New Solar Cell Device Surpasses Theoretically Predicted Efficiency Limit

Thomas Burton for Energy Technology Matters:  A team of researchers at the Massachusetts Institute of Technology (MIT) published a paper last week in the journal Nature Energy that described how they built a working solar thermophotovoltaic device (STPV) that enables solar cells to break through a theoretically predicted ceiling on how much sunlight they can convert into electricity. With this revolutionary new technology, the researchers show the potential of how solar panels can generate even more energy than theoretically determined by harnessing some of the panels’ waste. To learn more about the STPV technology, read on!

Since 1961, the Shockley-Queisser Limit established an absolute theoretical limit on traditional solar cell efficiency regarding energy conversion. A single-layer of silicon cells—the type of cells most widely used in today’s solar panels—has an upper limit of 32 percent. But currently, researchers are studying ways to increase this overall efficiency by using multiple layers of cells or converting the sunlight first to heat before generating electrical power. This latter method uses devices called STPVs, which the MIT team used in their study.  Cont'd...

Futuristic device is helping scientists break solar-efficiency record

Ariel Bogle for Yahoo News:  Looking a little like the world-saving stones from sci-fi classic The Fifth Element, a new device is expected to have a big impact on renewable energy.

Built by Mark Keevers and Martin Green from the University of New South Wales (UNSW), the unique prism could help make solar panels cheaper and more efficient. In fact, it's already broken a world record for the amount of solar energy it can create from unfocused sunlight.

The prism has a sunlight-to-electricity conversion efficiency rate of 34.5 percent, Keevers told Mashable Australia. That's about a 44 percent improvement in efficiency on the previous record, he said, which sat at 24 percent efficiency but over 800 square centimetres (124 square inches). The UNSW team's record was achieved over a smaller surface area of 28 square centimetres (4.34 square inches).

Importantly, it does this with normal, un-concentrated light — the type household solar panels already use.  Cont'd...

Solar cells of the future could be based on iron molecules

Researchers at Lund University in Sweden have successfully explained how iron-based dyes work on a molecular level in solar cells. The new findings will accelerate the development of inexpensive and environmentally friendly solar cells. The goal is to be able to use iron-based dyes in solar cells in the future.

Solar Cell "Wonder Material"-Perovskite-Falls Short of Expectations

Hugh Cowley for Scientific American:  Perovskites have arguably transformed solar energy more in the last few years than other technologies have in decades. But British researchers have called into question optimistic predictions of undiscovered perovskites.

Hybrid perovskites are a mix of organic and inorganic ions with the same crystal structure as calcium titanium oxide (CaTiO3). Halide perovskites are a subset of these structures containing halide ions such as fluoride or chloride. Iodide perovskites such as methylammonium lead iodide (CH3NH3PbI3) can convert sunlight to electricity.

Researchers use a decades-old geometric 'tolerance factor' to propose new combinations of ions that will form stable perovskites. Now, Robert Palgrave and his team at University College London, UK, have reassessed the validity of the tolerance factor in predicting new hybrid perovskite structures.  Cont'd...

Permanent Magnet Technology: The Wind Industry's New Drive Train Standard

As PMG+FPC drive trains outperform DFIGs from both a full-cycle cost-efficiency and reliability perspective, the turbine manufacturing industry needs to revise some of its old assumptions and obsolete turbine technology choices to embrace the generator technology that leads to better AEP.

Apple leftovers key for future energy storage

By Tereza Pultarova for E&T:  German researchers have developed a new carbon-based active material that can be manufactured from apple leftovers and used to build better energy storage systems.

The apple-based material can be used as the negative electrode in sodium-ion batteries, which are currently being researched as a more environmentally friendly and cheaper alternative to lithium-ion batteries.

Instead of energy-intensive lithium mining, which frequently damages the environment, battery manufacturers in future could be using organic waste to make batteries.

In tests, the new material discovered by researchers from the Helmholtz Institute Ulm of Karlsruhe Institute of Technology, has demonstrated ‘excellent electrochemical properties’, allowing the researchers to carry out 1000 charge and discharge cycles during which the apple-based battery demonstrated high stability as well as capacity.  Cont'd...

These Creative Wind Turbines Will Have You Rethinking What You Know About Wind Power

By Alison Gillespie for SMITHSONIAN.COM: Although a lot of people are excited about wind energy, few are excited about the pinwheel-shaped machines that often produce it. Branded as noisy, blamed for spoiling bucolic views and proven deadly to some bats and migrating birds, the giant, white-bladed horizontal axis wind turbines that now dot the landscape of the American West have earned a fair number of detractors—even among environmentalists who generally favor renewable power.

But what if you turned the idea sideways, and created a turbine that could spin like a carousel? And what if you made a turbine small enough to sit on top of a building or inside an urban park? Could the result produce enough power to really matter?

The idea isn’t a new one—people have been playing with windmill designs and experimenting with alternatives to the horizontal axis turbine for almost a century now. But in the last two decades, a flurry of interest in expanding renewable energy in cities has attracted the attention of a large number of inventors and artists, many of whom see the vertical axis wind turbine as promising.

There is no single design for these upended wind catchers, but all share one key aspect: the blades turn around an axis that points skyward. And unlike their horizontal brethren, the components and associated generators of a vertical turbine are placed at its base, giving it a lower center of gravity. Most are also relatively small, and unlike horizontal units, they can be grouped very closely together to optimize efficiency.  Cont'd...

Sand could be the key to unlocking more efficient solar power, Masdar scientists find

Naser Al Wasmi for The National UAE: Masdar Institute scientists have published a breakthrough research into more efficient solar power – and they will not have to look far for the raw material ­needed.

Using sand, they hope to drive concentrated solar power technology to compete with the traditional photovoltaic method.

Named “Sandstock”, the research published at the Solar Power and Chemical Energy Systems Conference in South Africa yesterday, showed sand can withstand temperatures of up to 1,000°C.

Concentrated solar power, or CSP, uses mirrors to reflect heat from the sun to one point, most typically a tower filled with a material capable of storing heat and then converting it into electricity.

CSP’s benefit is that the energy derived is easy to store, but in recent years it has lost out to the more popular photovoltaics, which is more cost-efficient.

That may now change.

“Sand is really always a drawback in this country but in this project we wanted to use it as an advantage because it can withstand very high temperature, and of course it is very cheap here,” said Dr Nicolas Calvet, assistant professor of mechanical and materials engineering, and guide for the research project.  Cont'd...

Could this be the future of biofuels?

Anmar Frangoul for CNBC:  A common sight in the British countryside, bracken -- a type of fern -- is now being hailed as the next big source of biofuel. 

Based in the south west of England, Brackenburn produces "brackettes" – biomass pellets made from bracken that they shred and compress into briquettes which produce much more heat when burnt than oak.

"In our estimation there's 2.5 million acres of bracken in the UK… it's a huge area," Barry Smith, Brackenburn's marketing and sales director, told CNBC in a phone interview.

"Left unchecked, bracken encroaches by three percent a year… at the end of the day there's no use for it whatsoever," Smith added. "It's a nuisance and to call it a crop is kind of giving it a status it doesn't deserve."  Cont'd...

Thin film perovskite solar cell passes the efficiency test

Matthew Gunther for Chemistry World:  Perovskite solar cells may one day rival silicon-based technologies, but their performance outside the laboratory has been a constant source of contention in the past year. Now, an international team of scientists has manufactured the first thin film perovskite solar cell with a reported efficiency that has beenofficially recognised by an accredited national test laboratory.1

Since their development in 2012, the performance of light-harvesting metal–organo halide structures has seemingly improved at a staggering rate, with their efficiency increasing by six percentage points in just two years – the same increase took multi-crystalline solar cells over two decades.

But their stability has been brought into question, with some international test centres taking issue with perovskite solar cells that are so unstable that they may degrade spontaneously in air, making it hard for them to assess their performance.

It’s a state of affairs that Michael Grätzel from the Ecole Polytechnique Fédérale de Lausanne in Switzerland has had trouble dealing with. ‘Conspicuously, you could see that from the very beginning there was very scarce information on the stability of these devices,’ comments Grätzel. ‘I have raised that issue many times – one would think that now everybody does stability work after this alarm was sounded, but not so.'  Cont'd...

The Importance of Pyranometer Temperature Response

One of the main parameters affecting the real-world measurement of solar radiation by pyranometers is temperature response.

Increasing Wind Turbine AEP with Vortex Generators

Vortex Generators are small attachments made from durable material that energizes the flow around the blade and reduce flow separation.

Energy From Stars

This paper proposes possible new energy sources. One of these sources can be the "energy from stars".

Cloaking Principle Could Boost Solar Cell Performance

Invisibility cloaking may be a long way from reality, but the principle could help improve the performance of solar cells in the near term. 
In a series of simulations, researchers at the Karlsruhe Institute of Technology have demonstrated how cloaks made of metamaterials or freeform surfaces could eliminate shadows cast by energy-harvesting components onto the active surfaces of solar cells. 
Contact fingers, which extract electric current, cover up to one-tenth of the surface area of a solar cell. By guiding light around these features, more of the sun's energy could be captured by the solar cell. 
"Our model experiments have shown that the cloak layer makes the contact fingers nearly completely invisible," said doctoral student Martin Schumann.  Cont'd...
 

Researchers develop cool way to improve solar cell efficiency

By Kelly Hodgkins for Digital Trends:   A team of engineers from Stanford University have invented a cool way to improve the performance of solar panel arrays. A new material that the team produced literally will lower the temperature of solar cells even while they are operating in full-strength sunlight. As the solar cells cool, their efficiency will rise, leading to significant gains in the amount of energy harvested from the sun.

Solar panel technology has improved by leaps and bounds, but the technology has a flaw that limits the efficiency of the system. The panels must face the sun to operate, but the heat from this exposure diminishes their ability to convert light into energy. The hotter they get, the less efficient they become. This issue has perplexed the industry for years, but the Stanford team may have discovered a material that can help dissipate this excess heat without affecting the operation of the solar array.

The solution, proposed by Stanford electrical engineering professor Shanhui Fan, research associate Aaswath P. Raman, and doctoral candidate Linxiao Zhu, uses a material that is able to capture and emit thermal radiation (heat) away from the solar call. While deterring heat buildup, the thin, patterned silica material does not block sunlight, allowing the photons to enter the solar panel where they are converted to energy. It’s a win-win situation, allowing the free flow of sunlight and the removal of excess heat from the system.  Cont'd...

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