By Marlene Cimons
When the conversation turns to sources of clean renewable energy, evaporation usually isn't the first thing to come up, if at all.
Yet scientists think evaporation from U.S. lakes and reservoirs could generate almost 70 percent of the power the nation produces now. Even better, it could meet demand both day and night, solving the intermittency problems posed by solar and wind.
"Evaporation occurs day and night, all year round," said Ahmet-Hamdi Cavusoglu, a graduate student at Columbia University and lead author of a new study published in the journal Nature Communications that calculated the possible future impact of evaporation as a renewable energy source. "By controlling evaporation, we can store and control the power output, allowing us to potentially provide reliable energy on demand without needing batteries and other energy storage methods."
The evaporation engine sits on a shallow pool of blue water. When water on the surface below evaporates, it drives the flaps to move back and forth. When connected to a generator, that motion produces electricity. Xi Chen
Ozgur Sahin, a biophysicist at Columbia and the paper's senior author, has developed technology that uses spores from the harmless soil-dwelling bacterium B. subtilis to absorb and release water when the relative humidity of the surrounding air changes. At high humidity, the spores take in water and expand, and at low humidity they release water and contract. "In this process, they act like a muscle," he said. "They are highly effective muscles, and it is possible to assemble spores into larger materials that move and generate force when humidity levels change."
The machine, developed by Sahin's lab, controls humidity with shutters that open and close, prompting the spore-coated plastic strips to expand and contract. "When the shutters are closed, evaporation from the water surface raises the humidity level below the shutters, causing spore-coated strips to elongate," he explained. "The movement of the strip opens the shutters, which reduces humidity levels by letting moisture out. The cycle reaches completion when spore-coated strips shorten and close the shutters. Because the process is cyclical, the spore-coated strips repeatedly elongate and shorten."
The moving end of the strips is connected to a generator, which produces the electricity. "We have the technology to harness energy from wind, water and the sun, but evaporation is just as powerful," Sahin said. "We can now put a number on its potential."
The evaporation engine sits on a shallow pool of blue-colored water. When water on the surface below evaporates, it drives the flaps to move back and forth. When connected to a generator, that motion produces electricity. Sahin Laboratory
The technology also has the potential to save water. The study estimated that half of the water that evaporates naturally from lakes and reservoirs into the atmosphere could be conserved during the process, amounting to around 25 trillion gallons annually, or about a fifth of the water Americans consume.
Sahin added that conserving that much water would have little impact on weather patterns. Even if it were deployed at a large scale, his technology would not meaningfully reduce atmospheric moisture that later results in heavy rain because "precipitation and moisture is mostly imposed by the ocean," he said.
Klaus Lackner, an Arizona State University physicist not involved in the study, is developing artificial trees that draw carbon dioxide from the air, in part by using evaporation. "Evaporation has the potential to do a lot of work," Lackner said. "It's nice to see that drying and wetting cycles can also be used to collect mechanical energy."
In computing the potential output of evaporation, the authors confined their calculations to the U.S., where weather station data are readily available, and excluded areas such as farmland, rivers, the Great Lakes and coastlines to avoid errors associated with modeling more complex interactions.
To be sure, the researchers' work is still experimental and confined to the lab. However, "if the technology can be made efficient and scaled to the size of a football field, then widespread use of evaporation as an energy source could be possible," Sahin said. "There are many such bodies of water used by farmers, municipalities and water management agencies," which could provide sources of evaporation in addition to natural bodies of water. Moreover, since many of the materials used are biological and can be easily grown, the machinery likely would not be very expensive, he added.
One of its major advantages is the ability to produce power only when needed. Solar and wind, on the other hand, require backup batteries when the sun isn't shining or the wind isn't blowing. Moreover, batteries aren't cheap, and they often are made of toxic materials.
Harvesting energy from evaporation can cut the amount of water lost to natural evaporation in half, researchers say. Water-strapped cities with growing populations and energy needs could benefit most, including Phoenix, which is served by the reservoir pictured above.Central Arizona Project
"Human electricity demand varies seasonally and daily," Cavusoglu said. "We use more energy during the summer, and we use more energy in the early evening when people get home from work. However, the availability of wind and solar power does not match our demand. This need for energy on demand is important for our daily life, from keeping the lights on in hospitals to letting us stream Netflix at home."
Since evaporation packs more energy in warm and dry weather, drought-prone states like California, Nevada and Arizona could benefit greatly from the technology. "Interestingly, many dry-air areas do have some lakes or large bodies of water," Sahin said. "For example, the Colorado River and the large lakes formed by dams, such as Lake Mead, Lake Mohave, Lake Powell and Lake Havusu."
Still, "if there are no water bodies or other wet surfaces, evaporation will be negligible and this concept will not work," he added. "However, even in that situation, daily variations in relative humidity could be harnessed to generate power."
This turbine engine rotates as water evaporates from the wet paper lining the walls of the engine.Sahin Laboratory
Several years ago, Sahin's lab also developed an evaporation-fueled piston-driven engine that generates electricity causing a light to flash, and a rotary engine that drives a miniature car. The scientists now are working on improving the energy efficiency of their materials, and plan to test their concept on a lake, reservoir, or greenhouse where the technology could both conserve water and create power.
"Today, further expansion of renewable energy technologies faces many technical and non-technical challenges," Sahin said. "A renewable energy technology based on evaporation could nicely complement the existing ones by offering an alternative that might be more suitable in a particular location, or generate power when the other renewable energy technologies can't."
Reposted with permission from our media associate Nexus Media.
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By Ana Maldonado-Contreras
- Your gut is home to trillions of bacteria that are vital for keeping you healthy.
- Some of these microbes help to regulate the immune system.
- New research, which has not yet been peer-reviewed, shows the presence of certain bacteria in the gut may reveal which people are more vulnerable to a more severe case of COVID-19.
You may not know it, but you have an army of microbes living inside of you that are essential for fighting off threats, including the virus that causes COVID-19.
How Do Resident Bacteria Keep You Healthy?<p>Our immune defense is part of a complex biological response against harmful pathogens, such as viruses or bacteria. However, because our bodies are inhabited by trillions of mostly beneficial bacteria, virus and fungi, activation of our immune response is tightly regulated to distinguish between harmful and helpful microbes.</p><p>Our bacteria are spectacular companions diligently helping prime our immune system defenses to combat infections. A seminal study found that mice treated with antibiotics that eliminate bacteria in the gut exhibited an impaired immune response. These animals had low counts of virus-fighting white blood cells, weak antibody responses and poor production of a protein that is vital for <a href="https://doi.org/10.1073/pnas.1019378108" target="_blank">combating viral infection and modulating the immune response</a>.</p><p><a href="https://doi.org/10.1371/journal.pone.0184976" target="_blank" rel="noopener noreferrer">In another study</a>, mice were fed <em>Lactobacillus</em> bacteria, commonly used as probiotic in fermented food. These microbes reduced the severity of influenza infection. The <em>Lactobacillus</em>-treated mice did not lose weight and had only mild lung damage compared with untreated mice. Similarly, others have found that treatment of mice with <em>Lactobacillus</em> protects against different <a href="https://doi.org/10.1038/srep04638" target="_blank" rel="noopener noreferrer">subtypes of</a> <a href="https://doi.org/10.1038/s41598-017-17487-8" target="_blank" rel="noopener noreferrer">influenza</a> <a href="https://doi.org/10.1371/journal.ppat.1008072" target="_blank" rel="noopener noreferrer">virus</a> and human respiratory syncytial virus – the <a href="https://doi.org/10.1038/s41598-019-39602-7" target="_blank" rel="noopener noreferrer">major cause of viral bronchiolitis and pneumonia in children</a>.</p>
Chronic Disease and Microbes<p>Patients with chronic illnesses including Type 2 diabetes, obesity and cardiovascular disease exhibit a hyperactive immune system that fails to recognize a harmless stimulus and is linked to an altered gut microbiome.</p><p>In these chronic diseases, the gut microbiome lacks bacteria that activate <a href="https://doi.org/10.1126/science.1198469" target="_blank" rel="noopener noreferrer">immune cells</a> that block the response against harmless bacteria in our guts. Such alteration of the gut microbiome is also observed in <a href="https://doi.org/10.1073/pnas.1002601107" target="_blank" rel="noopener noreferrer">babies delivered by cesarean section</a>, individuals consuming a poor <a href="https://doi.org/10.1038/nature12820" target="_blank" rel="noopener noreferrer">diet</a> and the <a href="https://doi.org/10.1038/nature11053" target="_blank" rel="noopener noreferrer">elderly</a>.</p><p>In the U.S., 117 million individuals – about half the adult population – <a href="https://health.gov/our-work/food-nutrition/2015-2020-dietary-guidelines/guidelines/" target="_blank" rel="noopener noreferrer">suffer from Type 2 diabetes, obesity, cardiovascular disease or a combination of them</a>. That suggests that half of American adults carry a faulty microbiome army.</p><p>Research in my laboratory focuses on identifying gut bacteria that are critical for creating a balanced immune system, which fights life-threatening bacterial and viral infections, while tolerating the beneficial bacteria in and on us.</p><p>Given that diet affects the diversity of bacteria in the gut, <a href="https://www.umassmed.edu/nutrition/melody-trial-info/" target="_blank" rel="noopener noreferrer">my lab studies show how diet can be used</a> as a therapy for chronic diseases. Using different foods, people can shift their gut microbiome to one that boosts a healthy immune response.</p><p>A fraction of patients infected with SARS-CoV-2, the virus that causes COVID-19 disease, develop severe complications that require hospitalization in intensive care units. What do many of those patients have in common? <a href="https://www.cdc.gov/mmwr/volumes/69/wr/mm6912e2.htm" target="_blank" rel="noopener noreferrer">Old age</a> and chronic diet-related diseases like obesity, Type 2 diabetes and cardiovascular disease.</p><p><a href="http://doi.org/10.1016/j.jada.2008.12.019" target="_blank" rel="noopener noreferrer">Black and Latinx people are disproportionately affected by obesity, Type 2 diabetes and cardiovascular disease</a>, all of which are linked to poor nutrition. Thus, it is not a coincidence that <a href="https://www.cdc.gov/mmwr/volumes/69/wr/mm6933e1.htm" target="_blank" rel="noopener noreferrer">these groups have suffered more deaths from COVID-19</a> compared with whites. This is the case not only in the U.S. but also <a href="https://www.washingtonpost.com/world/europe/blacks-in-britain-are-four-times-as-likely-to-die-of-coronavirus-as-whites-data-show/2020/05/07/2dc76710-9067-11ea-9322-a29e75effc93_story.html" target="_blank" rel="noopener noreferrer">in Britain</a>.</p>
Discovering Microbes That Predict COVID-19 Severity<p>The COVID-19 pandemic has inspired me to shift my research and explore the role of the gut microbiome in the overly aggressive immune response against SARS-CoV-2 infection.</p><p>My colleagues and I have hypothesized that critically ill SARS-CoV-2 patients with conditions like obesity, Type 2 diabetes and cardiovascular disease exhibit an altered gut microbiome that aggravates <a href="https://theconversation.com/exercise-may-help-reduce-risk-of-deadly-covid-19-complication-ards-136922" target="_blank" rel="noopener noreferrer">acute respiratory distress syndrome</a>.</p><p>Acute respiratory distress syndrome, a life-threatening lung injury, in SARS-CoV-2 patients is thought to develop from a <a href="http://doi.org/10.1016/j.cytogfr.2020.05.003" target="_blank" rel="noopener noreferrer">fatal overreaction of the immune response</a> called a <a href="https://theconversation.com/blocking-the-deadly-cytokine-storm-is-a-vital-weapon-for-treating-covid-19-137690" target="_blank" rel="noopener noreferrer">cytokine storm</a> <a href="http://doi.org/10.1016/S2213-2600(20)30216-2" target="_blank" rel="noopener noreferrer">that causes an uncontrolled flood</a> <a href="http://doi.org/10.1016/S2213-2600(20)30216-2" target="_blank" rel="noopener noreferrer">of immune cells into the lungs</a>. In these patients, their own uncontrolled inflammatory immune response, rather than the virus itself, causes the <a href="http://doi.org/10.1007/s00134-020-05991-x" target="_blank" rel="noopener noreferrer">severe lung injury and multiorgan failures</a> that lead to death.</p><p>Several studies <a href="https://doi.org/10.1016/j.trsl.2020.08.004" target="_blank" rel="noopener noreferrer">described in one recent review</a> have identified an altered gut microbiome in patients with COVID-19. However, identification of specific bacteria within the microbiome that could predict COVID-19 severity is lacking.</p><p>To address this question, my colleagues and I recruited COVID-19 hospitalized patients with severe and moderate symptoms. We collected stool and saliva samples to determine whether bacteria within the gut and oral microbiome could predict COVID-19 severity. The identification of microbiome markers that can predict the clinical outcomes of COVID-19 disease is key to help prioritize patients needing urgent treatment.</p><p><a href="https://doi.org/10.1101/2021.01.05.20249061" target="_blank" rel="noopener noreferrer">We demonstrated</a>, in a paper which has not yet been peer reviewed, that the composition of the gut microbiome is the strongest predictor of COVID-19 severity compared to patient's clinical characteristics commonly used to do so. Specifically, we identified that the presence of a bacterium in the stool – called <em>Enterococcus faecalis</em>– was a robust predictor of COVID-19 severity. Not surprisingly, <em>Enterococcus faecalis</em> has been associated with <a href="https://doi.org/10.1053/j.gastro.2011.05.035" target="_blank" rel="noopener noreferrer">chronic</a> <a href="https://doi.org/10.1016/S0002-9440(10)61172-8" target="_blank" rel="noopener noreferrer">inflammation</a>.</p><p><em>Enterococcus faecalis</em> collected from feces can be grown outside of the body in clinical laboratories. Thus, an <em>E. faecalis</em> test might be a cost-effective, rapid and relatively easy way to identify patients who are likely to require more supportive care and therapeutic interventions to improve their chances of survival.</p><p>But it is not yet clear from our research what is the contribution of the altered microbiome in the immune response to SARS-CoV-2 infection. A recent study has shown that <a href="https://doi.org/10.1101/2020.12.11.416180" target="_blank" rel="noopener noreferrer">SARS-CoV-2 infection triggers an imbalance in immune cells</a> called <a href="https://doi.org/10.1111/imr.12170" target="_blank" rel="noopener noreferrer">T regulatory cells that are critical to immune balance</a>.</p><p>Bacteria from the gut microbiome are responsible for the <a href="https://doi.org/10.7554/eLife.30916.001" target="_blank" rel="noopener noreferrer">proper activation</a> <a href="https://doi.org/10.1126/science.1198469" target="_blank" rel="noopener noreferrer">of those T-regulatory</a> <a href="https://doi.org/10.1038/nri.2016.36" target="_blank" rel="noopener noreferrer">cells</a>. Thus, researchers like me need to take repeated patient stool, saliva and blood samples over a longer time frame to learn how the altered microbiome observed in COVID-19 patients can modulate COVID-19 disease severity, perhaps by altering the development of the T-regulatory cells.</p><p>As a Latina scientist investigating interactions between diet, microbiome and immunity, I must stress the importance of better policies to improve access to healthy foods, which lead to a healthier microbiome. It is also important to design culturally sensitive dietary interventions for Black and Latinx communities. While a good-quality diet might not prevent SARS-CoV-2 infection, it can treat the underlying conditions related to its severity.</p><p><em><a href="https://theconversation.com/profiles/ana-maldonado-contreras-1152969" target="_blank">Ana Maldonado-Contreras</a> is an assistant professor of Microbiology and Physiological Systems at the University of Massachusetts Medical School.</em></p><p><em>Disclosure statement: Ana Maldonado-Contreras receives funding from The Helmsley Charitable Trust and her work has been supported by the American Gastroenterological Association. She received The Charles A. King Trust Postdoctoral Research Fellowship. She is also member of the Diversity Committee of the American Gastroenterological Association.</em></p><p><em style="">Reposted with permission from <a href="https://theconversation.com/a-healthy-microbiome-builds-a-strong-immune-system-that-could-help-defeat-covid-19-145668" target="_blank" rel="noopener noreferrer" style="">The Conversation</a>. </em></p>
By Jeff Masters, Ph.D.
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