When looking for an environmentally friendly and cost-effective way to clean up contaminated water and soil, Georgia Tech researchers Patricia Stathatou and Christos Athanasiou turned to yeast. A cheap byproduct from fermentation processes — e.g., something your local brewery discards in mass quantities after making a batch of beer — yeast is widely known as an effective biosorbent. Biosorption is a mass transfer process by which an ion or molecule binds to inactive biological materials through physicochemical interactions.

When they initially studied this process, Stathatou and Athanasiou found that yeast can effectively and rapidly remove trace lead — at challenging initial concentrations below one part per million — from drinking water. Conventional water treatment methods either fail to eliminate lead at these low levels or result in high financial and environmental costs to do so. In a paper published today in RSC Sustainability, the researchers show how this process can be scaled.

“If you put yeast directly into water to clean it, you will need an additional treatment step to remove the yeast from the water afterward,” said Stathatou, a research scientist at the Renewable Bioproducts Institute and an incoming assistant professor at the School of Chemical and Biomolecular Engineering. “To implement this process at scale without requiring additional separation steps, the yeast cells need a housing.”

“Additionally, because yeast is abundant— in some cases, brewers even pay companies to haul it away as a waste byproduct — this process gives the yeast a second life,” said Athanasiou, an assistant professor in the Daniel Guggenheim School of Aerospace Engineering. “It’s a plentiful low, or even negative, value resource, making this purification process inexpensive and scalable.”

To develop a housing for the yeast, Stathatou and Athanasiou partnered with MIT chemical engineers Devashish Gokhale and Patrick S. Doyle. Gokhale and Stathatou are the lead authors of this new study that demonstrates the yeast water purification process’s scalability.

“We decided to make these hollow capsules— analogous to a multivitamin pill — but instead of filling them up with vitamins, we fill them up with yeast cells,” Gokhale said. “These capsules are porous, so the water can go into the capsules and the yeast are able to bind all of that lead, but the yeast themselves can’t escape into the water.”

The yeast-laden capsules are sufficiently large, about half a millimeter in diameter, for easy separation from water by gravity. This means they can be used to make packed-bed bioreactors or biofilters, with contaminated water flowing through these hydrogel-encased yeast cells and coming out clean.

Stathatou and Athanasiou envision using these hydrogel yeast capsules in small biofilters consumers can put on their kitchen faucets, or biofilters large enough to fit municipal or industrial wastewater treatment systems. But to enable such scalability, the yeast-laden capsules’ ability to withstand the force generated by water flowing inside such systems needed to be studied as well.

To determine this, Athanasiou tested the capsules’ mechanical robustness, which is how strong and sturdy they are in the presence of waterflow forces. He found they can withstand forces like those generated by water running from a faucet, or even flows like those in water treatment plants that serve a few hundred homes. “In previous attempts to scale up biosorption with similar approaches, lack of mechanical robustness has been a common cause of failure,” Athanasiou said. “We wanted to make sure our work addressed this issue from the very beginning to ensure scalability.”

“After assessing the mechanical robustness of the yeast-laden capsules, we made a prototype biofilter using a 10-ml syringe,” Stathatou explained. “The initial lead concentration of water entering the biofilter was 100 parts per billion; we demonstrated that the biofilter could treat the contaminated water, meeting EPA drinking water guidelines, while operating continuously for 12 days.”

The researchers hope to identify ways to isolate and collect specific contaminants left behind in the filtering yeast, so those too can be used for other purposes.

“Apart from lead, which is widely used in systems for energy generation and storage, this process could be used to remove and recover other metals and rare earth elements as well,” Athanasiou said. “This process could even be useful in space mining or other space applications.”

They also would like to find a way to keep reusing the yeast. “But even if we can’t reuse yeast indefinitely, it is biodegradable,” Stathatou noted. “It doesn’t need to be put into an industrial composter or sent to a landfill. It can be left on the ground, and the yeast will naturally decompose over time, contributing to nutrient cycling.”

This circular approach aims to reduce waste and environmental impact, while also creating economic opportunities in local communities. Despite numerous lead contamination incidents across the U.S., the team’s successful biosorption method notably could benefit low-income areas historically burdened by pollution and limited access to clean water, offering a cost-effective remediation solution. “We think there’s an interesting environmental justice aspect to this, especially when you start with something as low-cost and sustainable as yeast, which is essentially available anywhere,” Gokhale says.

Moving forward, Stathatou and Athanasiou are exploring other uses for their hydrogel-yeast purification method. The researchers are optimistic that, with modifications, this process can be used to remove additional inorganic and organic contaminants of emerging concern, such as PFAS — or “forever” chemicals — from the water or the ground.

Citation: Devashish Gokhale, Patritsia M. Stathatou, Christos E. Athanasiou, and Patrick S. Doyle, “Yeast-laden Hydrogel Capsules for Scalable Trace Lead Removal from Water,” RSC Sustainability. 

DOI: https://doi.org/10.1039/D4SU00052H

Funding: Patricia Stathatou was supported by funding from the Renewable Bioproducts Institute at Georgia Tech. Devashish Gokhale was supported by the Rasikbhai L. Meswani Fellowship for Water Solutions and the MIT Abdul Latif Jameel Water and Food Systems Lab (J-WAFS).

 

In a study by a Georgia Tech economist that could help inform future energy policy, half the participants cranked their thermostats despite knowing exactly how much each extra degree would cost them.

Prices are typically the first tool used to get people to save energy, noted Dylan Brewer, assistant professor in the Georgia Tech School of Economics. As climate change affects communities and utilities transition to sustainable sources, it’s increasingly critical for regulators and utilities to understand exactly how price affects consumers’ energy use.

“There's kind of a puzzle that exists in the literature on energy consumption,” Brewer said. When it comes to most commodities, price drives demand, but “if the price of electricity changes, most people are not very responsive.” He wanted to test the popular theory that inelastic demand is the result of consumers not knowing the exact price of turning up the thermostat.

In his 2023 study in the journal Energy Policy, Brewer surveyed a sample of Americans after a winter of real-time heating decisions. They were presented with different cost scenarios and asked about their “bliss point” — the temperature at which they’d keep their houses if money were no object.

As a Ph.D. student at Michigan State University, Brewer was struck by how many landlords offered “free heat” during East Lansing’s frigid winters.

He saw that when “people are not on the hook for a decision, they're often wasteful. But if they're paying for their environmental costs, they're going to conserve.” He focused on this phenomenon in his dissertation and has since launched other projects on the economics of thermostat settings. “It’s my niche,” he said.

In the study, participants knew exactly how much an extra degree of heat would cost them. Yet even at the highest price level ($8 per 5 degrees Fahrenheit), half of them exhibited zero response to price, Brewer reported. On average, doubling heating costs led respondents to say they would lower less than 1 degree Fahrenheit.

Brewer found that participants with incomes below $50,000 and those living in urban areas were more responsive to price changes, while older participants had less elastic demand.

It turns out, Brewer noted, “People simply do not like to be cold.”

The results are just as relevant for warm-weather states. In Georgia in 2022, 42% of the state's electricity was used for air conditioning and nearly three in five households with electric heating, according to the U.S. Energy Information Association.

Based on study results, Brewer noted that utilities confronted with extreme weather or a supply-side disruption might encourage customers to shift electricity usage to off-peak hours rather than assume they’ll be affected by an increase in rates. “If you have an energy emergency and need to curb energy consumption, this is telling you that prices are not going to do it,” he said.

“This is a daily choice that we make,” Brewer said. “Given that we spend a huge fraction of our time in climate-controlled buildings, these types of heating and cooling issues have pretty large implications.”

People using energy-efficient smart thermostats are willing to sacrifice comfort and control to save relatively small amounts of energy that could add up if enough people sign on, a Georgia Tech economist reported in a recent study.

With federal and state energy policies targeting aggressive decarbonization in the next 15 years, smart technologies have the potential to help achieve these goals at a reasonable cost, said Casey J. Wichman, associate professor in the Georgia Institute of Technology School of Economics.

In a forthcoming issue of American Economic Journal: Applied Economics, Wichman and colleagues report that automation within smart thermostats can lead to potentially large reductions in household electricity use and costs.

Utilities look to time-of-use (TOU) pricing — where prices are higher during peak demand and lower during lags in demand — to save consumers money and relieve pressure on the grid.

“From an economics perspective, there's this idea that if you set the price right, everything will work out,” Wichman said. “But if consumers don't actually respond to those prices, that limits the effectiveness of the solution.”

For the study, more than 2,100 Toronto-area residents using Ecobee smart thermostats agreed to share their usage data during the 2019 rollout of a suite of new thermostat features that included an automated component.

Participants opted to allow the thermostats to precool or preheat their homes at times of the day when electricity was less expensive, choosing on a sliding scale how aggressive they wanted the algorithm to be. Degree changes within the homes varied from around 1 to 5 degrees, saving participants up to 30 Canadian cents per day in the summer.

“I have always liked applying economic concepts to simple decisions we make in our daily lives,” Wichman said. “This allows me to answer new questions about how decisions matter for the environment, and how policies or technologies can be designed to generate social change. In this project, we’re leveraging new data sources to try to capture the unaccounted-for costs of those policies.”

Studies on energy savings, he said, often miss the in-home comfort cost. These results showed that people seemed willing to trade relatively small monetary savings for a small increase in discomfort, although discomfort was most pronounced for residents who typically spend more time at home. For the most part, people were willing to sacrifice control over their heating and cooling decisions to an algorithm.

This finding surprised Wichman. “We thought we would see more people turn off the feature,” he said. That didn't happen.

As time-varying electricity pricing rolls out across North America, utilities could provide incentives for customers to opt into energy-saving settings programmed into internet-connected home appliances, like water heaters, pool pumps, and electric vehicles.

The researchers’ results suggest that such programs could be designed in a way that customers will accept. This gives Wichman a sense of optimism for the future.

“What is interesting here is that technology can complement economic incentives,” he said. “You can have technology correct for humans’ inability to remember to set their heating and cooling schedule in a way that's consistent with social goals.”

Are you under the impression that air pollution is a dichotomous problem where the air is either polluted or it’s not? What else is there to know about air pollution? The surprising answer to this question lies not with a lab scientist but with an economist.

Assistant Professor Dylan Brewer of the School of Economics studies the health impacts of air pollution and the statistical methods useful for teasing apart factors that can confound those answers, all from the lens of an economist. It turns out that viewing the problem of air pollution through an economic framework and applying statistical methods commonly used in the field of economics can shed light on the multiple factors that influence the health impact of exposure to air pollution on different populations.

Recently, Brewer was the featured guest on the podcast The Health Deli, where the hosts were surprised to find an economist making waves at this critical research intersection. Brewer explains why viewing this problem from the perspective of an economist is so valuable and discusses some of his research team’s surprising findings.

The podcast, hosted by three pharmacists, approaches health news from a scientific bent, which turned out to be a great fit for an economist who studies air pollution. You can listen to the podcast episode, “Is It Safe To Breathe Air? How Is This a Real Question?’ on Apple Podcasts or Spotify, as well as other major podcast providers.

Spotify Link https://open.spotify.com/episode/1PDPUZNGEifWA5IvCnVUNK

Written by: Sharon Murphy, Research Associate, SEI

 

On April 12, the Energy, Policy, and Innovation Center (EPICenter) hosted its second round of the “Friday Lightning Talk Series” at the Scholars Event Network space in the Price Gilbert Library.

Eight multidisciplinary participants from Georgia Tech, including postdoctoral students, graduate students, research faculty, and research associates from public policy, economics, electrical and computer engineering, industrial and systems engineering, and EPICenter, presented an overview of an energy-related research project during the session.

Laura Taylor, chair of the School of Economics and interim director of EPICenter, introduced the organization’s new faculty affiliate program through which affiliates, their students, and postdocs present and share research ideas and receive feedback from the audience.

Topics covered during the session included understanding the social costs of natural gas deregulation, managing EV charging during emergencies, exploring whether daylight saving time saves energy, the green energy workforce, the effects of community solar on household energy use, the Atlanta Energyshed project, clean hydrogen production in Georgia, and household responses to grid emergencies.

The interactive session was well attended with over 25 attendees asking thought-provoking questions and providing suggestions on future areas to explore.

The first round was held on March 1 and was such a success that this second round had a full slate of presenters and a full house of audience members. The agendas for both lightning round talks are available below, along with links to presentation slides.

A unit of the Strategic Energy Institute of Georgia Tech, EPICenter’s mission is to conduct rigorous research and deliver high-impact insights that address the energy needs of the southeastern U.S., while keeping a national and global perspective. EPICenter calls upon broad, multidisciplinary expertise to engage the public and create solutions for critical emerging issues as our nation’s energy transformation unfolds.

On a recent visit to the Georgia Tech campus, Secretary of Energy Jennifer Granholm announced that a tri-city alliance of Atlanta, Decatur, and Savannah in partnership with Georgia Tech will receive funding to drive clean energy solutions.

The funding is part of DOE’s Energy Future Grants program, and the Atlanta-Decatur-Savannah partners will receive $500,000 during the planning phase to develop initiatives, policies, and tools to promote green energy deployment in their communities. In total, the grants will provide $27 million in financial and technical assistance to support strategies that increase resiliency and improve access to affordable clean energy. The team will compete with other recipients for additional funding in subsequent phases of the program.

The Georgia Energyshed (G-SHED) team, led by Richard Simmons of the Strategic Energy Institute, will partner with the tri-city team in this project. The modeling and simulation-driven analysis from G-SHED will be used by the Tri-City Alliance project to develop deployment-ready blueprints of clean energy innovations focused on community benefits.

The G-SHED team, formed through another DOE grant, is developing a metropolitan energy planning organization informed by an integrated modeling effort that includes technical, social, and community inputs. Georgia Tech is collaborating with the Atlanta Regional Commission and the Southface Institute in this project. 

Granholm said announcing the funding at Georgia Tech was fitting because its tools “are going to be magnificent for this project for communities to decide the best path for them based on data.” Atlanta Mayor Andrew Dickens, U.S. Rep. Nikema Williams, and several other dignitaries were present during the announcement. Secretary Granholm toured parts of the Georgia Tech campus including the Carbon Neutral Energy Solutions building during her visit.

“It’s exciting when the Secretary of Energy makes a special trip to campus to announce a new Award. I appreciate Secretary Granholm and the Department of Energy for enabling this innovative energy partnership with Atlanta, Decatur, and Savannah,” said Tim Lieuwen, executive director of the Strategic Energy Institute.

Engineers at Georgia Tech have designed a process that converts carbon dioxide removed from the air into useful raw material that could be used for new plastics, chemicals, or fuels.

Their approach dramatically reduces the cost and energy required for these direct air capture (DAC) systems, helping improve the economics of a process the researchers said will be critical to addressing climate change.

The key is a new kind of catalyst and electrochemical reactor design that can be easily integrated into existing DAC systems to produce useful carbon monoxide (CO) gas. It’s one of the most efficient such design ever described in scientific literature, according to lead researcher Marta Hatzell and her team. They published details April 16 in Energy and Environmental Science, a top journal for energy-related research.

Get the full story on the College of Engineering website.

The College of Sciences is funding two research centers through a new seed grant program. 

Selected from a finalist pool of nine proposals, Associate Professors Yuanzhi Tang and Thackery Brown’s ideas were chosen for their high potential for novel interdisciplinary research and impact. 

Tang’s center will focus on sustainable mineral research, and Brown’s on spatial computation and navigation. Applications for the research will span the development of more sustainable batteries, as well as seeking to improve human health and well-being.

“Improving the human condition, fostering community, and pursuing research excellence are at the forefront of Georgia Tech’s mission, and these new centers will play a critical role in furthering that goal,” says Laura Cadonati, associate dean for Research in the College of Sciences and a professor in the School of Physics. “The College of Sciences is thrilled to support these new initiatives, and is excited to continue to develop the seed grant program.” 

A second call for research center proposals is planned for January 2025, with funding to start in July 2025.

The new Center for Sustainable and Decarbonized Critical Energy Mineral Solutions (CEMS), to be led by Yuanzhi Tang, an associate professor in the School of Earth and Atmospheric Sciences, will serve as a hub for sustainable procurement solutions for critical energy mineral resources, including rare earth elements and metals used for battery production.

Thackery Brown, an associate professor in the School of Psychology, will lead the second center, the Center for Research and Education in Navigation (CRaNE). CRaNE will investigate problems related to spatial computation, cognition, and navigation — which has implications for human health, animal conservation, smart architecture and urban design.

“This generous support from the College of Sciences will enable us to host a conference on spatial cognition, computation, design, and navigation; to provide collaborative multi-lab seed grants; and to establish the first of a series of explicitly co-mentored, interdisciplinary graduate student Fellowships,” Brown says. “Collectively, these are the seeds of a high-impact and self-sustaining center.”

About the Center for Sustainable Decarbonized Critical Energy Mineral Solutions (CEMS)

Yuanzhi Tang, School of Earth and Atmospheric Sciences 

Co-sponsored by the College of Sciences, Strategic Energy Institute (SEI), Brook Byers Institute for Sustainable Systems (BBISS), Institute for Electronics and Nanotechnology (IEN), and Institute for Materials (iMat), CEMS began as a joint BBISS-SEI initiative lead project that has since grown into a joint center focused on critical elements and materials for sustainable energy.

Sustainably sourcing these materials provides a critical foundation for both high-tech industry and green economy. “Rare earth elements and battery metals like lithium, copper, and nickel are in high demand, but low domestic resources and production have resulted in a heavy reliance on imports,” Tang explains. “How can we domestically produce these resources, and how can we do this sustainably? Georgia Tech and the College of Sciences are in a unique position for developing a large regional research umbrella to connect these dots.”

CEMS will leverage on three key pillars: science and technology development, strengthening collaboration among the University System of Georgia (USG) universities, and developing regional resources and economy, Tang says. “By leveraging collaboration among Georgia universities, and fostering engagement with regional industries, the Center will develop new science and technology, leading the way in research on how to procure these ‘essential vitamins’ for clean energy transition in a sustainable and decarbonized manner.”

About the Center for Research and Education in Navigation (CRaNE)

Thackery Brown, School of Psychology 

CRaNE will focus on solving problems related to spatial computation, cognition, and navigation. “How do we treat catastrophic loss of one’s ability to get from A to B in Alzheimer's disease? How do we build smarter cities that are easier and more carbon efficient to navigate? How can we develop robots,” Brown says, “which navigate with the flexibility and efficiency of our own minds? CRaNE will bring together experts from many different fields to help address these problems with truly creative and integrative scientific and technological solutions.”

CRaNE will support interdisciplinary collaborative research, including developing a graduate student fellowship program, and conducting K-12 outreach.

“Our goal for CRaNE is to position the College of Sciences, Georgia Tech, and our extended network of collaborator institutions as a center of gravity for cutting-edge work on how the mind, brain, and artificial systems process space — how they can be made better at it, and how we can engineer our world around us in ways that support the humans and animals that need to navigate it to survive,” Brown says.

Emphasizing the collaborative nature of CRaNE, Brown adds that “by targeting collaborative grants, research, and education, and by promoting outreach and education earlier in the STEM pipeline, we hope to accelerate progress at the frontiers of these fields — and to invest in future science that cannot be easily addressed by a single lab or discipline.”