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Wednesday, April 16, 2014

20 Cities Shining Brightest With Solar Energy

Environment America scanned the nation find out which cities are shining the brightest when it comes to solar energy.
Those cities are doing more than just leading the way—the top 20 cities contain more solar power today than the entire country had just six years ago.
Not surprisingly, you’ll see plenty of California cities in the top 20 featured in Environment America’s report, Shining Cities At the Forefront of America’s Solar Energy Revolution, released this week in several variations by the organization’s various state arms around the country.
“California cities are leaders in creating solar energy capacity,” California Sen. Marty Block, D-San Diego, said in an Environment California statement. “Of the top 20 American cities listed for this clean and safe energy alternative, California has five cities ranked in the top 12—Los Angeles, San Diego, San Jose, San Francisco and Sacramento. It’s leadership that means a cleaner environment, better jobs and a stronger economy.”
The report also includes listings of cities split into categories that extend from “beginners” to “stars.” It should be no surprise that states with politicians that tried passing anti-renewable legislation don’t contain cities that would even qualify as “beginners.” The fact that states like California have federal and state politicians willing to stand behind solar energy certainly aids in its deployment.
“Solar energy is renewable and clean, which is why I’m such an advocate for its role in our national energy portfolio,” U.S. Rep. Scott Peters, D-CA, said. “The solar industry is creating jobs, including more than 675 in my district alone and powering our economy toward a more sustainable future. I’m proud that San Diego and California are leading the way as an example for the rest of the country.”
Some cities, like New York, were pleased with their standing, but look forward to doing more.
“New York City is home to a wealth of industries and it is crucial that it continues to lead the way to nurture and build the solar industry,” said David Sandbank, vice president of New York Solar Energy Industries Association. “With the support of our state and local government officials and the creation of the NY Sun-Initiative, we are well on our way to achieving this goal.
“It is very important that we continue our momentum and create more solar jobs while reducing our carbon footprint and dependence on traditional electrical power.” 
In Ohio, where legislation to freeze renewable energy standards indefinitely is on the table, some desperately want to deploy more clean energy. Cleveland and Columbus were considered “beginners” by Environment America, while Cincinnati is considered a “builder,” ranking 24th in the nation. 
“We’ve made progress here in Columbus, but we’ve just begun,” said Ragan Davis of Environment Ohio. “By committing to bold goals and putting strong policies in place, we can make Columbus shine as a national leader and reap the environmental and economic benefits of the solar revolution.”
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Flowing a drop of salt water over graphene generates electricity

Tuesday, 15 April 2014

Scientists have found that dragging small droplets of salt water across graphene generates electricity.

Graphene_Wikimedia 
 
Graphene, the material that just keeps on giving, could provide the basis of small-scale hydroelectric generators, new research suggests.
Researchers from China have shown that running a droplet of salt water across a layer of graphene can generate a small amount of electricity - and the faster the water flows, the higher the voltage they generated.
The study, published in Nature Nanotechnology, is the first to demonstrate this effect, and also revealed that the voltage increased when multiple droplets of the same size were moved across the graphene at once.
The scientists found that electrons are desorbed from the graphene at one end of the droplet and are adsorbed into the graphene at another end, which results in a large potential on one side of the droplet and generates a measurable voltage across its length.
The researchers also scaled up the technology using a droplet of copper chloride and a tilted surface of graphene for it to flow across, and revealed this system could generate a measurable voltage of around 30mV.
This may not be much right now - it's relatively much lower than the amount produced by today's large-scale hydroelectric generators - but the nano-sized generators could work with small devices and can easily be scaled up, giving them pretty huge potential.

Source: Ars Technica

New nuclear power in SA dependent on future electricity demand

Low growth in electricity demand in South Africa will delay, or eliminate the need for, new nuclear power plants. So warned Eskom Transmission Division Energy Planning and Market Development Department power system economics: chief adviser Keith Bowen, addressing an Academy of Science of South Africa symposium in Pretoria.
 
He highlighted that, regarding electricity in South Africa, the "biggest issue is the drop in demand" over the past five years. "Even though electricity demand has been pretty much flat, the economy has grown as we have predicted." South Africa's "electricity intensity" has decreased.
This decrease began before the current electricity crisis and has not been caused by the state of the economy (which has grown, albeit slowly). The key factor, he suggested, was the price of electricity. This raised the issue of what will happen when South Africa restores its electricity supply to comfortable and secure levels. He observed that pricing might prevent an increase in the demand for electricity. He predicted that electricity demand would not resume its previous growth rate.
Assuming a target annual economic growth rate of 5.4% over the next 20 years, the level needed to reduce poverty in the country, this would now only need an increase in electricity supply of 2.8% a year. While the country is unlikely to achieve economic growth of 5.4% a year, if the electricity supply does not increase at 2.8% a year that 5.4% target will not be achievable.
"If demand grows at a very low level, nuclear wouldn't be the preferred option," said Bowen. "If there is low growth, then, under those conditions, we wouldn't build nuclear before 2035."
"We don't compare nuclear with solar [power], you don't compare nuclear with wind [power]. They provide a different service," he explained. "Nuclear really is competing with gas, coal and coal with carbon capture and storage." Nuclear power does lack flexibility -- it is operated at a certain level or it is not built at all. In comparison, for example, a gas power plant can be operated at different output levels. Nevertheless, "[t]here is a role for nuclear".
As for coal, regarding climate change South African policy is that there should be a carbon emissions cap, leading to a decline in carbon emissions. Consequently, the country could build new coal power plants until that cap was reached. The preference is to build smaller coal power plants, not major projects like the current Medupi and Kusile projects.

Friday, April 11, 2014

Win-win situation: Growing crops on photovoltaic farms

A new model for solar farms that 'co-locates' crops and solar panels could result in a harvest of valuable biofuel plants along with solar energy. This co-location approach could prove especially useful in sunny, arid regions such as the southwestern United States where water is scarce, researchers said.
This co-location approach could prove especially useful in sunny, arid regions such as the southwestern United States where water is scarce, said Sujith Ravi, who is conducting postdoctoral research with professors David Lobell and Chris Field, both on faculty in environmental Earth system science and senior fellows at the Stanford Woods Institute for the Environment. "Co-located solar-biofuel systems could be a novel strategy for generating two forms of energy from uncultivable lands: electricity from solar infrastructure and easily transportable liquid fuel from biofuel cultivation," said Ravi, the lead author of a new study published in a recent issue of the journal Environmental Science & Technology that details the idea.
Photovoltaic (PV) solar farms run on sunlight, but water is required to remove dust and dirt from the panels to ensure they operate at maximum efficiency. Water is also used to dampen the ground to prevent the buildup and spread of dust. Crops planted beneath the solar panels would capture the runoff water used for cleaning the PV panels, thus helping to optimize the land. The plants' roots would also help anchor the soil and their foliage would help reduce the ability of wind to kick up dust.
Computer simulations of a hypothetical co-location solar farm in Southern California's San Bernardino County by Ravi and colleagues suggest that these two factors together could lead to a reduction in the overall amount of water that solar farms need to operate. "It could be a win-win situation," Ravi said. "Water is already limited in many areas and could be a major constraint in the future. This approach could allow us to produce energy and agriculture with the same water."
But which crops to use? Many solar farms operate in sunny but arid regions that are inhospitable to most food crops. But there is one valuable plant that thrives at high temperatures and in poor soil: agave. Native to North and South America, the prickly plant can be used to produce liquid ethanol, a biofuel that can be mixed with gasoline or used to power ethanol vehicles. "Unlike corn or other grains, most of the agave plant can be converted to ethanol," Ravi said.
The team plans to test the co-location approach around the world to determine the ideal plants to use and to gather realistic estimates for crop yield and economic incentives.
"Sujith's work is a great example of how thinking beyond a single challenge like water or food or energy sometimes leads to creative solutions," said Lobell, who is a coauthor on the new study. "Of course, creative solutions don't always work in the real world, but this one at least seems worthy of much more exploration."

Story Source:  Stanford University

Tuesday, April 8, 2014

Organic solar cells more efficient with molecules face-to-face

New research from North Carolina State Univ. and UNC-Chapel Hill reveals that energy is transferred more efficiently inside of complex, 3-D organic solar cells when the donor molecules align face-on, rather than edge-on, relative to the acceptor. This finding may aid in the design and manufacture of more efficient and economically viable organic solar cell technology.
Organic solar cell efficiency depends upon the ease with which an exciton—the energy particle created when light is absorbed by the material—can find the interface between the donor and acceptor molecules within the cell. At the interface, the exciton is converted into charges that travel to the electrodes, creating power. While this sounds straightforward enough, the reality is that molecules within the donor and acceptor layers can mix, cluster into domains, or both, leading to variances in domain purity and size which can affect the power conversion process. Moreover, the donor and acceptor molecules have different shapes, and the way they are oriented relative to one another matters. This complexity makes it very difficult to measure the important characteristics of their structure.
NC State physicist Harald Ade, UNC-Chapel Hill chemist Wei You and collaborators from both institutions studied the molecular composition of solar cells in order to determine what aspects of the structures have the most impact on efficiency. In this project the team used advanced soft x-ray techniques to describe the orientation of molecules within the donor and acceptor materials. By manipulating this orientation in different solar cell polymers, they were able to show that a face-on alignment between donor and acceptor was much more efficient in generating power than an edge-on alignment.
“A face-on orientation is thought to allow favorable interactions for charge transfer and inhibit recombination, or charge loss, in organic solar cells,” Ade says, “though precisely what happens on the molecular level is still unclear.
“Donor and acceptor layers don’t just lie flat against each other,” Ade explains. “There’s a lot of mixing going on at the molecular level. Picture a bowl of flat pasta, like fettucine, as the donor polymer, and then add ‘ground meat,’ or a round acceptor molecule, and stir it all together. That’s your solar cell. What we want to measure, and what matters in terms of efficiency, is whether the flat part of the fettuccine hugs the round pieces of meat—a face-on orientation—or if the fettuccine is more randomly oriented, or worst case, only the narrow edges of stacked up pasta touch the meat in an edge-on orientation. It’s a complicated problem.
“This research gives us a method for measuring this molecular orientation, and will allow us to find out what the effects of orientation are and how orientation can be fine-tuned or controlled.”
The paper appears online in Nature Photonics.

Friday, April 4, 2014

Nanostructures show promise for efficient LEDs

Nanostructures half the breadth of a DNA strand could improve the efficiency of light emitting diodes (LEDs), especially in the “green gap,” a portion of the spectrum where LED efficiency plunges, simulations at the U.S. Department of Energy’s National Energy Research Scientific Computing Center (NERSC) have shown.
 
Using NERSC’s Cray XC30 supercomputer “Edison,” University of Michigan researchers Dylan Bayerl and Emmanouil Kioupakis found that the semiconductor indium nitride (InN), which typically emits infrared light, will emit green light if reduced to 1 nanometer-wide wires. Moreover, just by varying their sizes, these nanostructures could be tailored to emit different colors of light, which could lead to more natural-looking white lighting while avoiding some of the efficiency loss today’s LEDs experience at high power.
 
“Our work suggests that indium nitride at the few-nanometer size range offers a promising approach to engineering efficient, visible light emission at tailored wavelengths,” said Kioupakis.
 
Their results, published online as “Visible-Wavelength Polarized Light Emission with Small-Diameter InN Nanowires,” will also be featured on the cover of the July issue of Nano Letters.
 
LEDs are semiconductor devices that emit light when an electrical current is applied. Today’s LEDs are created as multilayered microchips. The outer layers are doped with elements that create an abundance of electrons on one layer and too few on the other. The missing electrons are called holes. When the chip is energized, the electrons and holes are pushed together, confined to the intermediate quantum-well layer where they are attracted to combine, shedding their excess energy (ideally) by emitting a photon of light.
 
At low power, nitride-based LEDs (most commonly used in white lighting) are very efficient, converting most of their energy into light. But turn the power up to levels that could light up a room and efficiency plummets, meaning a smaller fraction of electricity gets converted to light. This effect is especially pronounced in green LEDs, giving rise to the term “green gap.”
 
Nanomaterials offer the tantalizing prospect of LEDs that can be “grown” in arrays of nanowires, dots or crystals. The resulting LEDs could not only be thin, flexible and high-resolution, but very efficient, as well.
 
“If you reduce the dimensions of a material to be about as wide as the atoms that make it up, then you get quantum confinement. The electrons are squeezed into a small region of space, increasing the bandgap energy,” Kioupakis said. That means the photons emitted when electrons and holes combine are more energetic, producing shorter wavelengths of light.
 
The energy difference between an LED’s electrons and holes, called the bandgap, determines the wavelength of the emitted light. The wider the bandgap, the shorter the wavelength of light. The bandgap for bulk InN is quite narrow, only 0.6 electron volts (eV), so it produces infrared light. In Bayerl and Kioupakis’ simulated InN nanostructures, the calculated bandgap increased, leading to the prediction that green light would be produced with an energy of 2.3eV.
 
“If we can get green light by squeezing the electrons in this wire down to a nanometer, then we can get other colors by tailoring the width of the wire,” said Kioupakis. A wider wire should yield yellow, orange or red. A narrower wire, indigo or violet.
 
That bodes well for creating more natural-looking light from LEDs. By mixing red, green and blue LEDs engineers can fine tune white light to warmer, more pleasing hues. This “direct” method isn’t practical today because green LEDs are not as efficient as their blue and red counterparts. Instead, most white lighting today comes from blue LED light passed through a phosphor, a solution similar to fluorescent lighting and not a lot more efficient. Direct LED lights would not only be more efficient, but the color of light they produce could be dynamically tuned to suit the time of day or the task at hand.
 
Using pure InN, rather than layers of alloy nitride materials, would eliminate one factor that contributes to the inefficiency of green LEDs: nanoscale composition fluctuations in the alloys. These have been shown to significantly impact LED efficiency.
 
Also, using nanowires to make LEDs eliminates the “lattice mismatch” problem of layered devices. “When the two materials don’t have the same spacing between their atoms and you grow one over the other, it strains the structure, which moves the holes and electrons further apart, making them less likely to recombine and emit light,” said Kioupakis, who discovered this effect in previous research that also drew on NERSC resources. “In a nanowire made of a single material, you don’t have this mismatch and so you can get better efficiency,” he explained.
 
The researchers also suspect the nanowire’s strong quantum confinement contributes to efficiency by squeezing the holes and electrons closer together, a subject for future research. “Bringing the electrons and holes closer together in the nanostructure increases their mutual attraction and increases the probability that they will recombine and emit light.” Kioupakis said.
 
While this result points the way towards a promising avenue of exploration, the researchers emphasize that such small nanowires are difficult to synthesize. However, they suspect their findings can be generalized to other types of nanostructures, such as embedded InN nanocrystals, which have already been successfully synthesized in the few-nanometers range.
 
NERSC’s newest flagship supercomputer (named “Edison” in honor of American inventor Thomas Edison) was instrumental in their research, said Bayerl. The system’s thousands of compute cores and high memory-per-node allowed Bayerl to perform massively parallel calculations with many terabytes of data stored in RAM, which made the InN nanowire simulation feasible. “We also benefited greatly from the expert support of NERSC staff,” said Bayerl. Burlen Loring of NERSC’s Analytics Group created visualizations for the study, including the journal’s cover image. The researchers also used the open-source BerkeleyGW code, developed by NERSC’s Jack Deslippe.
 
Source: NERSC

Energy breakthrough uses sun to create solar energy materials

In a recent advance in solar energy, researchers have discovered a way to tap the sun not only as a source of power, but also to directly produce the solar energy materials that make this possible.
 
This breakthrough by chemical engineers at Oregon State University could soon reduce the cost of solar energy, speed production processes, use environmentally benign materials, and make the sun almost a “one-stop shop” that produces both the materials for solar devices and the eternal energy to power them.
 
The findings were published in RSC Advances, a journal of the Royal Society of Chemistry, in work supported by the National Science Foundation.
 
“This approach should work and is very environmentally conscious,” said Chih-Hung Chang, a professor of chemical engineering at Oregon State University, and lead author on the study.
 
“Several aspects of this system should continue to reduce the cost of solar energy, and when widely used, our carbon footprint,” Chang said. “It could produce solar energy materials anywhere there’s an adequate solar resource, and in this chemical manufacturing process, there would be zero energy impact.”
 
The work is based on the use of a “continuous flow” microreactor to produce nanoparticle inks that make solar cells by printing. Existing approaches based mostly on batch operations are more time-consuming and costly.
 
In this process, simulated sunlight is focused on the solar microreactor to rapidly heat it, while allowing precise control of temperature to aid the quality of the finished product. The light in these experiments was produced artificially, but the process could be done with direct sunlight, and at a fraction of the cost of current approaches.
 
“Our system can synthesize solar energy materials in minutes compared to other processes that might take 30 minutes to two hours,” Chang said. “This gain in operation speed can lower cost.”
 
In these experiments, the solar materials were made with copper indium diselenide, but to lower material costs it might also be possible to use a compound such as copper zinc tin sulfide, Chang said. And to make the process something that could work 24 hours a day, sunlight might initially be used to create molten salts that could later be used as an energy source for the manufacturing. This could provide more precise control of the processing temperature needed to create the solar energy materials.
 
State-of-the-art chalcogenide-based, thin film solar cells have already reached a fairly high solar energy conversion efficiency of about 20 percent in the laboratory, researchers said, while costing less than silicon technology. Further improvements in efficiency should be possible, they said.
 
Another advantage of these thin-film approaches to solar energy is that the solar absorbing layers are, in fact, very thin- about 1 to 2 microns, instead of the 50 to 100 microns of more conventional silicon cells. This could ease the incorporation of solar energy into structures, by coating thin films onto windows, roof shingles or other possibilities.
 
Additional support for this work was provided by the Oregon Nanoscience and Microtechnologies Institute, or ONAMI, and the Oregon Built Environment and Sustainable Technologies Center, or Oregon BEST.
 

Tuesday, April 1, 2014

Hybrid vehicles more fuel efficient in India, China than in U.S.

March 31, 2014
What makes cities in India and China so frustrating to drive in -- heavy traffic, aggressive driving style, few freeways -- makes them ideal for saving fuel with hybrid vehicles, according to new research. In a pair of studies using real-world driving conditions, they found that hybrid cars are significantly more fuel-efficient in India and China than they are in the United States.
These findings could have an important impact in countries that are on the brink of experiencing an explosion in the sales of personal vehicles; the government of India has already taken note of the findings. "Currently greenhouse gas emissions from the transportation sector in India and China are a smaller piece of the pie compared with other sectors," said lead researcher Anand Gopal. "But vehicle ownership is going to skyrocket in these countries. That is why we decided to focus on this area. Hybrid and electric vehicles can significantly reduce carbon emissions and other pollutants."
What's more, hybrids in India are also more fuel-efficient than they are officially rated for. "With the official fuel economy test procedure currently used in India, fuel savings for hybrids are fairly grossly underestimated, showing only a 29 percent savings over conventional vehicles," Gopal said. "The test cycle is not representative of driving conditions in India, so that's sending the wrong signal to the consumer."
Their results were reported in two papers, "Understanding the fuel savings potential from deploying hybrid cars in China," published in Applied Energy, and "Understanding fuel savings mechanisms from hybrid vehicles to guide optimal battery sizing for India," accepted for publication in the International Journal of Powertrains, also co-authored by Berkeley Lab battery scientist Venkat Srinivasan. The studies are believed to be the first of their kind.
About 50 percent fuel savings over conventional cars
Gopal, working with Berkeley Lab scientists Samveg Saxena and Amol Phadke, used a powertrain simulation model called Autonomie to create a hypothetical hybridized version of the top-selling conventional car in each country -- in China it was the Buick Excelle and in India the Maruti Alto. The reason for creating a hypothetical version was to isolate the improvement from hybridization and measure only that benefit.
For the India analysis the researchers simulated drive cycles in two Indian cities (New Delhi and Pune) taken from published studies and also used the Modified Indian Drive Cycle, the test for the official fuel economy rating. In China they simulated drive cycles in 11 cities and with three types of hybrid powertrains (start-stop, parallel and power-split). In both cases they compared it to drive cycles used for U.S. fuel efficiency ratings, which include about 55 percent city driving and 45 percent highway driving.
They found that driving a hybrid would achieve fuel savings of about 47 to 48 percent over a conventional car in India and about 53 to 55 percent in China. In the United States, hybrids are rated to produce a fuel savings of about 40 percent over their conventional counterparts. Currently hybrid and electric vehicles have a tiny share of the market in India and China and are seen as a higher-end product.
Gopal describes the traffic in India as "pretty slow, pretty crazy, always congested." In technical terms, the frequent starting and stopping, considerable amount of time spent idling, and low percentage of time spent on highways provide hybrids three ways to save additional fuel.
"One is regenerative braking, another is being able to turn off the engine when the car is stopped or in low-power condition, and another is that the hybrid system -- the electric motor, the batteries -- enable the engine to operate at a higher efficiency operating condition," Saxena explained. "We weighed the importance of these three mechanisms against each other for the Indian vehicles, and found that the ability to increase engine efficiency was the most important reason, second was regenerative braking, then engine shutdown."
The engineering results were a little surprising, Saxena said. "We went into the study thinking regenerative braking would make for very unique fuel-saving opportunities," he said.
Indian government analyzing Berkeley Lab results
The government of India, which launched a national plan last year with the goal of getting 6 to 7 million hybrid and electric vehicles (EVs) on the road by 2020, is already working with the Berkeley Lab researchers to further analyze their results. India is a member country of the Electric Vehicles Initiative (EVI) of the Clean Energy Ministerial, a global forum of governments focused on accelerating the transition to clean energy technologies. Through EVI, Berkeley Lab's research will guide India in moving forward with its EV plan.
"This research performed by Berkeley Lab has helped us understand in much better detail the real-world value of electric vehicles to India," said Ambuj Sharma, Additional Secretary of India's Department of Heavy Industry. "Their work has shown that Indian conditions are much more conducive to electric vehicles than we expected and has given a greater impetus and importance to the National Mission on Electric Mobility."
Gopal says one of the next steps is to work on China, which is also a participant in the Electric Vehicles Initiative. China has been the world's largest car market since 2009, with double-digit percentage increases in annual car sales, but sales are expected to grow even faster as household income rises. "The main reason for the impending vehicle boom is that people are getting wealthier, and there's a very strong tie between greater household wealth and vehicle ownership," Gopal said. "It's not about transportation. Owning a car is a social symbol."
In a third paper by Gopal, Saxena, and Phadke they also looked at electrical consumption of all-electric vehicles in India. "Electrical consumption of two-, three- and four-wheel light-duty electric vehicles in India," published in Applied Energy, quantified the electrical consumption of EVs in India. The study lays the groundwork for their next project, which is to analyze how EVs can be integrated into the existing electrical grid and how to minimize grid emissions.


Wind energy: New insight into best arrangement of wind turbines on large installations

April 1, 2014
Researchers have developed a new way to study wake effects that includes the airflow both within and around a wind farm and challenges the conventional belief that turbines arrayed in checker board patterns produce the highest power output. Their study provides insight into factors that determine the most favorable positioning
Optimally spacing turbines allows them to capture more wind, produce more power and increase revenue for the farm. Knowing this, designers in the industry typically apply simple computer models to help determine the best arrangements of the turbines. This works well for small wind farms but becomes less precise for larger wind-farms where the wakes interact with one another and the overall effect is harder to predict.
Now a team of researchers at Johns Hopkins University (JHU) has developed a new way to study wake effects that takes into account the airflow both within and around a wind farm and challenges the conventional belief that turbines arrayed in checker board patterns produce the highest power output. Their study provides insight into factors that determine the most favorable positioning -- work described in a new paper in theJournal of Renewable and Sustainable Energy, which is produced by AIP Publishing.
This insight is important for wind project designers in the future to configure turbine farms for increased power output -- especially in places with strong prevailing winds.
"It's important to consider these configurations in test cases," said Richard Stevens, who conducted the research with Charles Meneveau and Dennice Gayme at JHU. "If turbines are built in a non-optimal arrangement, the amount of electricity produced would be less and so would the revenue of the wind farm."
How Wind Farms are Currently Designed
Many considerations go into the design of a wind farm. The most ideal turbine arrangement will differ depending on location. The specific topology of the landscape, whether hilly or flat, and the yearlong weather patterns at that site both dictate the specific designs. Political and social considerations may also factor in the choice of sites.
Common test cases to study wind-farm behavior are wind farms in which turbines are either installed in rows, which will be aligned against the prevailing winds, or in staggered, checkerboard-style blocks where each row of turbines is spaced to peek out between the gaps in the previous row.
Staggered farms are generally preferred because they harvest more energy in a smaller footprint, but what Stevens and his colleagues showed is that the checkerboard style can be improved in some cases.
Specifically, they found that better power output may be obtained through an "intermediate" staggering, where each row is imperfectly offset -- like a checkerboard that has slipped slightly out of whack.
This work was funded by the National Science Foundation (grant #CBET 1133800 and #OISE 1243482) and by a "Fellowship for Young Energy Scientists" awarded by the Foundation for Fundamental Research on Matter in the Netherlands. The work used XSEDE (NSF) and SURFsara (Netherlands) computer resources.

Sunday, March 30, 2014

Scientists develop silicon cells capable of absorbing infrared radiation from the sun

March 25, 2014
Researchers have developed a silicon photovoltaic cell capable of turning infrared radiation into electricity. The sun is an inexhaustible source of energy which well-exploited, could solve many of the energy suply problems we have today. The photovoltaic cell, commonly known as solar cell, is a device capable of turning solar light into electricity. However, there are many obstacles that prevent a massive use, such as a relatively high cost (0.02 euros per watt generated) and the low efficiency of silicon based solar cells, around 17 per cent.
Nature Communications magazine has published this new development led by Francisco Meseguer professor from the CSIC, at the joint lab UPV/CSIC.
The sun is an inexhaustible source of energy which well-exploited, could solve many of the energy suply problems we have today. The photovoltaic cell, commonly known as solar cell, is a device capable of turning solar light into electricity. However, there are many obstacles that prevent a massive use, such as a relatively high cost (0.02 euros per watt generated) and the low efficiency of silicon based solar cells, around 17 per cent.
The low efficiency is related to the material the solar cell is made of. Most solar cells are made of silicon which is relatively cheap to produce. However these solar cells can generate electricity from the visible part of the sun spectrum, but the infrared region is, unfortunately, useless.
The professor Francisco Meseguer, explains that, "after three years of work, our research team has developed a new concept of silicon solar cells able to absorb infrared radiation from the sun and turning them into electricity." Moisés Garín, a researcher from the CSIC and the Universitat Politècnica de Catalunya, adds that, "what we have done is create photovoltaic cells on silicon micrometre scale sphere, where infrared light is trapped until it is absorbed turning it into electricity."
This work is a new scientific achievement for the development of high-performance photovoltaic cells in the future.

Story Source:  Asociación RUVID