TL;DR

• Researchers have found an environmentally friendlier solution with enhanced performance, utilizing PEDOT:PSS/silicon heterojunction solar cells. This hybrid type is made of organic-inorganic material, which could potentially ease the production process compared to conventional silicon-only solar cells. It avoids manufacturing solar cells in vacuums and high-temperature processes, which require large and expensive equipment and a great amount of time.
• They’ve been called ‘dream’ plastics: polyhydroxyalkanoates, or PHAs. Already the basis of a fledgling industry, they’re a class of polymers naturally created by living microorganisms, or synthetically produced from biorenewable feedstocks. They’re biodegradable in the ambient environment, including oceans and soil. Researhecrs report a new class of redesigned PHAs, readily accessible via chemical catalysis.
• A research team has demonstrated a unique method that reduces the aerodynamic resistance of ships by 7.5 per cent. This opens the way for large cargo ships borne across the oceans by wind alone, as wind-powered ships are more affected by aerodynamic drag than fossil-fueled ones.
• A previously underestimated risk lurks in the frozen soil of the Arctic. When the ground thaws and becomes unstable in response to climate change, it can lead to the collapse of industrial infrastructure, and in turn to the increased release of pollutants. Moreover, contaminations already present will be able to more easily spread throughout ecosystems. According to new findings, there are at least 13,000 to 20,000 contaminated sites in the Arctic that could pose a serious risk in the future.
• Can humans endure long-term living in deep space? The answer is a lukewarm maybe, according to a new theory describing the complexity of maintaining gravity and oxygen, obtaining water, developing agriculture and handling waste far from Earth.
• Dense urban areas amplify the effects of higher temperatures, due to the phenomenon of heat islands in cities. This makes cities more vulnerable to extreme climate events. Large investments in the electricity network will be necessary to cool us down during heatwaves and keep us warm during cold snaps, according to a new study.
• To manage atmospheric carbon dioxide and convert the gas into a useful product, scientists have dusted off an archaic — now 120 years old — electrochemical equation.
• About 12% of the total global energy demand comes from heating and cooling homes and businesses. A new study suggests that using underground water to maintain comfortable temperatures could reduce consumption of natural gas and electricity in this sector by 40% in the United States. The approach, called aquifer thermal energy storage (ATES), could also help prevent blackouts caused by high power demand during extreme weather events.
• A new, inexpensive technology can limit the buildup of algae on the walls of photobioreactors that can help convert carbon dioxide into useful products. Reducing this fouling avoids costly cleanouts and allows more photosynthesis to happen within tanks.
• Soil stores more carbon than plants and the atmosphere combined, and soil microbes are largely responsible for putting it there. However, the increasing frequency and severity of drought, such as those that have been impacting California, could disrupt this delicate ecosystem. Microbial ecologists warn that soil health and future greenhouse gas levels could be impacted if soil microbes adapt to drought faster than plants do.
• And more!

Green Technology Market

Green technology is an applicable combination of advanced tools and solutions to conserve natural resources and environment, minimize or mitigate negative impacts from human activities on the environment, and ensure sustainability development. Green technology is also referred to as clean technology or environmental technology which includes technologies, such as IoT, AI, analytics, blockchain, digital twin, security, and cloud, which collect, integrate, and analyze data from various real-time data sources, such as sensors, cameras, and Global Positioning System (GPS).

Green technology, also known as sustainable technology, protects the environment by using various forms of sustainable energy. Some of the best examples of green technologies include solar panels, LED lighting, wind energy, electric vehicles, vertical farming, and composting.

The global Green Technology and Sustainability market size to grow from USD 11.2 billion in 2020 to USD 36.6 billion by 2025, at a Compound Annual Growth Rate (CAGR) of 26.6% during the forecast period. The growing consumer and industrial interest for the use of clean energy resources to conserve environment and increasing use of Radio Frequency Identification sensors across industries are driving the adoption of green technology and sustainability solutions and services in the market.

The blockchain segment is estimated to grow at the highest CAGR: Energy-intensive cryptocurrency mining has caused a spike in carbon emission, and hence blockchain is capable of driving innovation in the field of green technology.

Latest Research

An all ambient, room temperature–processed solar cell from a bare silicon wafer

by Kazuya Okamoto, Yutaka Fujita, Kosuke Nishigaya, Katsuaki Tanabe in PNAS Nexus

An environmentally friendlier solution to solar cell production with enhanced performance utilizes PEDOT:PSS/silicon heterojunction solar cells. This hybrid type is made of organic-inorganic material, which could potentially ease the production process compared to conventional silicon-only solar cells. It avoids manufacturing solar cells in vacuums and high-temperature processes, which require large and expensive equipment and a great amount of time. Ongoing challenges in solar cell production may partly explain why non-renewable energy resources — such as coal, oil, and natural gas — have overshadowed current optoelectronic devices.

Now, researchers at Kyoto University may have found an environmentally friendlier solution with enhanced performance, utilizing PEDOT:PSS/silicon heterojunction solar cells. This hybrid type is made of organic-inorganic material, which could potentially ease the production process compared to conventional silicon-only solar cells.

“We wanted to avoid manufacturing solar cells in vacuums and high-temperature processes, which require large and expensive equipment and a great amount of time,” explains lead author Katsuaki Tanabe.

Solar cell structure and doping concentration of Si.

Anticipating a challenge, the team set out to fabricate solar cells from silicon wafers under only ambient temperature and pressure conditions. However, their efforts proved to yield worthy results after optimizing process conditions for the wafers. These polished wafers were first diced into 8-mm square pieces and coated with PEDOT:PSS aqueous solution and silver electrodes, in a variety of sequences.

“Our approach enabled us to achieve improved production speed at lower cost and with a power generation efficiency above 10%,” remarks the author.

Tanabe’s team posits that this new, more efficient production process may lead to large-scale diffusion of photovoltaic power generation. This system could see wider utility in various settings, such as in education or in developing economies.

“Next, we will focus on optimizing impurities and additive concentrations in our production, as well as other structural innovations,” concludes Tanabe.

Chemically circular, mechanically tough, and melt-processable polyhydroxyalkanoates

by Li Zhou, Zhen Zhang, Changxia Shi, Miriam Scoti, Deepak K. Barange, Ravikumar R. Gowda, Eugene Y.-X. Chen in Science

They’ve been called “dream” plastics: polyhydroxyalkanoates, or PHAs. Already the basis of a fledgling industry, they’re a class of polymers naturally created by living microorganisms, or synthetically produced from biorenewable feedstocks. They’re biodegradable in the ambient environment, including oceans and soil.

But there’s a reason PHAs haven’t taken off as a sustainable, environmentally benign alternative to traditional plastics. Crystalline PHAs are brittle, so not as durable and convenient as conventional plastics. They cannot easily be melt-processed and recycled, making them expensive to produce.

Colorado State University polymer chemists led by Eugene Chen, University Distinguished Professor in the Department of Chemistry, have created a synthetic PHA platform that addresses each of these problems, paving the way for a future in which PHAs can take off in the marketplace as truly sustainable plastics. Chen and colleagues report a new class of redesigned PHAs, readily accessible via chemical catalysis.

The redesigned PHA in as-synthesized powder form (left), melt-processed and molded into test specimens (middle), and mechanically tested for toughness (right).

The researchers had been searching for a strategy to address the intrinsic thermal instability of conventional PHAs; their lack of heat resistance also makes it difficult to melt-process them into end products. The CSU chemists made fundamental changes to the structures of these plastics, substituting reactive hydrogen atoms responsible for thermal degradation with more robust methyl groups. This structural modification drastically enhances the PHAs’ thermal stability, resulting in plastics that can be melt-processed without decomposition.

What’s more, these newly designed PHAs are mechanically tough, even outperforming the two most common commodity plastics: high-density polyethylene — used in products like milk and shampoo bottles — and isotactic propylene, which is used to make automotive parts and synthetic fibers. The best part is that the new PHA can be chemically recycled back to its building-block molecule, called a monomer, with a simple catalyst and heat, and the recovered clean monomer can be reused to reproduce the same PHA again — in principle, infinitely.

“We are adding three key desired features to the biological PHAs, including closed-loop chemical recycling, which is essential for achieving a circular PHA economy,” Chen said.

Large eddy simulation of ship airflow control with steady Coanda effect

by Kewei Xu, Xinchao Su, Rickard Bensow, Sinisa Krajnovic in Physics of Fluids

A research team at Chalmers University of Technology is the first to demonstrate a unique method that reduces the aerodynamic resistance of ships by 7.5 per cent. This opens the way for large cargo ships borne across the oceans by wind alone, as wind-powered ships are more affected by aerodynamic drag than fossil-fueled ones.

To hit international climate targets, the carbon emissions from shipping must be reduced by more than 50 per cent by 2050 compared to 2008 levels. As much as 99 per cent of global shipping is currently dependent on fossil fuels. Even though electricity may carry smaller ferries across shorter distances, the electrification of larger, longer-haul ships is hampered by range limitations. This means that the need for new energy-efficient propulsion technology solutions for shipping is both major and urgent.

Researchers at Chalmers University of Technology, Sweden, are the first to have successfully demonstrated a new method that may pave the way to significantly lessen the climate impact of shipping. Inspired by an aerodynamic technology used in aviation, the researchers have found a way to reduce a ship’s aerodynamic drag by 7.5 per cent. The result is increased energy efficiency and reduced fuel consumption.

“For an oil tanker going from Saudi Arabia to Japan, this would mean a reduction in fuel consumption of about ten metric tons,” says Kewei Xu, postdoc researcher in marine technology at the Department of Mechanics and Maritime Sciences at Chalmers. “Reducing aerodynamic drag has seldom been examined; our study is one of the first of its kind.”

The Chalmers ship model (top) and its dimensions in plan (middle) and side (bottom) views.

The unique method is particularly relevant to future wind-powered shipping. Wind-powered propulsion is not a new technology per se; it was dormant for decades, with strong interest in it only resuming in recent years. A ship with wind-powered propulsion requires a more efficient aerodynamic design, as it does not have the constant, high-power output of a fossil-fueled ship. Previously, the aerodynamic effect was not deemed important compared to a ship’s total resistance in water. But when it comes to wind-powered propulsion, the researchers’ method could open up new possibilities.

“In the next few years, we will probably see ships combining wind and fuel-powered propulsion. But our long-term aim is to make wind power the sole energy source for cargo ships and the like,” says Kewei Xu.

Central to the method is the steady flow Coanda effect. This is based on the tendency of a fluid to flow — like water down the back of a spoon — along an outwardly curved surface (convex), instead of launching away from it. In shipping, one of the main sources of aerodynamic drag is the square-shaped back of the ship’s superstructure; the part that emerges from the deck. The new method developed by the Chalmers researchers induces the Coanda effect around this area.

“By creating a design with convex edges on the ship’s superstructure and allowing highly compressed air to flow through “jet slots,” the Coanda effect allows air pressure on the ship’s hull to balance out. This, in turn, reduces aerodynamic drag considerably, making the ship more energy-efficient,” says Kewei Xu.

“By showing that our method can reduce aerodynamic resistance by 7.5 per cent, we hope the shipping industry will welcome this solution as part of its necessary transition to lower emissions,” says Kewei Xu. “Our study also indicates great potential for reducing drag even more through further optimisation.”

The Chalmers researchers’ new method would also enable safer take-offs and landings on ships for helicopters. Turbulence usually arises as air flows down from the ship’s superstructure, destabilising the helicopter. Since pilots need to land or take off on a very precise location on the ship, this comes with major risks and some helicopters do crash. Currently, fences or an adapted shape on the ship are used to minimise risks, but they are not very effective. The new method dampens the turbulence, as it affects the wind flowing down behind the superstructure. Thus, it would reduce the accident risk for helicopters.

Thawing permafrost poses environmental threat to thousands of sites with legacy industrial contamination

by Moritz Langer, Thomas Schneider von Deimling, Sebastian Westermann, Rebecca Rolph, Ralph Rutte, Sofia Antonova, Volker Rachold, Michael Schultz, Alexander Oehme, Guido Grosse in Nature Communications

Many of us picture the Arctic as largely untouched wilderness. But that has long-since ceased to be true for all of the continent. It is also home to oilfields and pipelines, mines and various other industrial activities. The corresponding facilities were built on a foundation once considered to be particularly stable and reliable: permafrost. This unique type of soil, which can be found in large expanses of the Northern Hemisphere, only thaws at the surface in summer. The remainder, extending up to hundreds of metres down, remains frozen year-round.

Accordingly, permafrost has not only been viewed as a solid platform for buildings and infrastructure.

“Traditionally, it’s also been considered a natural barrier that prevents the spread of pollutants,” explains Moritz Langer from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). “Consequently, industrial waste from defunct or active facilities was often simply left on-site, instead of investing the considerable effort and expense needed to remove it.”

As a result of the industrial expansion during the cold war, over the decades this led to micro-dumps full of toxic sludge from oil and gas exploration, stockpiles of mining debris, abandoned military installations, and lakes in which pollutants were intentionally poured.

“In many cases, the assumption was that the permafrost would reliably and permanently seal off these toxic substances, which meant there was no need for costly disposal efforts,” says Guido Grosse, who heads the AWI’s Permafrost Research Section. “Today, this industrial legacy still lies buried in the permafrost or on its surface. The substances involved range from toxic diesel fuel to heavy metals and even radioactive waste.”

But as climate change progresses, this “sleeping giant” could soon become an acute threat: since the permafrost regions are warming between twice as fast and four times as fast as the rest of the world, the frozen soil is increasingly thawing. When this happens, it changes the hydrology of the region in question, and the permafrost no longer provides an effective barrier. As a result, contaminants that have accumulated in the Arctic over decades can be released, spreading across larger regions.

In addition, thawing permafrost becomes more and more unstable, which can lead to further contamination. When the ground collapses, it can damage pipelines, chemical stockpiles and depots. Just how real this risk already is can be seen in a major incident from May 2020 near the industrial city Norilsk in northern Siberia: a destabilized storage tank released 17,000 metric tons of diesel, which polluted the surrounding rivers, lakes and tundra. According to Langer: “Incidents like this could easily become more frequent in the future.”

Potential impacts of thawing permafrost on above- and below-ground industrial infrastructure containing toxic substances or waste.

In order to more accurately assess such risks, he and an international team of experts from Germany, the Netherlands and Norway took a closer look at industrial activities in the High North. To do so, they first analysed freely available data from the portal OpenStreetMap and from the Atlas of Population, Society and Economy in the Arctic. According to these sources, the Arctic permafrost regions contain ca. 4,500 industrial sites that either store or use potentially hazardous substances.

“But this alone didn’t tell us what types of facilities they were, or how badly they could potentially pollute the environment,” says Langer. More detailed information on contaminated sites is currently only available for North America, where roughly 40 percent of the global permafrost lies. The data from Canada and Alaska showed that, using the location and type of facility, it should be possible to accurately estimate where hazardous substances were most likely to be found.

Industrial and contaminated sites within permafrost dominated regions of the North American continent.

For Alaska, the Contaminated Sites Program also offers insights into the respective types of contaminants. For example, roughly half of the contaminations listed can be attributed to fuels like diesel, kerosene and petrol. Mercury, lead and arsenic are also in the top 20 documented environmental pollutants. And the problem isn’t limited to the legacy of past decades: although the number of newly registered contaminated sites in the northernmost state of the USA declined from ca. 90 in 1992 to 38 in 2019, the number of affected sites continues to rise. There are no comparable databases for Siberia’s extensive permafrost regions.

“As such, our only option there was to analyse reports on environmental problems that were published in the Russian media or other freely accessible sources between 2000 and 2020,” says Langer. “But the somewhat sparse information available indicates that industrial facilities and contaminated sites are also closely linked in Russia’s permafrost regions.”

Using computer models, the team calculated the occurrence of contaminated sites for the Arctic as a whole. According to the results, the 4,500 industrial facilities in the permafrost regions have most likely produced between 13,000 and 20,000 contaminated sites. 3,500 to 5,200 of them are located in regions where the permafrost is still stable, but will start to thaw before the end of the century.

“But without more extensive data, these findings should be considered a rather conservative estimate,” Langer emphasises. “The true scale of the problem could be even greater.”

Making matters worse, the interest in pursuing commercial activities in the Arctic continues to grow. As a result, more and more industrial facilities are being constructed, which could also release toxic substances into nearby ecosystems. Further, this is happening at a time when removing such environmental hazards is getting harder and harder — after all, doing so often requires vehicles and heavy gear, which can hardly be used on vulnerable tundra soils that are increasingly affected by thaw.

“In a nutshell, what we’re seeing here is a serious environmental problem that is sure to get worse,” summarises Guido Grosse. What is urgently called for, according to the experts: more data, and a monitoring system for hazardous substances in connection with industrial activities in the Arctic. “These pollutants can, via rivers and the ocean, ultimately find their way back to people living in the Arctic, or to us.”

Other important aspects are intensified efforts to prevent the release of pollutants and undo the damage in those areas that are already contaminated. And lastly, the experts no longer consider it appropriate to leave industrial waste behind in the Arctic without secure disposal options. After all, the permafrost can no longer be relied upon to counter the associated risks.

Pancosmorio (world limit) theory of the sustainability of human migration and settlement in space

by Lee G. Irons, Morgan A. Irons in Frontiers in Astronomy and Space Sciences

Can humans endure long-term living in deep space? The answer is a lukewarm maybe, according to a new theory describing the complexity of maintaining gravity and oxygen, obtaining water, developing agriculture and handling waste far from Earth.

Dubbed the Pancosmorio theory — a word coined to mean “all world limit” — it was described in a paper.

“For humans to sustain themselves and all of their technology, infrastructure and society in space, they need a self-restoring, Earth-like, natural ecosystem to back them up,” said co-author Morgan Irons, a doctoral student conducting research with Johannes Lehmann, professor in the School of Integrative Plant Science at Cornell University. Her work focuses on soil organic carbon persistence under Earth’s gravity and varying gravity conditions. “Without these kinds of systems, the mission fails.”

The first key is gravity, which Earth life needs to function properly, said co-author Lee Irons, Morgan Irons’ father and executive director of the Norfolk Institute, a group that aims to solve problems of human resilience on Earth and in space.

“Gravity induces a gradient in the fluid pressure within the body of the living thing to which the autonomic functions of the life form are attuned,” he said. “An example of gravity imbalance would be the negative affect on the eyesight of humans in Earth orbit, where they don’t experience the weight necessary to induce the pressure gradient.”

Heat engine exergy diagrams indicate useful work in the form of exergy buildup.

Morgan Irons said that it would be unwise to spend billions of dollars to set up a space settlement only to see it fail, because even with all other systems in place, you need gravity. Humans and all Earth life have evolved within the context of 1G of gravity.

“Our bodies, our natural ecosystems, all the energy movement and the way we utilize energy is all fundamentally based upon 1G of gravity being present,” she said. “There is just no other place in space where there is 1G of gravity; that just doesn’t exist anywhere else in our solar system. That’s one of the first problems we must solve.”

Oxygen is another key factor. Earth’s ecosystem generates oxygen for humans and other life forms. If a technologically advanced primary and a back-up system failed to provide oxygen for the moon base, for example, it would mean instant doom for the astronauts.

“A reserve exists everywhere in Earth’s nature,” Lee Irons said. “Think of the hundreds of thousands of species of plants that generate oxygen. That’s the kind of system reserve we need to replicate to be truly sustainable.”

Such an ecological system of an outpost would need an enormous amount energy from the sun. The more distant planets and moons from the sun in our own solar system get decreased amounts of energy.

“You’ll need a lot of energy,” Lee Irons said. “Otherwise powering the ecological system of an outpost will be like trying to run your car on a cell phone battery or probably even worse, trying to run your entire house and household on a cell phone battery.”

Challenges resulting from urban density and climate change for the EU energy transition

by A. T. D. Perera, Kavan Javanroodi, Dasaraden Mauree, Vahid M. Nik, Pietro Florio, Tianzhen Hong, Deliang Chen in Nature Energy

Dense urban areas amplify the effects of higher temperatures, due to the phenomenon of heat islands in cities. This makes cities more vulnerable to extreme climate events. Large investments in the electricity network will be necessary to cool us down during heatwaves and keep us warm during cold snaps, according to a new study led by Lund University in Sweden.

“Unless we account for extreme climate events and continued urbanisation, the reliability of electricity supply will fall by up to 30%. An additional outlay of 20–60 per cent will be required during the energy transition in order to guarantee that cities can cope with different kinds of climate,” says Vahid Nik, Professor of Building Physics at Lund University and one of the authors of the article.

The study presents a modelling platform that ties together climate, building and energy system models in order to facilitate simulation and evaluation of cities’ energy transition. The aim is to secure the cities’ resilience against future climate changes at the same time as densification of urban areas is taking place. In particular, researchers have looked closely at extreme weather events (e.g. heatwaves and cold snaps) by producing simulations of urban microclimates.

“Our results show that high density areas give rise to a phenomenon called urban heat islands, which make cities more vulnerable to the effects of extreme climate events, particularly in southern Europe. For example, the outdoor temperature can rise by 17% while the wind speed falls by 61%. Urban densification — a recommended development strategy in order to reach the UN’s energy and climate goals — could make the electricity network more vulnerable. This must be taken into consideration when designing urban energy systems, says Kavan Javanroodi, Assistant Professor in Building and Urban Physics.

The impact of climate change on heating and cooling demand.

“The framework we have developed connects future climate models to buildings and energy systems at city level, taking the urban microclimate into account. For the first time, we are getting to grips with several challenges around the issues of future climate uncertainty and extreme weather situations, focussing in particular on what are known as ‘HILP’ or High Impact Low Probability events,” says Vahid Nik.

There is still a large gap between future climate modelling and building and energy analyses and their links to one another. According to Vahid Nik, the model now being developed makes a great contribution to closing that gap.

“Our results answer questions like ‘how big an effect will extreme weather events have in the future, given the predicted pace of urbanisation and several different future climate scenarios?’, ‘how do we take them and the connections between them into account?’ and ‘how does the nature of urban development contribute to exacerbating or mitigating the effects of extreme events at regional and municipal level?’

The results show that the peaks in demand in the energy system increase more than previously thought when extreme microclimates are taken into account, for example with an increase in cooling demand for 68% in Stockholm and 43% in Madrid on the hottest day of the year. Not considering this can lead to incorrect estimates of cities’ energy requirements, which can turn into power shortage and even blackouts.

“There is a marked deviation between the heat and cooling requirements shown in today’s urban climate models, compared to the outcomes of our calculations when urban morphology, the physical design of the city, is more complex. For example, if we fail to take into account the urban climate in Madrid, we could underestimate the need for cooling by around 28%,” says Kavan Javanroodi.

Vahid Nik explains that an increasing number of countries have become interested in extreme weather events, energy issues and the impact on public health. At the same time, there are no methods of quantifying the effects of climate change and planning for adapting to them, especially when it comes to extreme weather events and climate variations across space and time.

“Our efforts can contribute to making societies more prepared for climate change. Future research should aim to examine the relationship between urban density and climate change in energy forecasts. Furthermore, we ought to develop more innovative methods of increasing energy flexibility and climate resilience in cities, which is a major focus of research for our team at the moment,” says Vahid Nik.

Mechanistic Insights into the Formation of CO and C2 Products in Electrochemical CO2 Reduction─The Role of Sequential Charge Transfer and Chemical Reactions

by Rileigh Casebolt DiDomenico, Kelsey Levine, Laila Reimanis, Héctor D. Abruña, Tobias Hanrath in ACS Catalysis

To manage atmospheric carbon dioxide and convert the gas into a useful product, Cornell University scientists have dusted off an archaic — now 120 years old — electrochemical equation.

The calculation — named the Cottrell equation for chemist Frederick Gardner Cottrell, who developed it in 1903 — can help today’s researchers understand the several reactions that carbon dioxide can take when electrochemistry is applied and pulsed on a lab bench. The electrochemical reduction of carbon dioxide presents an opportunity to transform the gas from an environmental liability to a feedstock for chemical products or as a medium to store renewable electricity in the form of chemical bonds, as nature does.

“For carbon dioxide, the better we understand the reaction pathways, the better we can control the reaction — which is what we want in the long term,” said lead author Rileigh Casebolt DiDomenico, a chemical engineering doctoral student at Cornell under the supervision of Prof. Tobias Hanrath.

“If we have better control over the reaction, then we can make what we want, when we want to make it,” DiDomenico said. “The Cottrell equation is the tool that helps us to get there.”

The equation enables a researcher to identify and control experimental parameters to take carbon dioxide and convert it into useful carbon products like ethylene, ethane or ethanol. Many researchers today use advanced computational methods to provide a detailed atomistic picture of processes at the catalyst surface, but these methods often involve several nuanced assumptions, which complicate direct comparison to experiments, said senior author Tobias Hanrath.

“The magnificence of this old equation is that there are very few assumptions,” Hanrath said. “If you put in experimental data, you get a better sense of truth. It’s an old classic. That’s the part that I thought was beautiful.”

DiDomenico said: “Because it is older, the Cottrell equation has been a forgotten technique. It’s classic electrochemistry. Just bringing it back to the forefront of people’s minds has been cool. And I think this equation will help other electrochemists to study their own systems.”

Enhancing flexibility for climate change using seasonal energy storage (aquifer thermal energy storage) in distributed energy systems

by A.T.D. Perera, Kenichi Soga, Yujie Xu, Peter S. Nico, Tianzhen Hong in Applied Energy

About 12% of the total global energy demand comes from heating and cooling homes and businesses. A new study suggests that using underground water to maintain comfortable temperatures could reduce consumption of natural gas and electricity in this sector by 40% in the U.S. The approach, called aquifer thermal energy storage (ATES), could also help prevent blackouts caused by high power demand during extreme weather events.

“We need storage to absorb the fluctuating energy from solar and wind, and most people are interested in batteries and other kinds of electrical storage. But we were wondering whether there’s any opportunity to use geothermal energy storage, because heating and cooling is such a predominant part of the energy demand for buildings,” said first author A.T.D Perera, a former postdoctoral researcher at Lawrence Berkeley National Laboratory (Berkeley Lab), now at Princeton University’s Andlinger Center for Energy and Environment.

“We found that, with ATES, a huge amount of energy can be stored, and it can be stored for a long period of time,” Perera said. “As a result, the heating and cooling energy demand during extreme hot or cold periods can be met without adding an additional burden on the grid, making urban energy infrastructure more resilient.”

The study is one of the first examinations of how ATES could fit into the larger goal of decarbonizing U.S. energy systems by storing intermittent renewable energy to use when the sun isn’t shining and the turbines aren’t spinning. After building a comprehensive technological and economic simulation of an energy system, the authors found that ATES is a compelling option for heating and cooling energy storage that, alongside other technologies such as batteries, could help end our reliance on fossil fuel-derived backup power and enable a fully renewable grid.

Aquifer thermal energy storage (ATES) uses naturally occurring underground water to store energy that can be used to heat and cool buildings. When paired with wind and solar energy, ATES becomes a zero-carbon option for temperature regulation. These illustrations show how the water is moved upward for heating in the hot months, then pumped back down and stored until winter, when the (still) warm water is brought back up to heat buildings.

ATES is a delightfully simple concept that leverages the heat-absorbing property of water and the natural geological features of the planet. You simply pump water up from existing underground reservoirs and heat it at the surface in the summer with environmental heat or excess energy from solar, or any time of the year with wind. Then you pump it back down.

“It actually stays fairly hot because the Earth is a pretty good insulator,” explained co-author Peter Nico, deputy director of the Energy Geosciences Division at Berkeley Lab and lead of the Resilient Energy, Water and Infrastructure Domain. “So then when you pull it up in the winter, months later, that water’s way hotter than the ambient air and you can use it to heat your buildings. Or vice versa, you can pull up water and let it cool and then you can put it back down and store it until you need cooling during hot summer months. It’s a way of storing energy as temperature underground.”

ATES is not yet widely used in the U.S., though it is gaining recognition internationally, most notably in the Netherlands. One major perk is that these systems get “free” thermal energy from seasonal temperature changes, which can be bolstered by the addition of artificial heating and cooling generated by electricity. As such, they perform very well in areas with large seasonal fluctuations, but have the potential to work anywhere, so long as there is wind or solar to hook up to. In regards to other impacts, ATES systems are designed to avoid impinging upon critical drinking water resources — often the water used is from deeper aquifers than the drinking water supply — and do not introduce any chemicals into the water.

To get some concrete numbers estimating how much energy ATES could save on the U.S. grid, and how much it would cost to deploy, the team designed a case study using a computational model of a neighborhood in Chicago. This virtual neighborhood was composed of 58 two-story, single-family residence buildings with typical residential heating and cooling that were hooked up to a simulation of an energy grid with multiple possible energy sources and storage options, including ATES. Future climate projections were used to understand how much of the neighborhood’s total energy budget is taken up by heating and cooling demands currently, and how this might change in the future. Finally, a microgrid simulation was designed for the neighborhood that included renewable energy technologies and ATES to evaluate the technoeconomic feasibility and climate resilience. Putting all these factors together into one model would not have been possible without the team’s diverse expertise across the energy geosciences, climate science, and building science fields. The results showed that adding ATES to the grid could reduce consumption of petroleum products by up to 40%, though it would cost 15 to 20% more than existing energy storage technologies.

“But, on the other hand, energy storage technologies are having sharp cost reductions, and after just a few years of developing ATES, we could easily break even. That’s why it’s quite important that we start to invest in this research and start building real-world prototype systems,” said Perera.

“ATES does not need space compared with above-ground tank-based water or ice storage systems. ATES is also more efficient and can scale up for large community cooling or heating compared with traditional geothermal heat pump systems that rely on heat transfer with the underground earth soil,” added Tianzhen Hong, a co-author and senior scientist at the Building Technology and Urban Systems Division.

Another major benefit of ATES is that it will become more efficient as weather becomes more extreme in the coming years due to climate change. The hotter summers and harsher winters predicted by the world’s leading climate models will have many downsides, but one upside is that they could supercharge the amount of free thermal energy that can be stored with ATES. “It’s making lemonade, right? If you’re going to have these extreme heat events, you might as well store some of that heat for when you have the extreme cold event,” said Nico.

ATES will also make the future grid more resilient to outages caused by high power demands during heat waves — which happen quite often these days in many high-population U.S. areas, including Chicago — because ATES-driven cooling uses far less electricity than air conditioners, it only needs enough power to pump the water around.

“It’s very much a realistic thing to do and this work was really about showing its value and how the costs can be offset,” said Nico. “This technology is ready to go, so to speak. We just need to do it.”

Externally Tunable, Low Power Electrostatic Control of Cell Adhesion with Nanometric High‐k Dielectric Films

by Victor J. Leon, Baptiste Blanc, Sophia D. Sonnert, Kripa K. Varanasi in Advanced Functional Materials

Algae grown in transparent tanks or tubes supplied with carbon dioxide can convert the greenhouse gas into other compounds, such as food supplements or fuels. But the process leads to a buildup of algae on the surfaces that clouds them and reduces efficiency, requiring laborious cleanout procedures every couple of weeks.

MIT researchers have come up with a simple and inexpensive technology that could substantially limit this fouling, potentially allowing for a much more efficient and economical way of converting the unwanted greenhouse gas into useful products.

The key is to coat the transparent containers with a material that can hold an electrostatic charge, and then applying a very small voltage to that layer. The system has worked well in lab-scale tests, and with further development might be applied to commercial production within a few years. The findings are being reported in a paper by recent MIT graduate Victor Leon PhD ’23, professor of mechanical engineering Kripa Varanasi, former postdoc Baptiste Blanc, and undergraduate student Sophia Sonnert.

No matter how successful efforts to reduce or eliminate carbon emissions may be, there will still be excess greenhouse gases that will remain in the atmosphere for centuries to come, continuing to affect global climate, Varanasi points out. “There’s already a lot of carbon dioxide there, so we have to look at negative emissions technologies as well,” he says, referring to ways of removing the greenhouse gas from the air or oceans, or from their sources before they get released into the air in the first place.

Experimental setup and system characterization.

When people think of biological approaches to carbon dioxide reduction, the first thought is usually of planting or protecting trees, which are indeed a crucial “sink” for atmospheric carbon. But there are others. “Marine algae account for about 50 percent of global carbon dioxide absorbed today on Earth,” Varanasi says. These algae grow anywhere from 10 to 50 times more quickly than land-based plants, and they can be grown in ponds or tanks that take up only a tenth of the land footprint of terrestrial plants. What’s more, the algae themselves can then be a useful product. “These algae are rich in proteins, vitamins and other nutrients,” Varanasi says, noting they could produce far more nutritional output per unit of land used than some traditional agricultural crops.

If attached to the flue gas output of a coal or gas power plant, algae could not only thrive on the carbon dioxide as a nutrient source, but some of the microalgae species could also consume the associated nitrogen and sulfur oxides present in these emissions. “For every two or three kilograms of CO2, a kilogram of algae could be produced, and these could be used as biofuels, or for Omega-3, or food,” Varanasi says. Omega-3 fatty acids are a widely used food supplement, as they are an essential part of cell membranes and other tissues but cannot be made by the body and must be obtained from food. “Omega 3 is particularly attractive because it’s also a much higher-value product,” Varanasi says.

Most algae grown commercially are cultivated in shallow ponds, while others are grown in transparent tubes called photobioreactors. The tubes can produce seven to 10 times greater yields than ponds for a given amount of land, but they face a major problem: The algae tend to build up on the transparent surfaces, requiring frequent shutdowns of the whole production system for cleaning, which can take as long as the productive part of the cycle, thus cutting overall output in half and adding to operational costs.

Systematic study of cell adhesion against applied shear and voltage.

The fouling also limits the design of the system. The tubes can’t be too small because the fouling would begin to block the flow of water through the bioreactor and require higher pumping rates. Varanasi and his team decided to try to use a natural characteristic of the algae cells to defend against fouling. Because the cells naturally carry a small negative electric charge on their membrane surface, the team figured that electrostatic repulsion could be used to push them away. The idea was to create a negative charge on the vessel walls, such that the electric field forces the algae cells away from the walls. To create such an electric field requires a high-performance dielectric material, which is an electrical insulator with a high “permittivity” that can produce a large change in surface charge with a smaller voltage.

“What people have done before with applying voltage [to bioreactors] has been with conductive surfaces,” Leon explains, “but what we’re doing here is specifically with nonconductive surfaces.”

He adds: “If it’s conductive, then you pass current and you’re kind of shocking the cells. What we’re trying to do is pure electrostatic repulsion, so the surface would be negative and the cell is negative so you get repulsion. Another way to describe it is like a force field, whereas before the cells were touching the surface and getting shocked.”

The team worked with two different dielectric materials, silicon dioxide — essentially glass — and hafnia (hafnium oxide), both of which turned out to be far more efficient at minimizing fouling than conventional plastics used to make photobioreactors. The material can be applied in a coating that is vanishingly thin, just 10 to 20 nanometers (billionths of a meter) thick, so very little would be needed to coat a full photobioreactor system.

“What we are excited about here is that we are able to show that purely from electrostatic interactions, we are able to control cell adhesion,” Varanasi says. “It’s almost like an on-off switch, to be able to do this.”

Additionally, Leon says, “Since we’re using this electrostatic force, we don’t really expect it to be cell-specific, and we think there’s potential for applying it with other cells than just algae. In future work, we’d like to try using it with mammalian cells, bacteria, yeast, and so on.” It could also be used with other valuable types of algae, such as spirulina, that are widely used as food supplements.

The same system could be used to either repel or attract cells by just reversing the voltage, depending on the particular application. Instead of algae, a similar setup might be used with human cells to produce artificial organs by producing a scaffold that could be charged to attract the cells into the right configuration, Varanasi suggests.

Microbial drought resistance may destabilize soil carbon

by Steven D. Allison in Trends in Microbiology

Soil stores more carbon than plants and the atmosphere combined, and soil microbes are largely responsible for putting it there. However, the increasing frequency and severity of drought, such as those that have been impacting California, could disrupt this delicate ecosystem. Microbial ecologist Steven Allison warns that soil health and future greenhouse gas levels could be impacted if soil microbes adapt to drought faster than plants do. He argues that we need to better understand how microbes respond to drought so that we can manage the situation in both agricultural and natural settings.

“Soil microbes are beneficial, and we couldn’t live without their cycling of carbon and nutrients, but climate change and drought can tweak that balance, and we have to be aware of how it’s changing,” says Allison of the University of California, Irvine.

Some soil microbes take carbon from decomposing plants and store it in the soil, while others release plant carbon back into the atmosphere. The carbon that ends up in the soil is beneficial in multiple ways.

“The carbon in the soil has these reverberating effects out to the rest of the world in terms of the infrastructure in our natural and managed ecosystems,” says Allison. “Carbon-rich soils hold more nutrients, so plants growing in those soils tend to be more productive, and the carbon changes the physical properties of the soil, which prevents erosion.”

“In California now, we have this system where the droughts are more intense, and then the rainfall is more intense,” he says. “So, if you’re losing your soil carbon, when it rains really hard it could carry away your soil and cause erosion, landslides, mudslides, sediments, and all kinds of problems that we’re actually seeing right now.”

Direct and indirect feedbacks of trait-based microbial strategies on soil carbon decomposition.

The carbon that is released back into the atmosphere is another story.

“From a climate mitigation standpoint, what we want is for more carbon to be in plants and soils and less carbon to be in the atmosphere, so the more carbon we can absorb into plants through photosynthesis and the more we can transfer and keep in the soil, the better off we’re going to be in terms of climate change,” says Allison. “That’s why it’s really important to know how the balance of incoming versus outflowing carbon changes with drought, or warming, or any other climate factor.”

Plants and microbes will both be impacted by the increasing frequency of drought, but Allison suspects that microbes will be able to bounce back faster. “Microbes are really adaptable — they can change their physiology, they can change their abundances so that more drought-adapted microbes take over, and they can potentially evolve — so we expect that they are going to resist or bounce back from drought,” says Allison. “All those different processes can happen pretty quickly with microbes, and much more quickly than with plants.”

If more carbon-releasing microbes survive than carbon-sequestering microbes, we could end up with carbon-depleted soils, which would have serious negative implications for plant productivity and future greenhouse gas levels.

We may be able to nudge the balance in the right direction, Allison says, but more research is needed first. “There’s still a lot to be done. Right now, we have data that suggests that when we have drought, something changes that results in carbon loss, but we don’t understand exactly how or why that’s happening, whether drought’s changing the abundance of beneficial plant associated microbes versus the carbon releasing microbes, or if it’s causing the evolution of one of the microbe groups, or if it’s more determined by changes to their immediate physiology,” says Allison.

Some microbes could actually help plants cope with drought. If we knew which microbes were most beneficial to plants, and most likely to retain carbon in soil, we could try to tip the balance in their favor.

“There’s a lot of potential for us to manage or engineer soil microbes,” says Allison. “In agricultural systems, we can look into manipulating the soil or adding beneficial microbes back in. In more natural systems, management would probably be on the plant side: soil microbes are often closely intertwined with plants, so managing the plants can also benefit the microbial part of the ecosystem.”

“We also need more measurements to get a good sense of how drought affects soil carbon change in different ecosystems,” says Allison. “There’s a lot of landscape out there — from the Arctic tundra to the deserts — and we could use more research across those diverse habitats.”

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