Smart windows that protect against solar radiation can help reduce greenhouse gases

by Fraunhofer-Gesellschaft

For buildings with large glass façades, installing electrochromic or

 thermochromic windows can save up to 70 percent of heating and

 cooling energy consumption. Credit: Fraunhofer-Gesellschaft

Fraunhofer researchers have developed an intelligent coating for glass windows that darkens in the sun. This uses electrochromic and thermochromic materials that react to electricity and heat. In buildings with large glass façades, it stops the rooms from getting too hot because of solar radiation, thereby reducing the demand for energy-intensive air conditioning.The building sector is one of the biggest emitters of greenhouse gases. According to the German Environment Agency, buildings are responsible for around 30 percent of the country's CO2 emissions and 35 percent of its final energy consumption. Buildings with large glass façades and roofs are particularly problematic, such as the office towers that dominate modern cities. They heat up in the sun, especially in summer. However, using blinds and jalousies to provide shade is often unpopular, as they detract from the aesthetic appeal of the glass and disturb the view outside. Instead, the interior is cooled with air conditioning, which requires enormous amounts of electricity and increases the carbon footprint of the building.

The Fraunhofer Institute for Silicate Research ISC in Würzburg and the Fraunhofer Insti-tute for Organic Electronics, Electron Beam and Plasma Technology FEP in Dresden have developed a sophisticated solution to this problem. In the Switch2Save project, researchers have been working on transparent coatings for windows and glass façades using electrochromic and thermochromic materials. These add a variable, transparent dark tint to the outside of the windows, which keeps the rooms cool. The Fraunhofer Institutes have partnered with universities and industrial partners across six EU countries for this EU-funded research project.

Electrochromic and thermochromic coating

"The electrochromic coating is applied to a transparent, conductive film which can then be "switched on." Applying an electrical voltage triggers the transfer of ions and electrons, which darkens the coating and tints the window. On the other hand, thermochromic coating works passively. When a certain ambient temperature is reached, it reflects the heat radiation of sun," explains Dr. Marco Schott, Group Manager of Electrochromic Systems at Fraunhofer ISC.

The structure of a window with Switch2Save technology: versions with

 electrochromic or thermochromic coating are possible, as well as a 

combination of the two technologies in one window. Credit: Fraunhofer-Gesellschaft

With electrochromic elements, sensors can be used to measure factors such as bright-ness and temperature, sending the results to control systems. This sends a current or voltage pulse to the conductive film, triggering the window to darken. The surface of the glass gradually darkens whenever the temperature or brightness level becomes too high. This stops rooms from becoming overheated and reduces the need for air conditioning, which is particularly useful in sunnier climes and buildings with large, glazed façades. It also serves as anti-glare protection on sunny days. On cloudy days and in the evening the windows will be kept in bright state.

Fraunhofer researchers have also thought about the suitability of the technology for everyday use. "The windows don't turn dark suddenly, but are gradually tinted over a few minutes," explains Schott. Energy consumption is very low. In optimal circumstances, electrochromic film only requires electricity for the switching process and a very low voltage is enough to initiate the tinting process. Thermochromic materials do not require electricity at all, instead reacting passively to the heat generated by the sun. They can be used to complement a switchable system or as an alternative, where a switchable solution is not required.

Demonstration buildings in Athens and Uppsala

Switch2Save promises huge energy savings in areas where outside temperatures are high, i.e., in southern regions, by reducing use of air conditioning systems or removing the need for them entirely. Dr. John Fahlteich, Switch2Save Project Coordinator and Head of the Research Group at Fraunhofer FEP, explains: "In warm regions of Europe, the cooling and heating energy demands of modern buildings can be reduced by up to 70 percent." Savings are not so extensive in colder, northerly regions, but the systems could also be used here as anti-glare protection against direct sunlight.

In principle, the combination of electrochromic and thermochromic layers in a composite window offers the greatest possible flexibility. By using this, architects and developers can provide individual solutions for a variety of regions and buildings. "We are in the process of installing the technology in the Pediatric Clinic of the second-largest hospital in Greece, in Athens, and an office building in Uppsala, Sweden. In both buildings, energy consumption will be monitored and compared for a whole year both before and after installation of the new windows. By doing this, we can demonstrate the real-life performance of the Switch2Save technology and can continue to test and refine the technology for different climate zones," says Fahlteich.

The coatings are manufactured using a roll-to-roll process. At just a few hundred micrometers thick, both the electrochromic film and the thermochromic thin glass substrate are extremely thin. Credit: Fraunhofer-Gesellschaft

Roll-to-roll manufacturing

The researchers have also resolved challenges for manufacturing. The electrochromic coating is applied to a polymer-based film substrate. The thermochromic coating, on the other hand, uses a thin glass substrate. Wet chemical and vacuum coating processes are used in a cost-effective roll-to-roll manufacturing system. The switchable components are then laminated under vacuum onto a 4 mm thick sheet of window glass, which is integrated to an insulating glass unit thereafter. The coating process is also economically feasible on an industrial scale. The electrochromic and thermochromic switchable elements are only a few 100 μm thick and less than 500 g per square meter. Thus, they hardly add any weight to the windows, which means that they can be retrofitted in existing buildings without needing to alter the building structure.

Curved glass and colorful windows

The project consortium is currently working on improving the technology further. For example, the team of experts is researching how electrochromic and thermochromic elements can be combined in a composite window to make even better use of the technology's potential. Further research objectives include adapting the coating to curved glass forms and adding more colors to the existing options of blue and gray.

Global warming and the objectives of the European Green Deal will significantly increase the demand for energy-efficient building technology in the next few years—and all buildings in the EU are expected to be carbon neutral by 2050. The electrochromic and thermochromic windows of the EU Switch2Save project can make an important contribution to this.

Colorful perovskites: Lab advances thermochromic window technologies

Provided by Fraunhofer-Gesellschaft 

 

New report details Switzerland's geo-energy potential

by Ecole Polytechnique Federale de Lausanne

Credit: Pixabay/CC0 Public Domain

When the Swiss government decided to phase out nuclear power in the wake of the Fukushima accident on 11 March 2011, it also launched a major nationwide research program to explore alternative energy sources, with the goal of fully replacing the country's nuclear power with renewable energy by 2050. Some CHF 250 million in funding was deployed to develop and implement a comprehensive strategy. The nationwide research program entailed setting up eight Swiss Competence Centers for Energy Research (SCCERs) to explore seven energy-related topics. Universities and research institutes from across the country, in association with around 900 businesses and public-sector organizations, conducted 1,500 research projects through these Centers between 2013 and 2020. Innosuisse was commissioned to evaluate the results of the projects, and it issued its final report on 22 July 2021.

As part of this nationwide research program, EPFL led the effort in the area of geo-energy, which included assessing Switzerland's potential for carbon storage and for deep and shallow geothermal energy. What are the main conclusions?

Carbon storage in Switzerland

"The research we've done over the past eight years shows that there's enough underground capacity in Switzerland to store large amounts of CO2, primarily in the Swiss Plateau, from Fribourg to Zurich," says Prof. Laloui. "In fact, the carbon storage process would be easier than burying nuclear waste." Experts involved in the project estimate that 50–700 million tons of CO2 could be stored in Switzerland's ground. These would mainly be emissions from the construction industry (cement and steel production), the biochemicals industry and agriculture. "Of the about 40 million tons CO2-eq emitted in Switzerland each year, some 12 million could potentially be stored underground. That means for those emissions the country could become carbon-neutral, or even achieve negative emissions, for 70 years," says Prof. Laloui. However, he also points out that reaching this goal would require that today's greenhouse gas emitters decarbonize their production chains.

Over 20% share of shallow geothermal energy by 2035

Prof. Laloui's research on shallow geothermal energy indicates that there's considerable potential for this type of renewable resource. "The Swiss government had set a target of having 11% of the energy used for its buildings' heating and cooling systems come from geothermal energy by 2035. The project outcomes show that this percentage could easily be doubled," he says. With regard to deep geothermal energy—that is, natural heat located one to three kilometers underground—The activities conducted in the context of the geo-energy SCCER-SoE project with the Geneva Canton public utility which found that if heat accumulated during the summer was stored below Lake Geneva, it could be used to warm up some of the Canton's buildings during the winter.

The geo-energy SCCER-SoE study also looked at the scope for using geothermal energy to generate electricity. For now, the results indicated that as something that could be an option in the future. "Many researchers have looked at how rocks can be fractured without triggering seismic movements, but more research is still needed. We'll surely be able to do it one day, but we're not there yet."

Prof. Laloui believes a lot of important findings have come out of these years of intensive research. Switzerland now ranks among Europe's top centers of excellence in geo-energy, and the joint effort by 250 scientists across the country has been highly effective. He now hopes that the research will be taken further. "I strongly encourage the Swiss government to set up a national research center on geo-energy and carbon storage in order to leverage the discoveries we've already made and keep our solid skills in this area within the country."

Pilot test planned in Iceland

The latest report by the Intergovernmental Panel on Climate Change (IPCC) is unequivocal: it is only by implementing a portfolio of measures that the signatories of the Paris Agreement will be able to meet their targets and cut their greenhouse gas emissions. One measure that's needed urgently is carbon storage, and Switzerland has not yet decided what steps it will take in this regard. However, on 20 July 2021, Switzerland and Iceland signed a statement of intent to jointly support and develop negative-emission technology—and this includes carbon storage. A pilot test to that effect will soon be carried out in Iceland. For now, Switzerland does not have any plans for underground carbon storage within its borders.

A carbon-neutral response to rising electricity demand

More information: Energy Funding Programme 2013-2020: Final Report and evaluation. www.innosuisse.ch/inno/en/home … programme-SCCER.html

Provided by Ecole Polytechnique Federale de Lausanne 

 

Environmentally friendly manufacture of battery electrodes

by Fraunhofer-Gesellschaft

A fine coating film forms on the faster-rotating roller. Credit: Fraunhofer-Gesellschaft

Conventional processes for manufacturing battery electrodes involve mostly toxic solvents and require a lot of space and energy. This is not the case with DRYtraec—a new dry-coating process developed by the Fraunhofer Institute for Material and Beam Technology IWS. The technology is environmentally friendly and cost effective and can be used on a large scale, giving it the potential to revolutionize the manufacturing of battery electrodes.

The Federal Ministry for Economic Affairs and Energy (BMWi) predicts that Germany will consume around 655 terawatt hours in the year 2030—an increase of almost 20 percent compared to today. Prognos AG carried out a corresponding study on behalf of the ministry. This figure is an initial estimate; final results are expected to be available in the fall. However, it is clear that society's overall energy demand is continuously increasing. The fast-growing electromobility sector is therefore looking for new ways to reduce the energy required to manufacture batteries and thus to design them to be as cost effective and environmentally friendly as possible. DRYtraec is a promising solution developed by an interdisciplinary research team at Fraunhofer IWS in Dresden that focuses on the production of the battery electrodes.

A key component of any battery, electrodes normally consist of a metal foil with a thin coating. This coating contains the active components that are responsible for storing energy. "The conventional coating process uses a wet chemical method that applies what is known as slurry," explains Dr. Benjamin Schumm, Group Manager for Chemical Coating Technologies at Fraunhofer IWS. The active material, conductive carbon and binders are dispersed in a solvent to make a kind of paste, which is initially applied to the metal foil to form a wet coating. "Extremely large machines with very long drying tracks are needed to ensure that the solvent will evaporate afterward. With DRYtraec, we can design this process more efficiently."

Credit: Fraunhofer-Gesellschaft

Special binder and shear forces from rotating rollers

The new coating process essentially uses similar raw materials as in the slurry process. The dry coating technology developed at Fraunhofer IWS works without solvents, but instead uses a special binder. Together, the materials form a dry mixture that is fed into a calender gap—a gap between two rollers rotating in opposite directions. The crucial detail is that one of the rollers must be turning faster than the other. This induces a shear force, which ensures that the binder forms thread-like networks known as fibrils.

"Imagine it as a spider's web that mechanically embeds the particles," says Schumm. The pressure and motion form a fine film on the faster-rotating roller. This film is then transferred in a second calender gap onto a current collector foil. This allows both sides to be coated simultaneously without significant additional work. In the final step, the resulting coil is cut to the required size and the individual parts are stacked as appropriate in order to produce the finished battery cell.

Success thanks to combined expertise in chemistry and manufacturing engineering

DRYtraec therefore has clear ecological and economic advantages over existing battery electrode coating processes. Removing toxic solvents and long, energy-intensive drying machines from the process benefits the environment. The new process also accelerates production and requires only one-third of the equipment space of a conventional solution, saving costs in number of ways. In Schumm's view, the success of the DRYtraec process comes primarily from the diversity of expertise in the research team at Fraunhofer IWS. Colleagues with a background in chemistry worked on the opti-mum powder mixture, but experts in manufacturing engineering, for example, developed equipment that prevents the dry film from ever being self-supporting, ensuring that it remains stable.

DRYtraec machines do not require long drying tracks and so take up 

significantly less space than conventional battery electrode manufacturing 

systems. Credit: Fraunhofer-Gesellschaft

A wide range of possible applications

The first prototype DRYtraec systems were commissioned as part of the "DryProTex" funding project. This project demonstrated that it is possible to manufacture electrodes continuously, regardless of the type of battery: "The range of possible uses for the technology is not limited to a particular cell chemistry," Schumm points out. "It could equally be used on lithium-ion cells as on lithium-sulfur or sodium-ion cells. We are even looking at solid-state batteries. These will be increasingly important in the future, but the materials cannot tolerate wet chemical processing. Thus, DRYtraec allows us to offer a very promising solution to this problem."

The industry is showing a lot of interest in the process. Discussions are currently underway with several automobile and cell manufacturers to plan the construction of a number of pilot systems. Beyond manufacturing electrodes with DRYtraec, the researchers at Fraunhofer IWS are engaged in many other research projects to examine the entire battery cell development process chain. By doing so, they are playing a key role in shaping the future of the battery.

Economical energy storage for the electric car of tomorrow

Provided by Fraunhofer-Gesellschaft 

 

Simulation of bamboo's response to moisture used to prevent mold growth in building materials

by Fraunhofer-Gesellschaft

The WUFI software from Fraunhofer IBP shows a material's response to

 moisture over time by means of a film. The y axis indicates temperature

 and moisture content, while the x axis shows a cross-section of the 

component. Credit: Fraunhofer-Gesellschaft

As a rapidly growing renewable raw material, bamboo is an ideal substitute for wood. However, bamboo's susceptibility to mold in damp conditions poses a problem. Researchers at Fraunhofer have now analyzed bamboo's response to moisture under specific climatic conditions. By using simulation software, building owners can plan and implement measures to prevent the growth of mold.

In the era of climate change, bamboo ranks among the most promising construction materials. Bamboo is a rapidly growing renewable raw material, which absorbs CO2, and is resource-efficient and biodegradable. For this reason, the construction industry is increasingly choosing to use it as a substitute for wood, which is becoming scarce due to the increase in building activities across the globe.

However, Bambusoideae (scientific name for bamboo), part of the perennial grass family, poses a structural issue: Over the course of their centuries-long lifespan, trees build up resistance to harmful bacteria and mold. The lifespan of a bamboo stem, however, is only 20 years. As a result, it is less able to protect itself and is therefore vulnerable to mold infestation.

The Fraunhofer Institute for Building Physics IBP is now presenting a solution that helps to forecast bamboo's response to moisture, thereby enabling the humidity of the material to be managed efficiently. "The goal is to prevent the growth of mold without using chemical preservatives that can also harm humans," explains Prof. Dr. Hartwig Künzel, Head of Hygrothermics at Fraunhofer IBP.

Laboratory testing to determine material properties

The first step was to determine the hygrothermal material properties of bamboo under certain climatic conditions. Following studies in China, further tests were carried out at the outdoor testing facility at Fraunhofer IBP in Holzkirchen near Munich, Germany. Here, bamboo products were exposed to the weather while the climatic conditions were recorded in detail by a meteorological station. An expert team then examined the material in the laboratory. How much water and water vapor did the bamboo absorb? How much was released and how was moisture transported within the material? In the latter case, the material was examined using an MRI scanner, which revealed how the absorbed water was distributed and moved about within the material.

In a similar way to wood, bamboo can be used to manufacture sturdy panels. Credit: Fraunhofer-Gesellschaft

Simulation software for all climatic conditions

At the technological heart of the project was the hygrothermal simulation software WUFI. It uses a transient calculation method that has been validated in experiments across the world. This software enables the thermal and moisture conditions in components and buildings to be realistically simulated. Using the properties determined in the laboratory, the software simulates the behavior of bamboo when exposed to specific climatic conditions and presents the findings using an animated chart that shows progression over time. This can be used to derive the probability that mold will grow. Typically, mold starts to pose a risk to bamboo in ambient conditions of 80 percent relative atmospheric humidity. A construction company that uses bamboo for sustainable building construction can use the software analysis to implement measures that will provide effective framework conditions, such as protection against humidity.

"The WUFI software delivers reliable and detailed results on bamboo's response to moisture. This enables construction companies and architects to plan and build ecologically safe and sustainable buildings using bamboo as a building material," says Künzel. In addition, these findings can also be used to open up new areas of application for different materials made from bamboo.

The researchers developed the simulation software years ago. In light of the present increase in demand for wood substitutes, researchers at Fraunhofer have now also validated the software for bamboo. "There is a variety of versions of WUFI available, depending on the application and requirements. We also license these to international partners," says Künzel. Bamboo is best suited as a wood substitute. It is a fibrous, light material, which offers great long-term stability, and can be used to manufacture panels (such as wall paneling) in a similar way to wood. Bamboo can also be used for floorboards because it is very hard. Due to its flexibility, bamboo is ideal for construction in earthquake areas.

Fields of research: indoor climate, structural engineering and biohygrothermics

Reeds (Typha) are another environmentally friendly replacement for wood that Fraunhofer IBP has researched in the past. When used to construct walls, reeds act well as a stable, insulating and sustainable building material. Expertise regarding materials which can replace wood only makes up part of the specialist competence offered by Fraunhofer IBP. The institute, with sites in Stuttgart and Holzkirchen, has many years of expertise in building physics. This includes, for example, structural engineering, indoor climate and biohygrothermics, all of which are viewed from the standpoint of sustainability. By means of example, scientists are also researching air conditioning in aircraft and moisture management in packaging. Currently, there are plans for a project to assess the possibilities for climate-stable transport of sensitive goods.Bamboo lights a fire under Australian construction industry

Provided by Fraunhofer-Gesellschaft 

 

Biofuels offer a cost-effective way to lower shipping emissions

by Argonne National Laboratory

Credit: CC0 Public Domain

Marine shipping traffic has grown steadily over the past decade—and so have the associated greenhouse gas emissions. Carbon emissions from ships grew almost 10% between 2012 and 2018, and the industry is a large consumer of petroleum fuel.

Substituting biofuel could reduce the amount of greenhouse gases and other pollutants entering the air from ocean shipping, according to a study from researchers at the U.S. Department of Energy (DOE) and Department of Transportation. Compared with conventional heavy fuel oil, the study found, biomass-based fuel could reduce greenhouse gas emissions between 40 and 93%.

Without any changes to the status quo, greenhouse gas emissions from shipping in 2050 could be 40% higher than they are today, according to the United Nations' International Maritime Organization (IMO). The IMO has set a target to instead cut those emissions by at least half.

Shipping is also a key source of sulfur oxides and soot or particulate matter emissions, which worsen air quality and have been linked to human health problems. The IMO recently imposed new fuel standards aimed at reducing emissions of sulfur oxides, requiring lower concentrations of sulfur in shipping fuel.

"The push to cut pollutants from shipping is an emerging opportunity for biofuels, but the potential impact has gone relatively unexplored," said Troy Hawkins, a scientist at DOE's Argonne National Laboratory who co-led the study, published in the journal Environmental Science & Technology. "Our analysis found biofuels can significantly reduce shipping emissions while remaining cost-effective."

The vast majority of cargo ships today run on heavy fuel oil, which is cheap and energy dense but very dirty to burn.

"These engines are multiple stories tall and so large you could climb inside them," Hawkins said. "They are just huge, and they are burning hundreds of millions of tons of thick, tar-like fuel to move freight internationally."

The study evaluated costs and emissions of biofuel alternatives including bio-oil and renewable diesel made from wood waste or fats such as used cooking oil. They also looked at mixtures of these biobased feedstocks with petroleum-based feedstocks including petroleum, natural gas and coal.

To conduct the emissions analysis, the researchers used Argonne's Greenhouse gases, Regulated Emissions, and Energy use in Transportation model (GREET). GREET is an analytical tool used to calculate the energy and environmental impacts of different fuels across their full life cycle. Instead of just considering the energy use and emissions that result when a fuel is burned, a life-cycle analysis considers the bigger picture, including extracting the fuel, refining it, and transporting it to users.

The GREET model is a well-established tool for life cycle analysis of transportation and other technologies. For this study, Argonne researchers significantly expanded the fuel pathways considered for marine shipping. Their collaborators at Pacific Northwest National Laboratory (PNNL) and the National Renewable Energy Laboratory (NREL) analyzed costs of the various fuels compared. They found the 100% biofuel options offered emissions reductions up to 93% compared with heavy fuel oil and also the lowest cost among the alternative fuel pathways considered.

Across the board, the biofuels lowered emissions of greenhouse gases, sulfur oxides and particulate matter—and at costs that could be competitive with heavy fuel oil, after considering incentives such as California's Low Carbon Fuel Standard. Due to the low sulfur content of the biobased feedstocks, the biofuels analyzed reduced sulfur oxides emissions by 97% or more; particulate matter emissions came down between 84 and 90%.

The research, which was funded by the Department of Transportation Maritime Administration and DOE's Bioenergy Technologies Office within the Office of Energy Efficiency and Renewable Energy, is part of a broader effort at DOE to study the feasibility of using biofuels to lower emissions from cargo ships. Recently, DOE also announced a partnership with the governments of the United States, Denmark and Norway to develop technologies for zero-emission shipping as part of Mission Innovation, a global initiative to accelerate affordable, accessible clean energy solutions.

The datasets developed in the recent study are publicly available and could also support the evaluation of fuels to meet California's Low Carbon Fuel Standard, which takes a similar life-cycle view of fuels to encourage options with the lowest carbon intensity. Co-authors with Hawkins are Eric Tan and Ling Tao at NREL; Uisung Lee and Michael Wang at Argonne; Pimphan Meyer at PNNL and Tom Thompson at the Maritime Administration.

"This study offers a foundation for fairly evaluating marine shipping fuels," Hawkins said. "With many options on the horizon for cleaner shipping, our goal is to support decision-making about which ones offer the best potential for mitigating greenhouse gas emissions and are the most cost-effective to pursue."

Environmental concerns propel research into marine biofuels

More information: Eric C. D. Tan et al, Biofuel Options for Marine Applications: Technoeconomic and Life-Cycle Analyses, Environmental Science & Technology (2021). DOI: 10.1021/acs.est.0c06141

Journal information: Environmental Science & Technology 

Provided by Argonne National Laboratory 

 

Early COVID-19 shutdowns helped St. Louis area avoid thousands of deaths

by Washington University School of Medicine

A new study from Washington University School of Medicine in St. Louis 

estimates the number of deaths that could have occurred had public

 health orders been delayed for one week, two weeks or four weeks as the 

pandemic was first taking hold in St. Louis city and St. Louis County. 

The analysis suggests that, in the first three months of the pandemic,

 the region avoided thousands of hospitalizations and deaths with early

 and coordinated public health measures. Shown, a health-care provider 

tends to a patient with COVID-19 in the intensive care unit at

 Barnes-Jewish Hospital. Credit: MATT MILLER

In March 2020, not long after the first cases of COVID-19 were reported locally, health officials in the city of St. Louis and St. Louis County issued emergency public health orders intended to reduce interactions between people and slow the transmission of the novel respiratory virus. Such action likely saved thousands of lives in the region, according to new research led by Washington University School of Medicine in St. Louis.

An analysis indicates that a delay of even two weeks in issuing local public health orders could have increased the number of deaths almost sevenfold in the city and county.

The researchers analyzed an epidemiological model to examine what was likely to have happened if the epidemic trajectory in St. Louis early in March had continued without the enactment of behavior-focused public health policies for another one, two and four weeks.

The research, published Sept. 1 in JAMA Network Open, demonstrates the importance of early and coordinated implementation of local public health policies in reducing deaths from the pandemic, particularly during a critical window at the onset of a new epidemic.

"We heard a lot about the dire situations in cities such as New York and Boston in the early part of the pandemic, where thousands of people died and hospitals were completely overwhelmed, but whether a similar situation would have happened in St. Louis is not obvious," said lead author Elvin H. Geng, MD, a professor of medicine. "Some may argue that because the same thing didn't happen here, it could never have happened here and that, therefore, early social-distancing policies were an overreaction. But our data suggest that a large number of deaths due to the pandemic was indeed possible in St. Louis, and therefore, the early implementation of public health orders helped prevent the number of deaths that cities such as New York and other places experienced."

The first known case of COVID-19 in St. Louis County was reported March 7, 2020. By March 13, the city and county had banned large gatherings. Four days later, they closed bars and restaurants, and the next day, March 18, they ordered all public schools to close their doors. On March 23, the city and county issued shelter-in-place orders. With these public health measures, area hospitals experienced a total of 2,246 COVID-19 hospitalizations and 482 deaths attributed to COVID-19 by June 15, 2020.

A new study from Washington University School of Medicine in St. Louis 

estimates the number of deaths that could have occurred had public health 

orders been delayed for one week, two weeks or four weeks as the pandemic

 was first taking hold in St. Louis city and St. Louis County. 

The analysis suggests that, in the first three months of the pandemic, t

he region avoided thousands of hospitalizations and deaths with early 

and coordinated public health measures. The actual number of deaths by

 June 15, 2020, is shown in blue. The projected numbers of deaths by

 June 15, 2020, under three different delay scenarios are shown in yellow. 

Credit: SARA MOSER

Had the orders been delayed two weeks, the researchers' modeling indicates that the city and county likely would have seen 3,292 deaths by June 15—a nearly sevenfold increase over what was actually recorded in the first three months of the pandemic. In the two-week delay scenario, the model predicts an increase in cumulative total hospitalizations by June 15 from the actual number of 2,246 to an estimated 19,600—a nearly ninefold increase.

"Because the virus spreads exponentially, the difference between a hospital at 25% capacity and over capacity is actually just a hair's breadth—a matter of one or two doubling intervals, which in an unmitigated epidemic with COVID-19 is probably a little longer than a week," Geng said. "In addition, it takes time for changes in behavior to translate into reductions in hospitalizations. As a rule of thumb, we estimate the St. Louis region has about 2,000 available hospital beds total. If the hospitals reach half capacity and only then are stay-at-home policies implemented, it's going to be too late."

Even a one-week delay in public health measures would have considerably increased hospitalizations and deaths, with an estimated 8,000 hospitalizations and 1,300 deaths by June 15, under that modeling scenario.

The researchers also estimated how these delays might have played out if the general public had voluntarily changed its behavior. In the absence of public health orders, even if the public had changed its behavior enough to cut viral transmission by half—an optimistic scenario—a two-week delay still would have resulted in an estimated 8,090 hospitalizations and about 1,400 deaths.

As cases rose in other regions of the country, data from cell phones in the St. Louis area showed the public made no changes in mobility before the city and county orders.

"At the moment when a pandemic is arriving, spontaneous collective behavior change—without any public health actions—that is drastic enough to significantly slow the epidemic is probably not realistic," Geng said. "If behavior changes after the hospitals fill up and the impact of the pandemic is obvious, it's already too late to avoid a high number of deaths. A pandemic is like a big ship; it takes time to change course. But as the virus ramped up, early social distancing policies in St. Louis mitigated it just before it really exploded."

A new study from Washington University School of Medicine in St. Louis 

estimates the number of deaths that could have occurred had public 

health orders been delayed for one week, two weeks or four weeks as

 the pandemic was first taking hold in St. Louis city and St. Louis County. 

The analysis suggests that, in the first three months of the pandemic,

 the region avoided thousands of hospitalizations and deaths with early

 and coordinated public health measures. The graph shows the actual

 hospitalizations (light blue) and deaths (dark blue) plus the projected

 hospitalizations (green) and deaths (yellow) had public health orders

 been delayed one week, two weeks or four weeks in St. Louis city and 

St. Louis County as the pandemic was just taking hold in March 2020. 

Credit: SARA MOSER

The researchers estimated that before March 15, each person in the city or county with COVID-19 infected almost four other people, on average. For a pandemic to be curbed, each person must infect fewer than one other person, on average. For St. Louis and St. Louis County, the model estimated that the average number of people each person with COVID-19 infected dropped from almost four to 0.93 after the stay-at-home policies went into effect.

"These data do not speak to the overall societal costs, which were formidable and painful," Geng added. "The best long-term strategies to mitigate a respiratory epidemic in the absence of a vaccine is a difficult question. Social distancing is only part of the solution. But if such strategies are to be used, implementing them early, during the initial arrival of the virus, might be the best time to deploy such actions."

Geng performed this analysis with colleagues at Washington University, BJC HealthCare, Saint Louis University, Mercy Health and elsewhere, including senior author Maya Peterson, MD, Ph.D., of the University of California at Berkeley, and lead programmer and co-author Joshua Schwab, of the University of California at San Francisco. The program—called Local Epidemic Modeling for Management & Action—is publicly available and open source, and the researchers hope that other public health officials across the country will be able to use it to inform pandemic responses in their communities. The most recent version of the program also can incorporate the dynamics of local vaccination rates.

Geng said that models are not crystal balls, but they do project forward what could happen under a set of behavioral and structural conditions.

"While we can never be sure about what would have happened, it's also not true that we know nothing about the behavior of epidemics," Geng said. "The model uses real data about the epidemic early on—what actually happened on the ground in St. Louis—to project epidemic course over time under a 'what if' scenario. These COVID-19 projections suggest that the city and county dodged a bullet with early social distancing measures."

In related research, Geng—along with first author Ingrid Eshun-Wilson, MBChB, an instructor in medicine, and colleagues at the university's Brown School, including Virginia McKay, Ph.D., a research assistant professor, and Vetta Thompson, Ph.D., the E. Desmond Lee Professor of Racial and Ethnic Diversity—also gauged public opinion on stay-at-home policies by surveying a random sample of Missouri residents. They found that the general public was broadly accepting of such public health policies, including the prohibition of large gatherings and closing social and lifestyle venues, such as bars, restaurants, gyms and hair salons. An analysis of the survey was published July 8 in JAMA Network Open

Los Angeles hopes new mask mandate will reverse virus spike

More information: Geng EH et al. Outcomes associated with social distancing policies in St. Louis, Missouri, during the early phase of the COVID-19 pandemic. JAMA Network Open. Sept. 1, 2021.

Eshun-Wilson I, et al. Public preferences for social distancing policy measures to mitigate the spread of COVID-19 in Missouri. JAMA Network Open. July 8, 2021.

Journal information: JAMA Network Open 

Provided by Washington University School of Medicine 

 

Prehistoric climate change repeatedly channelled human migrations across Arabia

by Max Planck Society

The site of Khall Amayshan 4 in northern Saudi Arabia, where evidence of repeated

 visits by early humans over the last 400,000 years was found, associated with the 

remains of ancient lakes. Credit: Palaeodeserts Project (Michael Petraglia)

Recent research in Arabia—a collaboration between scientists at the Max Planck Institute for the Science of Human History in Jena, Germany, the Heritage Commission of the Saudi Ministry of Culture, and many other Saudi and international researchers—has begun to document the incredibly rich prehistory of Saudi Arabia, the largest country in Southwest Asia. Previous research in the region has focused on the coastal and woodland margins, while human prehistory in the vast interior areas remained poorly understood.

The new findings, including the oldest dated evidence for humans in Arabia at 400,000 years ago, are described as a breakthrough in Arabian archaeology by Dr. Huw Groucutt, lead author of the study and head of the "Extreme Events' Max Planck Society Research Group in Jena, Germany, based at the Max Planck Institute for Chemical Ecology.

The discovery of thousands of stone tools reveals multiple waves of human occupation and shows changing human culture over time. At the site of Khall Amayshan 4 (KAM 4), nestled in a hollow between large dunes, researchers found evidence for six phases of lake formation, five of them associated with stone tools made by early humans at around 400,000, 300,000, 200,000, 100,000, and 55,000 years ago. Each phase of human occupation is characterized by a different kind of material culture, documenting the transition from the Lower Paleolithic Acheulean 'handaxe' culture to different kinds of stone flake-based Middle Paleolithic technologies. Excavations at the Jubbah Oasis, 150 km to the east, also recovered stone tools, dating to 200,000 and 75,000 years ago.

A 400,000 year ‘handaxe’ stone tool from Khall Amayshan 4. Credit: Palaeodeserts Project (Ian Cartwright)

Green Arabia

The dating of the archaeological sites—achieved primarily through a technique called luminescence dating, which records the length of time since tiny grains of sediment were last exposed to sunlight—shows that each occupation dates to a time when rainfall is known to have increased in the region. In addition, all of the stone tool assemblages are associated with the distinctive sediments produced by freshwater lakes. The findings therefore show that, within a dominant pattern of aridity, occasional short phases of increased rainfall led to the formation of thousands of lakes, wetlands, and rivers that crossed most of Arabia, forming key migration routes for humans and animals such as hippos.

While today the Nefud desert is a very arid region, deep hollows between the large sand dunes created places for small lakes to form during occasional increases in rainfall. As a result, the Nefud region was periodically transformed from one of the most uninhabitable parts of Southwest Asia into a lush grassland that provided opportunities for repeated population movements.

A storm arrives during archaeological excavation of the remains of ancient lake in 

northern Saudi Arabia, where ancient humans lived alongside animals such as hippos. 

Credit: Palaeodeserts Project (Klint Janulis)

Wider implications

Unlike bones and other organic materials, stone tools preserve very easily, and their character is largely influenced by learned cultural behaviors. As a result, they illuminate the background of their makers and show how cultures developed along their own unique trajectories in different areas. The Khall Amayshan 4 and Jubbah Oasis findings reflect short-lived pulses of occupation that represent the initial phases of migration waves.

Each phase of human occupation in northern Arabia shows a distinct kind of material culture, suggesting that populations arrived in the area from multiple directions and source areas. This diversity sheds unique light on the extent of cultural differences in Southwest Asia during this timeframe, and indicates strongly sub-divided populations. In some cases the differences in material culture are so great as to indicate the contemporary presence of different hominin species in the region, suggesting that Arabia may also have been an interface zone for different hominin groups originating in Africa and Eurasia. Animal fossils indicate a similar pattern: although the north Arabian fossil record shows a prominent African character, some species came from the north, while others represent long-time residents of Arabia.

The findings highlight the importance of filling in the gaps in the hominin map. "Arabia has long been seen as empty place throughout the past," says Dr. Groucutt. "Our work shows that we still know so little about human evolution in vast areas of the world and highlights the fact that many surprises are still out there."

"It's remarkable; every time it was wet, people were there," says project leader Prof. Michael Petraglia, from the Max Planck Institute for the Science of Human History. "This work puts Arabia on the global map for human prehistory," he adds.

The study is reported in Nature.

Stone tools linked to ancient human ancestors in Arabia have surprisingly recent date

More information: Multiple hominin dispersals into Southwest Asia over the past 400,000 years, Nature (2021). DOI: 10.1038/s41586-021-03863-y , www.nature.com/articles/s41586-021-03863-y

Journal information: Nature 

Provided by Max Planck Society