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Category: energy – Page 2

Nanotube Material Has Perfect Memory

A carbon nanotube foam springs back to its initial state, regardless of the speed of the compression, a property that could lead to a new type of shock absorber.

Spongy materials can spring back following compression, but they don’t return exactly to their original shape. New experiments show that a foam made with carbon nanotubes snaps back to its initial shape, implying a perfect mechanical “memory” [1]. The material is also uniquely insensitive to deformation rate, behaving the same under fast and slow compressions. The researchers found that this combination of memory and rate-independence leads to an unusual property: The material’s response to mechanical shocks can be adjusted by appropriately compressing it before the shock. They imagine using this foam in “smart” helmets that reduce injury risk by controlling the propagation of impact energy.

Polymer foams—like the ones in some mattresses—can spring back, but viscosity effects cause irreversible changes to the internal structure, preventing the material from returning to its initial state. With repeated cycles of compression and release, the material drifts further from its original condition. “People refer to this as fading memory,” says Ramathasan Thevamaran from the University of Wisconsin–Madison. He and his colleagues have found a material that isn’t so forgetful.

Pilot system couples seawater desalination with hydrogen production

Seawater holds enormous potential for green hydrogen production, but realizing that potential remains far from straightforward. Direct seawater electrolysis can damage electrodes, whereas conventional freshwater electrolysis loses much of its energy as low-grade waste heat. Researchers have now found a way to harness this otherwise wasted heat, using it to desalinate seawater and produce fresh water alongside hydrogen.

In a study published in Nature Energy on Sept. 15, a team led by Prof. Deng Dehui and Associate Prof. Liu Yanting from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) proposed a “seawater to hydrogen and fresh water (STHW)” route that couples alkaline water electrolysis (AWE) with low-temperature vacuum distillation desalination.

The STHW process uses waste heat generated during AWE to drive low-temperature seawater desalination, producing fresh water for electrolysis and external use. The resulting concentrated brine can also be used for resource recovery, including salt, uranium and bromine.

Weighing 600 million buildings to help construct a more efficient future

A new study helps show how builders and city planners can minimize the materials needed to accommodate the planet’s future population.

“How we plan cities today will shape their material demand for decades,” said Jinchao Song, the first author of the new study and a U-M research fellow with the School for Environment and Sustainability, or SEAS. “Using materials more efficiently can help cities accommodate future population growth while reducing the emissions associated with construction. If we use less material, we will have less energy consumption and carbon emissions.”

In the study, published in the journal Nature Cities, Song and colleagues combined high-resolution satellite imagery and other geospatial data with building material information to calculate the weight of 606 million buildings around the world. Working with experts from China, Denmark and the Netherlands, she then analyzed how economic conditions, population density and characteristics of the built environment, including urban form, were associated with material-use efficiency across cities.

Cells Put a Price Tag on Sensing Their World

A new model shows how cells could optimize biochemical sensing by balancing information gained against energy spent.

A cell never senses its environment directly. Instead, it receives a noisy stream of molecular cues—chemical markers binding to receptors, enzymes switching states, and messenger molecules appearing and disappearing. Extracting a meaningful signal from these fluctuations can improve survival, but doing so comes at a cost. Maintaining chemical currents and producing readout molecules consume energy. Giorgio Nicoletti of the Abdus Salam International Center for Theoretical Physics in Italy and his colleagues now show how achieving optimal sensing performance requires a balance between gained information and spent energy [1]. Their key idea is to formulate this balance in terms of quantities that can be estimated from statistical observations rather than from hard-to-measure microscopic forces.

Scientists melted a diamond and cracked a secret of ice giants

Ask a planetary scientist, and they will tell you that diamonds aren’t really all that uncommon. In fact, there are billions of tons of them hiding away in the deep interiors of planets in our solar system and beyond. The most enthusiastic will tell you about diamond rain—where a planet’s temperature and pressure are so great that diamond literally melts and forms a liquid, dropping toward the planet’s core.

The friction and heat these diamond raindrops generate are among the primary drivers of Neptune’s excess energy, which it then radiates back out into space. For the first time, the LLNL paper provides solid experimental data on the precise pressures and temperatures needed for such an awe-inspiring event to occur.

Single nanostructure enables independent control of two light resonance modes

Metallic nanostructures are exceptionally effective at concentrating light into tiny volumes, while dielectric nanostructures excel at storing light with minimal energy loss. Combining these complementary properties has traditionally required complicated hybrid structures in which the two optical modes become mixed, making them difficult to control independently.

Achieving both resonance types within a single nanostructure without mode interference has therefore remained a major challenge in nanophotonics, limiting the development of compact, multifunctional optical devices.

The Universe Has Plenty of Fuel. So Why Is It Making Fewer Stars?

The Universe still has plenty of hydrogen, but its ability to turn that fuel into new stars appears to be fading.

The Universe is producing far fewer new stars than it did billions of years ago. Over the past 4.5 billion years, the cosmic star formation rate has fallen to less than half its former level. Yet one of the most important ingredients needed to make stars has declined only modestly.

An international team led by researchers from the Chinese Academy of Sciences (CAS), working with the Dark Energy Spectroscopic Instrument (DESI) project, reached this conclusion after studying the evolution of neutral atomic hydrogen across the Universe. The researchers used China’s Five-hundred-meter Aperture Spherical radio Telescope (FAST) to make exceptionally precise measurements spanning the past 4.5 billion years.

New model measures economic risks solar storms pose to US power grid

In 1967, a solar storm nearly triggered World War III by jamming early-warning radar systems in the United States, causing U.S. leaders to think the Soviet Union was responsible. Though society averted catastrophe thanks to timely information from solar forecasters, the threat from space weather remains real.

Solar, or geomagnetic, storms form as the sun expels plasma and magnetic fields from its corona during coronal mass ejections. After traversing space and encountering Earth’s magnetic field, the energy can interact with conducting materials such as the crust or ocean and induce geoelectric fields. The currents destabilize electrical transmission as they flow through extrahigh-voltage transformers that regulate voltage in the grid.

Yet despite their potential for havoc, geomagnetic storms are an underquantified threat. Existing socioeconomic assessments of space weather are often siloed by discipline and overlook the relationship between geophysical drivers and the function of the power grid.

Embedded platinum channels bring nanoscale spin-based thermoelectric conversion to bulk materials

A joint research team from NIMS and the University of Tokyo has developed a new composite in which three-dimensional nano-interfaces are distributed throughout the material by coating the surfaces of magnetic-insulator powders with a metal and sintering them. Using this structure, the team succeeded in observing thermoelectric conversion driven by spins in an insulator, a phenomenon previously observed only at nanoscale thin-film interfaces, in a macroscale material.

This research was published in Nature Communications.

Thermoelectric conversion, which uses the vast amounts of waste heat and unused heat around us as electrical energy, is one of the key technologies for improving energy-use efficiency and achieving carbon neutrality. The spin Seebeck effect is a physical phenomenon discovered in Japan in 2008 in which applying a temperature gradient to a magnetic material enables thermoelectric conversion via spin currents.

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