Solar Energy
New perovskite LED emits a spin-polarized glow
The inclusion of a special new perovskite layer has enabled scientists to create a “spin-polarized LED” without needing a magnetic field or extremely low temperatures, potentially clearing the path to a raft of novel technologies.
Details of the research conducted at the National Renewable Energy Laboratory (NREL) and the University of Utah appear in the journal Science.
Researchers at NREL and around the world have been investigating the use of perovskite semiconductors for solar cells that have proven to be highly efficient at converting sunlight to electricity. Since a solar cell is one of the most demanding applications of any semiconductor, scientists are discovering other uses exist as well.
“We are exploring the fundamental properties of metal-halide perovskites, which has allowed us to discover new applications, beyond photovoltaics,” said Joseph Luther, a co-author of the new paper, “Chiral-induced spin selectivity enabling a room-temperature spin light-emitting diode.” “Because metal-halide perovskites, and other related systems, are some of the most fascinating semiconductors, they exhibit a host of novel phenomena that can be utilized in transforming energy.”
The other co-authors from NREL are Matthew Beard, a senior research fellow and director of the Center for Hybrid Organic Inorganic Semiconductors for Energy (CHOISE), Young-Hoon Kim, Yaxin Zhai, Haipeng Lu, Chuanxiao Xiao, E. Ashley Gaulding, Steven Harvey, and Joseph Berry. Valy Vardeny and Xin Pan are co-authors from Utah. All are part of CHOISE, an Energy Frontier Research Center (EFRC) funded by the Office of Science within DOE.
The goals of the CHOISE EFRC are to control the interconversion of charge, spin, and light using carefully designed chemical systems. Most opto-electronic devices in use today only control charge and light and not the spin of the electron. An electron can have either “up” or “down” spins. Using two different perovskite layers, the researchers were able to control the spin by creating a filter that blocks electrons “spinning” in the wrong direction.
One way to produce spin-polarized currents is through a “chiral-induced spin selectivity” layer, where the transport of electrons with “up” or “down” spin states depends upon the chirality of the transporting materials. Chirality refers to the materials structure where it is not identical to its mirror image. For example, a “left-handed” oriented chiral system may allow transport of electrons with “up” spins but block electrons with “down” spins and vice versa.
The filter enabled the researchers to inject spin-polarized charges into a light-emitting diode (LED) at room temperature–instead of at hundreds of degrees below zero Fahrenheit–and without the use of magnetic fields or ferromagnetic contacts that are typically needed to control the spin degree of freedom.
The LED, in response, emits light with special chiral properties, accordingly. The concept proves that using these chiral-hybrid systems gains control over spin without magnets and has “broad implications for applications such as quantum-based optical computing, bioencoding, and tomography,” according to Beard.
Producing highly efficient LEDs based on 2D perovskite films
Hong Kong (SPX) Mar 11, 2021
Energy-efficient light-emitting diodes (LEDs) have been used in our everyday life for many decades. But the quest for better LEDs, offering both lower costs and brighter colours, has recently drawn scientists to a material called perovskite. A recent joint-research project co-led by the scientist from City University of Hong Kong (CityU) has now developed a 2D perovskite material for the most efficient LEDs.
From household lighting to mobile phone displays, from pinpoint lighting needed for endosc … read more
Solar Energy
So you want to build a solar or wind farm? Here’s how to decide where
So you want to build a solar or wind farm? Here’s how to decide where
by David L. Chandler | MIT News
Boston MA (SPX) Dec 08, 2024
Deciding where to build new solar or wind installations is often left up to individual developers or utilities, with limited overall coordination. But a new study shows that regional-level planning using fine-grained weather data, information about energy use, and energy system modeling can make a big difference in the design of such renewable power installations. This also leads to more efficient and economically viable operations.
The findings show the benefits of coordinating the siting of solar farms, wind farms, and storage systems, taking into account local and temporal variations in wind, sunlight, and energy demand to maximize the utilization of renewable resources. This approach can reduce the need for sizable investments in storage, and thus the total system cost, while maximizing availability of clean power when it’s needed, the researchers found.
The study, appearing in the journal Cell Reports Sustainability, was co-authored by Liying Qiu and Rahman Khorramfar, postdocs in MIT’s Department of Civil and Environmental Engineering, and professors Saurabh Amin and Michael Howland.
Qiu, the lead author, says that with the team’s new approach, “we can harness the resource complementarity, which means that renewable resources of different types, such as wind and solar, or different locations can compensate for each other in time and space. This potential for spatial complementarity to improve system design has not been emphasized and quantified in existing large-scale planning.”
Such complementarity will become ever more important as variable renewable energy sources account for a greater proportion of power entering the grid, she says. By coordinating the peaks and valleys of production and demand more smoothly, she says, “we are actually trying to use the natural variability itself to address the variability.”
Typically, in planning large-scale renewable energy installations, Qiu says, “some work on a country level, for example saying that 30 percent of energy should be wind and 20 percent solar. That’s very general.” For this study, the team looked at both weather data and energy system planning modeling on a scale of less than 10-kilometer (about 6-mile) resolution. “It’s a way of determining where should we, exactly, build each renewable energy plant, rather than just saying this city should have this many wind or solar farms,” she explains.
To compile their data and enable high-resolution planning, the researchers relied on a variety of sources that had not previously been integrated. They used high-resolution meteorological data from the National Renewable Energy Laboratory, which is publicly available at 2-kilometer resolution but rarely used in a planning model at such a fine scale. These data were combined with an energy system model they developed to optimize siting at a sub-10-kilometer resolution. To get a sense of how the fine-scale data and model made a difference in different regions, they focused on three U.S. regions – New England, Texas, and California – analyzing up to 138,271 possible siting locations simultaneously for a single region.
By comparing the results of siting based on a typical method vs. their high-resolution approach, the team showed that “resource complementarity really helps us reduce the system cost by aligning renewable power generation with demand,” which should translate directly to real-world decision-making, Qiu says. “If an individual developer wants to build a wind or solar farm and just goes to where there is the most wind or solar resource on average, it may not necessarily guarantee the best fit into a decarbonized energy system.”
That’s because of the complex interactions between production and demand for electricity, as both vary hour by hour, and month by month as seasons change. “What we are trying to do is minimize the difference between the energy supply and demand rather than simply supplying as much renewable energy as possible,” Qiu says. “Sometimes your generation cannot be utilized by the system, while at other times, you don’t have enough to match the demand.”
In New England, for example, the new analysis shows there should be more wind farms in locations where there is a strong wind resource during the night, when solar energy is unavailable. Some locations tend to be windier at night, while others tend to have more wind during the day.
These insights were revealed through the integration of high-resolution weather data and energy system optimization used by the researchers. When planning with lower resolution weather data, which was generated at a 30-kilometer resolution globally and is more commonly used in energy system planning, there was much less complementarity among renewable power plants. Consequently, the total system cost was much higher. The complementarity between wind and solar farms was enhanced by the high-resolution modeling due to improved representation of renewable resource variability.
The researchers say their framework is very flexible and can be easily adapted to any region to account for the local geophysical and other conditions. In Texas, for example, peak winds in the west occur in the morning, while along the south coast they occur in the afternoon, so the two naturally complement each other.
Khorramfar says that this work “highlights the importance of data-driven decision making in energy planning.” The work shows that using such high-resolution data coupled with carefully formulated energy planning model “can drive the system cost down, and ultimately offer more cost-effective pathways for energy transition.”
One thing that was surprising about the findings, says Amin, who is a principal investigator in the MIT Laboratory of Information and Data Systems, is how significant the gains were from analyzing relatively short-term variations in inputs and outputs that take place in a 24-hour period. “The kind of cost-saving potential by trying to harness complementarity within a day was not something that one would have expected before this study,” he says.
In addition, Amin says, it was also surprising how much this kind of modeling could reduce the need for storage as part of these energy systems. “This study shows that there is actually a hidden cost-saving potential in exploiting local patterns in weather, that can result in a monetary reduction in storage cost.”
The system-level analysis and planning suggested by this study, Howland says, “changes how we think about where we site renewable power plants and how we design those renewable plants, so that they maximally serve the energy grid. It has to go beyond just driving down the cost of energy of individual wind or solar farms. And these new insights can only be realized if we continue collaborating across traditional research boundaries, by integrating expertise in fluid dynamics, atmospheric science, and energy engineering.”
Research Report:Decarbonized energy system planning with high-resolution spatial representation of renewables lowers cost
Related Links
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Solar Energy
China to send batteries to Europe via route bypassing Russia: Kazakhstan
China to send batteries to Europe via route bypassing Russia: Kazakhstan
by AFP Staff Writers
Almaty, Kazakhstan (AFP) Dec 6, 2024
China will soon send lithium-ion batteries to Europe via Kazakhstan on a trade route that bypasses sanctions-hit Russia, the Central Asian country said Friday.
Trade via the Trans-Caspian International Transport Route (TITR) that crosses the Caspian Sea has jumped since Moscow invaded Ukraine in 2022, as European countries seek to avoid imports that transit Russia.
Kazakhstan has agreed to “jointly develop” the route with Beijing, launching a “trial run for the transportation of lithium-ion batteries from China” in December, Kazakhstan’s transport ministry said Friday.
China is the world’s largest producer of lithium-ion batteries and among the top miners of the metal, which is used to power phones and electric vehicles.
“The volume of transportation from China along the TITR (in the direction of China to Europe) has exceeded the equivalent of 27,000 20-foot containers, which is 25 times more than in the same period last year,” the ministry said.
The ministry also noted an increase in goods transported between China and Kazakhstan, with both sides discussing the idea of opening new transport routes across their shared border.
Europe has looked to Central Asia as a key trading partner since Moscow launched its Ukraine offensive, triggering a barrage of Western sanctions on Moscow.
Beijing has also invested billions of dollars in building rail and road routes that traverse Central Asia, as it seeks to turn the region into a trading hub for its “New Silk Road”.
Construction is underway to build a China-Kyrgyzstan-Uzbekistan railroad that will shorten transport times between China and Europe.
Related Links
Solar Energy
Meta pushes zero-carbon energy strategy with solar deal
Meta pushes zero-carbon energy strategy with solar deal
by AFP Staff Writers
Washington (AFP) Dec 5, 2024
Meta has signed contracts with renewable energy firm Invenergy for 760 megawatts of solar power capacity, the companies said on Thursday.
The deal is part of the Facebook-owner’s search for cleaner power sources, including nuclear, as its power needs expand, namely because of the adoption of artificial intelligence.
The project involves solar facilities in four US states and pushes Meta’s total renewable energy agreements with Chicago-based Invenergy beyond 1 gigawatt. Operations are expected to begin between 2024 and 2027.
The electricity will supply local power grids while Meta receives clean energy credits, supporting its goal of powering all operations with renewable energy.
“Energy demand is soaring,” said Invenergy Executive Vice President Ted Romaine, noting the projects will create jobs and generate “millions in local economic benefits.”
Meta’s Head of Global Energy Urvi Parekh said the agreement helps match the company’s growing power needs with clean energy sources.
Invenergy, the largest privately held clean energy developer in the US, said it has developed over 32,000 megawatts of renewable energy projects across the Americas, Europe, and Asia.
Meta announced plans on Tuesday to seek proposals for 1-4 gigawatts of new nuclear generation capacity in the US, targeting operations in the early 2030s.
The nuclear initiative aims to support Meta’s growing artificial intelligence operations and data centers while contributing to grid reliability.
Building AI consumes a tremendous amount of electricity because it involves intensive computing operations. It also emits a lot of CO2 when using power generated by coal or natural gas.
As tech companies seek energy sources to meet these demands while maintaining their zero-carbon emission commitments, the chase for nuclear, wind and solar power has intensified.
Meta’s push into nuclear power follows similar initiatives by Microsoft and Amazon that are also scrambling to find enough power to needs of their AI ambitions, while also meeting zero-carbon targets.
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