Posts belonging to Category light

Green Solar Panels And Other Colors

Researchers from AMOLF, the University of Amsterdam (UvA) and the Energy Research Centre of the Netherlands (ECN) have developed a technology to create efficient bright green colored solar panels. Arrays of silicon nanoparticles integrated in the front module glass of a silicon heterojunction solar cell scatter a narrow band of the solar spectrum and create a green appearance for a wide range of angles. The remainder of the solar spectrum is efficiently coupled into the solar cell. The current generated by the solar panel is only  reduced by 10%. The realization of efficient colorful solar panels is an important step for the integration of solar panels into the built environment and landscape.
research has much focused on maximizing the electricity yield obtained from solar panels: nowadays, commercial panels have a maximum conversion efficiency from sunlight into electricity of around 22%. To reach such high efficiency, silicon solar cells have been equipped with a textured surface with an antireflection layer to absorb as much light as possible. This creates a dark blue or black appearance of the solar panels.

To create the colored solar panels the researchers have used the effect of Mie scattering, the resonant backscattering of light with a particular color by nanoparticles. They integrated dense arrays of silicon nanocylinders with a diameter of 100 nm in the top module cover slide of a high-efficiency silicon heterojunction solar cell. Due to the resonant nature of the light scattering effect, only the green part of the spectrum is reflected; the other colors are fully coupled into the solar cell. The current generated by the mini solar panel (0,7 x 0,7 cm2)  is only reduced by 10%. The solar panel appears green over a broad range of angles up to 75 degrees. The nanoparticles are fabricated using soft-imprint lithography, a technique that can readily be scaled up to large-area fabrication.
The light scattering effect due to Mie resonances is easily controllable: by changing the size of the nanoparticles the wavelength of the resonant light scattering can be tuned. Following this principle the researchers are now working to realize solar cells in other colors, and on a combination of different colors to create solar panels with a white appearance. For the large-scale application of solar panels, it is essential that their color can be tailored.

The new design was published online in the journal Applied Physics Letters.


Chinese Quantum Satellite Sends ‘Unbreakable’ Code

China has sent an “unbreakablecode from a satellite to the Earth, marking the first time space-to-ground quantum key distribution technology has been realized, state media said. China launched the world’s first quantum satellite last August, to help establish “hack proofcommunications, a development the Pentagon has called a “notable advance“. The official Xinhua news agency said the latest experiment was published in the journal Nature, where reviewers called it a “milestone“.

The satellite sent quantum keys to ground stations in China between 645 km (400 miles) and 1,200 km (745 miles) away at a transmission rate up to 20 orders of magnitude more efficient than an optical fiber, Xinhua cited Pan Jianwei, lead scientist on the experiment from the state-run Chinese Academy of Sciences, as saying.

That, for instance, can meet the demand of making an absolute safe phone call or transmitting a large amount of bank data,” Pan said. Any attempt to eavesdrop on the quantum channel would introduce detectable disturbances to the system, Pan said. “Once intercepted or measured, the quantum state of the key will change, and the information being intercepted will self-destruct,” Xinhua said.

The news agency said there were “enormous prospects” for applying this new generation of communications in defense and finance.


New WIFI Speeds Up To 300 Times Faster

Researchers at the Eindhoven University of Technology (Netherlands) say their new wireless network that uses harmless infrared rays will make wifi speeds up to 300 times faster.


“What we are doing actually is using rays of light which convey the information in a wireless way, and each ray is acting as a very high capacity channel. It’s actually the same as an optical fibre without needing the fibre, and what we achieved up to this moment is 112 gigabits per second,” says Professor Ton Koonen, Eindhoven University of Technology.

That’s the equivalent data of three full-length movies being downloaded per second. Light antennas radiate multiple invisible wavelengths at various angles. If a user’s smartphone or tablet moves out of one antenna’s sightline, another takes over. Infrared wavelengths don’t go into your eyes, making them safe to use. The lack of moving parts makes the system maintenance and power-free. While each user gets their own antenna.

The big benefits we see of our technique is that you offer unshared capacity to each individual user, so you get a guaranteed capacity. Next to that you only get a beam if you need the traffic. So we’re not illuminating the whole place where maybe a single user is there. That means it’s much more power efficient. Another efficiency, another advantage, is that light doesn’t go through walls. So that means your communication is really confined to the particular room. Nobody can listen in from outside, so it offers you a lot of security,” explains rofessor Ton Koonen.
The team is seeking funding to help make the technology widespread within five years.


No More Batteries For Cellphones

University of Washington (UW) researchers have invented a cellphone that requires no batteries — a major leap forward in moving beyond chargers, cords and dying phones. Instead, the phone harvests the few microwatts of power it requires from either ambient radio signals or light.

The team also made Skype calls using its battery-free phone, demonstrating that the prototype made of commercial, off-the-shelf components can receive and transmit speech and communicate with a base station.


We’ve built what we believe is the first functioning cellphone that consumes almost zero power,” said co-author Shyam Gollakota, an associate professor in the Paul G. Allen School of Computer Science & Engineering at the UW. “To achieve the really, really low power consumption that you need to run a phone by harvesting energy from the environment, we had to fundamentally rethink how these devices are designed.”

The team of UW computer scientists and electrical engineers eliminated a power-hungry step in most modern cellular transmissionsconverting analog signals that convey sound into digital data that a phone can understand. This process consumes so much energy that it’s been impossible to design a phone that can rely on ambient power sources. Instead, the battery-free cellphone takes advantage of tiny vibrations in a phone’s microphone or speaker that occur when a person is talking into a phone or listening to a call.

An antenna connected to those components converts that motion into changes in standard analog radio signal emitted by a cellular base station. This process essentially encodes speech patterns in reflected radio signals in a way that uses almost no power. To transmit speech, the phone uses vibrations from the device’s microphone to encode speech patterns in the reflected signals. To receive speech, it converts encoded radio signals into sound vibrations that that are picked up by the phone’s speaker. In the prototype device, the user presses a button to switch between these two “transmitting” and “listening” modes.

The new technology is detailed in a paper published July 1 in the Proceedings of the Association for Computing Machinery on Interactive, Mobile, Wearable and Ubiquitous Technologies.


By 2025 Renewables Will Power 67 Percent Of South Australia

Declining renewables and energy storage costs will increasingly squeeze out gas-fired generation in South Australia as early as 2025, a joint research report conducted by Wood Mackenzie and GTM Research shows. The South Australia experience is noteworthy in a global power mix set to increasingly shift to renewable energy. South Australia retired its last coal plant in 2016 and is projected to have installed renewable energy capacity exceed its peak demand by 2020.

By 2025, wind, solar and battery costs will fall by 15 percent, 25 percent and 50 percent respectively. By then, renewables and batteries could offer a lower cost alternative to combined-cycle gas turbine plants, which are commonly used to manage base load power generation in South Australia. Meanwhile by 2035, renewables and batteries will provide a commercial solution for both base loads and peak loads. As a consequence, gas will increasingly be used just for emergency back-up.

One determining factor is the rate with which battery charging costs declines. By 2025, we expect battery charging cost to decrease as off-peak prices will gradually be set by excess wind generation. Battery storage then becomes a potential solution for managing peak loads,” said Bikal Pokharel, principal analyst for Wood Mackenzie‘s Asia-Pacific power and renewables .
By 2025 it’s expected that 67 percent of South Australia’s power capacity will come from renewables. Gas demand in the power sector will then decline by 70 percent.

Currently, South Australia’s peak loads are managed by open-cycle gas turbine (OCGT) plants. But by 2025, battery storage would be cheaper than OCGTs in managing peak loads even at gas price of A$7/mmbtu. OCGTs would then be relegated as emergency back-ups.”


New Solar System Produces 50 Percent More Energy

A concentrating photovoltaic system (CPV) with embedded microtracking can produce over 50 percent more energy per day than standard silicon solar cells in a head-to-head competition, according to a team of engineers who field tested a prototype unit over two sunny days last fall.

Solar cells used to be expensive, but now they’re getting really cheap,” said Chris Giebink, Charles K. Etner Assistant Professor of Electrical Engineering, Penn State. “As a result, the solar cell is no longer the dominant cost of the energy it produces. The majority of the cost increasingly lies in everything else — the inverter, installation labor, permitting fees, etc. — all the stuff we used to neglect.

This changing economic landscape has put a premium on high efficiency. In contrast to silicon solar panels, which currently dominate the market at 15 to 20 percent efficiency, concentrating photovoltaics focus sunlight onto smaller, but much more efficient solar cells like those used on satellites, to enable overall efficiencies of 35 to 40 percent. Current CPV systems are large — the size of billboards — and have to rotate to track the sun during the day. These systems work well in open fields with abundant space and lots of direct sun.

What we’re trying to do is create a high-efficiency CPV system in the form factor of a traditional silicon solar panel,” said Giebink.


Move And Produce Electricity To Power Your Phone

Imagine slipping into a jacket, shirt or skirt that powers your cell phone, fitness tracker and other personal electronic devices as you walk, wave and even when you are sitting down. A new, ultrathin energy harvesting system developed at Vanderbilt University’s Nanomaterials and Energy Devices Laboratory has the potential to do just that. Based on battery technology and made from layers of black phosphorus that are only a few atoms thick, the new device generates small amounts of electricity when it is bent or pressed even at the extremely low frequencies characteristic of human motion.


In the future, I expect that we will all become charging depots for our personal devices by pulling energy directly from our motions and the environment,” said Assistant Professor of Mechanical Engineering Cary Pint, who directed the research.
This is timely and exciting research given the growth of wearable devices such as exoskeletons and smart clothing, which could potentially benefit from Dr. Pint’s advances in materials and energy harvesting,” observed Karl Zelik, assistant professor of mechanical and biomedical engineering at Vanderbilt, an expert on the biomechanics of locomotion who did not participate in the device’s development.

Doctoral students Nitin Muralidharan and Mengya Lic o-led the effort to make and test the devices. When you look at Usain Bolt, you see the fastest man on Earth. When I look at him, I see a machine working at 5 Hertz, said Muralidharan.

The new energy harvesting system is described in a paper titled “Ultralow Frequency Electrochemical Mechanical Strain Energy Harvester using 2D Black Phosphorus Nanosheets” published  by the journal ACS Energy Letters.


Sion, The Solar-Powered Car

What has room for 6 passengers, an all-electric range of up to 155 miles (250 kilometers), and a body covered in solar panels that can add as many as 18 miles (30 kilometers) of driving a day from sunlight? That would be the Sono Motors Sion, an innovative solar-powered car from a team of German entrepreneurs that is scheduled to have its world debut on July 27 (2017).

The Sion project was able to move forward thanks to an Indiegogo crowdfunding campaign last year that raised over a half million dollars. More than 1,000 people have participated so far.

The car will have two versions. The Urban comes with a 14.4 kilowatt-hour battery pack. It has a range of about 75 miles (121 kilometers) and will cost $13,200. The Extender version has a 30 kilowatt-hour battery and a range of 155 miles (250 kilometers). Its target price is $17,600. Neither price includes the battery. Like the Renault Zoe, customers will either buy the battery separately or lease it. The leasing option gives owners the flexibility to upgrade the battery later as improvements in battery technology become available.

The hood, roof, and rear hatch of the Sion are covered with monocrystalline silicon cells that are 21% efficient. On a sunny day, they can generate enough electricity to add 18 miles of range. The solar cells are 8 millimeters thick and embedded in a polycarbonate layer that is shatterproof, weather resistant, and light in weight. The Sion can also be 80% charged using an AC outlet in about 30 minutes, according to company claims. No DC charging option is available. The car also comes with an outlet that can power electronic devices.

Inside, all the seats of the 5 door hatchback fold flat, offering multiple configurations for carrying passengers and cargo. There is a 10 inch center display and smartphone connectivity via WiFi or Bluetooth. The ventilation system is called breSono and incorporates a dollop of moss, which is said to act as a natural filter when an electrical charge is applied.

The company will offer an online maintenance and repair system it calls reSono. It allows owners to order parts online and comes with a video that shows them how to install the parts when they arrive.  Or they can take the car and the parts to any local auto repair shop facility to get them installed.


Solar Energy Transforms Salt Water Into Fresh Drinking Water

A federally funded research effort to revolutionize water treatment has yielded an off-grid technology that uses energy from sunlight alone to turn salt water into fresh drinking water. The desalination system, which uses a combination of membrane distillation technology and light-harvesting nanophotonics, is the first major innovation from the Center for Nanotechnology Enabled Water Treatment (NEWT), a multi-institutional engineering research center based at Rice University.

NEWT’s “nanophotonics-enabled solar membrane distillation” technology, or NESMD, combines tried-and-true water treatment methods with cutting-edge nanotechnology that converts sunlight to heat. More than 18,000 desalination plants operate in 150 countries, but NEWT’s desalination technology is unlike any other used today.

Direct solar desalination could be a game changer for some of the estimated 1 billion people who lack access to clean drinking water,” said Rice scientist and water treatment expert Qilin Li, a corresponding author on the study. “This off-grid technology is capable of providing sufficient clean water for family use in a compact footprint, and it can be scaled up to provide water for larger communities.”

The technology is described online in the Proceedings of the National Academy of Sciences.


Nano-based Material Is 60 Times More Efficient To Produce Hydrogen

Global climate change and the energy crisis mean that alternatives to fossil fuels are urgently needed. Among the cleanest low-carbon fuels is hydrogen, which can react with oxygen to release energy, emitting nothing more harmful than water (H2O) as the product. However, most hydrogen on earth is already locked into H2O (or other molecules), and cannot be used for power.

Hydrogen can be generated by splitting H2O, but this uses more energy than the produced hydrogen can give back. Water splitting is often driven by solar power, so-called “solar-to-hydrogenconversion. Materials like titanium oxide, known as semiconductors with the wide band-gap, are traditionally used to convert sunlight to chemical energy for the photocatalytic reaction. However, these materials are inefficient because only the ultraviolet (UV) part of light is absorbed—the rest spectrum of sunlight is wasted.

Now, a team in Osaka University has developed a material to harvest a broader spectrum of sunlight. The three-part composites of this material maximize both absorbing light and its efficiency for water splitting. The core is a traditional semiconductor, lanthanum titanium oxide (LTO). The LTO surface is partly coated with tiny specks of gold, known as nanoparticles. Finally, the gold-covered LTO is mixed with ultrathin sheets of the element black phosphorus (BP), which acts as a light absorber.

BP is a wonderful material for solar applications, because we can tune the frequency of light just by varying its thickness, from ultrathin to bulk,” the team leader Tetsuro Majima says. “This allows our new material to absorb visible and even near infrared light, which we could never achieve with LTO alone.”

By absorbing this broad sweep of energy, BP is stimulated to release electrons, which are then conducted to the gold nanoparticles coating the LTO. Gold nanoparticles also absorb visible light, causing some of its own electrons to be jolted out. The free electrons in both BP and gold nanoparticles are then transferred into the LTO semiconductor, where they act as an electric current for water splitting.

Hydrogen production using this material is enhanced not only by the broader spectrum of light absorption, but by the more efficient electron conduction, caused by the unique interface between two dimensional materials of BP and LTO. As a result, the material is 60 times more active than pure LTO.


Super-Efficient Production Of Hydrogen From Solar Energy

Hydrogen is an alternative source of energy that can be produced from renewable sources of sunlight and water. A group of Japanese researchers has developed a photocatalyst that increases hydrogen production tenfold.

When light is applied to photocatalysts, electrons and holes are produced on the surface of the catalyst, and hydrogen is obtained when these electrons reduce the hydrogen ions in water. However, in traditional photocatalysts the holes that are produced at the same time as the electrons mostly recombine on the surface of the catalyst and disappear, making it difficult to increase conversion efficiency.

Professor Tachikawa’s research group from the Kobe University developed a photocatalyst made of mesocrystal, deliberately creating a lack of uniformity in size and arrangement of the crystals. This new photocatalyst is able to spatially separate the electrons and electron holes to prevent them recombining. As a result, it has a far more efficient conversion rate for producing hydrogen than conventional nanoparticulate photocatalysts (approximately 7%).

The team developed a new method called “Topotactic Epitaxial Growth” that uses the nanometer-sized spaces in mesocrystals.
Using these findings, the research group plans to apply mesocrystal technology to realizing the super-efficient production of hydrogen from solar energy. The perovskite metal oxides, including strontium titanate, the target of this study, are the fundamental materials of electronic elements, so their results could be applied to a wide range of fields.

The discovery was made by a joint research team led by Associate Professor Tachikawa Takashi (Molecular Photoscience Research Center, Kobe University) and Professor Majima Tetsuro (Institute of Scientific and Industrial Research, Osaka University). Their findings were published  in the online version of Angewandte Chemie International Edition.


Super-material Bends, Shapes And Focuses Sound Waves

These tiny 3D-printed bricks could one day allow people to create their own acoustics. That’s the plan of scientists from the universities of Bristol and Sussex. They’ve invented a metamaterial which bends and manipulates sound in any way the user wants. It’s helped scientists create what they call a ‘sonic alphabet‘.


We have discovered that you just need 16 bricks to make any type of sound that you can imagine. You can shape the sound just with 16 of them, just like you create any words with just 26 letters,” says Dr. Gianluca Memoli, researcher at Interact Lab at University of Sussex.

DIY kits like this, full of batches of the 16 aural letters, could help users create a sound library, or even help people in the same car to hear separate things.

With our device what you can have is you can strap a static piece on top of existing speakers and they can direct sound in two different directions without any overlap. So the passengers can hear completely different information from the driver,” explains Professor Sri Subramanian Interact Lab at University of Sussex. This technology is more than five years away, but smaller versions could be used to direct medical ultrasound devices far sooner.  “In a year we could have a sleeve that we can put on top of already existing projects in the market and make them just a little bit better. For example, we can have a sleeve that goes on top of ultrasound pain relieving devices that are used for therapeutic pain,” he adds.
Researchers say spatial sound modulators will one day allow us to perform audible tasks previously unheard of.