Out of Thin Air: A Fresh Solution to Farming’s Water Shortages
California has been plagued by perilous droughts for decades. Freshwater shortages have sparked raging wildfires and killed fruit and vegetable crops. And California is not alone in its danger of running out of water for farming; parts of the Southwest, including Texas, are battling severe drought conditions, according to the North American Drought Monitor. These two states account for 316,900 of the 2 million total U.S. farms.
But even as farming becomes more vulnerable due to water shortages, the world's demand for food is projected to increase 70 percent by 2050, according to Guihua Yu, an associate professor of materials science at The University of Texas at Austin.
"Water is the most limiting natural resource for agricultural production because of the freshwater shortage and enormous water consumption needed for irrigation," Yu said.
As scientists have searched for solutions, an alternative water supply has been hiding in plain sight: Water vapor in the atmosphere. It is abundant, available, and endlessly renewable, just waiting for the moment that technological innovation and necessity converged to make it fit for use. Now, new super-moisture-absorbent gels developed by Yu and a team of researchers can pull that moisture from the air and bring it into soil, potentially expanding the map of farmable land around the globe to dry and remote regions that suffer from water shortages.
"This opens up opportunities to turn those previously poor-quality or inhospitable lands to become useable and without need of centralized water and power supplies," Yu said.
A renewable source of freshwater
The hydrogels are a gelatin-like substance made from synthetic materials. The gels activate in cooler, humid overnight periods and draw water from the air. During a four-week experiment, Yu's team observed that soil with these gels provided enough water to support seed germination and plant growth without an additional liquid water supply. And the soil was able to maintain the moist environment for more than a month, according to Yu.
The super absorbent gels developed at the University of Texas at Austin.
Xingyi Zhou, UT Austin
"It is promising to liberate underdeveloped and drought areas from the long-distance water and power supplies for agricultural production," Yu said.
Crops also rely on fertilizer to maintain soil fertility and increase the production yield, but it is easily lost through leaching. Runoff increases agricultural costs and contributes to environmental pollution. The interaction between the gels and agrochemicals offer slow and controlled fertilizer release to maintain the balance between the root of the plant and the soil.
The possibilities are endless
Harvesting atmospheric water is exciting on multiple fronts. The super-moisture-absorbent gel can also be used for passively cooling solar panels. Solar radiation is the magic behind the process. Overnight, as temperatures cool, the gels absorb water hanging in the atmosphere. The moisture is stored inside the gels until the thermometer rises. Heat from the sun serves as the faucet that turns the gels on so they can release the stored water and cool down the panels. Effective cooling of the solar panels is important for sustainable long-term power generation.
In addition to agricultural uses and cooling for energy devices, atmospheric water harvesting technologies could even reach people's homes.
"They could be developed to enable easy access to drinking water through individual systems for household usage," Yu said.
Yu and the team are now focused on affordability and developing practical applications for use. The goal is to optimize the gel materials to achieve higher levels of water uptake from the atmosphere.
"We are exploring different kinds of polymers and solar absorbers while exploring low-cost raw materials for production," Yu said.
The ability to transform atmospheric water vapor into a cheap and plentiful water source would be a game-changer. One day in the not-too-distant future, if climate change intensifies and droughts worsen, this innovation may become vital to our very survival.
This is part 2 of a three part series on a new generation of doctors leading the charge to make the health care industry more sustainable - for the benefit of their patients and the planet. Read part 1 here.
After graduating from her studies as an engineer, Nora Stroetzel ticked off the top item on her bucket list and traveled the world for a year. She loved remote places like the Indonesian rain forest she reached only by hiking for several days on foot, mountain villages in the Himalayas, and diving at reefs that were only accessible by local fishing boats.
“But no matter how far from civilization I ventured, one thing was already there: plastic,” Stroetzel says. “Plastic that would stay there for centuries, on 12,000 foot peaks and on beaches several hundred miles from the nearest city.” She saw “wild orangutans that could be lured by rustling plastic and hermit crabs that used plastic lids as dwellings instead of shells.”
While traveling she started volunteering for beach cleanups and helped build a recycling station in Indonesia. But the pivotal moment for her came after she returned to her hometown Kiel in Germany. “At the dentist, they gave me a plastic cup to rinse my mouth. I used it for maybe ten seconds before it was tossed out,” Stroetzel says. “That made me really angry.”
She decided to research alternatives for plastic in the medical sector and learned that cups could be reused and easily disinfected. All dentists routinely disinfect their tools anyway and, Stroetzel reasoned, it wouldn’t be too hard to extend that practice to cups.
It's a good example for how often plastic is used unnecessarily in medical practice, she says. The health care sector is the fifth biggest source of pollution and trash in industrialized countries. In the U.S., hospitals generate an estimated 6,000 tons of waste per day, including an average of 400 grams of plastic per patient per day, and this sector produces 8.5 percent of greenhouse gas emissions nationwide.
“Sustainable alternatives exist,” Stroetzel says, “but you have to painstakingly look for them; they are often not offered by the big manufacturers, and all of this takes way too much time [that] medical staff simply does not have during their hectic days.”
When Stroetzel spoke with medical staff in Germany, she found they were often frustrated by all of this waste, especially as they took care to avoid single-use plastic at home. Doctors in other countries share this frustration. In a recent poll, nine out of ten doctors in Germany said they’re aware of the urgency to find sustainable solutions in the health industry but don’t know how to achieve this goal.
After a year of researching more sustainable alternatives, Stroetzel founded a social enterprise startup called POP, short for Practice Without Plastic, together with IT expert Nicolai Niethe, to offer well-researched solutions. “Sustainable alternatives exist,” she says, “but you have to painstakingly look for them; they are often not offered by the big manufacturers, and all of this takes way too much time [that] medical staff simply does not have during their hectic days.”
In addition to reusable dentist cups, other good options for the heath care sector include washable N95 face masks and gloves made from nitrile, which waste less water and energy in their production. But Stroetzel admits that truly making a medical facility more sustainable is a complex task. “This includes negotiating with manufacturers who often package medical materials in double and triple layers of extra plastic.”
While initiatives such as Stroetzel’s provide much needed information, other experts reason that a wholesale rethinking of healthcare is needed. Voluntary action won’t be enough, and government should set the right example. Kari Nadeau, a Stanford physician who has spent 30 years researching the effects of environmental pollution on the immune system, and Kenneth Kizer, the former undersecretary for health in the U.S. Department of Veterans Affairs, wrote in JAMA last year that the medical industry and federal agencies that provide health care should be required to measure and make public their carbon footprints. “Government health systems do not disclose these data (and very rarely do private health care organizations), unlike more than 90% of the Standard & Poor’s top 500 companies and many nongovernment entities," they explained. "This could constitute a substantial step toward better equipping health professionals to confront climate change and other planetary health problems.”
Compared to the U.K., the U.S. healthcare industry lags behind in terms of measuring and managing its carbon footprint, and hospitals are the second highest energy user of any sector in the U.S.
Kizer and Nadeau look to the U.K. National Health Service (NHS), which created a Sustainable Development Unit in 2008 and began that year to conduct assessments of the NHS’s carbon footprint. The NHS also identified its biggest culprits: Of the 2019 footprint, with emissions totaling 25 megatons of carbon dioxide equivalent, 62 percent came from the supply chain, 24 percent from the direct delivery of care, 10 percent from staff commute and patient and visitor travel, and 4 percent from private health and care services commissioned by the NHS. From 1990 to 2019, the NHS has reduced its emission of carbon dioxide equivalents by 26 percent, mostly due to the switch to renewable energy for heat and power. Meanwhile, the NHS has encouraged health clinics in the U.K. to install wind generators or photovoltaics that convert light to electricity -- relatively quick ways to decarbonize buildings in the health sector.
Compared to the U.K., the U.S. healthcare industry lags behind in terms of measuring and managing its carbon footprint, and hospitals are the second highest energy user of any sector in the U.S. “We are already seeing patients with symptoms from climate change, such as worsened respiratory symptoms from increased wildfires and poor air quality in California,” write Thomas B. Newman, a pediatrist at the University of California, San Francisco, and UCSF clinical research coordinator Daisy Valdivieso. “Because of the enormous health threat posed by climate change, health professionals should mobilize support for climate mitigation and adaptation efforts.” They believe “the most direct place to start is to approach the low-lying fruit: reducing healthcare waste and overuse.”
In addition to resulting in waste, the plastic in hospitals ultimately harms patients, who may be even more vulnerable to the effects due to their health conditions. Microplastics have been detected in most humans, and on average, a human ingests five grams of microplastic per week. Newman and Valdivieso refer to the American Board of Internal Medicine's Choosing Wisely program as one of many initiatives that identify and publicize options for “safely doing less” as a strategy to reduce unnecessary healthcare practices, and in turn, reduce cost, resource use, and ultimately reduce medical harm.
A few U.S. clinics are pioneers in transitioning to clean energy sources. In Wisconsin, the nonprofit Gundersen Health network became the first hospital to cut its reliance on petroleum by switching to locally produced green energy in 2015, and it saved $1.2 million per year in the process. Kaiser Permanente eliminated its 800,000 ton carbon footprint through energy efficiency and purchasing carbon offsets, reaching a balance between carbon emissions and removing carbon from the atmosphere in 2020, the first U.S. health system to do so.
Cleveland Clinic has pledged to join Kaiser in becoming carbon neutral by 2027. Realizing that 80 percent of its 2008 carbon emissions came from electricity consumption, the Clinic started switching to renewable energy and installing solar panels, and it has invested in researching recyclable products and packaging. The Clinic’s sustainability report outlines several strategies for producing less waste, such as reusing cases for sterilizing instruments, cutting back on materials that can’t be recycled, and putting pressure on vendors to reduce product packaging.
The Charité Berlin, Europe’s biggest university hospital, has also announced its goal to become carbon neutral. Its sustainability managers have begun to identify the biggest carbon culprits in its operations. “We’ve already reduced CO2 emissions by 21 percent since 2016,” says Simon Batt-Nauerz, the director of infrastructure and sustainability.
The hospital still emits 100,000 tons of CO2 every year, as much as a city with 10,000 residents, but it’s making progress through ride share and bicycle programs for its staff of 20,000 employees, who can get their bikes repaired for free in one of the Charité-operated bike workshops. Another program targets doctors’ and nurses’ scrubs, which cause more than 200 tons of CO2 during manufacturing and cleaning. The staff is currently testing lighter, more sustainable scrubs made from recycled cellulose that is grown regionally and requires 80 percent less land use and 30 percent less water.
The Charité hospital in Berlin still emits 100,000 tons of CO2 every year, but it’s making progress through ride share and bicycle programs for its staff of 20,000 employees.
Anesthesiologist Susanne Koch spearheads sustainability efforts in anesthesiology at the Charité. She says that up to a third of hospital waste comes from surgery rooms. To reduce medical waste, she recommends what she calls the 5 Rs: Reduce, Reuse, Recycle, Rethink, Research. “In medicine, people don’t question the use of plastic because of safety concerns,” she says. “Nobody wants to be sued because something is reused. However, it is possible to reduce plastic and other materials safely.”
For instance, she says, typical surgery kits are single-use and contain more supplies than are actually needed, and the entire kit is routinely thrown out after the surgery. “Up to 20 percent of materials in a surgery room aren’t used but will be discarded,” Koch says. One solution could be smaller kits, she explains, and another would be to recycle the plastic. Another example is breathing tubes. “When they became scarce during the pandemic, studies showed that they can be used seven days instead of 24 hours without increased bacteria load when we change the filters regularly,” Koch says, and wonders, “What else can we reuse?”
In the Netherlands, TU Delft researchers Tim Horeman and Bart van Straten designed a method to melt down the blue polypropylene wrapping paper that keeps medical instruments sterile, so that the material can be turned it into new medical devices. Currently, more than a million kilos of the blue paper are used in Dutch hospitals every year. A growing number of Dutch hospitals are adopting this approach.
Another common practice that’s ripe for improvement is the use of a certain plastic, called PVC, in hospital equipment such as blood bags, tubes and masks. Because of its toxic components, PVC is almost never recycled in the U.S., but University of Michigan researchers Danielle Fagnani and Anne McNeil have discovered a chemical process that can break it down into material that could be incorporated back into production. This could be a step toward a circular economy “that accounts for resource inputs and emissions throughout a product’s life cycle, including extraction of raw materials, manufacturing, transport, use and reuse, and disposal,” as medical experts have proposed. “It’s a failure of humanity to have created these amazing materials which have improved our lives in many ways, but at the same time to be so shortsighted that we didn’t think about what to do with the waste,” McNeil said in a press release.
Susanne Koch puts it more succinctly: “What’s the point if we save patients while killing the planet?”
The Friday Five covers five stories in research that you may have missed this week. There are plenty of controversies and troubling ethical issues in science – and we get into many of them in our online magazine – but this news roundup focuses on scientific creativity and progress to give you a therapeutic dose of inspiration headed into the weekend.
Here are the promising studies covered in this week's Friday Five:
- Kids stressing you out? They could be protecting your health.
- A new device unlocks the heart's secrets
- Super-ager gene transplants
- Surgeons could 3D print your organs before operations
- A skull cap looks into the brain like an fMRI