starts skyrocketing.
And then there's a third approach, which is what I have been focusing on mostly, which are the absorption-based water harvesting devices. And those have the advantage that they can work across the entire humidity range. The idea is simple. So you might have seen desiccants. For example, you might have seen with clothes, you have these silica gel packs that keep your clothes dry and prevent mold from growing. We work with a similar material that, much like this silica package, captures humidity from the air. So you can imagine you have your material, you, during the night typically, expose your material to the moisture in the air. And then during the day you put your material in a box, you close off that box, you use heat, and then that releases back the vapor from your material. And then within your device, you condense that water.
And you're essentially at the end producing distilled water from this cyclic process. And what we did in Chile was doing this in a cyclic way. So during the night we would harvest the moisture. And then during the day we would release that moisture with sunlight heating.
Chai Nussbaumer:
And how did the materials that you just mentioned impact the ability to scale up in future costs?
Carlos Diaz-Marin:
Yeah. So that was one of the things that we early on realized and that pushed us in this direction. The challenge with water is that water is extremely cheap. In the United States, that's around a dollar per meter cubed. There's nothing that cheap, essentially. So if you want to develop a technology that produces water, it has to be extremely cheap. Recognizing that, we decided to go with this route of hydrogels with salts. Hydrogels are the materials used in diapers. So they're really good at retaining liquids. As you can imagine, that's what we like in diapers. And we put salts into them to make them not only good with liquids, but also good at capturing moisture. The advantage with the salts that we're using is that they're really inexpensive. For example, we are using, in some cases, the salts that we throw to the streets to de-ice them when there's snow. You might have seen these blue or purple salts on the streets.
Chai Nussbaumer:
Yes. Yes.
Carlos Diaz-Marin:
And that tells you about how cheap these materials can be. If we throw them to the streets, that makes these materials really low cost and potentially, we forecast that they can cost around a dollar per kilogram to make these materials.
Micah Schweizer:
Hey, Chai.
Chai Nussbaumer:
Hey, Micah.
Micah Schweizer:
In this conversation, we've talked a lot about data centers and how much water they use. So do you want to hear some stats that show just how big an issue this is?
Chai Nussbaumer:
Absolutely. Let's hear it.
Micah Schweizer:
Well, the UN predicts that by 2030, AI data centers could use as much water as the basic annual domestic needs of the 1.3 billion people in Sub-Saharan Africa. That's a huge amount.
Chai Nussbaumer:
It really is. But I've seen a lot of facts and figures about data center water use, and they're all quite different. Why is that?
Micah Schweizer:
A lot of the figures change depending on what exactly you measure. For example, cooling a data center, like Carlos mentioned, uses a different amount of water than say, powering it with a hydroelectric plant. So if you only measure one and not the other, you're going to get very different numbers.
Chai Nussbaumer:
I guess that regardless of the method used, we know that data centers aren't going away. So ultimately, finding methods to help them consume less water makes sense.
Micah Schweizer:
Exactly.
Chai Nussbaumer:
So at the top of the episode, we heard Carlos talking about how he tested his devices. Let's hear a little more about that.
Carlos Diaz-Marin:
So we went to Chile for around a couple of weeks and we did experiments in two places. One was in the Atacama Desert. That's the driest desert in the world.
Chai Nussbaumer:
Wow.
Carlos Diaz-Marin:
And we went there again to stress test this device. And then we did also experiments in another region in Chile called Coquimbo. That is more in the mountains. So we did those two experiments. And then we did experiments back at MIT in Cambridge. That helped us probe a little bit the impact of these conditions and the limits of these devices across weathers. And yeah, we found that things like humidity and things like the amount of sun irradiance that you have are going to be key. So the experiments we did in Atacama, for example, that was in the Chilean fall. So the amount of sunlight we had was actually not as good as it could have been say in the summer. And that was perhaps a bottleneck. We forecast that these devices in the summer when there's more sunlight irradiance and there's longer days would produce more water.
Chai Nussbaumer:
And are there any locations where the devices are currently installed or was it mainly for testing when you were traveling?
Carlos Diaz-Marin:
That was mostly for testing. Now at Stanford, we're building a device more on the second side of what I had described before. So I mentioned the small scale devices and the larger scale devices. So we're now building a waste heat powered device. And again, using this cooking knowledge that we have now to optimize also this type of device and seeing how much water we can produce. We forecast that these are going to be higher productivity devices, but perhaps a little bit more expensive because the complexity of the system could be a little bit higher.
Chai Nussbaumer:
And the durability as well, is that a factor?
Carlos Diaz-Marin:
Yeah, so that was basically, as I said, water has to be extremely cheap. That forces you to have a really good material and a really durable material. For the longest time, we're really happy with how well performing we were. But then we also were realizing, okay, these also have to be extremely durable. So at the end of my PhD, we did experiments for something like two years testing the durability of these materials. We tested, I don't know, maybe 500 samples. We did experiments for nine months, for example, at accelerated conditions. And we did some separate experiments where we cycled our materials around 200 times. And we found basically that there are strategies that you can have for these materials to last that long. These materials, you usually put them in a device where you have a metal. That metal, under some conditions, can destroy your material, but it can also prevent that. And we found ways to do that that led us to have, again, materials that lasted for nine months or materials that lasted for 200 cycles.
Chai Nussbaumer:
And so let's look a little bit into the future. It is really a fascinating technology that you've built. Where do you see it going in the next five to 10 years? And what are the challenges and roadblocks?
Carlos Diaz-Marin:
Yeah. So I think there are two challenges. Everybody cares about water. It's so vital. There are two challenges with that. One is that it's so inexpensive. And two is that it has to be extremely, extremely reliable. When you want to have water, you can do that at any point of your life. Again, then if you develop a technology, it has to be extremely cheap in the cost of producing water and it has to be extremely reliable. I think those are the two challenges. There are a few companies in this space. You can actually buy a household device for your say, kitchen counter that produces water from the air. It's not the cheapest and it consumes quite a bit of energy.
So the question is how do we make these things cheaper through materials, through systems? And that's something that my group is working on as well as other people. And that is key if we want to unlock this, not only as a, say, commodity appliance, but also as a widespread solution. So prioritizing things that get us to that reliability and to that low cost, I think it's a priority. That's the reason we're excited about our materials because they have these high performance, high durability, low costs. And I think at least in my lab, there are a few companies in this space. There are a few startups in this space. In my lab, we're starting to explore the potential to bring this outside of the lab to say, a company and to start tackling these two sites that I mentioned, the household scale devices and the more industrial scale devices.
Chai Nussbaumer:
And what are the next steps that are really needed to achieve wider impact with this technology?
Carlos Diaz-Marin:
So one reason I like the data center space, it's a space where you can afford to pay a little bit more for water than other sectors. And that is good for water harvesting from air because right now we're probably a little bit more expensive than what we want to be in the future. But by going to these first initial customers that can pay for that, we can start lowering down the cost of these technologies through improvements. I think that's key. Going for those first markets that need water and using that to learn, I think it's going to be key. In my own lab, as I said, we're exploring, we're interested in translating this from the lab to the outside world. We are right now improving our materials, improving our energy efficiency, exploring these industrial scale devices, and starting to talk to more potential customers and potential people in this space to understand a little bit better on what are their needs and what is the potential for technology to meet their needs.
Chai Nussbaumer:
And would you like to patent this technology in the future?
Carlos Diaz-Marin:
Yeah. Across all the time we've been working on this, we've been patenting several parts of it. Some on the material, some on the system integration, some on the system. We're probably going to continue this here at Stanford. And again, our overarching goal is for this to become a reality and for this to potentially contribute to this water problem. This could be done through many ways. It could be through a startup. It could be through licensing to a company. It could be by open sourcing, perhaps the technology. I think we're still trying to understand what is the most impactful thing that we can do there.
Chai Nussbaumer:
You've been listening to Balancing the Future from METTLER TOLEDO.
Micah Schweizer:
If you're enjoying the show, you can help other listeners find us by leaving a review. Or if you listen on Spotify, leave a message in the comments section.
Chai Nussbaumer:
Also, if you haven't already, be sure to subscribe wherever you get your podcasts.
