De overstap naar zonne-energie erg dichtbij?

Folding light: Wrinkles and twists boost power from solar panels

Taking their cue from the humble leaf, researchers have used microscopic folds on the surface of photovoltaic material to significantly increase the power output of flexible, low-cost solar cells.

The team, led by scientists from Princeton University, reported online April 22 in the journal Nature Photonics that the folds resulted in a 47 percent increase in electricity generation. Yueh-Lin (Lynn) Loo, the principal investigator, said the finely calibrated folds on the surface of the panels channel light waves and increase the photovoltaic material's exposure to light.

"On a flat surface, the light either is absorbed or it bounces back," said Loo, a professor of chemical and biological engineering at Princeton. "By adding these curves, we create a kind of wave guide. And that leads to a greater chance of the light's being absorbed."

The research team's work involves photovoltaic systems made of relatively cheap plastic. Current solar panels are typically made of silicon, which is both more brittle and more expensive than plastics. So far, plastic panels have not been practical for widespread use because their energy production has been too low. But researchers have been working to increase that efficiency with the goal of creating a cheap, tough and flexible source of solar power.

If researchers can increase the plastic panels' efficiency, the material could produce power from an array of surfaces from inserts in window panels to overlays on exterior walls or backpacks.

"It is flexible, bendable, light weight and low cost," Loo said.

In most cases, researchers have focused on increasing the efficiency of the plastic photovoltaic material itself. Recent developments have been promising: a team from UCLA recently announced a system with a 10.6 percent efficiency. That approaches the 10 to 15 percent level seen as the target for commercial development.

Loo said the folding method promises to increase those numbers. Because the technique works with most types of plastic photovoltaic materials, it should provide a boost to efficiency across the board.

"This is a very simple process that you can use with any material," she said. "We have tested it with other polymers and it works as well."

Jong Bok Kim, a postdoctoral researcher in chemical and biological engineering and the paper's lead author, explained in the Nature Photonics paper that the folds on the surface of the panels channel light waves through the material in much the same way that canals guide water through farmland. By curving the light through the material, the researchers essentially trap the light inside the photovoltaic material for a longer time, which leads to greater absorption of light and generation of energy.



"I expected that it would increase the photocurrent because the folded surface is quite similar to the morphology of leaves, a natural system with high light harvesting efficiency," said Kim, a postdoctoral researcher in chemical and biological engineering. "However, when I actually constructed solar cells on top of the folded surface, its effect was better than my expectations."

Although the technique results in an overall increase in efficiency, the results were particularly significant at the red side of the light spectrum, which has the longest wavelengths of visible light. The efficiency of conventional solar panels drops off radically as light's wavelength increases, and almost no light is absorbed as the spectrum approaches the infrared. But the folding technique increased absorption at this end of the spectrum by roughly 600 percent, the researchers found.

"If you look at the solar spectrum, there is a lot of sunlight out there that we are wasting," Loo said. "This is a way to increase efficiency."

The research team created the folded surface in Howard Stone's laboratory in the mechanical and aerospace engineering department by carefully curing a layer of liquid photographic adhesive with ultraviolet light. By controlling how fast different sections of the adhesive cured, the team was able to introduce stresses in the material and generate ripples in the surface. The shallower ripples were classified as wrinkles and the deeper ones are called folds. The team found that a surface containing a combination of wrinkles and folds produced the best results.

Although the math underlying the process is complex, the actual production is straightforward. Loo said it would be quite practical for industrial purposes.

"Everything hinges on the fact that you can reproduce the wrinkles and folds," Loo said. "By controlling the stresses, we can introduce more or fewer wrinkles and folds."

Another benefit of the process is that it increases the durability of the solar panels by relieving mechanical stresses from bending. The researchers found the panels with folded surfaces were able to retain their effectiveness after bending. A standard plastic panel's energy production would be diminished by 70 percent after undergoing bending.

Loo said the researchers drew their inspiration from leaves. Seemingly a simple object, the leaf is a miracle of natural engineering. Its green surface is perfectly constructed to bend and control light to ensure that a maximum amount of solar energy is absorbed to create energy and nutrients for the tree. Recent work by Pilnam Kim, a postdoctoral researcher in Stone's lab, provided insight into how these microscopic structures could be applied to synthetic devices.

"If you look at leaves very closely, they are not smooth, they have these sorts of structures," said Loo, who is deputy director of Princeton's Andlinger Center for Energy and the Environment. "We'd like to mimic this geometric effect in synthetic, man-made light-harvesting systems."

http://www.zeitnews.org/e(...)om-solar-panels.html

Sharp Hits Solar Cell Efficiency Record of 43.5%

With all of the different types of solar cells being developed from thin-film to crystalline silicon as well as new ways of boosting light absorption it seems there is always a new solar cell efficiency record being announced, but this new record from Sharp of 43.5% is a pretty big deal. A large jump over the company's previous record of 36.9% efficiency in November 2011, it shows that solar technology is getting ever closer to that 50% mark that could revolutionize the industry.



Sharp achieved the conversion efficiency record with their concentrator triple-junction compound solar cell that uses a lens-based system to focus sunlight on the cells to generate electricity.

According to Sharp:

Compound solar cells utilize photo-absorption layers made from compounds consisting of two or more elements, such as indium and gallium. The basic structure of this latest triple-junction compound solar cell uses Sharp’s proprietary technology that enables efficient stacking of the three photo-absorption layers, with InGaAs (indium gallium arsenide) as the bottom layer.

To achieve this latest increase in conversion efficiency, Sharp capitalized on the ability of this cell to efficiently convert sunlight collected via three photo-absorption layers into electricity. Sharp also optimized the spacing between electrodes on the surface of the concentrator cell and minimized the cell’s electrical resistance.



Conventional solar panels that are on the market now still have an efficiency of only about 15 to 20 percent, but these breakthroughs made in labs will eventually lead to climbing efficiencies in mass market solar panels too. Sharp's compound solar cell technology is currently only used in space satellites, but the company wants to adapt the technology into small-surface-area solar cells that would be practical for use down here on the ground.

The conversion efficiency record was confirmed by the Fraunhofer Institute for Solar Energy in April 2012 and it is the same exact conversion efficiency achieved by Solar Junction of the United States in March 2011. The fact that two companies have been able to achieve the same high efficiency is a good sign that the industry is quickly scaling up efficiency across the board.

http://www.zeitnews.org/e(...)y-record-of-435.html

German researchers developing higher-efficiency organic solar cells

The Karlsruhe Institute of Technology, through its Light Technology Institute, this month will initiate new research on printable organic solar cells. The four-year project aims at increasing the efficiency of such cells to more than 10 percent. These promising, cheaper solar cells can be manufactured using existing techniques such as screen printing and continuous roll-to-roll processes. So far, however, low efficiency rates have stood between these cells and the market.

The methodology the KIT researchers are going to use is based on a tandem architecture, which involves combining multiple solar cells that offer complementary levels of light absorption. They stack two solar cells directly on top of each other and together they can harvest more sunlight and, consequently, achieve better efficiency rates.

Organic solar cells are also known as plastic solar cells. They are light, flexible, semi-transparent, more environmentally-friendly than other types of cells, and offer a quicker return on investment. Such characteristics open up possibilities for exciting new applications, especially in architecture, where the cells could be integrated into the design of buildings. Other areas offering potential for the technology include the manufacturing of automotive parts and consumer goods.



The research will also look into new materials, as well as ways to improve the cells’ stability. All testing will be done in real-life contexts, including manufacturing processes, which will be done in an industry-compatible production environment in order to improve chances of commercially-applicable results.

KIT researchers are not the only ones working to improve organic solar cell efficiency, but if they achieve their desired goal, this type of solar cell could get closer to becoming competitive with standard, non-organic silicon models.

The research has been made possible with ¤4.25 million (US$5.32 million) in funding from the German Federal Ministry of Education and Research.

http://www.zeitnews.org/e(...)nic-solar-cells.html

quote:

Op donderdag 5 juli 2012 19:27 schreef KeimpeHart het volgende:
1 kanttekening: het materiaal waarmee die zonnepanelen geproduceerd worden, is toch zeldzaam. En erg milieuvervuilend om dat te opgraven en tot bruikbare stof om te vormen?

Straks zijn de grondstoffen voor zonnepanelen op, en olie is ook al op, en het schiet niet op voor het milieu wanneer die zonnepanelen geproduceerd worden.

Er zijn steeds meer materialen die gebruikt kunnen worden. Vergeet niet dat we met nano-technologie de meesters over de materie aan het worden zijn. We kunnen zelf vanuit goedkope en veel aanwezige stoffen andere stoffen maken door op nano niveau deze stoffen te bewerken. Vroeger toen we nog geen nano-tech hadden, waren we afhankelijk van de stoffen die aanwezig waren op aarde en deze konden we dan aanpassen maar dan vaak met arbeidsintensieve en dure processen.

Nu hoeven we niet meer langs allerlei tussenstations om tot een eindproduct te komen, we bouwen dat product gewoon op nanoniveau

quote:

Op donderdag 5 juli 2012 20:13 schreef Maanvis het volgende:
als we nanotech hebben dan is alles wat daarmee gebouwd wordt zo energie-efficiënt dat we ook met veel minder energie toe kunnen.
maareh welke stoffen heeft ie het over?

Ik denk dat hij silicon bedoelt.

bSolar’s Double-Sided Photovoltaic Cells Produce Up to 50% More Energy

Standard photovoltaic cells only harvest energy from a single surface – the side facing the sun. Israeli startup bSolar has found a way to improve upon this unidirectional design with a double-sided solar cell that is able to produce up to 50% more energy. The trick to bSolar’s bifacial design lies in the cells’ boron “back surface field”, which is used instead of opaque aluminum backing – this enables the potent monocrystalline silicon photovoltaic cells to capture light reflected by rooftops, clouds, the earth, and the atmosphere.



While dual-sided solar cells have been developed in the past, bSolar claims that their bifacial solar cells are more powerful, more efficient, and cheaper to produce. The company engineered monocrystalline silicon wafers to collect light from both sides of the solar cell and encased them with a boron “back surface field”, which increases the cells’ efficiency and durability. bSolar says that their design boosts electricity generation by 10-30% on flat surfaces, and by 30-50% on vertical installations such as fences and highway sound barriers.

So far response to bSolar‘s bifacial photovoltaics has been strong – solar panel manufacturers interested in the technology include Aleo Solar, Asola and Solar-Fabrik, and a new 730 KW project in Japan will use the cells.

http://www.zeitnews.org/e(...)-50-more-energy.html

New Solar Panel Designs Make Installation Cheaper

With solar panel prices falling more than 80 percent in the last few years, many solar companies are turning their attention to reducing the cost of installing them. Two leading solar companies, Solon Energy, based in Berlin, and Trina Solar, based in Changzhou, China, have announced new designs for mounting solar panels to roofs—the companies say these designs can reduce the installation time by more than half, greatly reducing labor costs. The new designs reduce or eliminate the tools and hardware needed to install solar panels, and standardize solar installations, which have largely been ad hoc, reducing the time needed to design them.

While solar panels themselves used to account for most of the cost of large solar installations on commercial rooftops, the modules now account for about 40 percent of the cost. The rest comes from things like the necessary hardware, power electronics, and labor—which alone accounts for about 30 percent of the total.

Mounting solar panels on the flat rooftops of commercial installations typically involves anchoring long metal racks to the roof to create a framework that will angle the panels toward the sun and hold them together. Installers bolt the panels to this frame, wire the panels together, and electrically ground the racks.



Trina's design gets rid of most of this metal framework. It starts with some simple changes to the solar panels themselves. Solar panels resemble framed pictures—they consist of solar cells sealed behind a piece of glass and held in place and protected by a metal frame. This frame is typically bolted to the metal rack framework that angles the panel toward the roof. Trina uses the frame of the solar panel itself to provide the framework. Special hardware locks into grooves cut into the frame, propping the panel at the correct angle without the need of any tools.

The company says this reduces installation time by two-thirds, and reduces the chance that stray bolts and screws might get caught under the framework and damage the roof. Savings in materials and labor costs can add up to a 10-cent-per-watt reduction in costs for solar power, a significant drop considering that solar panels now sell for less than $1 per watt.

While Trina modifies the solar panel's metal frame, Solon eliminates it altogether. It takes an array of solar cells that have been sealed behind a layer of glass and then glues that to a plastic form that angles the cells toward the sun. This complete module is assembled in a factory, reducing the amount of work that needs to be done on site. Installers set the modules on the roof, link them together with plastic connectors (they also add some ballast), and plug wires together to establish electrical connections. Because the modules have no exposed metal, it isn't necessary to ground them, which helps reduce costs. Solon says the design reduces the time needed for mechanically mounting the panels by 75 percent, and the time needed for making the electrical connections by half. (Solon says that the impact on costs varies widely, depending on factors like labor costs.)

Both designs come with some trade-offs—for example, to achieve economies of scale, the systems provide only one standard angle for pointing the panels at the sun. At some latitudes, the panels would generate more power if they were tilted more or less than that angle.

http://www.zeitnews.org/e(...)llation-cheaper.html

Record Efficiency for Next-Generation Solar Cells

Researchers from the University of Toronto (U of T) and King Abdullah University of Science & Technology (KAUST) have made a breakthrough in the development of colloidal quantum dot (CQD) films, leading to the most efficient CQD solar cell ever. Their work is featured in a letter published in Nature Nanotechnology.

The researchers, led by U of T Engineering Professor Ted Sargent, created a solar cell out of inexpensive materials that was certified at a world-record 7.0% efficiency.

"Previously, quantum dot solar cells have been limited by the large internal surface areas of the nanoparticles in the film, which made extracting electricity difficult," said Dr. Susanna Thon, a lead co-author of the paper. "Our breakthrough was to use a combination of organic and inorganic chemistry to completely cover all of the exposed surfaces."

Quantum dots are semiconductors only a few nanometres in size and can be used to harvest electricity from the entire solar spectrum -- including both visible and invisible wavelengths. Unlike current slow and expensive semiconductor growth techniques, CQD films can be created quickly and at low cost, similar to paint or ink. This research paves the way for solar cells that can be fabricated on flexible substrates in the same way newspapers are rapidly printed in mass quantities.



The U of T cell represents a 37% increase in efficiency over the previous certified record. In order to improve efficiency, the researchers needed a way to both reduce the number of "traps" for electrons associated with poor surface quality while simultaneously ensuring their films were very dense to absorb as much light as possible. The solution was a so-called "hybrid passivation" scheme.

"By introducing small chlorine atoms immediately after synthesizing the dots, we're able to patch the previously unreachable nooks and crannies that lead to electron traps," explained doctoral student and lead co-author Alex Ip. "We follow that by using short organic linkers to bind quantum dots in the film closer together."

Work led by Professor Aram Amassian of KAUST showed that the organic ligand exchange was necessary to achieve the densest film.

"The KAUST group used state-of-the-art synchrotron methods with sub-nanometer resolution to discern the structure of the films and prove that the hybrid passivation method led to the densest films with the closest-packed nanoparticles," stated Professor Amassian.

The advance opens up many avenues for further research and improvement of device efficiencies, which could contribute to a bright future with reliable, low cost solar energy.

According to Professor Sargent, "Our world urgently needs innovative, cost-effective ways to convert the sun's abundant energy into usable electricity. This work shows that the abundant materials interfaces inside colloidal quantum dots can be mastered in a robust manner, proving that low cost and steadily-improving efficiencies can be combined."

http://www.zeitnews.org/a(...)neration-solar-cells

quote:

Op donderdag 6 september 2012 06:17 schreef Digi2 het volgende:

[..]

Deze techniek zou ook moeten werken bij andere typen zonnecellen zoals thin film solarcells die vaak goedkoper te fabriceren zijn maar een relatief laag rendament hebben. 2,5 x een rendament van 6 tot 8% levert toch een cell op die een respectabele 18 tot 24% kan halen.

Ray Kurzweil gaat gelijk krijgen met zijn voorspellingen denk ik

Met de exponentiele groei van het rendement van de zonnecellen, worden we straks ineens overspoeld met zonnepanelen. Net zoals met de mobiele telefoon en pc's destijds.

Hier nog wat leuke grafieken en diagrammen:

quote:

Op vrijdag 7 september 2012 00:57 schreef Eyjafjallajoekull het volgende:

[..]

Dat denk ik ook ja. Als het aan de techniek ligt wel. Maar het ligt ook aan de markt/politiek.

Nou de reden dat we overspoeld gaan worden, is dat zonne-energie straks veel goedkoper is dan fossiele brandstoffen. De markt daar ligt het niet aan en dat is ook de reden dat de politiek dit niet gaat tegenhouden. De mensen willen dit en de markt wil het graag (lagere energiekosten).

Germany Added 543 Megawatts of Solar Power Capacity in July

Matt recently wrote about Germany's impressive solar PV growth for the first half of 2012. He wrote:

"[In] the first hald of 2012 Germany has installed just over 4.37 gigawatts of grid-tied solar power. Remarkably just about 1.8 GW of that happened in June alone (perhaps even more remarkable, this isn't even a record amount for one month in Germany)."

Well, July is nowhere near as good as June was, but it still added quite a significant amount of PV capacity to the country with 543.225 MW of newly installed PV output, based on the data received by the German Federal Network Agency.



"All in all, this results in an additional 4.9 GW for 2012. Last year, just 2,285 MW were recorded in the same period. Thus, the total of all installations subsidized by the Renewable Energy Resources Act up to July 31, 2012 amounted to 29.7 GW." (source)

Part of the reason for the rapid pace of new installation during the first half of the year is the changes in subsidies that took effect then. We should expect a slower pace of growth in the rest of the year, but hopefully other countries will pick up the slack (like India!).

http://www.zeitnews.org/a(...)-power-capacity-july

Een verdubbeling ten opzichte van vorig jaar! En 2012 is nog niet eens afgelopen

Weer een mooie nieuwe stap:

GeS “nanoflowers” could blossom in next-gen solar cells

Researchers have already turned to the humble sunflower for inspiration to design more efficient Concentrating Solar Power (CSP) plant layouts, and now a team from North Carolina State University has developed a “nanoflower” structure out of germanium sulfide (GeS) that shows great promise for use in energy-storage devices and more efficient solar cells. The secret is the material's ultrathin petals that provide a large surface area in only a small amount of space.

The researchers created the flower-like structures by first heating GeS powder in a furnace until it began to vaporize. The vapor is then blown into a cooler region of the furnace, where the GeS settles into a layered sheet measuring just 20 to 30 nanometers thick and up to 100 micrometers long. A flower-like structure similar to a carnation or marigold is formed as additional layers are added causing the sheets branch out from one another.



GeS is a semiconductor material that is attractive for use in solar cells because it is inexpensive and non-toxic, while its atomic structure makes it good at absorbing solar energy and converting it into useable power. But solar cells aren’t the only potential applications for the nanoflower technology.

“This could significantly increase the capacity of lithium-ion batteries, for instance, since the thinner structure with larger surface area can hold more lithium ions,” says Dr. Linyou Cao, an assistant professor of materials science and engineering at NC State and co-author of a paper on the research. “By the same token, this GeS flower structure could lead to increased capacity for supercapacitors, which are also used for energy storage.”

The team’s paper is published in the journal ACS Nano.

http://www.zeitnews.org/a(...)next-gen-solar-cells

En een docu van VPRO tegenlicht:

http://tegenlicht.vpro.nl(...)r-to-the-people.html

Er is een grote revolutie in het ‘kleine’ aan de hand. Zoals we van lezers bloggers zijn geworden, transformeren we nu van consument naar producent. Van energievoorziening tot verzekering, alles wordt kleinschalig en lokaal. In Tegenlicht het revolutionaire antwoord op de wereld van de multinationals.

Na de industriële en de digitale revolutie staan we aan het begin van een nieuwe: de energierevolutie. Steeds meer mensen laden het dak van hun huis vol met zonnepanelen of kopen samen een windmolen om zo minder afhankelijk te worden van grote energieleveranciers. We maken onze eigen stroom en onze woonwijk wordt een energiemaatschappij. Het energieoverschot wordt verkocht en zo maakt de hele buurt winst, zoals dat nu al op het Deense eiland Samsø gebeurt. Maar als we de energiemarkt kunnen decentraliseren, wat kunnen we dan nog meer? Waarom ook niet de zorg of onze verzekeringen in eigen hand nemen? Het revolutionaire antwoord op het doorgeslagen multinationale kapitalisme en de mogelijke overgang naar een ander, socialer systeem.

In Power to the People brengt regisseur Sabine Lubbe Bakker bezoeken aan het 'energiepositieve' Samsø (waar zij wordt rondgeleid door initiatiefnemer Søren Hermansen), aan Texel Energie –dat streeft naar energieonafhankelijkheid in 2020-, aan Grunneger Power, één van de meest succesvolle energiecoöperaties en aan de Utrechtse bedenkers van het ‘broodfonds’, een nieuwe collectieve kijk op arbeidsongeschiktheid. Marjan Minnesma van stichting Urgenda verklaart waarom de beweging van onderop nu ook in Nederland overal opduikt. En de Amerikaanse econoom Jeremy Rifkin, al jarenlang voorvechter van verduurzaming, voorspelt dat het burgerkapitalisme binnen twee jaar onze wereld zal veranderen.

Het devies: doe het zelf, doe het samen.

quote:

Op zaterdag 13 oktober 2012 04:50 schreef Probably_on_pcp het volgende:
En een docu van VPRO tegenlicht:

http://tegenlicht.vpro.nl(...)r-to-the-people.html

Er is een grote revolutie in het ‘kleine’ aan de hand. Zoals we van lezers bloggers zijn geworden, transformeren we nu van consument naar producent. Van energievoorziening tot verzekering, alles wordt kleinschalig en lokaal. In Tegenlicht het revolutionaire antwoord op de wereld van de multinationals.

Na de industriële en de digitale revolutie staan we aan het begin van een nieuwe: de energierevolutie. Steeds meer mensen laden het dak van hun huis vol met zonnepanelen of kopen samen een windmolen om zo minder afhankelijk te worden van grote energieleveranciers. We maken onze eigen stroom en onze woonwijk wordt een energiemaatschappij. Het energieoverschot wordt verkocht en zo maakt de hele buurt winst, zoals dat nu al op het Deense eiland Samsø gebeurt. Maar als we de energiemarkt kunnen decentraliseren, wat kunnen we dan nog meer? Waarom ook niet de zorg of onze verzekeringen in eigen hand nemen? Het revolutionaire antwoord op het doorgeslagen multinationale kapitalisme en de mogelijke overgang naar een ander, socialer systeem.

In Power to the People brengt regisseur Sabine Lubbe Bakker bezoeken aan het 'energiepositieve' Samsø (waar zij wordt rondgeleid door initiatiefnemer Søren Hermansen), aan Texel Energie –dat streeft naar energieonafhankelijkheid in 2020-, aan Grunneger Power, één van de meest succesvolle energiecoöperaties en aan de Utrechtse bedenkers van het ‘broodfonds’, een nieuwe collectieve kijk op arbeidsongeschiktheid. Marjan Minnesma van stichting Urgenda verklaart waarom de beweging van onderop nu ook in Nederland overal opduikt. En de Amerikaanse econoom Jeremy Rifkin, al jarenlang voorvechter van verduurzaming, voorspelt dat het burgerkapitalisme binnen twee jaar onze wereld zal veranderen.

Het devies: doe het zelf, doe het samen.

Wat ik wel apart vond om te horen is dat de fossiele brandstof industrie volgens mij 4 miljard aan subsidie krijgt, terwijl er voor duurzame energie 2 miljard aan subsidie wordt gegeven.

Scientists Build the First All-Carbon Solar Cell

Stanford University scientists have built the first solar cell made entirely of carbon, a promising alternative to the expensive materials used in photovoltaic devices today.

The results are published in the Oct. 31 online edition of the journal ACS Nano.

"Carbon has the potential to deliver high performance at a low cost," said study senior author Zhenan Bao, a professor of chemical engineering at Stanford. "To the best of our knowledge, this is the first demonstration of a working solar cell that has all of the components made of carbon. This study builds on previous work done in our lab."

Unlike rigid silicon solar panels that adorn many rooftops, Stanford's thin film prototype is made of carbon materials that can be coated from solution. "Perhaps in the future we can look at alternative markets where flexible carbon solar cells are coated on the surface of buildings, on windows or on cars to generate electricity," Bao said.

The coating technique also has the potential to reduce manufacturing costs, said Stanford graduate student Michael Vosgueritchian, co-lead author of the study with postdoctoral researcher Marc Ramuz.

"Processing silicon-based solar cells requires a lot of steps," Vosgueritchian explained. "But our entire device can be built using simple coating methods that don't require expensive tools and machines."

Carbon nanomaterials

The Bao group's experimental solar cell consists of a photoactive layer, which absorbs sunlight, sandwiched between two electrodes. In a typical thin film solar cell, the electrodes are made of conductive metals and indium tin oxide (ITO). "Materials like indium are scarce and becoming more expensive as the demand for solar cells, touchscreen panels and other electronic devices grows," Bao said. "Carbon, on the other hand, is low cost and Earth-abundant."

The Bao group's all-carbon solar cell consists of a photoactive layer, which absorbs sunlight, sandwiched between two electrodes.



For the study, Bao and her colleagues replaced the silver and ITO used in conventional electrodes with graphene -- sheets of carbon that are one atom thick -and single-walled carbon nanotubes that are 10,000 times narrower than a human hair. "Carbon nanotubes have extraordinary electrical conductivity and light-absorption properties," Bao said.

For the active layer, the scientists used material made of carbon nanotubes and "buckyballs" -- soccer ball-shaped carbon molecules just one nanometer in diameter. The research team recently filed a patent for the entire device.

"Every component in our solar cell, from top to bottom, is made of carbon materials," Vosgueritchian said. "Other groups have reported making all-carbon solar cells, but they were referring to just the active layer in the middle, not the electrodes."

One drawback of the all-carbon prototype is that it primarily absorbs near-infrared wavelengths of light, contributing to a laboratory efficiency of less than 1 percent -- much lower than commercially available solar cells. "We clearly have a long way to go on efficiency," Bao said. "But with better materials and better processing techniques, we expect that the efficiency will go up quite dramatically."

Improving efficiency

The Stanford team is looking at a variety of ways to improve efficiency. "Roughness can short-circuit the device and make it hard to collect the current," Bao said. "We have to figure out how to make each layer very smooth by stacking the nanomaterials really well."

The researchers are also experimenting with carbon nanomaterials that can absorb more light in a broader range of wavelengths, including the visible spectrum.

"Materials made of carbon are very robust," Bao said. "They remain stable in air temperatures of nearly 1,100 degrees Fahrenheit."

The ability of carbon solar cells to out-perform conventional devices under extreme conditions could overcome the need for greater efficiency, according to Vosgueritchian. "We believe that all-carbon solar cells could be used in extreme environments, such as at high temperatures or at high physical stress," he said. "But obviously we want the highest efficiency possible and are working on ways to improve our device."

"Photovoltaics will definitely be a very important source of power that we will tap into in the future," Bao said. "We have a lot of available sunlight. We've got to figure out some way to use this natural resource that is given to us."

Other authors of the study are Peng Wei of Stanford and Chenggong Wang and Yongli Gao of the University of Rochester Department of Physics and Astronomy. The research was funded by the Global Climate and Energy Project at Stanford and the Air Force Office for Scientific Research.

http://www.zeitnews.org/a(...)ll-carbon-solar-cell

Effective Thermal Energy Storage System for Storing Energy from Solar Panels Developed

Engineering researchers at the University of Arkansas have developed a thermal energy storage system that will work as a viable alternative to current methods used for storing energy collected from solar panels. Incorporating the researchers' design into the operation of a concentrated solar power plant will dramatically increase annual energy production while significantly decreasing production costs.

Current storage methods use molten salts, oils or beds of packed rock as media to conduct heat inside thermal energy storage tanks. Although these methods do not lose much of the energy collected by the panels, they are either expensive or cause damage to tanks. Specifically, the use of a packed rock, currently the most efficient and least expensive method, leads to thermal "ratcheting," which is the stress caused to tank walls because of the expansion and contraction of storage tanks due to thermal cycling.



"The most efficient, conventional method of storing energy from solar collectors satisfies the U.S. Department of Energy's goal for system efficiency," said Panneer Selvam, professor of civil engineering. "But there are problems associated with this method. Filler material used in the conventional method stresses and degrades the walls of storage tanks. This creates inefficiencies that aren't calculated and, more importantly, could lead to catastrophic rupture of a tank."

As an alternative to conventional methods, Selvam and doctoral student Matt Strasser designed and tested a structured thermocline system that uses parallel concrete plates instead of packed rock inside a single storage tank. Thermocline systems are units -- bodies of water, such as oceans and lakes, for example, but also smaller units that contain fluids or gas -- with distinct boundaries separating layers that have different temperatures. The plates were made from a special mixture of concrete developed by Micah Hale, associate professor of civil engineering. The mixture has survived temperatures of up to 600 degrees Celsius, or 1,112 degrees Fahrenheit. The storage process takes heat, collected in solar panels, and then transfers the heat through steel pipes into the concrete, which absorbs the heat and stores it until it can be transferred to a generator.

Modeling results showed the concrete plates conducted heat with an efficiency of 93.9 percent, which is higher than the Department of Energy's goal and only slightly less than the efficiency of the packed-bed method. Tests also confirmed that the concrete layers conducted heat without causing damage to materials used for storage. In addition, energy storage using the concrete method cost only $0.78 per kilowatt-hour, far below the Department of Energy's goal of achieving thermal energy storage at a cost of $15 per kilowatt-hour.

"Our work demonstrates that concrete is comparable to the packed-bed thermocline system in terms of energy efficiency," Selvam said. "But the real benefit of the concrete layers is that they do not cost a lot to produce compared to other media, and they have the unique ability to conduct and store heat without damaging tanks. This factor alone will increase production and decrease operating expenses for concentrated solar power plants."

In 2008, Selvam, holder of the James T. Womble Professor of Computational Mechanics and Nanotechnology Modeling, received a $770,000 award from the U.S. Department of Energy to develop a novel method of storing thermal energy in concrete. The award and research project were part of the federal government's initiative to develop technology for low-cost energy storage of solar power.

Selvam also directs the university's Computational Mechanics Laboratory.

Strasser is a Doctoral Academy Fellow. The Doctoral Academy Fellowships were created in 2002 as part of a $100 million endowment established by a $300 million gift from the Walton Charitable Support Foundation.

http://www.zeitnews.org/a(...)olar-panels-develope

High-efficiency solar energy tech turns water into steam

A team of researchers at Rice University has developed a new technology that uses light-absorbing nanoparticles to convert solar energy directly into steam. Even though it is already significantly more efficient than solar panels at producing electricity, the technology will likely find its first applications in low-cost sanitation, water purification and human waste treatment for the developing world.

Approximately 90 percent of the world's electricity is produced from steam turbines. Most industrial steam is produced in large, expensive boilers, but because of its very small footprint and high efficiency, this new development promises to make steam economically viable on a much smaller scale. Sterilizing medical waste and surgical instruments, preparing food and purifying water could soon become within reach of a large chunk of the developing world, that doesn't have access to the electrical grid.



The Rice technology relies on light-absorbing nanoparticles. When they are submerged and then illuminated, these particles can very quickly reach temperatures well above the boiling point of water. At this stage, they quickly dissipate heat through their very small surface area, which almost instantly results in 150°C (300°F) steam generated right at the surface of the particle. The system is so effective that it can even turn icy-cold water directly into vapor with ease.

The technology converts about 80 percent of the energy coming from the sun into steam. With the current iteration, passing the resulting steam to a turbine would generate electricity with an overall efficiency of 24 percent (compared to a solar panel's typical efficiency of around 15 percent). As the technology is further refined, the researchers say there is still room for improvement on the efficiency front.

Other potential uses could be powering hybrid air-conditioning and heating systems that run off of sunlight during the day and off of electricity at night. The system has also proved very promising in distilling water, with an experiment finding that the technology is about two and a half times more efficient than existing commercially available systems.

The project was awarded a grant from the Bill and Melinda Gates Foundation to create a small-scale system for treating human waste in areas lacking sewer systems or electricity. In the meantime, Rice engineering undergraduates have already created a solar steam-powered autoclave that can sterilize medical and dental instruments in clinics lacking electricity.

An open-access paper detailing the research efforts was published in the journal ACS Nano.

http://www.zeitnews.org/a(...)ch-turns-water-steam

Zonnepanelen zijn in België rendabel zonder overheidssteun

De Belgische overheidssteun voor zonnepanelen kan per 1 januari 2013 mogelijk al stoppen, omdat de energieopbrengst er al rendabel is. Dat blijkt uit een studie van het Vlaams Energieagentschap. De oorzaken zijn de gedaalde prijzen voor zonnepanelen en de hoge energieprijzen.

Het Vlaams Energieagentschap berekent jaarlijks hoeveel steun er nodig is om investeringen in duurzame energie rendabel te maken. Voor het eerst komt de berekening uit op een negatief bedrag, meldt De Standaard. Het agentschap komt uit op een benodigde steun van -60,5 euro per megawattuur. Het is voor Belgen dus goedkoper zonnepanelen te plaatsen en daar energie mee op te wekken, dan om die energie van het elektriciteitsnet te betrekken.

De oorzaak van de mijlpaal moet gezocht worden bij het sterk dalen van de prijzen voor de panelen, in combinatie met het stijgen van de prijzen voor elektriciteit in België. De energiesector kan nog wijzigingen voorstellen bij de studie en de Vlaamse regering moet er ook nog over oordelen, maar daarna zou de overheidssteun per 1 januari 2013 van 90 euro naar 0 euro per Mwh kunnen gaan.

De sector voor de installatie van fotovoltaïsche panelen reageert verheugd op het nieuws, hoewel eerdere voorstellen voor een verlaging van de steun op stevige kritiek konden rekenen. Wel waarschuwt een vertegenwoordiger van de sector, Alex Polfliet, dat het rendement op de investering volgens de studie maar vier procent is, wat laag zou zijn. Ook vreest hij een verhoging van de netvergoeding voor eigenaren van zonnepanelen, omdat ze het elektriciteitsnet niet alleen gebruiken voor energieconsumptie, maar ook om stroom terug te leveren, terwijl ze nu minder betalen. Hier zou de studie geen rekening mee gehouden hebben.

http://tweakers.net/nieuw(...)-overheidssteun.html

quote:

Op zondag 2 december 2012 03:06 schreef Probably_on_pcp het volgende:
Zonnepanelen zijn in België rendabel zonder overheidssteun

De Belgische overheidssteun voor zonnepanelen kan per 1 januari 2013 mogelijk al stoppen, omdat de energieopbrengst er al rendabel is. Dat blijkt uit een studie van het Vlaams Energieagentschap. De oorzaken zijn de gedaalde prijzen voor zonnepanelen en de hoge energieprijzen.

Het Vlaams Energieagentschap berekent jaarlijks hoeveel steun er nodig is om investeringen in duurzame energie rendabel te maken. Voor het eerst komt de berekening uit op een negatief bedrag, meldt De Standaard. Het agentschap komt uit op een benodigde steun van -60,5 euro per megawattuur. Het is voor Belgen dus goedkoper zonnepanelen te plaatsen en daar energie mee op te wekken, dan om die energie van het elektriciteitsnet te betrekken.

De oorzaak van de mijlpaal moet gezocht worden bij het sterk dalen van de prijzen voor de panelen, in combinatie met het stijgen van de prijzen voor elektriciteit in België. De energiesector kan nog wijzigingen voorstellen bij de studie en de Vlaamse regering moet er ook nog over oordelen, maar daarna zou de overheidssteun per 1 januari 2013 van 90 euro naar 0 euro per Mwh kunnen gaan.

De sector voor de installatie van fotovoltaïsche panelen reageert verheugd op het nieuws, hoewel eerdere voorstellen voor een verlaging van de steun op stevige kritiek konden rekenen. Wel waarschuwt een vertegenwoordiger van de sector, Alex Polfliet, dat het rendement op de investering volgens de studie maar vier procent is, wat laag zou zijn. Ook vreest hij een verhoging van de netvergoeding voor eigenaren van zonnepanelen, omdat ze het elektriciteitsnet niet alleen gebruiken voor energieconsumptie, maar ook om stroom terug te leveren, terwijl ze nu minder betalen. Hier zou de studie geen rekening mee gehouden hebben.

http://tweakers.net/nieuw(...)-overheidssteun.html

Nog geen twee jaar geleden begonnen met dit topic

En dit topic begon met Ray Kurzweil:

Surging Solar in 2011 Proof of Ray Kurzweil’s Bold Prediction?

A recent report by British Petroleum (BP) found solar power generating capacity surged 73.3% last year. If you’re a dedicated fan of the singularity, statistics like that are reminiscent of Ray Kurzweil’s solar dictum—that solar power is on an exponential path, doubling every two years. To what end? A cheap, clean, and virtually boundless power source for humankind in two decades. Nothing major.

The report has some sunny stats for solar enthusiasts. Beyond that 73.3% global capacity jump in 2011 (a record since the data set’s 1996 inception), capacity ended the period at 63.4 gigawatts (GW), ten times greater than its level five years previously.



That’s pretty positive news. As Kurzweil notes, “We are awash in sunlight.” Just 1/10,000 of the sunlight falling on the Earth’s surface can satisfy humanity’s energy requirements. And that doesn’t imply a landscape littered with panels—in fact, an area equal to just a few percent of the Earth’s unused deserts would suffice.

After we’ve solved the energy puzzle, we can move on to other intractable issues, like insufficient food and water. Cheap energy means we can finally afford energy intensive processes like sea water desalination or hydroponic farming. See Kurzweil discuss solar power here (minute 06:15):

But let’s temper our enthusiam for a moment. Mark Twain said, “Facts are stubborn, but statistics are more pliable.”

What’s missing here? Scale, for one thing. Growth of 73.3% isn’t as significant if it’s from a tiny base to a less tiny base.

According to the US Energy Information Administration, renewable energy accounts for 12% of the US energy pie. Hydroelectric is top dog at 4.35% of US energy. Biomass contributes 3.15%, biofuels add 2.57%, wind accounts for 1.45%, and geothermal another 0.29%. Solar contributes just 0.15%. (Of course, those numbers vary country to country and globally—see here for a nice page of energy charts, with sources, from Columbia University.)



Solar capacity is capable of dramatic expansion rates right now, in part, because the technology is still a bit player in the renewable energy drama—and even more so on the larger non-renewable stage. That seemingly gangbusters 100% two-year growth rate would but nudge solar to a tie with geothermal at around 0.3% in the US.

You’ll see similarly stunning growth rates posted by start-up businesses early on. Going from $5,000 in profits to $8,665 doesn’t seem like a giant leap, yet it too is an example of 73.3% growth. The bigger the numbers get, however, the more difficult it is to stay the course. Going from $1 billion to $1.1 billion requires $100 million more in profits—yet is just 10% growth.

Still, Kurzweil thinks people too easily dismiss solar. Sure, it’s as yet a tiny percentage of total energy consumption (0.5% of the whole, he said in 2011), but that doesn’t matter when you’re talking about an information technology. And he thinks that’s just what solar is.

Kurzweil contends solar has been doubling every two years for the last twenty. Proof that it’s already undergoing sustainable exponential growth.

As Singularity Hub readers know, exponential growth is the very foundation of the singularity. We’ve seen computing power grow exponentially in recent decades, tracking Moore’s Law. And the exponential gains of computing spill over into other information-based realms, like genomics, for example.

Solar power has been doubling every two years for the last two decades.

So, while solar power may only be around 0.5% of the whole, that is a mere eight doublings (or 16 years, 20 including rising energy usage) away from 100%—thanks to the power of exponential growth. (See here for Kurzweil’s chart on solar power’s last two decades.)

The question is, can we compare solar power’s exponential growth to microchips? Is it too an information technology?

Kurzweil compares solar to iPhones, “If you buy an iPhone today, it’s twice as good as two years ago for half the cost.” But the fact that solar capacity has doubled every two years doesn’t prove it’s twice as good at half the cost. There are other factors that must be accounted for also.

The last 20 years have shown exponential growth in solar power—and rising sustainable energy subsidies in parallel.

Can we disentangle growth due to government incentives from growth due to improvements in the technology?

In the BP report, Europe is the clear leader in new solar capacity—and, not coincidentally, Europe is also the leader in solar subsidies. Artificial demand makes it difficult to see how much of solar’s rapid growth is solely due to advances in the technology.



For example, last year’s solar capacity growth set records because firms expected dramatic cuts in government incentives, thus pulling future demand into the present. And while subsidies add to solar capacity growth now, what might fewer subsidies mean in the future?

Politics are fickle—future growth may prove equally erratic.

Further, the solar industry is battling plummeting solar panel prices in an oversupplied market. Many firms may be caught with a large, expensively produced inventory and no one to sell it to—or at least no way to make a profit.

Government incentives may mask solar power’s true growth potential, but that’s not to say the technology isn’t improving.

The cost of photovoltaic (PV) power modules has decreased 75% in the last three years. Added to lower cost, efficiency is getting better too. The National Renewable Energy Laboratory (NREL) has built photovoltaic devices capable of converting light to electricity at 40.8% efficiency.

The point everyone is aiming for is “grid parity,” when solar becomes cost competitive with traditional energy sources.

While solar hasn’t hit grid parity the world over, it is approaching parity, aided by falling solar prices and rising fossil fuel prices. (Keep in mind parity is not a still point—abundant natural gas, for example, could reverse the trend of rising fossil fuel prices.)

But Kurzweil does not claim to know how we’ll get there, simply that the power of compounding growth rates is immense. And if we extrapolate solar technology’s average growth in the last two decades into the future—our energy woes may be history.

He may be right. Depending on how significantly historical and future growth rates are affected by non-market factors—it may happen in 20 years or 30 or 50. Or never, if some even better technology supplants solar.

What we can say is that solar technology holds promise. And future generations of the technology will build on learning from prior generations. So, subsidies or no subsidies, there is no reason the technology can’t keep up with and eventually leapfrog the competition.

http://singularityhub.com(...)ils-bold-prediction/