It’s been one year now since we were awarded the STEM-In-Action Grant to continue work on our moisture harvester, bringing our critical solution closer to fruition, and this week we turned in our Final Report. We are grateful for the opportunity the grant has provided us to make significant progress over the last year. The analysis and improvements we have made over the past year show that our moisture harvester should be a viable option for cost-effective water production in drought-affected areas using green energy. However, there is still work to be done to fully realize our design. We look forward to continuing our progress in the future.

What We Did

Accomplished:

• July:
  • Created a website to communicate with the public about our project and the drought crisis in the Southwest
  • Consulted with an expert to advance our knowledge regarding the physics of the condensation system, to allow further Improvement
  • Selected and purchased humidity and temperature sensors and Raspberry PIs to automate measurements and control
• August:
  • Met with an expert to learn about metal-organic frameworks and their production. This expert is going to virtually demonstrate the production of MOF-801, as we are unable to go to the lab in person.
  • Made flowcharts for the programs
  • Educated ourselves in programming for microcontrollers
  • Designed experiment to perform a fan speed adjustment test
  • Selected necessary equipment to perform a fan speed adjustment test
• September:
  • Purchased equipment to perform a fan speed adjustment test
  • Completed Initial Report for eCybermission
  • Ran airflow experiment
  • Began working with school in partnership to get MOF
  • Designed condensation system experiment
• October:
  • Submitted official blog post
  • Acquired materials for constructing our condensation system test
  • Updated our website with information on our air flow test
• November:
  • Constructed condensation system test
• December:
  • Setup Raspberry Pi 4 Model B’s
  • Initialized public-facing git repositories for our codebase (https://github.com/AZWaterWarriors/)
  • Wrote programs for condensation system test and the overall control system as well as a RPi GPIO library that they are dependent on
• January:
  • Met with Ms. Kulisiewicz to get further information on the MOF-801 and its synthesis
  • Built condensation system experiment apparatus
  • Completed agreement with DEVCOM for MOF-801
• February:
  • Built condensation system experiment apparatus
• March:
  • Ran condensation experiment multiple times
  • Considered design challenges given small anticipated amount of MOF
• April:
  • Received MOF and video on creation
  • Reviewed video and worked on identifying design changes for reduced amount
  • Worked on reconfiguring condensation apparatus
  • Created poster to support outreach.Worked with local teachers to identify presentation opportunities
• May:
  • Presented at our local elementary school, Sonoran Sky Elementary School, to help inform kids about drought and get them excited about science and engineering. We also talked them about how to make a good eCybermission project (POST ABOUT THIS PENDING)
  • Brainstormed possible MOF tests given small amount
• June:
  • Ran two experiment with initial MOF Packet (LAB REPORT PUBLICATION PENDING)
  • Procured larger amount of MOF
  • Featured in spot by Arizona KJZZ radio station (https://www.kjzz.org/news/2024-06-27/az-high-schoolers-showcase-invention-focusing-on-states-drought)

Scheduled:

• Fall:
  • We are scheduled to present about our project and eCybermission to the freshman class in Paradise Valley High School’s CREST STEM program.

What It Means

One of our primary goals with the grant was to help educate the public. We created this website to chronicle our progress, posting regular updates and blog posts about our design. We also presented at our local elementary school to help inform kids about drought and get them excited about science and engineering.

We began by investing in some Raspberry Pi’s to serve as the control system, due to their versatility and portability. We wrote a control system that would automate the device’s cycles, allowing it to run 24 hours per day with no human intervention. However, we ran into issues with the driver that allows directly controlling the circuitry. We are currently working on resolving this issue.

You can read more about our control system here: Programming the Control System

Our fan system moves air through the MOF-801, so it can adsorb water continuously. If the air is moving too slowly, the moisture cannot be adsorbed as quickly as if it were moving faster, but if the air moves too quickly, all the moisture is adsorbed at the front of the material, blocking the air from passing through the rest. We constructed a wind tunnel to analyze the fan system and we found that there was a dead spot in the center of the fans from their hubs. We moved the fans slightly off-center to correct this and got much better airflow.

You can read more about our fan system tests here: Experiment: Airflow

We wanted to optimize the collection of the water from the adsorbent at the end of a cycle to have minimal water loss. We ran several tests, including testing different ways of condensing the water. We determined that a central Peltier plate was insufficient to cool the entire area, we learned that we will need multiple Peltiers, as well as to maximize the surface area to collect the most water.

You can read more about our condensation system tests here: Condensation System Proof-of-Concept

One of the most important parts of our whole device is the actual adsorbent material: MOF-801. Our grant allowed us to get in contact with a research scientist Ann Kulisiewicz at DEVCOM who provided MOF for a proof-of-concept. We had originally planned for the MOF to be in a brick form, however, the new synthesis method meant that it came in packets and a much smaller quantity. As a result, we had to scale down our design to accommodate the new size and redesign the condensation system to hold the packets better. We have only just started testing, but we can see the MOF is absorbing water from the air.

You can read more about our MOF tests here: We Got Some MOF!, First MOF Test

Moving Forward

We plan to move forward with our project to create a complete functional prototype. Over the previous year we have been refining individual components systems, but hopefully we can put these individual parts together to make a cohesive device. Most of our individual components are working, however we are still making fixes to our control and condensation systems.

While our control system itself has no issues, the library we wrote that it uses to directly control the circuitry is experiencing a number of issues. Instead of using a third-party general purpose input/output (GPIO) library, we wrote our own using the Linux gpiomem interface. Our code appears to be correctly sending the requests to the kernel, but the kernel does not seem to be actually transmitting them to the pins. However, it appears we may not be using the interface correctly. Going forward, we hope to troubleshoot this issue forward and debug the code in detail.

Because we didn’t receive our MOF-801 until April, we were unable to complete testing and prototyping the condensation system; those tests are ongoing. We completed some preliminary tests of the adsorption potential of both packet form MOF-801 and powder form, and while these tests are promising, they are not to a satisfactory level of accuracy, and we plan to use the lab equipment obtained with the grant to run much more detailed and rigorous tests of the limits. We hope to more effectively dehydrate our sample before conducting a much more controlled test in the low humidities of the desert.

We plan to also do more community outreach. While our solution helps address supply, the real future of Arizona’s water supply lies in the hands of the people. We plan to continue presenting to local kids and teens to teach them about drought and how they can help reverse it, as well as about engineering and eCybermission. We have scheduled to present to the freshman class of the CREST STEM program at Paradise Valley High School this fall. We will also continue posting progress updates on our website at AZWaterWarriors.Org.

Our combination of successful modeling and prototyping stand to show that our design is a viable and efficient solution for moisture harvesting in the low relative humidities of the desert.

Stay tuned for updates on our progress going forward, as we continue turning science fiction into science fact!

We are at the eCybermission National Judging & Educational Event in Chantilly, VA this month. You can watch us present on our grant and VOTE FOR US to bring the People’s Choice Award back to Phoenix. You don’t have to watch to vote. Just use the link below during the voting window. We’ve included a calendar file to make it easy to remember!

The National Showcase (Livestream)

10:00 AM – 1:00 PM MST Thursday, June 27th, 2024

Livestream Link: https://youtube.com/live/xRlcp_HyUi0

Students will give their five-minute presentation during the National Showcase for friends, family, and live for viewers online. The audience, in-person and virtually, will have an opportunity to ask questions of the team. Friends and family canattend this event in-person but must register to attend.

People’s Choice Award

10:30 AM – 1:30 PM MST Thursday, June 27th, 2024

Voting Link: https://forms.gle/iVBeRwkXNkakvoQDA

The National Science Teaching Association (NSTA) sponsors a People’s Choice Award. This is an opportunity for friends and family to vote for their favorite team. Please share the voting link, in advance, however voting will not open until 1:30 PM ET on June 27th.

The National Awards Ceremony (Livestream)

7:00 AM – 9:00 AM MST, Friday, June 28th, 2024

Livestream: https://youtube.com/live/WfIJbA1aG6o

The Awards Ceremony highlights the achievements of all teams and recognizes the community of scientists, engineers, STEM educators, and mentors that assisted eCYBERMISSION teams throughout the competition year. The ceremony recognizes the 2023 STEM-In-Action Grant awardees and culminates with the announcements of this year’s National Winners.

Arizona has been in a megadrought since 2000. Access to water is decreasing by the day, and we’re here to change that. Inspired by Star Wars, and with a grant from eCybermission, we’re building a moisture harvester to combat water shortages across the globe.

Now that our desiccant has arrived, we are excited to start testing the material in an out-of-lab real-world situation, to better integrate it into our prototype.  Since our material had been shipped from a lab in Maryland (at about 40-60% RH, way more humid than Arizona, at 7% RH today), we started by dehydrating it, to remove all the humidity, so we can properly test its absorption potential.  Our plan was to weigh the MOF-801 packet, dehydrate, and weigh it again afterwards.

To complete the drying process, we invested in a standard dehydrator (often used in drying fruits and vegetables).  This operates by drying out and heating air and blowing it over the drying racks.  We placed the MOF-801 packet on a drying rack, and turned the device to its maximum setting, in an attempt to heat the packet to the boiling point of water and evaporate its contents, similar to how our device wrings out the moisture.  We further placed the device in direct sunlight, outside, to aid the process.  (We registered the ambient temperature at 113 degrees Fahrenheit.)

We let the device run for exactly four hours in the hottest part of the day, before removing it, and weighing it.  We registered a weight decrease of 0.17 grams, or approximately 0.05% (the initial weight was 3.36, and the final weight after dehydration was 3.19).

These results are promising.  They demonstrate that there is adsorption occurring, and the moisture can be wrung out by the same means as our design.  We suspect the lower moisture loss may be a result of the fact that the material was not insulated from the Arizona heat in storage, and moisture may have evaporated out over the past few weeks.  We are excited to continue testing MOF-801, to determine more precise limits of its absorption potential in the arid Sonoran Desert.

While our desiccant was being produced and shipped, we began testing our condensation system so we would be prepared to integrate the material.  We needed to determine what form of Peltier plate apparatus would condense the most water out of the air, and funnel it into a container.

To conduct the experiments, we constructed an apparatus that contained a Peltier plate mounted on a larger metal plate.  We divided the metal plate into nine equal sections, and mounted a different shape on the underside of each section, with two blank sections as controls.  We then inserted a remote weather station inside, to track internal temperature and humidity, before insulating the entire device.

Our first step was to make sure we could create a big enough temperature differential with the Peltier plate to condense water out of the air.  We set up our apparatus without the collection vessels and tracked the change in temperature and humidity inside our apparatus.  It proved successful, as when we removed the insulation, we found a puddle of water on the floor of the device.

The MOF will allow us to concentrate moisture and raise the humidity in our device higher, which will further reduce the temperature differential we have to create to collect water.

In the next experiment, we set a ceramic collection vessel for each section under the plate.  We wired up the Peltier, and ran the device for 24 hours, taking internal temperature and humidity readings regularly.  After the 24 hours, we weighed the collection dishes to determine the amount of water they collected.  We relied on the ambient humidity (averaging about 38% RH) to provide the water, and treated anything less than 0.5 grams as within the margin of error.

We found that the central heatsink rendered the most liquid (3.1 grams), followed by the whistle-like hollow tubes (0.57 g), vertical solid rods (0.5 g), and a strainer-like mesh (0.5 g), with the device collecting a total of 5.87 g of water.  Further analysis revealed that the heatsink may have collected more water, not from its geometry, but rather because it was directly attached to the Peltier plate, while the other sections were attached to the metal plate, which has a much larger mass yet less thermal contact with the Peltier.

From these results, we determined that whatever shape we use will need to be directly connected to the Peltier plate, with full thermal contact.  This could mean adding additional Peltier plates to chill the entire plate evenly.  Further testing will be needed to narrow down between the four best geometries, however.

One of the design decisions that distinguishes our concept from other devices designed to collect atmospheric moisture is our choice of desiccant, a chemical compound that absorbs water from thin air.  We use a metal-organic framework, MOF-801, which is the most effective water adsorber in low relative humidity (such as here, in Arizona).  MOF-801 is at the center of our design, but during our initial tests, we were unable to get hold of this item due to budgetary restrictions and our lack of access to proper lab equipment. 

After we won the grant, we were able to make contact with a scientist who taught us more about MOF-801 and helped us obtain the material.  Our initial design consisted of a 2 kg block of MOF-801, but our contact was only able to give us about 5 grams of the material, and our design had to be scaled. 

In the production of MOF-801, a solvent is used to clean the material, after which it is flushed with water.  Unfortunately, during the flushing process, some residue can remain and taint collected water.  With this in mind, our contact informed us of a “green” synthesis method which doesn’t require solvent and is better for the environment. With this new synthesis method, the produced water is potable, but it is infeasible to produce it in block form, so we used packets (like the silica gel packets in food) instead.  We had to further revise the design to use these packets.

We are looking forward to carrying out experiments on the MOF, and testing it in an actual prototype.

Automation without the necessity of human intervention has been a key component of our design from the start. We chose to use Raspberry Pis as our control system, for their relatively small scale but large operating capacity, ability to interface directly with electronic components, and ubiquity of technical support.

We initiated a GitHub repository and began working on the code base.  The majority is written in C, due to its speed and universality.  We are, of course, using Linux as the operating system, for obvious reasons.

We soon wrote a GPIO library to interface directly with the electronic subsystems, and a control system, however we also ran into a roadblock.  Our limited prior experience (and the majority of documentation we could locate) focused on the old Linux gpiomem interface, however in recent versions that has been replaced with the gpiochip interface, which is considerably more difficult to use without the aid of a bloated third-party library.  It is unclear whether we are energizing the wrong pin or our request is not being completed at all.  We hope to resolve this issue soon.

One of the problems with our original design was that the fans were moving air through the material too quickly.  Consulting with an expert further revealed that this would not only be less effective but also cause condensation on the front of the material, resulting in decreased adsorption potential.  Under the guidance and consultation of a professional engineer, we constructed a wind tunnel and invested in an anemometer, taking measurements of the airflow at various voltages and locations, in order to determine what level of resistance we needed on our fans and where to place our hygroscopic material.

For our first test, we placed the anemometer between the fans in the center of the wind tunnel. We were getting low air speeds and learned there was a blind spot in the center of the wind tunnel between the fans, due to the shape of the fans.  This gave us insight into where we needed to place our material.

For our second test, we placed the anemometer outside the tunnel, behind the outlet fan. This test was conducted to calibrate the anemometer and verify that some of our readings and assumptions were correct.  We measured much higher air speeds at this location.

For our final test, we placed the anemometer in the center of the tunnel, raised slightly, so as to avoid the dead spot. This batch of tests was the most helpful as we were able to get good readings and find a place to place the hygroscopic material, the lower limits of the fans, and the range for our results.

We are proud to announce that we won the eCybermission Stem-In-Action grant! We will continue working on refining our solution over the next year, using this grant, after which we will report on our progress at eCybermission in Maryland, next summer.

Our Grant Plan

Today, many members of our community have decreasing access to water as it becomes more scarce due to an ongoing megadrought.   How can we create an affordable solution that allows our community to have access to water?  Our solution was to design a Star Wars-inspired moisture harvester that can collect water from the air year-round and help members of our community and communities around the world, in places such as Africa and the Middle East, have better access to clean water.

We began by researching ways to collect moisture and discovered the most efficient water-adsorber at the low humidity of the desert, MOF-801.  Our design uses this material along with a condensing system to allow multiple absorption/desorption cycles per day in theory making our device more efficient than similar products/devices.  We tested our design with a combination of modeling and prototyping.  Since we were unable to obtain this material due to the constraints of this project, we ran a computer model which showed the material would work well in our desert environment.  We also ran a number of tests on a physical prototype of the condensing system.  This revealed several necessary enhancements, and we used what we learned from the results to build and test a revised design.  Using these results, we were able to create a design for a future, even more efficient water harvester.  Widespread deployment of our creation in the future could save lives and make our community, and the world, a better, healthier place for everyone.

Our STEM-in-Action proposal will address community outreach, and design improvement.  We will maintain a website providing information about our research and links to conservation resources.  We will also attempt to schedule presentations and/or write editorials or educational pieces whenever we have access.  This will be an ongoing activity for the life of the grant.  At the end of our final construction we saw a number of necessary modifications in our condensing and collecting system, which will be completed by the third quarter.

Finding a cheaper and more accessible supply of MOF-801 than is available in our current situation would help cut costs and improve availability.  We will attempt to get hold of a sample to validate our modeling. This will be completed in the final quarter.

If you or someone you know has access to MOF-801, let us know!

We have already identified advisors who will work with us to address questions and issues.  We may run into problems with our design or materials, in which case we will conduct more and more research into the possible causes.

Testing Plan

To test our design, we began by constructing the subsystems involved and testing them separately, to save time in troubleshooting. We were unable to obtain our hygroscopic material, MOF-801, due to budgetary, access, and time restraints, so we modeled it using local weather data, and simulated it with a cup of water during our final tests.

After we had refined our subsystems, we tested the fully assembled prototypes.

We used the data from tests of our first prototype to design and build our second prototype. We used the test data of the second prototype to create a revised design, which we hope to pursue further.

Results

While neither fully assembled test was completely successful, the combination of successful tests of the subsystems show that:

• Our solution is a viable option for cost-effective water production in drought-affected areas using green energy
• We will continue to refine and test our design
• Our solution could be scaled up for even more collection
• Star Wars is one step closer to reality

Living in a desert, a water shortage is very impactful to the people of Arizona. Deserts are hot and arid, with low precipitation. With water scarce in Arizona, even during average years, droughts attack one of the most sensitive aspects of daily life in Arizona.

Politics haven’t made the situation any better. A series of agreements has tossed Arizona the brunt of the worst of the water allocation measures in southwest America. The federal government has declared a Tier 1 water shortage on the Colorado River, further decreasing how much water Arizona can use (“Officials Impose New Cuts to Colorado River Water Use in Arizona”). This means allocation from the Colorado River will go down by about 30% in total. Scottsdale’s water allocation went down by 5% this year (Schneider). 

With over 50% of the water in Scottsdale being used residentially, and 70% of that water being used in yards, this will likely be the first thing that is cut (Schneider). For example, lawns have been banned in other desert communities so no water is used for watering them. As Scottsdale water provider Julie Schneider says, “Grass is one of the biggest water usages outdoors.” In Phoenix, single-family outdoor spaces take up 26% of their water, about 26 billion gallons of water every year (Interview with Water Scientist Dr. Max Wilson).

If we could harvest water from the atmosphere, that would give us another water source that can be used in the desert. 

However, if we do nothing, the consequences can be dire. Water scientist Dr. Max Wilson says, “The dams are so close to empty that they are approaching deadpool.  Water would be so low that it could not be moved.” This would cause the Central Arizona Project, a massive network of canals, to dry up. Drought is not just an Arizona problem. Other states reliant on the Colorado River, like California, are affected too. 

References