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Category: sustainability – Page 602

Psst! A whispering gallery for light boosts solar cells

Trapping light with an optical version of a whispering gallery, researchers at the National Institute of Standards and Technology (NIST) have developed a nanoscale coating for solar cells that enables them to absorb about 20 percent more sunlight than uncoated devices. The coating, applied with a technique that could be incorporated into manufacturing, opens a new path for developing low-cost, high-efficiency solar cells with abundant, renewable and environmentally friendly materials.

The consists of thousands of tiny glass beads, only about one-hundredth the width of a human hair. When sunlight hits the coating, the waves are steered around the nanoscale bead, similar to the way sound waves travel around a curved wall such as the dome in St. Paul’s Cathedral in London. At such curved structures, known as acoustic whispering galleries, a person standing near one part of the wall easily hears a faint sound originating at any other part of the wall.

Whispering galleries for light were developed about a decade ago, but researchers have only recently explored their use in solar-cell coatings. In the experimental set up devised by a team including Dongheon Ha of NIST and the University of Maryland’s NanoCenter, the light captured by the nanoresonator coating eventually leaks out and is absorbed by an underlying solar cell made of gallium arsenide.

Using an algorithm to reduce energy bills—rain or shine

Researchers proposed implementing the residential energy scheduling algorithm by training three action dependent heuristic dynamic programming (ADHDP) networks, each one based on a weather type of sunny, partly cloudy, or cloudy. ADHDP networks are considered ‘smart,’ as their response can change based on different conditions.

“In the future, we expect to have various types of supplies to every household including the grid, windmills, and biogenerators. The issues here are the varying nature of these power sources, which do not generate electricity at a stable rate,” said Derong Liu, a professor with the School of Automation at the Guangdong University of Technology in China and an author on the paper. “For example, power generated from windmills and solar panels depends on the weather, and they vary a lot compared to the more stable power supplied by the grid. In order to improve these power sources, we need much smarter algorithms in managing/scheduling them.”

The details were published on the January 10th issue of IEEE/CAA Journal of Automatica Sinica, a joint bimonthly publication of the IEEE and the Chinese Association of Automation.

The ESA Just Discovered a Second Magnetic Field Surrounding Our Planet

A trio of satellites studying our planet’s magnetic field have shown details of the steady swell of a magnetic field produced by the ocean’s tides.

Four years of data collected by the European Space Agency’s (ESA) Swarm mission have contributed to the mapping of this ‘other’ magnetic field, one that could help us build better models around global warming.

Physicist Nils Olsen from the Technical University of Denmark presented the surprising results at this year’s European Geosciences Union meeting in Vienna, explaining how his team of researchers managed to detail such a faint signature.

This imaging sensor is powered by sunlight

A simultaneous imaging and energy harvesting sensor is in the news. Samuel Moore at IEEE Spectrum informed readers that a team of four from University of Michigan published their paper describing what they achieved. They built a prototype sensor, and what it does—-think of a future camera that just about watches you non-stop—is described in the journal, IEEE Electron Device Letters.

The article is titled “Simultaneous Imaging and Energy Harvesting in CMOS Image Sensor Pixels.” The four authors are from University of Michigan: Sung-Yun Park, Kyuseok Lee, Hyunsoo Song and Euisik Yoon.

Their technology “puts the equivalent of a solar cell under each pixel,” said IEEE Spectrum.

Harnessing ‘Rashba spin-Seebeck effect’ phenomenon will enable commercial devices to turn waste heat into electricity

Mechanical engineers at the University of California, Riverside, have reported success in using inexpensive materials to produce thermoelectric devices that transform low-level waste heat into electricity.

Their advance could enable a wide variety of commercial applications. For example, integrating thermoelectric generating devices into computer chips could enable the they produce to provide a power source. Waste heat from automobile engines could run a car’s electronics and provide cooling. Photovoltaic solar cells could be made more efficient by harnessing the heat from sunlight striking them to generate more electricity.

Also, using the same basic technology, economical thermoelectric refrigerators could be produced that would be more energy efficient and with fewer moving parts than refrigerators that use compressors and coolant. Current thermoelectric refrigerators are expensive and relatively inefficient. In essence, they operate in reverse of , with an electric current applied to generate a temperature gradient that could be used in cooling.

Sodium-ion battery packs a punch

A new sodium-ion battery chemistry that shows superior performance to existing state-of-the-art sodium-based batteries could be the catalyst to enabling mass-production of the emerging technology for large-scale energy storage, such as in applications including storing solar power for industrial sites.

Despite sodium’s appeal as a low-cost, abundant and environmentally friendly building block for storage, it is a relatively new entrant in the field of battery technology research and development.

A key issue for sodium-ion batteries is that many of the active materials used in their chemistry are sensitive to air—exposure to even a few molecules of air can degrade the material and reduce battery performance.

Researchers developing renewable energy approach for producing ammonia

Researchers at the University of Notre Dame are developing a renewable energy approach for synthesizing ammonia, an essential component of fertilizers that support the world’s food production needs. The Haber-Bosch process developed in the early 1900s for producing ammonia relies on non-renewable fossil fuels and has limited applications for only large, centralized chemical plants.

The new process, published in Nature Catalysis, utilizes a plasma—an ionized gas—in combination with non-noble metal catalysts to generate at much milder conditions than is possible with Haber-Bosch. The energy in the plasma excites nitrogen molecules, one of the two components that go into making ammonia, allowing them to react more readily on the catalysts. Because the energy for the reaction comes from the plasma rather than high heat and intense pressure, the process can be carried out at small scale. This makes the new process well-suited for use with intermittent renewable sources and for distributed .

“Plasmas have been considered by many as a way to make ammonia that is not dependent on fossil fuels and had the potential to be applied in a less centralized way,” said William Schneider, H. Clifford and Evelyn A. Brosey Professor of Engineering, affiliated member of ND Energy and co-author of the study. “The real challenge has been to find the right combination of plasma and . By combining molecular models with results in the laboratory, we were able to focus in on combinations that had never been considered before.”