Solar Energy

Giant clams may hold the answers to making solar energy more efficient

Published

6 months ago

July 4, 2024

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Giant clams may hold the answers to making solar energy more efficient

by Jim Shelton for Yale News

New Haven CT (SPX) Jul 03, 2024

Solar panel and biorefinery designers could learn a thing or two from iridescent giant clams living near tropical coral reefs, according to a new Yale-led study.

This is because giant clams have precise geometries – dynamic, vertical columns of photosynthetic receptors covered by a thin, light-scattering layer – that may just make them the most efficient solar energy systems on Earth.

“It’s counter-intuitive to a lot of people, because clams operate in intense sunlight, but actually they’re really dark on the inside,” said Alison Sweeney, associate professor of physics and of ecology and evolutionary biology in Yale’s Faculty of Arts and Sciences. “The truth is that clams are more efficient at solar energy conversion than any existing solar panel technology.”

In the new study, published in the journal PRX: Energy, a research team led by Sweeney presents an analytical model for determining the maximum efficiency of photosynthetic systems based on the geometry, movement, and light-scattering characteristics of giant clams. It is the latest in a series of research studies from Sweeney’s lab that highlight biological mechanisms from the natural world that could inspire new sustainable materials and designs.

In this case, the researchers looked specifically at the impressive solar energy potential of iridescent giant clams in the shallow waters of Palau in the Western Pacific.

The clams are photosymbiotic, with vertical cylinders of single-celled algae growing on their surface. The algae absorb sunlight – after the light has been scattered by a layer of cells called iridocytes.

Both the geometry of the algae and the light scattering of the iridocytes are important, the researchers say. The algae’s arrangement in vertical columns – which makes them parallel to the incoming light – enables the algae to absorb sunlight at the most efficient rate. This is because the sunlight has been filtered and scattered by the layer of iridocytes, and the light then wraps uniformly around each vertical algae cylinder.

Based on the giant clams’ geometry, Sweeney and her colleagues developed a model to calculate quantum efficiency – the ability to convert photons into electrons. The researchers also factored in fluctuations in sunlight, based on a typical day in the tropics with a sunrise, midday sun intensity, and sunset. The quantum efficiency was 42%.

But then the researchers added a new wrinkle: the way giant clams stretch themselves in reaction to changes in sunlight. “Clams like to move and groove throughout the day,” Sweeney said. “This stretching moves the vertical columns farther apart, effectively making them shorter and wider.”

With this new information, the clam model’s quantum efficiency jumped to 67%. By comparison, Sweeney said, a green leaf system’s quantum efficiency in a tropical environment is only about 14%.

An intriguing comparison, according to the study, would be northern spruce forests. The researchers said boreal spruce forests, surrounded by fluctuating layers of fog and clouds, share similar geometries and light-scattering mechanisms with giant clams, but on a much larger scale. And their quantum efficiency is nearly identical.

“One lesson from this is how important it is to consider biodiversity, writ large,” Sweeney said. “My colleagues and I continue to brainstorm about where else on Earth this level of solar efficiency might happen. It is also important to recognize we can only study biodiversity in places where it is maintained.”

She added: “We owe a major debt to Palauans, who put vital cultural value on their clams and reefs and work to keep them in pristine health.”

Such examples may offer inspiration and insights for more efficient sustainable energy technology.

“One could envision a new generation of solar panels that grow algae, or inexpensive plastic solar panels that are made out of a stretchy material,” Sweeney said.

The study’s first author is Amanda Holt, an associate research scientist in Sweeney’s lab. The study’s co-author is Lincoln Rehm, a Palauan-American and former graduate student at Drexel University and researcher at the Palau International Coral Reef Center, who is now at the National Oceanography and Atmospheric Administration.

The research was funded by a Packard Foundation fellowship and the National Science Foundation.

Research Report:Simple Mechanism for Optimal Light-Use Efficiency of Photosynthesis Inspired by Giant Clams

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Solar Energy

Buried interface engineering drives advances in tin-lead perovskite solar cell efficiency

Published

1 day ago

December 20, 2024

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Buried interface engineering drives advances in tin-lead perovskite solar cell efficiency

by Simon Mansfield

Sydney, Australia (SPX) Dec 20, 2024

A team led by Prof. Meng Li from Henan University’s School of Nanoscience and Materials Engineering has unveiled an innovative approach to overcoming stability and efficiency challenges in tin-lead (Sn-Pb) perovskite solar cells. The researchers’ work focuses on optimizing the buried hole-selective interface using a specially designed self-assembled material, offering major implications for single-junction and tandem solar cell technologies.

Tin-lead perovskites are valued for their narrow bandgap properties, which position them as key materials for producing high-efficiency solar cells. However, energy level mismatches and degradation at the buried interface have constrained both their performance and long-term stability. Addressing these issues, Prof. Meng’s team designed a boronic acid-anchored hole-selective contact material, 4-(9H-carbazole-9-yl)phenylboronic acid (4PBA).

Compared to conventional materials, 4PBA demonstrated superior stability and compatibility at the substrate surface. Its high adsorption energy of -5.24 eV and significant molecular dipole moment (4.524 D) improved energy level alignment between the substrate and perovskite layer, facilitating efficient charge extraction. Additionally, the interface engineered using 4PBA improved perovskite crystallization and substrate contact, reducing defects and non-radiative recombination.

These advancements enabled Sn-Pb perovskite solar cells incorporating 4PBA to achieve a power conversion efficiency (PCE) of 23.45%. The material’s reduced corrosiveness also mitigated the degradation effects typically caused by PEDOT:PSS, a widely used hole-transport material, enhancing chemical stability and storage durability. The cells retained 93.5% of their initial efficiency after 2,000 hours of shelf storage.

“This approach offers a practical path to enhancing both the efficiency and stability of Sn-Pb perovskite solar cells, addressing energy level mismatches and interfacial stability concerns,” the research team commented.

The findings provide a foundation for advancing efficient and stable Sn-Pb perovskite solar cells and highlight the importance of interface engineering in next-generation photovoltaic technologies.

Research Report:Buried Hole-Selective Interface Engineering for High-Efficiency Tin-Lead Perovskite Solar Cells with Enhanced Interfacial Chemical Stability

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Solar Energy

New solar material advances green hydrogen production

Published

1 day ago

December 20, 2024

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New solar material advances green hydrogen production

by Simon Mansfield

Sydney, Australia (SPX) Dec 20, 2024

Researchers in nano-scale chemistry have made a significant stride in advancing the sustainable and efficient production of hydrogen from water using solar energy.

A collaborative international study led by Flinders University, with partners in South Australia, the US, and Germany, has identified a novel solar cell process that could play a crucial role in photocatalytic water splitting for green hydrogen production.

The research introduces a new class of kinetically stable ‘core and shell Sn(II)-perovskite’ oxide solar material. Paired with a catalyst developed by US researchers under Professor Paul Maggard, this material shows potential as a catalyst for the essential oxygen evolution reaction, a key step in generating pollution-free hydrogen energy.

The findings, published in The Journal of Physical Chemistry C, offer new insights into the development of carbon-free hydrogen technologies, leveraging renewable and greenhouse-gas-free power sources for high-performing and cost-effective electrolysis processes.

“This latest study is an important step forwards in understanding how these tin compounds can be stabilised and effective in water,” said Professor Gunther Andersson, lead author from the Flinders Institute for Nanoscale Science and Technology.

Professor Paul Maggard, from Baylor University, added, “Our reported material points to a novel chemical strategy for absorbing the broad energy range of sunlight and using it to drive fuel-producing reactions at its surfaces.”

Tin and oxygen compounds like those used in the study are already applied in diverse fields such as catalysis, diagnostic imaging, and therapeutic drugs. However, Sn(II) compounds are typically reactive with water and dioxygen, limiting their technological potential.

Global solar photovoltaic research continues to focus on developing cost-effective, high-performance perovskite-based systems as alternatives to conventional silicon and other existing technologies.

Hydrogen, often touted as a clean fuel, can be produced through various processes, including electrolysis powered by renewable energy, thermochemical water splitting using concentrated solar power, or waste heat from nuclear reactors. While fossil fuels and biomass can also generate hydrogen, the environmental and energy efficiency depends largely on the production method.

Solar-driven hydrogen production, which uses light to initiate the process, is emerging as a promising alternative for industrial-scale hydrogen generation.

This study builds on earlier research led by Professor Maggard, initially at North Carolina State University and now at Baylor University, and includes contributions from University of Adelaide experts such as Professor Greg Metha and collaborators from Universitat Munster in Germany. Professor Metha’s work explores the photocatalytic activity of metal clusters on oxide surfaces for reactor technologies.

Research Report:Chemical and Valence Electron Structure of the Core and Shell of Sn(II)-Perovskite Oxide Nanoshells

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Solar Energy

University of Houston scientists solving meteorological mysteries on Mars

Published

1 day ago

December 20, 2024

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University of Houston scientists solving meteorological mysteries on Mars

by Bryan Luhn for UH News

Houston TX (SPX) Dec 20, 2024

A groundbreaking achievement by scientists at the University of Houston is changing our understanding of climate and weather on Mars and providing critical insights into Earth’s atmospheric processes as well.

The study, led by Larry Guan, a graduate student in the Department of Physics at UH’s College of Natural Sciences and Mathematics, under the guidance of his advisors, Professor Liming Li from the Department of Physics and Professor Xun Jiang from the Department of Earth and Atmospheric Sciences and several world-renowned planetary scientists, generated the first-ever meridional profile of Mars’ radiant energy budget, or REB, which represents the balance or imbalance between absorbed solar energy and emitted thermal energy across the latitudes. On a global scale, an energy surplus leads to global warming, while a deficit results in global cooling. Furthermore, the meridional profile of Mars’ REB fundamentally influences weather and climate patterns on the red planet.

The findings are in a new paper just published in AGU Advances and will be featured in AGU’s prestigious science magazine EOS.

“The work in establishing Mars’ first meridional radiant energy budget profile is noteworthy,” Guan said. “Understanding Earth’s large-scale climate and atmospheric circulation relies heavily on REB profiles, so having one for Mars allows critical climatological comparisons and lays the groundwork for Martian meteorology.”

The profile, based on long-term observations from orbiting spacecraft, offers a detailed comparison of Mars’ REB to that of Earth, uncovering striking differences in the way each planet receives and radiates energy. While Earth exhibits an energy surplus in the tropics and a deficit in the polar regions, Mars displays the opposite configuration.

“On Earth, the tropical energy surplus drives warming and upward atmospheric motion, while the polar energy deficit causes cooling and downward atmospheric motion,” Jiang explained. “These atmospheric motions significantly influence weather and climate on our home planet. However, on Mars, we observe a polar energy surplus and a tropical energy deficit.”

That surplus, Guan says, is especially pronounced in Mars’ southern hemisphere during spring, playing a critical role in driving the planet’s atmospheric circulation and triggering global dust storms, the most prominent feature of Martian weather. These massive storms, which can envelop the entire planet, significantly alter the distribution of energy, providing a dynamic element that affects Mars’ weather patterns and climate.

“The interaction between dust storms and the REB, as well as with polar ice dynamics, brings to light the complex feedback processes that likely shape Martian weather patterns and long-term climate stability,” Guan said.

Earth’s global-scale energy imbalance has been recently discovered, which significantly contributes to global warming at a magnitude comparable to that caused by increasing greenhouse gases. Mars presents a distinct environment due to its thinner atmosphere and lack of anthropogenic effects. The research team is now examining potential long-term energy imbalances on Mars and their implications for the planet’s climate evolution.

“The REB difference between the two planets is truly fascinating, so continued monitoring will deepen our understanding of Mars’ climate dynamics,” Li said. “This research not only deepens our knowledge of the red planet but also provides critical insights into planetary atmospheric processes.”

Research Report:Distinct Energy Budgets of Mars and Earth