Solar Energy

Optimizing Thermal Stability in Solid Oxide Fuel Cells

Published

4 months ago

July 23, 2024

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Optimizing Thermal Stability in Solid Oxide Fuel Cells

by Simon Mansfield

Sydney, Australia (SPX) Jul 23, 2024

Solid oxide fuel cells (SOFCs) represent a highly efficient and clean energy conversion technology, directly converting chemical energy into electrical energy through electrochemical reactions. These cells are increasingly used for distributed and stationary power generation. However, practical application demands consideration of user operations and maintenance, which often subjects the device to significant temperature fluctuations. In residential settings, SOFC systems frequently cycle on and off based on the homeowner’s needs.

SOFCs can experience temperature changes during operation, especially when generating electricity from waste heat in industrial processes or thermal power plants, where heat supply is inconsistent. Additionally, environmental factors like diurnal temperature variations and extreme weather conditions can lead to substantial thermal fluctuations. These temperature variations cause thermal stresses due to the mismatch in the thermal expansion coefficients (TEC) of different SOFC components, potentially degrading the interfaces and reducing the power output. Therefore, maintaining thermal cycle stability is critical for the commercialization of SOFC technology.

A recent study by a team of material scientists, led by Liangzhu Zhu from the Key Laboratory of Advanced Fuel Cells and Electrolyzers Technology of Zhejiang Province, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, China, proposed a novel approach. They synthesized single perovskite oxide decorated R-P structured oxide using a self-assembly method to enhance catalytic activity and stability. This work demonstrated excellent TEC matching between strontium lanthanum ferrate and the electrolyte, showcasing its potential as a competitive air electrode for SOFCs.

“In this report, we synthesized dual-phase La0.8Sr1.2FeO4+d and La0.4Sr0.6FeO3-d by the simple self-assembly method. The single perovskite oxide, La0.4Sr0.6FeO3-d (LSF-P), with cubic structure and high catalytic activity was introduced to facilitate charge transport across the R-P structured oxides La0.8Sr1.2FeO4+d (LSF-RP) with various orientations. This approach overcomes the anisotropy inherent in the structure and concurrently enhances the catalytic activity of the composite electrode. The intimate hetero-interfaces that may form in situ between LSF-RP and LSF-P particles are anticipated to expedite the charge transfer process, thereby enhancing the ORR kinetics. We present the influence of the LSF-P content in dual phase on the phase structure, thermal expansion coefficient, electrode reaction kinetics, single cell performance under thermal cycling and reversible conditions in detail. The obtained results indicate that the incorporation of LSF-P improves the oxygen surface exchange kinetics, reduces the polarization resistance and significantly enhances the single-cell performance without sacrificing the stability of the composite electrode,” said Liangzhu Zhu, professor at Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, China.

“The TEC values of R-P oxides are comparable to those of the electrolytes commonly utilized in SOFCs. However, it is important to note that R-P oxides exhibit two-dimensional conduction. They demonstrate significant anisotropy in the diffusion of oxygen ions and electrons, with transport predominantly occurring within the a-b plane and minimal movement along the c-axis. Consequently, there is a need to modify the R-P structured material to enhance its charge transfer capability, thereby increasing their catalytic activity, without sacrificing stability for application in SOFCs,” said Liangzhu Zhu.

Introducing a secondary phase is a common strategy to boost the catalytic activity of R-P oxides. “Mechanical mixing is a relatively straightforward method for the introduction of secondary phase. While mechanical mixing can enhance electrode performance to some degree, it struggles with achieving a homogeneous distribution of the phases, which in turn restricts the interfacial contact between them. Infiltration is another alternative for introducing the second phase material. However, it is a cumbersome and time-consuming process that requires multistep operations,” said Yang Zhang, one of the co-first authors and a postdoctoral researcher at Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, China.

“The self-assembly synthesis technique for fabricating composite materials is capable of yielding thermodynamically stable and homogeneously dispersed dual-phase structures in a single, streamlined operation. By merely adjusting the ratios of the starting materials, the incorporation of the second phase can be finely tuned. Furthermore, this self-assembly approach holds significant promise for creating numerous heterogeneous structural interfaces within composite air electrodes, which in turn can significantly boost the kinetics of the oxygen reduction reaction (ORR). Additionally, the method has the potential to greatly enhance the performance of composite air electrodes by optimizing the ORR process,” said Liangzhu Zhu.

Research Report:An innovative and facile synthesis route of (La,Sr)2FeO4+d-La0.4Sr0.6FeO3-d composite as a highly stable air electrode for reversible solid oxide cell applications

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Solar Energy

More energy and oil possible through combining photovoltaic plants with hedgerow olive groves

Published

2 days ago

November 20, 2024

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More energy and oil possible through combining photovoltaic plants with hedgerow olive groves

by Hugo Ritmico

Madrid, Spain (SPX) Nov 20, 2024

The integration of photovoltaic plants on agricultural land has long sparked debate over balancing energy production with crop cultivation. Now, the innovative approach of combining both has gained momentum with promising results. This “agrivoltaic” system, which involves placing solar panels within agricultural setups, has been examined by a University of Cordoba research team to see if solar energy and agricultural production could mutually enhance each other.

The research group, including Marta Varo Martinez, Luis Manuel Fernandez de Ahumada, and Rafael Lopez Luque from the Physics for Renewable Energies and Resources group, along with Alvaro Lopez Bernal and Francisco Villalobos from the Soil-Water-Plant Relations group, developed a model that simulates an agrivoltaic system in hedgerow olive plantations. This simulation model combined predictions for oil yield from olive hedgerows and energy generation from solar collectors to assess combined productivity. The study concluded that using both in tandem increased overall productivity, marking a potential shift in land-use strategy that could cater to the needs for both clean energy and food.

The key findings show that mutual benefits arise when solar panels provide shade, acting as windbreaks that don’t compete for water, enhancing agricultural production. Meanwhile, the cooling effect from plant evapotranspiration can improve the efficiency of solar collectors by reducing their temperature, boosting energy output.

This model allows researchers to experiment with various collector configurations, adjusting heights, widths, and spacing, to pinpoint the most effective designs. Despite generally positive outcomes, the team noted that overly dense arrangements might limit space for machinery or complicate maintenance of the olive grove. The approach underscores the importance of balancing land-use density and operational accessibility.

Research Report:Simulation model for electrical and agricultural productivity of an olive hedgerow Agrivoltaic system

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Solar Energy

New initiative empowers Native American women with solar training

Published

2 days ago

November 20, 2024

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New initiative empowers Native American women with solar training

by Clarence Oxford

Los Angeles CA (SPX) Nov 20, 2024

Native American women across the country are gaining access to hands-on training in photovoltaic panel installation aimed at empowering them to establish solar systems in their communities and homes on tribal land.

Sandra Begay, an engineer at Sandia National Laboratories and a Navajo Nation member, is one of four mentors guiding this effort.

This training initiative is part of a Cooperative Research and Development Agreement between Sandia and Red Cloud Renewable, a nonprofit organization in Pine Ridge, South Dakota, that focuses on advancing energy independence for tribal members and communities.

Known as the Bridging Renewable Industry Divides in Gender Equality, or BRIDGE, Program, the initiative provides a five-week immersive training experience that emphasizes practical skills in photovoltaic installation.

In August, Begay joined the first group of participants in South Dakota.

“Five weeks is a long time to be away from home,” Begay said. “I provided encouragement and reminded the women that they made the right choice to participate in this program. We also used the time to reflect on what they learned.”

Participants are taught the components of photovoltaic systems and how to install them safely and effectively.

Begay also provided insight into the energy challenges faced by tribal communities.

“There are more than 20,000 homes on the Navajo Nation and some rural homes on the Hopi reservation that don’t have electricity. These are off-grid homes,” Begay said, noting that many of these homes depend on diesel generators. “We’re looking at a clean energy future. We want to move away from those types of fuels and look at clean energy sources such as solar.”

She highlighted that large-scale solar projects are being developed by the Navajo Nation and the Mountain Ute Tribe in Colorado.

“This program will provide participants with new employment opportunities and a better understanding of where we’re headed with clean energy,” Begay said.

Red Cloud Renewable also supports the women with resume building, interview training, networking, and job placement services.

With over 30 years of experience championing renewable energy in Native American communities, Begay is committed to maintaining relationships with participants.

“I am making a long-term commitment to the women in the BRIDGE Program,” Begay said. “I will share any job openings I see with them and support them in their job searches.”

Teamwork for success

Begay emphasized the critical role teamwork plays in photovoltaic installations.

“Photovoltaic installation happens with a team of people. How do you work through that group dynamic? How do you work with each other as a team? Those questions are underemphasized in the work we do. They’re going to rely on each other when installing photovoltaic systems,” she said.

Alicia Hayden, Red Cloud Renewable’s communications manager, noted the strong bond formed among the participants.

“What stood out to me was the incredible camaraderie among the women,” Hayden said. “They were genuinely supportive of each other and grateful to be participating in this program alongside women who share similar backgrounds.”

Funded by the Department of Energy’s Solar Energy Technology Office, the project is set to continue over the next few years and aims to train two additional groups, eventually involving around 45 women.

“These women will be equipped to take on installer jobs within their own reservations, bringing valuable skills and opportunities for sustainable development to their people,” Hayden said.

Despite being highly underrepresented in the solar industry – comprising just 0.05% of the sector, according to Red Cloud Renewable – Native American women stand to gain from this initiative.

Begay expressed optimism about the impact of the BRIDGE Program.

“It’s very gratifying both professionally and personally to see where we can help women who are underrepresented in the workforce, let alone in a unique technology like photovoltaic installation,” Begay said. “We’re seeding ideas for the women that they would never have thought of doing. I think that’s what’s unique.”

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Solar Energy

Perovskite advancements improve solar cell efficiency and longevity

Published

2 days ago

November 20, 2024

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Perovskite advancements improve solar cell efficiency and longevity

by Sophie Jenkins

London, UK (SPX) Nov 20, 2024

A global team led by the University of Surrey, in collaboration with Imperial College London, has pioneered a method to enhance the efficiency and durability of solar cells constructed from perovskite by addressing an unseen degradation pathway.

The University of Surrey’s Advanced Technology Institute (ATI) detailed their findings in ‘Energy and Environmental Science’, showing that by employing specific design strategies, they successfully created lead-tin perovskite solar cells achieving over 23% power conversion efficiency (PCE) – a significant result for this material type. Notably, these improvements also boosted the operational lifespan of these cells by 66%. PCE measures the proportion of sunlight converted to usable energy by a solar cell.

While traditional silicon solar panels are already widely used, advancements are steering towards perovskite/silicon hybrid panels, and fully perovskite-based panels promise even higher efficiencies. However, improving the stability and efficiency of lead-tin perovskite cells remains a significant hurdle. This research by the University of Surrey sheds light on mechanisms contributing to these limitations and offers a pathway to overcoming them, aiding in the broader advancement of solar technology.

Hashini Perera, Ph.D. student and lead author at ATI, stated: “The understanding we have developed from this work has allowed us to identify a strategy that improves the efficiency and extends the operational lifetime of these devices when exposed to ambient conditions. This advancement is a major step towards high efficiency, long-lasting solar panels which will give more people access to affordable clean energy while reducing the reliance on fossil fuels and global carbon emissions.”

The team focused on minimizing losses caused by the hole transport layer, crucial for solar cell functionality. By introducing an iodine-reducing agent, they mitigated the degradation effects, enhancing both the cell’s efficiency and its lifespan. This innovation paves the way for more sustainable and economically feasible solar technology.

Dr. Imalka Jayawardena from the University of Surrey’s ATI, co-author of the study, said: “By significantly enhancing the efficiency of our perovskite-based solar cells, we are moving closer to producing cheaper and more sustainable solar panels. We are already working on refining these materials, processes and the device architecture to tackle the remaining challenges.”

Professor Ravi Silva, Director of the ATI, added: “This research brings us closer to panels that not only generate more power over their lifetime but are also longer lasting. Greater efficiency and fewer replacements mean more green energy with less waste. The University of Surrey are in the process of building a 12.5MW solar farm, where we can test some of these modules. We’re confident that our innovative perovskite research will accelerate the widespread commercial adoption of perovskite-based solar panels.”

This progress aligns with the UN Sustainable Development Goals, specifically Goals 7 (affordable and clean energy), 9 (industry, innovation, and infrastructure), and 13 (climate action).

Research Report:23.2% efficient low band gap perovskite solar cells with cyanogen management