It provides carbon-neutral energy all year round and, unlike coal, gas or hydroelectric power plants, takes up minimal space, since most of the plant is located deep below the Earth’s surface. In the past, however, earthquakes, caused by hydraulic stimulation, have been cause for concern. So where do we stand today?Several research groups at ETH Zurich are hard at work investigating the possibilities of geothermal energy. They all agree on one thing: geothermal energy holds immense potential for Switzerland. The risk of earthquakes, which varies from one form of deep geothermal energy to the next, has also become much more manageable.<h2>Not all geothermal energy is created equal</h2>Geothermal energy is an old technology. Thermal springs have been in use since the time of the Romans and even today, hot groundwater that circulates in natural reservoirs is used to generate heat as part of hydrothermal systems (examples include the district heating networks in Riehen, Munich or Paris).Other modern geothermal systems – known as EGS (Enhanced Geothermal Systems) – go one step further: where there are no layers of water-bearing rock, hydraulic stimulation is used to create artificial fractures in the deep crystalline rock, providing space for water. This water heats up and is pumped back to the surface to provide heat or generate electricity.However, EGS also carry the risk of triggering earthquakes – as happened in Basel in 2006. Although targeted stimulation and improved monitoring have greatly reduced this risk, challenges remain: drilling is costly and not always successful, and fractures in the rock tend to close up again over time due to mineral deposits.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1735004738390-1735004738390.png" class="fr-fic fr-dib">While hydrothermal geothermal energy relies on natural flow paths, EGS requires hydraulic stimulation. &nbsp;(Graphics: Martin Saar, modified by Nicolas Rangel-Jurado, MSc. 2021)<h2 id="isPasted">Traffic light system reliable way of minimising risk</h2>Deep in the Swiss bedrock, at a facility known as the BedrettoLab, Stefan Wiemer, a professor in the Department of Earth and Planetary Sciences at ETH Zurich and Director of the Swiss Seismological Service (SED), is conducting research. Scientists are investigating new methods for making EGS safer, with researchers focusing on many small, controlled stimulations in isolated zones of the borehole. “We need small vibrations to create the fractures in the rock, but we have to avoid larger quakes at all costs,” explains Wiemer.The findings from the BedrettoLab are being included in plans for the pilot geothermal power plant in the commune of Haute-Sorne. ETH scientists have also been tasked by the canton with monitoring seismic activity on this project.Sensors in the boreholes transmit large amounts of seismological and hydraulic data to the researchers in real-time. A specially developed machine learning model continuously calculates how many quakes above a certain threshold can be expected if the planned stimulation continues. If there is a risk of exceeding the thresholds, the system immediately sounds the alarm and suggests which adjustments need to be made to prevent major tremors.Wiemer emphasises that the starting point for EGS is very different now compared to 20 years ago. “Today, we have very good control mechanisms. This is thanks to improved data collection and the ability of AI to process enormous volumes of data in real-time. That allows us to better understand and minimise risks, although we cannot exclude them altogether,” says Wiemer.<h2>Back-up power from the Earth</h2>Martin Saar is Professor of Geothermal Energy and Geofluids at the Department of Earth and Planetary Sciences at ETH Zurich. He and his team are also researching how geothermal systems can be improved. And they have an innovative idea for how they might achieve this: instead of creating fractures in the rock by injecting water, they plan to drill entire closed-pipe systems deep underground. This works regardless of the geology and entails only the usual minimal risk of earthquakes associated with underground drilling. The pipes would then circulate CO₂ rather than water, which increases the efficiency of the geothermal power plant. Deep underground, CO₂ heats up, expands and rises by itself, where it is expanded in a turbine to generate electricity. As the name suggests, these so-called deep closed-loop Advanced Geothermal Systems (AGS) constitute a closed loop, meaning they do not emit any operational CO₂.When there is no wind or sunshine, AGS could provide a reliable source of energy and act as a back-up power supply. “In view of the increasing demand for electricity in winter, AGS could offer an environmentally friendly alternative to the carbon-intensive gas-fired reserve power plants which are currently being talked about,” says Saar.One downside, however, is the high cost of drilling, but there is hope, as the cost of traditional rotary drilling has been significantly reduced in recent years. Work is also under way around the world, including on Saar’s team, to investigate modern contactless drilling methods, using lightning or microwaves, for example, which could greatly reduce the cost of deep drilling in the future.<h2>Long-term carbon storage and energy generation in one</h2>Another type of deep geothermal energy is a CO2-Plume Geothermal (CPG) system which Saar’s research group invented in 2009. Saar observed already then that more and more countries are interested in storing carbon permanently in geological reservoirs as a way of counteracting global warming: “I wondered at the time what would happen if we could not just pump the CO2 underground and store it there permanently, but also get it back out temporarily and use it to produce heat or generate electricity.” &nbsp;The CO₂ that is injected into deeper layers of the Earth for storage heats up and flows upwards. There, it drives a turbine, cools down and flows back down again – a closed cycle that ensures that all CO₂ is permanently stored deep underground. Using CO₂ as an energy carrier instead of water, which is more viscous, increases heat production – and therefore electricity generation – typically by a factor of two to three. Another advantage is that because heat is extracted from the geothermal reservoir, reducing pore-fluid pressures, more CO₂ can be stored in the underground reservoir.Development of the CPG concept is continuing in a dedicated CPG Consortium (<a href="https://geg.cpg.ethz.ch/">https://geg.cpg.ethz.ch/</a>) Saar has founded in 2023, in collaboration with industrial partners such as Shell, Petrobras, Holcim and Ad Terra Energy, which is also supported by the Swiss Federal Office of Energy. The CPG consortium is currently evaluating various locations for an initial pilot plant to demonstrate technical feasibility at commercial scale.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1735004771120-1735004771120.png" class="fr-fic fr-dib">Two innovative geothermal systems, as researched by Martin Saar's group. &nbsp;(Graphics: Martin Saar, modified by Nicolas Rangel-Jurado, MSc. 2021)<h2 id="isPasted">Using the Earth as a battery</h2>But geothermal probes can be used for more than just extracting heat from below the Earth’s surface; they can also be used to inject heat, as is the case in Switzerland, for example, where geothermal probes are frequently used as a sustainable way of heating buildings. According to Maren Brehme, a researcher on Saar’s team, medium-depth geothermal energy (down to several hundred metres) holds additional potential for advancing the heating transition in Switzerland. “When it comes to heat generation, in particular, Switzerland is still heavily dependent on gas, and therefore on other countries,” says Brehme.With this form of geothermal energy, excess heat from the summer or from industrial processes is led underground through boreholes, stored in the rock and then pumped out again in winter and used for heating. It is a process that has already been rolled out successfully in countries like the Netherlands where it is used to heat greenhouses. Now, Brehme and her team want to adapt the process for geological conditions in Switzerland. At the BedrettoLab, scientists are investigating how to store heat in crystalline rock.Here, too, drilling costs are still relatively high, and not enough is known about the subsurface in Switzerland, which increases the risk of not finding sufficient permeability underground. “Switzerland hardly has oil or gas deposits. Because of that, the subsurface has never been investigated as thoroughly as in other countries. We have to plug these gaps in our knowledge,” says Brehme.Overall, however, she believes that the prospects for geothermal energy in Switzerland are good: drilling technologies are improving and are becoming more affordable all the time, while regulatory hurdles are being removed, and the very first insurance companies have begun offering cover against drilling risk. On top of that, surveys show that the population is, generally speaking, open to geothermal energy.

ETH researchers use a camera probe to check whether a sensor is correctly positioned in the borehole. (©WSS, Image: Felix Wey, Baden)

Deep geothermal energy is climate-friendly and base-load capable - but how can this heat be tapped safely? ETH researchers are working on minimizing the earthquake risk and developing completely new systems, for example with closed CO2 cycles.

Energy from underground

In a recipe for a net-zero future, hydrogen is sometimes considered the secret ingredient. A team of Carnegie Mellon researchers is moving beyond the hype to analyze the realities—and risks—of using hydrogen as part of our energy and manufacturing systems.“Many businesses and communities across the United States are putting their chips on hydrogen hubs,” says <a href="https://engineering.cmu.edu/directory/bios/karplus-valerie.html">Valerie Karplus</a>, a professor of <a href="https://www.cmu.edu/epp/people/faculty/valerie-karplus.html">engineering and public policy</a> and associate director of the <a href="https://www.cmu.edu/energy/" rel="noopener" target="_blank">Scott Institute for Energy Innovation</a>. “To realize their potential, hubs will need to navigate the tricky balance between maintaining the financial incentives necessary for early market development while upholding their commitment to reduce greenhouse gas emissions.”In the wake of $8 billion in federal funding that has helped regional stakeholders start up hydrogen hubs across the United States, Karplus and <a href="https://engineering.cmu.edu/directory/bios/morgan-m-granger.html">Granger Morgan</a> have summarized the two types of risks associated with early investment in hydrogen systems: economic, that maintaining hubs won’t be financially viable; and environmental, that hubs won’t reduce greenhouse gasses at a sufficient level, or that their use will exacerbate local pollution.<blockquote>To realize their potential, hubs will need to navigate the tricky balance between maintaining the financial incentives necessary for early market development while upholding their commitment to reduce greenhouse gas emissions.<cite>Valerie Karplus, Professor, Engineering and Public Policy</cite></blockquote>Karplus and Morgan, a professor of engineering and public policy, point out that in the effort to curb the effects of climate change, hydrogen offers many advantages, but it is not a panacea. A crucial step to making it a viable energy source is finding a production method that reduces greenhouse gas emissions and has increasingly favorable economics. They suggest that starting with hubs can address many of the economic risks, but regulation is required to address the environmental risks.“The bottom line is that hydrogen would be very useful if we could get it without environmental consequences,” said Morgan.Hydrogen can still indirectly contribute to greenhouse warming, putting particular pressure on making sure that transport, storage, and sequestration are handled properly.“Hydrogen is the lightest molecule, so it leaks very easily,” said Morgan. “Building a hydrogen system that doesn’t leak is really tough and takes a lot of attention.”As Morgan notes, hydrogen leaks are difficult to detect, and its presence extends the atmospheric lifetime of methane, a greenhouse gas that’s 40 times more potent than carbon dioxide.Morgan and Karplus’ research, which appears in the journal <a href="https://onlinelibrary.wiley.com/doi/10.1111/risa.17449" rel="noopener" target="_blank">Risk Analysis</a>, includes a set of design principles to help hydrogen hubs capitalize on their potential.Recommendations include streamlining of the regulatory requirements for hydrogen hubs, combined with efforts to engage with end users and address their concerns about the social and economic equity of new infrastructure appearing in communities.Beyond financial viability and climate mitigation, how hydrogen development affects workers and communities will shape its broader growth prospects. A hydrogen economy could provide a new source of employment in parts of the country that are already being hard hit by a decline in manufacturing or fossil energy production, given similarities in skills requirements. At the same time, a shift to hydrogen-based ironmaking processes for steel production could improve air quality and reduce associated negative health impacts to communities.

Hydrogen is sometimes considered a secret ingredient in the recipe for a net-zero future. As a team of Carnegie Mellon researchers points out, hydrogen offers many advantages, but it’s not a panacea.

Hubs: A step towards a hydrogen future?

The effective utilization of renewable energies such as solar and wind power is an essential element to achieve carbon neutrality. According to the <a href="https://kpmg.com/xx/en/home/insights/2023/06/statistical-review-of-world-energy-2023.html" target="_blank">Statistical Review of World Energy 2023</a> report published by the Energy Institute in the U.K., renewable energies including hydropower already account for approximately 30% of the world's power supplies. The total amount of that renewable energy is 8,539 TWh. This means it has grown more than four times the 2,058 TWh that it was in 1985.When it comes to ways to fully utilize renewable energy, many people may think of large-scale power generation in places brimming with natural energy. Examples of that include solar power generation in vast places like deserts or grasslands and wind power generation on the sea. However, there are forms of renewable energy even in the middle of any big city. In fact, efforts are being proactively promoted to introduce power generation with renewable energy in urban areas. In Japan, for instance, solar panels are being installed on the rooftops of buildings and the roofs of houses. The amount of power these solar panels generate is small. This means they are being positioned as auxiliary power supplies. Nevertheless, they are being effectively utilized. Moreover, new efforts are underway to also develop and introduce solar power generation technologies on the walls and in the windows of buildings and technologies that generate power using the vibrations that come from people walking.Looking at the situation from a global perspective, many small and medium-sized cities are striving to achieve local production for local consumption in which the power consumed locally is supplied by utilizing wind power, solar power, hydropower, and other forms of renewable energy in that locality. Furthermore, an increasing number of companies are also participating in RE100. RE100 is an international initiative the aim of which is for companies to supply the power they use in their businesses with 100% renewable energy. These companies are proactively introducing power generation equipment into their factories and other facilities to generate as much power as possible on their own (Fig. 1).<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1725259865043-microgrid-img0001.jpg" style="width: 100%px;" class="fr-fic fr-dib">Fig. 1: An increasing number of companies are participating in RE100 and promoting power generation on their own with renewable energy (Left: Kanazu Murata Manufacturing Clean Energy Park / Right: Carport solar panels capable of dealing with fallen snow)<h2 id="isPasted">Microgrids: Supporting the Local Production for Local Consumption of Renewable Energy</h2>We can call efforts to achieve local production for local consumption by converting renewable energy into power an extremely effective means of utilizing energy. This is because it is possible to minimize the power loss that always occurs in power systems during the transmission and distribution of that power.Large-scale power plants are located far from cities where a large amount of power is consumed in current power systems. The power generated in those power plants is transmitted and distributed to the areas where it is consumed to be utilized in daily life and socio-economic activities. However, approximately 30% of the power generated in the power plants is wastefully lost in the process up to its use via the power transmission and distribution network (also known as the grid). This is because a large amount of power is dissipated as heat or electromagnetic waves due to power lines and power converter loads. The shorter the distance of power transmission and distribution, the fewer times the power is converted, making it possible to reduce power loss. Therefore, we can minimize the occurrence of power loss by achieving local production for local consumption using the natural energy all around us as a distributed power supply.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1725259887421-microgrid-img0002_en.jpg" style="width: 100%px;" class="fr-fic fr-dib">Fig. 2: Microgrid configuration and method of usage during normal times and emergenciesSource: <a href="https://www.meti.go.jp/shingikai/energy_environment/energy_resource/pdf/015_s01_00.pdf" target="_blank" data-lf-fd-inspected-kn9eq4roawkarlvp="true">Materials from the Ministry of Economy, Trade and Industry's (a Japanese administrative agency) 4th Information Liaison Committee on the Introduction of Sustainable Renewable Energy in Local Communities</a>*This linked page is in Japanese.A small-scale power network aiming to achieve local production for local consumption of power is called a microgrid (Fig. 2). In addition to effectively utilizing renewable energy, microgrids have other benefits, as they are distributed power systems. For example, microgrids are capable of stably supplying power to communities even in the event of a large-scale power outage during an emergency such as a disaster. This allows us to maintain our daily life and business activities.<h2>Major Prerequisite of Operating Power Systems: Balancing Principle</h2>The concept of microgrids is simple. However, realizing microgrids is not that easy. This is because there is a major principle to the building and operating of power systems called the "balancing principle."The balancing principle is the rule that the amount of power supplied from a power plant must always match the amount of demand for power no matter what the power system. If we operate a power system in violation of this principle, the voltage of the power will become unstable and the equipment may fail, leading to a large-scale power outage.However, power derived from renewable energy like solar power is produced from unstable natural phenomena. Accordingly, we cannot conveniently adjust the amount of power generated. Therefore, it is difficult to supply the power we use and to fully use it with only power generated in the community. This means it is necessary to employ a mechanism that accommodates for surpluses and deficiencies with advanced operation and management like the fine adjustment of the balance in supply and demand in the community or the utilization of a large energy storage system (ESS).<h2>Smart Grids: Major Prerequisite for the Realization of Microgrids</h2>The means to solving this issue is a very similar concept to the microgrid called a "smart grid." A smart grid is a mechanism that automatically controls the necessary power so it can be supplied without surpluses or deficiencies by utilizing smart meters and other telecommunications devices to visualize in real time power demand in each individual household, business establishment, or other facility.Microgrids and smart grids are different concepts. Nevertheless, it is difficult to realize a microgrid that achieves local production for local consumption of power efficiently and effectively without introducing a smart grid mechanism. Smart grids grasp in real time and in detail the amount of power generated in distributed renewable energy power generation facilities and the amount of power consumed in daily life and business to achieve a balance between both while managing the charging and discharging of multiple distributed ESSs. If there is a deficiency in the power generated with just the charging and discharging permissible values of the installed ESSs, smart grids procure and release power from the wider grid to preserve the balance.The technology that uses IoT technology to control the amount of power supplied as if the multiple pieces of power generation equipment and ESSs in a microgrid were one power plant is called a "virtual power plant (VPP)." Meanwhile, smart meters are used to grasp in real time the power consumption situation in households and business establishments. Looking at the situation globally, smart meters are rapidly spreading. Smart meters began to be installed in households in 2014 in the greater Tokyo Metropolitan area in Japan. Installation was completed in almost all households and business establishments by the end of FY2020. The installation of smart meters across Japan is scheduled to be completed by the end of FY2024. In other words, we can say that the groundwork to promote the building of microgrids is steadily being laid.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1725259914808-microgrid-img0003.jpg" style="width: 100%px;" class="fr-fic fr-dib">Fig. 3: The spread of smart meters is a major prerequisite to smart grids and microgrids<h2 id="isPasted">DC Power Transmission and Distribution Systems Aiming for Further Improvements in Efficiency</h2>Attempts are also being advanced to further raise the energy utilization rate with microgrids. Currently, technological development is underway to introduce a new power transmission and distribution network called a "DC microgrid." This DC microgrid will transmit and distribute DC power instead of the AC power used for commercial power supplies.DC power supplies such as solar batteries and storage batteries are often used on the power supply side of microgrids. On the other hand, looking at the power consumption side, telecommunications devices made using semiconductors and electronic components and energy-saving electronic goods made using inverters operate on DC power. This means both sides handle DC power.Currently, however, AC power is being transmitted and distributed, so it is necessary to convert the power both when it is transmitted and when it is used. Power loss occurs at that time. DC microgrids are a technology aiming to minimize this waste. It is envisioned that DC buses of about 400 V will be laid in place of conventional AC 200 V / 100 V power lines and that high-voltage commercial grids will operate by being connected via a bidirectional AC/DC converter. In addition to microgrids, DC power transmission systems are being used to transmit power over long distances. There are already examples of this technology being put to practical use in Europe and America.The building and operation of microgrids will no doubt progress at the same time as there is an expansion in the usage settings of renewable energy. It is expected that demand will further increase for even more highly efficient and flexible microgrids that can handle various usage settings and the electronic components that support the building of those microgrids.<hr><h2 id="isPasted">Other Links</h2><ul><li><a href="https://corporate.murata.com/en-eu/csr/environment_murata/climate_change?intcid1=mar_art_xxx_tao_xxx_tao-link" target="_blank">Reinforcement of climate change countermeasures</a></li><li><a href="https://www.murata.com/en-eu/apps/industry/smartgrid/smartmeter?intcid1=mar_art_xxx_tao_xxx_tao-link" target="_blank">"Smart meter" application guide</a></li></ul>

Supporting the Transition away from Fossil Fuels with the Power of Electronic Components

Microgrids: Promoting Local Production for Local Consumption of Renewable Energy

Using a combination of machine learning and powerful X-rays, Cornell researchers have solved a mystery behind the unusual behavior seen in a class of materials with potential for thermoelectric energy conversion and other applications.Researchers have long shown that the cubic phase of germanium telluride (GeTe) exhibits an unexpected rise in lattice thermal conductivity as its temperature increases. But knowing that a property exists and explaining why it exists are two very different things.Zhiting Tian, associate professor at the Sibley School of Mechanical and Aerospace Engineering in Cornell Engineering, is the lead author of a new paper in&nbsp;<a href="https://doi.org/10.1038/s41467-024-51377-8" target="_blank">Nature Communications</a> that provides a convincing explanation for the unexpected behavior of GeTe. More generally, the research deepens researchers’ understanding of thermal transport in a class of materials known as phase-change materials.What Tian and her team of researchers found is that as a sample of GeTe is heated to the point where its phase changes from a rhombohedral structure to a cubic structure, the bonds between second-nearest neighbors of like atoms (Ge-Ge and Te-Te) strengthen considerably. Ge-Ge bond strength increased by 8.3% and the strength of Te-Te bonds increased by a remarkable 103% as the sample’s temperature rose from 693 degres Kelvin to 850 degrees Kelvin.The group used machine learning-assisted first-principles calculations corroborated by X-ray scattering measurements to computationally reproduce the increasing thermal conductivity trend for the first time. They then borrowed a commonly used chemistry technique to perform the bonding analysis, and confirmed that these increasingly strong second-nearest neighbor bonds play a major role in GeTe’s previously unexplained increase in lattice thermal conductivity.“Computationally, it was quite prohibitive to look at temperature effects and to consider higher-order scattering, for example,” Tian said. “But because we were able to leverage machine learning potential, we were able to more efficiently extract the interactions and consider the multiple effects – temperature dependence, four-phonon scattering, and coherence contribution – all at once.”Phase-change materials such as GeTe are valued for their usefulness in a range of optical and electronic applications. Their optical and electrical properties change markedly depending on which of several stable phase states they are in and these phase states can be easily reversed. Moreover, GeTe has been talked about as a replacement for the semiconductor lead telluride as a thermoelectric material, due to lead’s inherent toxicity, according to Tian, who is a faculty fellow at the Cornell Atkinson Center for Sustainability.The work demonstrates an efficient and thorough pathway toward accurate modeling of materials near phase transitions or at high temperatures that have promise for phase change, thermoelectric and other energy applications.“We also identified other materials which showed a similar increase in conductivity, including tin-telluride and tin-selenide,” Tian said. “And so we hope our work will spark interest in looking deeper into the thermal transport behavior of other phase-change materials.”The work was supported by Tian’s National Science Foundation CAREER Award.

Using a combination of machine learning and powerful X-rays, Cornell researchers have solved a mystery behind the unusual behavior seen in a class of materials with potential for thermoelectric energy conversion and other applications.

Machine learning explains material's thermal conductivity

To transition away from fossil fuels and towards renewables – which are intermittent by nature – we’ll need to rework our entire system of power storage, transmission and distribution. Yet experts haven’t yet found the right energy mix or power storage system, or how to balance supply and demand effectively.Decarbonizing our society will mean replacing much of the oil and gas we currently use with electricity. And demand for electricity will only grow as consumers trade out their heating oil for heat pumps and their combustion engine vehicles for electric ones. Wind and solar power will meet a growing share of this demand, while nuclear power is set to be phased out, at least in Switzerland. But there’s one big drawback to electricity: it’s best used right when it’s generated, because storing it for more than short periods is difficult and comes with a relatively high economic, environmental and energy costs. Given the intermittent, variable and decentralized nature of renewable energy, it’s clear why we’ll need to rethink our existing approach to power grids – or the way in which we generate, carry, distribute and manage electrical power.<h2>A matter of timing</h2>“The more we rely on renewables with unpredictable power generation, the more we’ll also need to rely on reserves,” says Mario Paolone, the head of EPFL’s Distributed Electrical Systems Laboratory (DESL). Especially since today, it’s demand that sets the pace. Demand is seen as immutable, and so it’s the supply part of the equation that must be adjusted accordingly. People want to be able to switch on a light, heat up the oven and charge their vehicles at any time of day or night, in the summer or in the winter. As a result, grid operators keep reserves of electricity on hand that can be tapped into at different time intervals. These include a primary reserve deployable in a few minutes, a secondary reserve deployable within 15 minutes and one hour, and a supplemental reserve for periods beyond that. Each type of reserve comes with the appropriate power storage system.Fortunately, Switzerland isn’t alone. Our power grid is connected to the rest of Europe, allowing us to pool resources, storage systems and costs with other countries. “The dream of becoming self-sufficient in terms of our power supply is neither technically nor financially optimal if we limit our view to Switzerland,” says Paolone. “It’s Europe as a whole that needs to become energy independent.”Electrifying our processes and transitioning to renewables will impact power grids in two ways. First, it will change how operators balance the load on their grids and store reserves. “For now, synthesis gas made from renewable energy is the most promising method for storing power and responding to seasonal fluctuations,” says Paolone. Gas-fired power plants can step in to meet excess demand. Operators can also set up power-to-gas systems, which use surplus power to produce clean hydrogen, which in turn is processed to make synthesis gas. “Natural gas companies are really interested in power-to-gas technology because it will let them keep using their existing transmission and distribution infrastructure,” says Mario Paolone. “But for that, engineers will need to develop efficient, large-scale carbon capture systems.”He also points out that “as we decarbonize Switzerland, hydropower will play an important role in providing this kind of flexibility to power grids. It’s the only completely renewable energy source that we can control. That’ll be a crucial advantage going forward.”Hydropower plants provide the flexibility to cover load variations throughout the day or across seasons. Their flexibility depends in part on the type of plant – for instance, whether it’s an impoundment plant (i.e., one that collects precipitation and glacier runoff) or a pumped-storage plant. EPFL recently coordinated the EU’s biggest R&amp;D program on hydropower facilities, called XFLEX Hydro. The program studied small-scale modifications that can be made to hydropower plants to increase their capacity, so as to improve the overall reliability of Europe’s power grids. The technology developed under the program can enhance the ancillary services provided by grid operators – the services that continually match supply with demand – which will help keep local and regional grids reliable and make them resilient to fluctuations in the energy supply, both now and in the future.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1721953932379-e9632e06.jpg" style="width: 100%px;" class="fr-fic fr-dib">Illustration © Eric Buche<h2 id="isPasted">Batteries to the rescue</h2>When it comes to intraday load balancing, batteries can be a powerful ally. Paolone believes that lithium batteries will be a key feature in tomorrow’s decarbonized power grids. “They deliver very high yields and can quickly switch between absorbing and injecting electricity,” he says. “These capabilities will be essential for managing primary reserves. In addition, lithium batteries will soon be able to complete tens of thousands of cycles. That’s a huge benefit for grid operators. The power stations they build are intended to last 10 or 20 years, and the technology is starting to be compatible with that time frame.”What’s more, the potential is already out there. “The world’s power grids will need a total battery capacity of around 180 GWh/year by 2035,” says Paolone. “And at roughly the same time, some 100 GWh to 200 GWh of capacity will become available as electric vehicle (EV) batteries reach end-of-life. It’s a perfect match.” There are still some technological hurdles to overcome, however. Engineers at DESL are developing methods for measuring car batteries’ residual capacity in order to give them a second life. “We can now determine how many and which cycles second-life batteries can run through within a power grid cycle,” says Paolone. “Given that a grid’s cycles are much less intense than those in cars, these batteries could be useful for several more years.”<h2>Building a stronger grid</h2>The second way that the transition to renewables will impact power grids relates to the grid infrastructure itself. Paolone explains: “We need more power transmission lines. Today, transmission lines at all levels – from very high voltage to distribution – are currently operating at full capacity during certain periods, and this issue will continue to worsen over time.” In Switzerland, assuming nuclear power is phased out and all personal vehicles and residential heating units are electric, we’ll need around 40 GWp of photovoltaic power. But the DESL model shows that medium-voltage power lines start getting congested at 13 GWp. So the country will need to make hefty investments to upgrade its power infrastructure.Local, decentralized power storage systems – or in other words, batteries – would help reduce the need for new power lines. DESL engineers have designed optimization algorithms that, based on the solar power generated within a community and the load on the local grid, can precisely identify where storage systems should be installed and where grid capacity needs to be expanded to minimize the community’s electricity costs.Yet there’s another problem standing in the way of finding the optimal energy mix, power storage system and load balancing strategy. “Today, our grids remain stable and reliable due to effective control over power generation, as well as robust grid planning and operational processes,” says Paolone. “That’s possible because we have relatively few power stations to manage. But what will happen when we have millions of decentralized power generators that are outside the control of grid operators? When 1 GW of today’s nuclear power is replaced by 5 GWp of distributed solar panels, how will that be managed? There’ll be an explosion in the number of variables that grid operators will have to juggle. Technically, we could supply all our power needs with photovoltaics, but that would require making major changes to our grid control systems, transmission and distribution systems, and electricity market.”Of course, there’s still the demand part of the equation. Another way to reduce our need for power storage is to gain better control over variations in demand. “If we’re able to effectively modulate the load on the grid, then we can do just about anything,” says Paolone. Technology being developed in this direction includes control systems for EV charging stations, bidirectional EV charging and real-time variable electricity pricing.

To transition away from fossil fuels and towards renewables – which are intermittent by nature – we’ll need to rework our entire system of power storage, transmission and distribution.

Renewable energy puts power grids to the test

Researchers from ITMO University have managed to improve the efficacy of perovskite solar cells with the help of silicon nanoantennas, which increase the concentration of light in the material at certain wavelengths. In the future, specialists can employ the new method to create solar cells for indoor lighting and even the space industry. The results of the study are <a href="https://www.sciencedirect.com/science/article/abs/pii/S138589472404258X" target="_blank" id="isPasted">published</a> in Chemical Engineering Journal.Solar panels are the driving force of wireless autonomous electronics. At their core are solar cells – electronic devices that convert light directly into electricity. The main obstacle to the widespread use of solar panels is their low efficiency: the maximum efficiency of solar panels at top laboratories reaches values of just about 26%. However, even the 26% figure is hard to obtain, as physicists have to comply with strict requirements such as sterile rooms and materials.Solar cells and batteries in general can be improved by developing semiconductor materials that efficiently absorb light. Perovskites are considered promising since they are light, thin, and easy-to-produce and can be used to make thin solar cells with varied bending shapes, low weight, and multiple applications. Like other semiconductors, perovskites, however, absorb just a fraction of the spectrum and therefore generate less energy than they receive from the source.To that end, ITMO scientists have developed perovskite solar cells using silicon-based optical resonant nanoantennas. Depending on their size and refractive index, nanoantennas resonantly scatter light, thus increasing its concentration in the perovskite at certain wavelengths (in this case, 500-800 nm). The method is suitable for different types of perovskite-based semiconductors that absorb light in various spectral ranges.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1720662640362-1381101.png" style="width: 100%px;" class="fr-fic fr-dib">A nanoantenna solution. Photo courtesy of Lev LogunovIn an experiment, the physicists infused several nanoparticle solutions into a solar cell to magnify light in various wavelengths: blue, green, yellow, red, and near IR. The specialists tested the obtained samples via a sun simulator and measured the conversion rate.&nbsp;The experiment showed that the efficiency of the cells increased as compared to the initial samples, which demonstrated a 19% rate. The best effect was achieved in two solutions of nanoantenna particles. The sample with nanoparticles with an average size of 160 nm showed a maximum efficiency of up to 20.5%; the efficiency of a sample with 140 nm nanoparticles, which scatter light in the green wavelength range, increased to 20.3%. The researchers are satisfied with the results of the study, as it was achieved in genuine systems, rather than in an ideal laboratory environment, which means the method can be massively introduced for a broader class of perovskite solar cells.“We’re going to further improve our solar cells and broaden the range of their uses; in particular, we want to adapt them for diffuse sources (such as indoor lighting solutions), which come with their own spectral properties. We'll also continue our work with nanoantennas. Perhaps, in the future, our solar cells will be used underwater or even in space,” -says&nbsp;Aleksandra Furasova, the first author of the paper and a researcher at the Laboratory of Hybrid Nanophotonics and Optoelectronics of ITMO’s Faculty of Physics.

Perovskite solar cells with nanoantennas. Photo by Dmitry Grigoryev / ITMO.NEWS

Researchers from ITMO University have managed to improve the efficacy of perovskite solar cells with the help of silicon nanoantennas, which increase the concentration of light in the material at certain wavelengths.

Solar Cells Made More Efficient Thanks to Silicon Nanoantennas

The sun’s rays are the source of all the Earth’s renewable energy. This manna from heaven supplies the equivalent of one barrel (159 liters) of oil per square meter per year – at least in sunny regions, like Switzerland’s canton of Valais – at no cost.What’s more, our capacity for turning solar energy into electrical power is on the rise. That’s partly because engineers are constantly making improvements to boost the yields of photovoltaic (PV) cells, and partly (or even mostly) because both supply and demand for these units are booming. Nearly 375 GW of solar-panel capacity was installed globally in 2023. That’s four times more than in 2019 and 20 times more than in 2010. It’s a lot, but still not enough.Christophe Ballif, the head of EPFL’s Laboratory of Photovoltaics and Thin-Film Electronics (PV Lab) in Neuchâtel, puts these figures in perspective: “By 2050, we’ll need to replace 80% of the fossil fuels we currently use with clean energy. It’s a huge challenge. If we continue at the same pace as in 2023, when 375 GW of solar capacity and 110 GW of wind capacity were installed, then it’ll take around 120 years to get there. But our goal is to accomplish the energy transition in 30 years – a more reasonable time frame in light of the climate crisis. That means we’ll need to increase annual solar capacity installation by a factor of nearly four, to 1,500 GW.” Yet he thinks this is possible: “China has invested between $60 billion and $80 billion over the past three years in new manufacturing capabilities for everything from polysilicon to complete solar units. By next year at the latest, it should have the required production capacity. But this Herculean effort on the supply side is actually coming a little too soon. We’re clearly in a situation of overcapacity.”<h2>A combination of solar and wind</h2>Solar power will make up a sharply growing share of the world’s energy mix, which is good news. In Switzerland, the government has introduced targets for transitioning to solar and other kinds of renewable energy by 2050. The goal is to have renewables supply 45 TWh, or more than half of the country’s total power demand based on current levels. Experts agree that the most effective way to reach this target is to combine solar with other forms of clean energy: hydropower, of course, but ideally also a sizable amount of wind power.To be employed with power grids, both solar and wind power need to be coupled with one or more storage systems such as batteries, dams and synthesis gas. For batteries in particular (including EV batteries), China is once again the world’s manufacturing powerhouse. Here too, the country has made massive investments in new facilities. “China is flooding the market and overproducing to the point where prices are collapsing, for both batteries and solar units,” says Ballif. “That’s good for consumers and the energy transition in general, but it will create a form of dependency that we don’t want. Governments in other regions, including in Europe, need to build and expand their manufacturing capacity in order to make the market more resilient.”<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1717983897855-8cd2ff71.jpg" style="width: 100%px;" class="fr-fic fr-dib">Illustration Éric Buche<h2 id="isPasted">Neuchâtel: A hub of yield-boosting technology</h2>That said, it’s not easy to invest in capacity when you’re up against that kind of competition. But it is possible to find ways of doing things better, or differently. Engineers at Ballif’s lab and at the Centre Suisse d’Électronique et de Microtechnique (CSEM) in Neuchâtel, where Ballif also heads a research group, have developed methods for considerably increasing the yields of PV cells. Some of their technology is being implemented in China’s new factories. For instance, the engineers designed “tandem” cells consisting of a perovskite layer deposited on a silicon cell. These devices set a new world record for power conversion efficiency and broke through the symbolic 30% yield barrier.A number of solar-energy startups have popped up in and around Neuchâtel, building on the research conducted by researchers there. Some of those companies are developing systems for integrating PV cells into a building’s architecture through panels and tiles with customizable colors (these firms include Freesuns, Solaxess and SwissINSO), while others are creating systems specifically for farming applications (Insolight and Voltiris). “It’s true that these startups operate in niche markets,” says Ballif. “But as far as Switzerland is concerned, their technology can go a long way towards meeting the government’s targets.” They’re also proof that Swiss businesses aren’t about to throw in the towel. Just look at Thun-based 3S, which recently built a new 200 MW/year production line for solar panels that can be integrated into buildings, and Meyer Burger, which now has a total production capacity of 1 GW/year at sites in Europe. Both these companies leverage technology developed in association with CSEM and EPFL.Forecasts by the Swiss Federal Office of Energy indicate that solar power will be a key component of the country’s energy mix in 2050 (see infographic). “The potential for solar is definitely there,” Ballif explains. “PV cells can be integrated into buildings’ architecture, placed on top of supermarkets and their parking lots, for example, and installed on mountains, where models with bifacial panels – which can also capture the sunlight that reflects off snow – are particularly effective during the winter. Switzerland’s total installed capacity was 1.5 GW in 2023, which can generate 1.5 TWh of solar power per year. This renewable energy should reach 10% of our energy mix in 2024. So it’s on track to make a major contribution to the government’s goal of having 45 TWh of power come from renewables.”<h2>Reshaping geopolitics</h2>Looking at the bigger picture, the pressure that Chinese manufacturers are putting on the prices of PV and wind components, batteries and electrolyzers could substantially alter the geopolitical playing field. “At these prices, operators could build plants in Africa’s deserts and generate power at less than 1.3 cents per kWh. That’s five to ten times cheaper than the cost at newly built nuclear plants. This would make it more economical to produce clean hydrogen by water electrolysis than to produce grey hydrogen from natural gas,” says Ballif. “Another option could be to turn the hydrogen into ammonia, initially for use in crop fertilizer and later for transporting energy to Europe.”If renewable energy gets that cheap, many governments and businesses could be tempted to ramp up their support for the energy transition, simply because it makes financial sense. That would be a blow to oil-exporting nations like Russia and Saudia Arabia. “China may be saving the planet – but that will create other challenges!” says Ballif.<hr>For more details, take a look at our longread "<a href="https://longread.epfl.ch/en/dossier/energies-go-green/" target="_blank" id="isPasted">Energies go green</a>".

Solar energy, which is both abundant and free, is poised to become the world’s leading power source by 2050. © iStock

Solar energy, which is both abundant and free, is poised to become the world’s leading power source by 2050. That’s thanks largely to technological advances and the unbridled manufacturing of solar cells, which bodes well for a successful energy transition.

The bright future of solar energy

Lower-income communities across the United States have long been much slower to adopt solar power than their affluent neighbors, even when local and federal agencies offer tax breaks and other financial incentives.But, commercial and industrial rooftops, such as those atop retail buildings and factories, offer a big opportunity to reduce what researchers call the “solar equity gap,” according to <a href="https://www.nature.com/articles/s41560-024-01485-y" data-extlink="" target="_blank">a new study</a>, published in Nature Energy and led by researchers at Stanford University.“The solar equity gap is a serious problem in disadvantaged communities, in part because of income inequalities, but also because residential solar isn’t usually practical for people who don’t own their homes,” said <a href="https://profiles.stanford.edu/ram-rajagopal" data-extlink="" target="_blank">Ram Rajagopal</a>, senior author of the study and associate professor of <a href="https://cee.stanford.edu/" data-extlink="" target="_blank">civil and environmental engineering</a> and of <a href="https://ee.stanford.edu/" data-extlink="" target="_blank">electrical engineering</a> at Stanford. “This new study shows that commercial and industrial properties have the capacity to host solar resources to fill in part of that gap.”<h2>Untapped resources</h2>First, the bad news. The researchers found that non-residential rooftops generate 38% less electricity in disadvantaged communities than in wealthier ones. That gap, which is mainly because of lower deployment in poorer areas, has widened over the past two decades. Nevertheless, this gap is significantly lower than that of residential solar in these neighborhoods.The good news, the researchers say, is that non-residential buildings have large unused capacity to produce solar power for their own benefit and to supply the communities around them. In low-income communities, commercial enterprises may be more responsive to government incentives for solar power than households are. <a href="https://engineering.stanford.edu/magazine/solar-panels-are-largely-confined-wealthy-americans" target="_blank">An earlier study</a> by the same researchers found that residential customers in disadvantaged communities, who may have fewer financial resources and often don’t own their homes, show less response to tax breaks and other financial inducements.“Using Stanford’s <a href="https://deepsolar.web.app/" data-extlink="" target="_blank">DeepSolar</a> database, we estimated that solar arrays on non-residential buildings could meet more than a fifth of annual residential electricity demand in almost two-thirds of disadvantaged communities,” said <a href="https://de.linkedin.com/in/moritz-wussow-35082453?original_referer=https%3A%2F%2Fwww.google.com%2F" data-extlink="" target="_blank">Moritz Wussow</a>, the study’s lead author.“Also, the raw cost of that power would be less in many communities than the residential rates that local electric utilities charge,” said Wussow, who was a visiting student researcher in Rajagopal’s lab group in 2022 and 2023.To quantify the distribution of non-residential solar power installations, the researchers used satellite images and artificial intelligence to identify the number and size of rooftop solar arrays in 72,739 census tracts across the United States. About one-third of those tracts are deemed disadvantaged by the U.S. government.The team tracked non-residential solar deployment as well as the amount of unused rooftops that would be good candidates for solar installation from 2006 through 2016 and then again for 2022. They then calculated the average annual cost of producing solar electricity in each area, based on the amount of local sun exposure and other variables. The costs ranged from about 6.4 cents per kilowatt-hour in sun-drenched New Mexico to almost 11 cents in Alaska. But those costs were lower than residential electricity rates in many of those areas – even in many northern states.<a href="https://www.linkedin.com/in/chad-zanocco-582a031a" data-extlink="" target="_blank">Chad Zanocco</a>, a co-author of the new study and a postdoctoral fellow in civil and environmental engineering, noted that getting the power to residential areas would include other costs, such as battery storage and the construction of microgrids.“We estimate that battery storage would increase total system costs by about 50%, but even that would be practical in almost two-thirds of the disadvantaged communities we studied,” Zanocco said.<h2>Economies of scale</h2>If commercial and industrial solar arrays can feed their surplus electricity into local power grids, the researchers write, lower-income residents could gain access through community subscriptions rather than by building their own rooftop panels. Commercial and industrial sites also offer greater economies of scale, compared to individual household solar panels. Another big advantage is that non-residential power customers could also be highly sensitive to tax incentives and other government inducements, leading to greater adoption.Further lowering barriers, the researchers noted, is the Inflation Reduction Act of 2022 which has provided billions of dollars for states and local communities for clean-energy infrastructure. That money has already reduced the cost of new microgrids.“Beyond reducing carbon emissions and slowing climate change, increased access to solar power would offer tangible local benefits to lower-income communities,” said <a href="https://www.linkedin.com/in/zhecheng-wang-96287b132/" data-extlink="" target="_blank">Zhecheng Wang</a>, a co-author and a postdoctoral fellow at Stanford’s Institute for Human-Centered Artificial Intelligence.“This would promote local clean and low-cost energy generation, which would also increase the resilience from outages and reduce the pollution caused by fossil fuel power plants – many of which are located in low-income areas.”Additional Stanford co-authors on the paper are:&nbsp;<a href="https://www.linkedin.com/in/rajanieprabha" data-extlink="" target="_blank">Rajanie Prabha</a>, a PhD student in Civil &amp; Environmental Engineering;&nbsp;<a href="https://profiles.stanford.edu/june-flora" data-extlink="" target="_blank">June Flora</a>, a senior research scholar in Civil &amp; Environmental Engineering, and in Stanford’s School of Medicine; and&nbsp;<a href="https://profiles.stanford.edu/arun-majumdar" data-extlink="" target="_blank">Arun Majumdar</a>, dean of Stanford Doerr School of Sustainability, professor in the departments of Energy Science &amp; Engineering, of Mechanical Engineering, and of Photon Science at SLAC National Accelerator Laboratory, and senior fellow at the Precourt Institute and Stanford Woods Institute for the Environment. Civil &amp; Environmental Engineering is a joint department of the&nbsp;<a href="https://engineering.stanford.edu/" target="_blank">Stanford School of Engineering</a>&nbsp;and the Stanford Doerr School of Sustainability.&nbsp;<a href="https://www.is.uni-freiburg.de/mitarbeiter-en/team/dirk-neumann" data-extlink="" target="_blank">Dirk Neumann</a>, a professor of information systems research at Albert-Ludwigs-Universität in Freiburg, Germany, is also a co-author. Ram Rajagopal is also co-director of the Bits &amp; Watts Initiative at the&nbsp;<a href="http://energy.stanford.edu/" data-extlink="" target="_blank">Precourt Institute for Energy</a>, which is part of the&nbsp;<a href="https://sustainability.stanford.edu/" data-extlink="" target="_blank">Stanford Doerr School of Sustainability</a>.

What measures can be taken to reduce the "solar equity gap"? | Image courtesy of Hans Wilschut

A new study finds that factory and warehouse rooftops offer a big untapped opportunity to help disadvantaged communities bridge the solar energy divide.

Stanford-led research shows how commercial rooftop solar power could bring affordable clean energy to low-income homes

As network reliability is&nbsp;increasingly tested by aging power infrastructure and the complex demands of renewable energy, cellular IoT provides timely solutions. LTE-M or NB-IoT provide a ready-made connectivity solution for smart grids because they are robust, wireless technologies tailor-made for large scale IoT deployments like sensor networks and smart meters.&nbsp;<h2>Feeling the heat&nbsp;</h2>Temperatures around 32 degrees Celsius are common in Northern India in July. Yet at 2:30am on July 30, 2012, two of the country’s four power grids were under such intense pressure circuit breakers began to trip. Soon India was in the grip of the largest power outage in history. And just when the grid returned to normal, it failed again on an even larger scale. An estimated 670 million people were affected in the ensuing chaos.&nbsp;&nbsp;At the time, India’s power network—like many countries—was aging and complex. It had been built to distribute conventional energy sources in straightforward ways. Constructed in the 1960s and 70s, the infrastructure was designed to support the one-way flow of energy from centralized power stations to consumers. It performed satisfactorily but lacked the flexibility and control to deal with new power sources.&nbsp;&nbsp;<h2>Renewables enter the energy mix&nbsp;</h2>Today, a lot of power in India and elsewhere is still generated using conventional power stations, but many other power sources are also used. Today, almost a third of electricity worldwide comes from renewable sources according to the International Energy Agency (IEA). Solar photovoltaic (PV) installations, wind farms, hydro power, geothermal and bioenergy all contribute.&nbsp;&nbsp;Many of these power sources are highly variable, so they need to be switched in and out quickly and efficiently as conditions dictate. But existing grids simply don’t have the inbuilt flexibility to manage all the added demands and intricacies renewable energy brings. And the rapid growth of the electric vehicle (EV) fleet, with its inherent recharging demands, puts even more strain on already struggling power infrastructure. So, how can the world’s distribution networks keep up with the increasingly complex nature of today’s mixed power portfolio yet still minimize outages?&nbsp;<h2>The&nbsp;IoT&nbsp;is the key&nbsp;</h2>Since its problems early in the last decade, India has invested millions in smart grid technology and smart metering to help prevent a recurrence of mass power outages. Smart grids use a network that supports the bidirectional energy flow and communication between many different generation sources and loads. Such a grid relies on the IoT to take advantage of information from sensors to encourage collaborative actions between the utility and its customers.&nbsp;For example,&nbsp;<a href="https://www.nordicsemi.com/Products/Wireless/Low-power-cellular-IoT" target="_blank">low power cellular IoT</a>&nbsp;can be used to monitor grid conditions, detect faults, and trigger preemptive maintenance before an outage occurs. No matter how geographically remote parts of the grid might be, if there’s cellular coverage, LTE-M or NB-IoT connected sensors can be installed on network infrastructure to flag malfunctions, power surges, fires, and even a transmission tower collapse. IoT sensors can also be used to trigger reclosers and other switching equipment to rapidly connect and disconnect energy sources.&nbsp;The IoT also helps speed up the return to service after problems. For example, before the IoT, fault detection relied on customers reporting a problem. Maintenance crews were then sent to locate the fault (which could take hours), then isolate lines, and restore power. It was a lengthy process especially in remote areas. Now, by using the Global Navigation Satellite Systems (GNSS) capability built into cellular IoT devices such as Nordic’s&nbsp;<a href="https://www.nordicsemi.com/Products/nRF9160" target="_blank">nRF9160</a>, the location of any faults can be accurately pinpointed and lines remotely isolated - saving time and resources.&nbsp;<h2>The non-cellular alternative for IoT&nbsp;</h2><a href="https://www.nordicsemi.com/Products/Wireless/DECT-NR" target="_blank">DECT NR+</a>&nbsp;(“NR+”) a non-cellular technology which supports kilometer range and up to one million devices per square kilometer, is highly scalable and offers enterprises such as solar or wind farms a standardized IoT alternative to existing proprietary technology. The technology operates on the global and license-exempt 1.9 GHz band.&nbsp;&nbsp;Designed with an emphasis on ultra-high reliability and ultra-low latency, NR+ enables the replacement of low latency wired systems with equivalent wireless communications in enterprise applications across the energy distribution grid. A further advantage is that NR+ cuts deployment costs by eliminating data charges and the need for certification from operators.&nbsp;<h2>Machine Learning (ML)&nbsp;sifts out the&nbsp;important data&nbsp;</h2>Devices such as Nordic’s nRF9160 SiP incorporate powerful processors that can support machine learning (ML) at the edge of the network. ML models can be used to reliably distinguish between a significant and insignificant event on the grid eliminating transmission of unimportant data to the Cloud.&nbsp;&nbsp;Instead, the device only sends a notification when it determines intervention is required. This not only lowers costs, but it also reduces the power consumption of potentially millions of devices operating in remote environments where battery replacement is simply impractical.&nbsp;While wind can’t be relied on to constantly blow, and sunlight can’t be relied on to continuously shine on solar panels. But what is a little more reliable is the many years of historical data. Because of this data, variations in wind and sunlight are largely predictable allowing grid operators to program ML models accordingly. The models can then supervise energy source switches ahead of anticipated variability.&nbsp;&nbsp;<h2>Stabilizing the grid&nbsp;with the IoT&nbsp;</h2>While historical data can be used to predict variable energy inputs, at the other end of the supply chain, utilities can incentivize customers to shift or shed electricity demand to help with grid balancing. The IoT helps here too with cellular IoT-powered smart meters not only measuring and recording electricity consumption and generation, plus communicating this information to consumers and utilities, but also receiving signals from utilities or other service providers such as price changes or other incentives designed to limit consumption.&nbsp;Cellular IoT provides a ready-made connectivity solution for “demand response” strategies. Using the IoT, demand response can be controlled automatically and seamlessly to reduce peak consumption and enable the aggregation and remote control of smaller dispersed renewable resources. According to the International Energy Agency (IEA), the U.S. has 200 gigawatts of cost-effective load flexibility potential that could be realized by 2030 if effective demand response is actively pursued.&nbsp;<h2>The Internet of Energy&nbsp;</h2>With fast, high-quality wireless networks, energy consuming devices can be connected to the smart grid to form the ‘The Internet of Energy’. Such a network will allow energy companies to optimize resources and maximize grid performance. Governments can develop informed policies and regulation, and consumers can save money. It’s a win-win-win for the smart grid of the future, and the planet.&nbsp;

As network reliability is increasingly tested by aging power infrastructure and the complex demands of renewable energy, cellular IoT provides timely solutions. 

Ensuring distribution network reliability in the age of renewable energy

Research and industry worldwide are working on the commercialization of perovskite photovoltaics.&nbsp;Most research laboratories focus on solvent-based manufacturing processes because they are versatile and easy to use.&nbsp;However, established photovoltaic companies today rely almost exclusively on vacuum processes to deposit high-quality thin films.&nbsp;An international consortium led by the Karlsruhe Institute of Technology (KIT) and the US Department of Energy's National Renewable Energy Laboratory (NREL, USA) has analyzed this critical discrepancy between laboratory and industry.&nbsp;They emphasize: Industrially proven vacuum processes could, with certain improvements, contribute to the rapid commercialization of perovskite solar cells.&nbsp;The results appeared in&nbsp;Energy &amp; Environmental Science (DOI:&nbsp;<a href="https://pubs.rsc.org/en/content/articlepdf/2024/ee/d3ee03273f" target="_blank">10.1039/d3ee03273f</a> ).Perovskite-silicon tandem solar cells have undergone rapid development in the past ten years: Efficiencies of more than 33 percent have been achieved in research.&nbsp;This means they are already better than conventional silicon-based solar cells.&nbsp;However, it is still not ready for the market.&nbsp;One of the hurdles is the unresolved question of which process can best be used to produce perovskite solar cells as a mass product.&nbsp;Solvent-based manufacturing processes that are used in laboratories worldwide are contrasted with vapor phase deposition processes in vacuum, which are still standard today in the production of thin films in photovoltaics or in the production of organic light-emitting diodes (OLEDs). &nbsp; In a current comparative study, an international consortium of academic and industrial partners led by NREL and KIT revealed major differences in the scientific approach to these production processes.&nbsp;Tenure-track professor Ulrich W. Paetzold from the Institute of Microstructure Technology and the Light Technology Institute of KIT explains: “98 percent of all scientific studies in 2022 were published on solvent-based processes.&nbsp;Vacuum-based processes that have proven themselves in industry for decades and could significantly advance the commercialization of solar cells are neglected.”To explain: Solvent-based production uses inks in which organic and inorganic salts are dissolved in a solvent.&nbsp;These inks can then be deposited onto the surface of a substrate via various printing techniques.&nbsp;In contrast, vacuum-based manufacturing uses dry and solvent-free processes.&nbsp;The materials are sublimated in a vacuum with the addition of heat, i.e. transferred from the solid to the gaseous state and condensed on the substrate surface.&nbsp;In principle, it is also possible to combine both processes for the production of perovskite solar cells.<h2>Laboratory efficiencies and throughput are not everything when it comes to mass production</h2>In the study, the authors analyzed the advantages and disadvantages of both methods.&nbsp;The dominance of solvent-based production in research so far lies in its uncomplicated handling in laboratories, which is the reason for very good results in terms of efficiency under laboratory conditions and its low costs.&nbsp;In addition, there is the possible scalable roll-to-roll production, i.e. endless deposition between two rolls, similar to newspaper printing.In comparison, the vacuum-based production process causes slightly higher investment costs and, based on the processes used in research, is currently still behind in terms of deposition speed, i.e. production throughput.&nbsp;However, the authors show a variety of possible solutions and estimate that it is competitive taking into account real parameters such as electricity costs, production yield, material, decommissioning or recycling costs.&nbsp;Above all, the good repeatability of the deposition, the simple process control, the availability of industrial process equipment and the easy scaling of the deposition from small solar cell areas in the laboratory to application-relevant product areas make the process highly interesting for commercialization.&nbsp;“Vacuum-based production performs better than its reputation,” says Tobias Abzieh.&nbsp;It is therefore not surprising that the authors, in a first-ever published overview of commercialization activities in perovskite technology, were already able to demonstrate a lively interest in vacuum-based processes for the production of perovskite solar cells on the part of industry - despite the discrepancy in this regard on the method mainly used in research.In order for vacuum-based processes to fully exploit their scaling effects, the manufacturing method still needs to be further improved, according to the researchers. Among other things, further research must be carried out on the quality of the separation in order to further increase the efficiency. It is also important to significantly increase the speed of deposition. “Vacuum-based manufacturing processes are not only the industry’s first choice when it comes to bringing thin-film technologies to market maturity. Our analysis also shows that the processes are competitive with solvent-based approaches,” adds David More from NREL.<hr>Original publicationTobias Abzieh, David T. Moore, Marcel Roß, Steve Albrecht, Jared Silvia, Hairen Tan, Quentin Jeangros, Christophe Ballif, Maximilian T. Hoerantner, Beom-Soo Kim, Henk J. Bolink, Paul Pistor, Jan Christoph Goldschmidt, Yu -Hsien Chiang, Samuel D. Stranks, Juliane Borchert, Michael D. McGehee, Monica Morales-Masis, Jay B. Patel, Annalisa Bruno and Ulrich W. Paetzold: Vapor phase deposition of perovskite photovoltaics: short track to commercialization? Energy &amp; Environmental Science, 2024. DOI: 10.1039/d3ee03273f

Perovskite photovoltaics promise high levels of efficiency. Researchers from KIT and partners have now analyzed different production approaches. (Photo: Tobias Zieher)

Various production approaches in research and industry – comparative study explores paths to mass production

Perovskite Solar Cells: Vacuum Process Can Lead to Market Readiness

Energy is everywhere, affecting everything, all the time. And it can be manipulated and converted into the kind of energy that we depend on as a civilization. But transforming this ambient energy (the result of gyrating atoms and molecules) into something we can plug into and use when we need it requires specific materials.These energy materials — some natural, some manufactured, some a combination — facilitate the conversion or transmission of energy. They also play an essential role in how we store energy, how we reduce power consumption, and how we develop cleaner, efficient energy solutions.“Advanced materials and clean energy technologies are tightly connected, and at Georgia Tech we’ve been making major investments in people and facilities in batteries, solar energy, and hydrogen, for several decades,” said&nbsp;<a href="https://ae.gatech.edu/directory/person/timothy-charles-lieuwen" target="_blank">Tim Lieuwen</a>, the David S. Lewis Jr. Chair and professor of aerospace engineering, and executive director of Georgia Tech’s Strategic Energy Institute (<a href="https://research.gatech.edu/energy" target="_blank">SEI</a>).That research synergy is the underpinning of&nbsp;<a href="https://research.gatech.edu/energymaterials" target="_blank">Georgia Tech Energy Materials Day (March 27)</a>, a gathering of people from academia, government, and industry, co-hosted by SEI, the Institute for Materials (<a href="https://research.gatech.edu/materials" target="_blank">IMat</a>), and the Georgia Tech Advanced Battery Center. This event aims to build on the momentum created by&nbsp;<a href="https://research.gatech.edu/georgia-tech-battery-day-reveals-opportunities-energy-storage-research" target="_blank">Georgia Tech Battery Day</a>, held in March 2023, which drew more than 230 energy researchers and industry representatives.“We thought it would be a good idea to expand on the Battery Day idea and showcase a wide range of research and expertise in other areas, such as solar energy and clean fuels, in addition to what we’re doing in batteries and energy storage,” said&nbsp;<a href="https://www.mse.gatech.edu/people/matthew-mcdowell" target="_blank">Matt McDowell</a>, associate professor in the George W.&nbsp;<a href="https://www.me.gatech.edu/" target="_blank">Woodruff School of Mechanical Engineering</a> and the&nbsp;<a href="https://www.mse.gatech.edu/" target="_blank">School of Materials Science and Engineering (MSE)</a>, and co-director, with&nbsp;<a href="https://www.mse.gatech.edu/people/gleb-yushin" target="_blank">Gleb Yushin</a>, of the Advanced Battery Center.Energy Materials Day will bring together experts from academia, government, and industry to discuss and accelerate research in three key areas: battery materials and technologies, photovoltaics and the grid, and materials for carbon-neutral fuel production, “all of which are crucial for driving the clean energy transition,” noted&nbsp;<a href="https://www.mse.gatech.edu/people/eric-vogel" target="_blank">Eric Vogel</a>, executive director of IMat and the Hightower Professor of Materials Science and Engineering.“Georgia Tech is leading the charge in research in these three areas,” he said. “And we’re excited to unite so many experts to spark the important discussions that will help us advance our nation’s path to net-zero emissions.”<h2>Building an Energy Hub</h2>Energy Materials Day is part of an ongoing, long-range effort to position Georgia Tech, and Georgia, as a go-to location for modern energy companies. So far, the message seems to be landing. Georgia has had more than $28 billion invested or announced in electric vehicle-related projects since 2020. And Georgia Tech was recently ranked by U.S. News &amp; World Report as the&nbsp;<a href="https://research.gatech.edu/georgia-tech-named-top-ranked-public-university-energy" target="_blank">top public university for energy research</a>.Georgia has become a major player in solar energy, also, with the announcement last year of a $2.5 billion plant being developed by Korean solar company Hanwha Qcells, taking advantage of President Biden’s climate policies. Qcells’ global chief technology officer, Danielle Merfeld, a member of SEI’s External Advisory Board, will be the keynote speaker for Energy Materials Day.“Growing these industry relationships, building trust through collaborations with industry — these have been strong motivations in our efforts to create a hub here in Atlanta,” said Yushin, professor in MSE and co-founder of Sila Nanotechnologies, a battery materials startup valued at more than $3 billion.McDowell and Yushin are leading the battery initiative for Energy Materials Day and they’ll be among 12 experts making presentations on battery materials and technologies, including six from Georgia Tech and four from industry. In addition to the formal sessions and presentations, there will also be an opportunity for networking.“I think Georgia Tech has a responsibility to help grow a manufacturing ecosystem,” McDowell said. “We have the research and educational experience and expertise that companies need, and we’re working to coordinate our efforts with industry.”<a href="https://research.gatech.edu/marta-hatzell" target="_blank">Marta Hatzell</a>, associate professor of mechanical engineering and chemical and biomolecular engineering, is leading the carbon-neutral fuel production portion of the event, while&nbsp;<a href="https://research.gatech.edu/juan-pablo-correa-baena" target="_blank">Juan-Pablo Correa-Baena</a>, assistant professor in MSE, is leading the photovoltaics initiative.They’ll be joined by a host of experts from Georgia Tech and institutes across the country, “some of the top thought leaders in their fields,” said Correa-Baena, whose lab has spent years optimizing a semiconductor material for solar energy conversion.“Over the past decade, we have been working to achieve high efficiencies in solar panels based on a new, low-cost material called halide perovskites,” he said. His lab recently discovered how to&nbsp;<a href="https://coe.gatech.edu/news/2023/12/researchers-find-they-can-stop-degradation-promising-solar-cell-materials" target="_blank">prevent the chemical interactions that can degrade it</a>. “It’s kind of a miracle material, and we want to increase its lifespan, make it more robust and commercially relevant.”While Correa-Baena is working to revolutionize solar energy, Hatzell’s lab is designing materials to clean up the manufacturing of clean fuels.“We’re interested in decarbonizing the industrial sector, through the production of carbon-neutral fuels,” said Hatzell, whose lab is designing new materials to make clean ammonia and hydrogen, both of which have the potential to play a major role in a carbon-free fuel system, without using fossil fuels as the feedstock. “We’re also working on a collaborative project focusing on assessing the economics of clean ammonia on a larger, global scale.”The hope for Energy Materials Day is that other collaborations will be fostered as industry’s needs and the research enterprise collide in one place — Georgia Tech’s Exhibition Hall — over one day. The event is part of what Yushin called “the snowball effect.”“You attract a new company to the region, and then another,” he said. “If we want to boost domestic production and supply chains, we must roll like a snowball gathering momentum. Education is a significant part of that effect. To build this new technology and new facilities for a new industry, you need trained, talented engineers. And we’ve got plenty of those. Georgia Tech can become the single point of contact, helping companies solve the technical challenges in a new age of clean energy.”

Energy materials facilitate the conversion or transmission of energy. They also play an essential role in how we store energy, reduce power consumption, and develop cleaner, efficient energy solutions.

Energy Materials: Driving the Clean Energy Transition

As the world looks to phase out fossil fuels in favor of cleaner, renewable energy sources, more effort is being put into improving existing renewable technologies and creating devices that can harness renewable energy sources in new ways. Sunlight captured in solar cells is currently one of the most used renewable energy sources. However, there are also a number of other ways in which sunlight can be harnessed to produce energy.Given the amount of sun that hits the Earth each day, there is excellent potential for solar-based energy harvesting devices to become one of the front runners in a cleaner and greener society—and expand on their existing position as one of the leading renewable technologies. Designers are testing and using 2D materials in a number of these solar-harvesting systems, from the widespread use of graphene in solar cells to the use of different 2D materials in photocatalytic and photothermal harvesting approaches.<h2>Photovoltaics (Solar Cells)</h2>Of all the solar harvesting methodologies and technologies in existence, solar cells are by and far the most commercialized, most popular, and most efficient choice. There are several bulk solar cells in existence composed of silicon and perovskite materials. In addition, a number of approaches are being developed where 2D materials (and other nanomaterials) are being used to either improve the performance of bulk silicon solar cells or offer a way to create much thinner and/or more flexible solar cells. In the latter, there are already a number of flexible organic solar cells; however, the active materials tend to suffer from a much lower performance than inorganic materials, so 2D materials offer a way of providing thinner solar cells with much-improved performance.<img src="https://s3-us-west-1.amazonaws.com/wevolver-project-images/froala%2F1707665382989-nuno-marques-0GbrjL3vZF4-unsplash.jpg" style="width: 766px;" class="fr-fic fr-dib">Photo by Nuno Marques on UnsplashMany devices are in existence where doped graphene has been used as the photoactive material in the semiconducting photovoltaic junction within solar cells, sometimes on its own and other times in conjunction with silicon in bulkier solar cells. Beyond this, graphene and its derivatives are touted as an alternative for the hole transport layer instead of expensive noble metals, such as silver and gold, in an attempt to lower the cost of large-scale solar cells. Graphene is also used in conjunction with silicon in a number of other hybrid devices, including in the creation of thinner, flexible and semi-transparent solar cells.While graphene is gathering the most interest, graphene and transition metal dichalcogenides (TMDCs) are being integrated into different solar cells—because of their stability and resistance to several potentially degrading stimuli—to improve their long-term stability and ensure that they run optimally for longer. These 2D materials are being integrated into a wide range of bulk solar cells on a commercial level, including in silicon and perovskite solar cells as well as in tandem solar cells.In recent years, the interest in flexible solar cells has significantly grown, and while graphene was the first 2D material tested for solar cells, the area has since expanded and continues to do so. In recent years, TMDCs have been used alongside graphene to create efficient, flexible solar cells and perovskite materials are now being made into 2D sheets to try and emulate the success of the bulkier perovskite solar cells—but in the form of a much smaller and flexible solar cell. 2D perovskite solar cells have not yet been able to reach the heights of their bulkier counterparts, but it is a much newer addition to the 2D family, so there is still plenty of time for them to play a part in 2D material-enhanced solar cells.<h2>Photocatalytic Harvesting</h2>Photocatalytic reactions generate new greener fuels and are different from many other energy harvesting technologies where the direct output is electricity. In photocatalytic harvesting, the energy from sunlight is harvested to produce fuel, which can then be used to power devices and electronic systems. Photocatalytic harvesting is currently a promising approach in water splitting technologies to produce hydrogen fuel.<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNzA3NjY1MTg2MzAzLWFuZHJlYXMtZ3Vja2xob3JuLUlscGYyZVVQcFVFLXVuc3BsYXNoLmpwZyIsImVkaXRzIjp7InJlc2l6ZSI6eyJ3aWR0aCI6OTUwLCJmaXQiOiJjb3ZlciJ9fX0=" style="width: 766px;" class="fr-fic fr-dib">Photo by Andreas Gücklhorn on UnsplashPhotocatalytic harvesting occurs when semiconducting materials are used. The photocatalytic harvesting occurs because the photons from the sunlight (with a high energy) generate an electron-hole pair in the semiconducting material once absorbed. However, these photogenerated excited states tend to be unstable, so the charge carriers recombine. During this separation and recombination process, the electrons and holes are transported across the surface of the material, which either reduces or oxidizes the absorbed atoms. It is this process that leads to the generation of hydrogen gas, and there is a similar photocatalytic process that can be used to generate oxygen molecules as well (often at the same time).Photocatalytic reactions can be initiated using a number of materials, and a number of different semiconducting 2D materials are used for these photocatalytic harvesting reactions. In many cases, the exposed edges on the 2D sheets offer an effective site for the photocatalytic reactions to take place. TMDCs, such as molybdenum disulfide, have gathered a great deal of interest because the sheets actively absorb hydrogen ions. Graphene and its derivatives—especially doped versions to make them semiconducting—are also well-tested materials because the high surface area of both graphene and TMDCs, alongside their absorption and electrical conductivity properties, make them suitable catalytic sites for hydrogen evolution reactions (HER) to produce hydrogen fuel.<h2>Photothermal Harvesting</h2>Photothermal harvesting approaches once again offer a different approach to many conventional solar harvesting technologies. In these harvesting methods, photothermal materials are used to absorb light energy and convert it into heat energy. 2D materials have a range of optical properties that can be harnessed to absorb light waves—and subsequently convert it into heat—with some of the 2D materials exhibiting optical properties that are unique and not found in other material classes, while others having very beneficial properties in general.2D materials are known to absorb wavelengths of electromagnetic radiation across a wide spectrum, including in the visible and near-infrared regions. However, these applications are very different in that these approaches are typically used in medical applications to enable different treatments to take place. The absorption of light and generation of heat means that different medical treatments can take place without the need for more invasive approaches. For example, heat is generated in the form of a vibrational energy, and this energy can be used to target and kill cancer cells.It's an approach that is more niche in nature, and while it doesn’t power devices, different 2D materials—from graphene derivatives, to TMDCs, to MXenes—are being used to harvest light to provide new and efficient medical treatments, and photothermal therapies are becoming an interesting application area for 2D materials alongside the more conventional solar energy harvesting operations.<h2>Conclusion</h2>Solar harvesting, in the form of solar cells, is already an established technology, but 2D materials are offering a way of improving the efficiencies and long-term stabilities of solar cells as well as offering new ways of creating thin, flexible, and transparent solar cells. Beyond solar cells, 2D materials offer great potential for creating hydrogen fuel via photocatalytic reactions and harvesting light for advanced cancer therapies. As modern society looks toward more ways of harvesting our natural environment, 2D materials offer a way to harvest solar rays into a usable output efficiently.

As the world looks to phase out fossil fuels in favor of cleaner, renewable energy sources, more effort is being put into improving existing renewable technologies and creating devices that can harness renewable energy sources in new ways.

Using 2D Materials in Photo-Harvesting Applications

What happens when you expose tellurite glass to femtosecond laser light? That’s the question that Gözden Torun at the Galatea Lab, in a collaboration with Tokyo Tech scientists, aimed to answer in her thesis work when she made the discovery that may one day turn windows into single material light-harvesting and sensing devices. The results are published in&nbsp;PR Applied.Interested in how the atoms in the tellurite glass would reorganize when exposed to fast pulses of high energy femtosecond laser light, the scientists stumbled upon&nbsp;<a href="https://doi.org/10.1002/adma.202210446" target="_blank" rel="noopener">the formation of nanoscale tellurium and tellurium oxide crystals</a>, both semiconducting materials etched into the glass, precisely where the glass had been exposed. That was the eureka moment for the scientists, since a semiconducting material exposed to daylight may lead to the generation of electricity.“Tellurium being semiconducting, based on this finding we wondered if it would be possible to write durable patterns on the tellurite glass surface that could reliably induce electricity when exposed to light, and the answer is yes,” explains Yves Bellouard who runs EPFL’s Galatea Laboratory. “An interesting twist to the technique is that no additional materials are needed in the process. All you need is tellurite glass and a femtosecond laser to make an active photoconductive material.”Using tellurite glass produced by colleagues at Tokyo Tech, the EPFL team brought their expertise in femtosecond laser technology to modify the glass and analyze the effect of the laser. After exposing a simple line pattern on the surface of a tellurite glass 1 cm in diameter, Torun found that it could generate a current when exposing it to UV light and the visible spectrum, and this, reliably for months.“It’s fantastic, we’re locally turning glass into a semiconductor using light,” says Yves Bellouard. “We’re essentially transforming materials into something else, perhaps approaching the dream of the alchemist!”.<hr>References<a href="https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.21.014008" target="_blank" rel="noopener">https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.21.014008</a>

A photoconductive circuit, where the circuit is directly patterned onto a glass surface with femtosecond laser light - 2024 EPFL / Lisa Ackermann - CC-BY-SA 4.0

EPFL physicists propose a novel way to create photoconductive circuits, where the circuit is directly patterned onto a glass surface with femtosecond laser light. The new technology may one day be useful for harvesting energy, while remaining transparent to light and using a single material.

Turning glass into a 'transparent' light-energy harvester

Tandem solar cells based on perovskite semiconductors can convert sunlight into electricity more efficiently than conventional silicon solar cells.&nbsp;In order to bring this technology to market, stability and production processes must be further improved.&nbsp;Researchers from the Karlsruhe Institute of Technology (KIT) as well as the Helmholtz Imaging platforms at the German Cancer Research Center (DKFZ) and Helmholtz AI have now found a way to predict the quality of the perovskite layers and thus the solar cells: using machine learning and new artificial methods Intelligence (AI) allows this to be recognized during production from variations in light emission.&nbsp;The team reports on the results from which improved production processes can be derived in Advanced Materials (DOI: 10.1002/adma.202307160).Perovskite tandem solar cells combine a perovskite with a conventional solar cell, for example based on silicon.&nbsp;They are considered next-generation technology because, with an efficiency of currently more than 33 percent, they are much more efficient than conventional silicon solar cells - with inexpensive starting materials and simple manufacturing methods.&nbsp;The prerequisite for achieving this level of efficiency is a very high-quality and extremely thin perovskite layer, which is only a fraction of the thickness of a human hair.&nbsp;“One of the biggest challenges is to produce these high-quality so-called multicrystalline thin films using cost-effective and scalable processes without defects and holes,” explains tenure-track professor Ulrich W. Paetzold from the Institute of Microstructure Technology and the Light Engineering Institute of KIT.&nbsp;Even under apparently perfect conditions in the laboratory, unknown influences lead to fluctuations in the quality of the semiconductor layers: “This ultimately prevents the rapid start of industrial production of these highly efficient solar cells, which we so urgently need for the energy transition,” says Paetzold.<h2>AI finds hidden signs of a good coating</h2>In order to find out which factors influence the coating, an interdisciplinary team of perovskite solar cell experts from KIT teamed up with machine learning and explainable artificial intelligence (XAI) specialists from Helmholtz Imaging (at the DKFZ in Heidelberg) and Helmholtz AI ( at KIT).&nbsp;The researchers have developed AI methods that train and analyze so-called neural networks using a large data set.&nbsp;The data set includes video recordings of the photoluminescence of the perovskite thin films during the manufacturing process.&nbsp;Photoluminescence refers to the radiant emission of the semiconductor layers after excitation by an external light source.&nbsp;“Since even experts couldn’t see anything remarkable on the thin films, the idea arose to train an AI for machine learning (deep learning) to find hidden indicators of a good or bad coating in the millions of data from the videos,” explain Lukas Klein and Sebastian Ziegler from Helmholtz Imaging at the DKFZ. &nbsp; In order to filter and analyze the very broad information provided by deep learning AI, the researchers subsequently used methods of explainable artificial intelligence.<h2>“Blueprint for follow-up research”</h2>The result: In the experiment, the researchers were able to see that the photoluminescence varies during production and this influences the coating quality. “What was crucial in our work was that we specifically used XAI methods to see which factors would have to change for a high-quality solar cell,” said Klein and Ziegler. That is usually not the case. Most of the time, XAI is only used as a kind of guardrail to avoid errors when building AI models: “This is a paradigm shift, and the fact that we can systematically gain highly relevant findings in materials science in this way is new.” Because the answer is based on the variation of the Photoluminescence enabled the researchers to go further. After appropriate training of the neural networks, the AI was able to predict whether the solar cell would achieve low or high efficiency, depending on when and what variation in light emission occurred during production. “These are extremely exciting results,” says Ulrich W. Paetzold. “Thanks to the combined use of AI, we have an idea of which adjustments we need to make first in order to improve production. We can carry out our experiments in a more targeted manner and no longer have to search for a needle in a haystack in the dark. This is a blueprint for follow-up research, including for many other aspects in energy research and materials science.”<hr><h3>Original publication</h3>Lukas Klein, Sebastian Ziegler, Felix Laufer, Charlotte Debus, Markus Götz, Klaus Maier-Hein, Ulrich W. Paetzold, Fabian Isensee, Paul F. Jäger: Discovering Process Dynamics for Scalable Perovskite Solar Cell Manufacturing with Explainable AI. Advanced Materials, 2023. DOI: 10.1002/adma.202307160

With the support of AI methods, researchers want to improve the manufacturing processes for highly efficient perovskite solar cells (Photo: Amadeus Bramsiepe, KIT)

Artificial intelligence methods show researchers the way to improved manufacturing processes for highly efficient solar cells - a blueprint for other research fields

AI for Perovskite Solar Cells: Key to Better Production

Photovoltaic systems in combination with battery storage enable more independence in energy supply.&nbsp;Researchers from the Karlsruhe Institute of Technology (KIT) and their partners have investigated how great the potential is for a completely self-sufficient energy supply for residential buildings.&nbsp;In the trade magazine&nbsp;Joule they show that 53 percent of single-family homes in Europe could already become technically energy self-sufficient.&nbsp;By 2050, more than two million buildings could leave the network through additional investments of 50 percent.&nbsp;(DOI:&nbsp;<a href="https://doi.org/10.1016/j.joule.2023.09.012" target="_blank">https://doi.org/10.1016/j.joule.2023.09.012</a> )Electricity prices in Europe have been rising for years - after Russia's attack on Ukraine, they have now reached a record level, according to Eurostat calculations.&nbsp;At the same time, photovoltaics and battery storage are making it increasingly easier to become less dependent on energy suppliers.&nbsp;“By investing in local energy supply systems, a large part of one's own electricity consumption can be covered by oneself and thus the dependence on high electricity prices can be reduced,” says lead author Max Kleinebrahm, group leader at the Institute for Industrial Management and Industrial Production (IIP) at KIT.&nbsp;In Europe, building owners are increasingly opting for more independence: “In addition to economic efficiency, non-monetary aspects such as a high proportion of renewable energies, the rejection of the use of nuclear and fossil energies and a high degree of self-sufficiency also play a role in the decision increasingly important role.” A team from KIT, together with researchers from Forschungszentrum Jülich, ETH Zurich and the Paul Scherrer Institute, calculated how big the step would be from partially self-sufficient to complete self-sufficiency with electricity and heat.<h2>How much does energy independence cost in your own home?</h2>The basis for their calculations is a database in which geographically high-resolution information on the European building stock and the households living in them was combined with local climatic and economic conditions.&nbsp;By using novel methods to reduce complexity on high-performance computers, cost-optimized, energy-autonomous supply systems were initially configured for 4,000 representative single-family homes.&nbsp;In a further step, neural networks were then used to transfer the results to the 41 million single-family homes examined.&nbsp;“Under today’s conditions, 53 percent of the 41 million buildings are technically capable of powering themselves through the use of local rooftop solar radiation alone, independent of external infrastructure, and this share could rise to 75 percent by 2050 due to improved technologies,” says Professor Russell McKenna from the Swiss Federal Institute of Technology Zurich (ETH Zurich) and head of the Laboratory for Energy Systems Analysis at the Paul Scherrer Institute in Switzerland.&nbsp;“If you now assume that building owners would be willing to invest up to 50 percent more than would be necessary for a comparable energy system with a grid connection, then up to two million single-family homes could leave the power grid by 2050.”The researchers see significant potential for energy self-sufficient residential buildings, especially in regions with low seasonal weather fluctuations, such as in Spain, or with high electricity prices, such as in Germany.&nbsp;The specific design of the cost-optimized energy systems has also been determined: “Our results show that a successful, cost-optimal and self-sufficient energy supply system for buildings in Central Europe will consist of photovoltaics to generate electricity as well as a combination of short-term battery storage and a long-term, seasonal hydrogen storage system,” says Dr.&nbsp;Jann Weinand, head of department at the Research Center Jülich.<h2>More stability for the energy system</h2>In further work, the researchers want to analyze in more detail what effects a possible large-scale spread of self-sufficient energy supply systems would have on the European energy system, but they suspect a positive effect.&nbsp;“Semi-autonomous residential buildings could help to stabilize the overall energy system in the future.&nbsp;A less pronounced demand profile from households could dampen demand for peak-load power plants,” says Elias Naber from KIT’s IIP.&nbsp;“However, it would then have to be prevented that building owners become completely disconnected from the grid – for example by rewarding them with special electricity tariffs for grid-friendly behavior.”Original publication Max Kleinebrahm, Jann Michael Weinand, Elias Naber, Russell McKenna, Armin Ardone, Wolf Fichtner: Two million European single-family homes could abandon the grid by 2050. (2023) <a href="https://doi.org/10.1016/j.joule.2023.09.012" target="_blank">https://doi.org/10.1016/j.joule .2023.09.012</a>

Ahead with solar power: Over half of European single-family homes could become energy independent. (Photo: Markus Breig, KIT)

Energy harvesting

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