Get Prepared Now is NOT Just a Slogan

Tuesday, December 17, 2013

Self-healing solar cells 'channel' natural processes


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Nicaragua Improves Ability to Respond to Natural Disasters with IDB Support - HispanicBusiness.com


WASHINGTON , Nov. 27 -- The Inter-American Development Bank issued the following news release: The Inter-American Development Bank (IDB) has approved a $186 million contingent loan to help Nicaragua mitigate the impact that severe or catastrophic natural disasters ( http://www.iadb.org/en/projects/project-description-title,1303.html?id=NI-X1007 ) could have on its public finance[1]s. Due to its geographic location, the country is highly exposed to meteorological and geophysical threats such as earthquakes, floods, tropical storms, and volcanic eruptions. In fact, Nicaragua is the second most vulnerable country in the world to hurricanes and tropical storms, and ranks thirtieth in the world in its vulnerability to earthquakes. Historically, natural disasters have occurred with great frequency in Nicaragua and, in recent decades, their occurrence has been trending upwards. In the last 40 years alone, the country has experienced 53 natural disasters of different types, and has posted economic losses of approximately $2.728 billion , affecting more than 3.9 million people. The loan will provide Nicaragua with rapid access to liquid resources so that it can deal, on a timely basis, with extraordinary expenditures that could arise in emergencies caused by severe or catastrophic natural disasters. This operation will help Nicaragua not only improve its financial planning but also promote the development of effective mechanisms for the comprehensive management of natural disaster risks through the Comprehensive Natural Disaster Risk Management Program (CNDRMP) required to access the proceeds of this loan. The CNDRMP promotes improvements in the identification, reduction, and financial management of risks, as well as in disaster management. The IDB financing consists of a $93 million 30-year loan from the Bank's ordinary capital with a 6-year grace period and fixed interest rate. An additional $93 million is from the Fund for Special Operations for a 40-year term, with a 40-year grace period and 0.25 percent interest rate. The IDB is one of the leading multilateral lending institutions in the area of disaster financial risk management. The Bank is providing support to Latin American and the Caribbean countries in designing financial strategies to manage the fiscal impact of natural disasters; improving financial information systems and data collection; and structuring financial coverage through different instruments such as reserve funds, contingent loans, and risk transfer instruments. At the end of the year, the Bank will be providing natural disaster coverage to seven countries in the region through contingent loans for nearly $1,000 million . TNS 30BautistaJude 131128-4563845 30BautistaJude

References

  1. ^ finance (www.hispanicbusiness.com)

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Monday, December 16, 2013

Philippine economic growth seen slower in Q4 due to natural disasters - Xinhua


MANILA, Nov. 28 (Xinhua) -- Typhoon Haiyan, locally named " Yolanda," and the magnitude 7.2 earthquake which struck central Philippines will put a dent on the country's economic growth in the fourth quarter. But a senior government official said Thursday that the cut will not be drastic.


National Economic and Development Authority (NEDA) Director- General Arsenio M. Balisacan said typhoon Haiyan and the earthquake would likely shave off 0.3 to 0.8 percentage point from the country's gross domestic product (GDP) in the October to December period.


"The aftermath of typhoon Haiyan plus the earthquake in Bohol province is sure to impact on the fourth quarter. Our earlier estimates suggest that the impact could be anywhere from 0.3-0.8 percentage point of what would be expected for the fourth quarter if there would have been no super typhoon and no earthquake," Balisacan said.


Despite this, Balisacan and analysts said the Philippines is well on its way to achieving a 7-percent GDP growth rate in 2013, barring more disasters.


"To reach our growth target of 6 to 7 percent in 2013, all you need is about a growth of 5.2 percent (in the fourth quarter). That's still very doable," he said.


Based on the latest data from the National Disaster Risk Reduction and Management Council, typhoon Haiyan alone destroyed 24.53 billion pesos (561.28 million U.S. dollars) worth of crops and infrastructure in central Philippines. The earthquake, meanwhile, caused damages amounting to 2.25 billion pesos (51.63 million U.S. dollars).


Analysts, however, are more worried about the impact of typhoon Haiyan and the earthquake on the country's economic performance in 2014, particularly if the Philippine government drags its foot on the reconstruction and rehabilitation of affected areas.


"If reconstruction works are stalled, then GDP growth in 2014 would settle at a lower rate of 5 percent," said University of the Philippines economist Benjamin Diokno.


University of Asia and the Pacific economist Cid Terosa said the impact of natural disasters on economic growth could spill over to the first semester of 2014.


"This can be traced to the lag effects of natural calamities that could lower consumption demand and investment flows. Also, export growth will continue to be tentative next year," Terosa said.


What could counter these, he said, is higher government spending in 2014.


The Philippine government said it is sticking to its target of growing the economy by 6.5 to 7.5 percent next year.


Related:


Philippine economy grows 7 pct in Q3[1]


MANILA, Nov. 28 (Xinhua) -- Philippine economy in the third quarter this year grew 7 percent on the back of the good performance of the services and manufacturing sectors, the National Economic and Development Authority (NEDA) said Thursday.


NEDA said this brought gross domestic product (GDP) growth to 7. 4 percent in January to September.  Full story[2]




References

  1. ^ Philippine economy grows 7 pct in Q3 (news.xinhuanet.com)
  2. ^ Full story (news.xinhuanet.com)

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Sunday, December 15, 2013

Superconductivity to meet humanity's greatest challenges


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Integrator safeguards client against natural disasters - CRN Australia

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Friday, December 13, 2013

Bringing color to solar panels


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Paradigm shift in organic solar cell research?

Nov. 19, 2013 ? Organic solar cells have long been touted as lightweight, low-cost alternatives to rigid solar panels made of silicon. Dramatic improvements in the efficiency of organic photovoltaics have been made in recent years, yet the fundamental question of how these devices convert sunlight into electricity is still hotly debated.

Now a Stanford University research team is weighing in on the controversy. Their findings, published in the Nov. 17 issue of the journal Nature Materials, indicate that the predominant working theory is incorrect, and could steer future efforts to design materials that boost the performance of organic cells.

"We know that organic photovoltaics are very good," said study coauthor Michael McGehee, a professor of materials science and engineering at Stanford. "The question is, why are they so good? The answer is controversial."

A typical organic solar cell consists of two semiconducting layers made of plastic polymers and other flexible materials. The cell generates electricity by absorbing particles of light, or photons.

When the cell absorbs light, a photon knocks out an electron in a polymer atom, leaving behind an empty space, which scientists refer to as a hole. The electron and the hole immediately form a bonded pair called an exciton. The exciton splits, allowing the electron to move independently to a hole created by another absorbed photon. This continuous movement of electrons from hole to hole produces an electric current.

In the study, the Stanford team addressed a long-standing debate over what causes the exciton to split.

"To generate a current, you have to separate the electron and the hole," said senior author Alberto Salleo, an associate professor of materials science and engineering at Stanford. "That requires two different semiconducting materials. If the electron is attracted to material B more than material A, it drops into material B. In theory, the electron should remain bound to the hole even after it drops.

"The fundamental question that's been around a long time is, how does this bound state split?"

Some like it hot

One explanation widely accepted by scientists is known as the "hot exciton effect." The idea is that the electron carries extra energy when it drops from material A to material B. That added energy gives the excited ("hot") electron enough velocity to escape from the hole.

But that hypothesis did not stand up to experimental tests, according to the Stanford team.

"In our study, we found that the hot exciton effect does not exist," Salleo said. "We measured optical emissions from the semiconducting materials and found that extra energy is not required to split an exciton."

So what actually causes electron-hole pairs to separate?

"We haven't really answered that question yet," Salleo said. "We have a few hints. We think that the disordered arrangement of the plastic polymers in the semiconductor might help the electron get away."

In a recent study, Salleo discovered that disorder at the molecular level actually improves the performance of semiconducting polymers in solar cells. By focusing on the inherent disorder of plastic polymers, researchers could design new materials that draw electrons away from the solar cell interface where the two semiconducting layers meet, he said.

"In organic solar cells, the interface is always more disordered than the area further away," Salleo explained. "That creates a natural gradient that sucks the electron from the disordered regions into the ordered regions."

Improving energy efficiency

The solar cells used in the experiment have an energy-conversion efficiency of about 9 percent. The Stanford team hopes to improve that performance by designing semiconductors that take advantage of the interplay between order and disorder.

"To make a better organic solar cell, people have been looking for materials that would give you a stronger hot exciton effect," Salleo said. "They should instead try to figure out how the electron gets away without it being hot. This idea is pretty controversial. It's a fundamental shift in the way people think about photocurrent generation."

Other authors of the paper are Koen Vandewal (lead author), Erik Hoke, William Mateker, Jason Bloking and George Burkhard of Stanford; Steve Albrecht, Marcel Schubert and Dieter Neher of the University of Potsdam; Johannes Widmer and Moritz Riede of the Institute for Applied Photophysics (IAPP); Jessica Douglas and Jean Frechet of the University of California-Berkeley; Aram Amassian of the King Abdullah University of Science and Technology (KAUST); and Alan Sellinger of the Colorado School of Mines and the University of Oxford. Author Kenneth Graham has a joint postdoctoral fellowship with Stanford and KAUST.

Support for the study was provided by the Stanford Center for Advanced Molecular Photovoltaics and the U.S. Department of Energy.


View the original article here

Thursday, December 12, 2013

The reality behind Europe's response to climate change

Nov. 25, 2013 — British cities -- unlike their counterparts on the mainland -- are taking the lead in making plans to curb and handle the impact of climate change. So says Diana Reckien, of Columbia University in the US, in a study published in Springer's journal Climatic Change that analysed the relevant strategic policies and planning documents of 200 urban areas in eleven European countries. They found that one in every three European cities has no plans on the table to reduce greenhouse gas emissions, while seven in every ten urban areas have no formal adaptation plans in place.

How cities respond to climate change is important as they are responsible for 31 to 80 percent of global greenhouse gas emissions. Cities are particularly vulnerable to climate hazards due to their high density of people, their assets and infrastructure. On the other hand, such urban areas are unencumbered by the complicated international negotiations that hamper climate change action at the international level.

Reckien's team, funded by the European Science Foundation COST Action TU0902, studied the response to climate change issues of 200 large and medium-sized cities in eleven European countries. Their analysis is the first to look objectively at strategic policy and planning documents rather than relying on self-reported measures such as questionnaires and interviews of city representatives. They scrutinized adaptation plans which incorporate urban planning and development actions that lead to the abatement or reduction of vulnerability to climate change, and mitigation plans that include actions such as improved energy efficiency and renewable energy generation to reduce greenhouse gas emissions.

Overall, 130 cities (65 percent) have at least a mitigation plan, and less than a third (28 percent) also an adaptation plan. More than one in every three cities (35 percent) has no plan whatsoever in place. Only one in every four cities (25 percent) had both, and also set quantitative targets to reduce greenhouse gas emissions. Most (88 percent) mitigation plans quantify targets for carbon dioxide or greenhouse gas emission reduction.

Countries vary in their planning: 93 percent of UK cities studied have a mitigation plan whereas only 43 percent of French and 42 percent of Belgian cities do. The highest proportion of cities with an adaptation plan are in the UK (80 percent of 30 cities), Finland (50 percent of 4 cities) and Germany (33 percent of 40 cities). Dutch cities are the most ambitious aiming to be 'carbon-', 'climate-' or 'energy-neutral' (100 percent reduction target) by 2050 or earlier.

If the planned actions within cities are nationally representative, the European Union would achieve its 20 percent reduction target, but fall short of the 80 percent emission reduction recommended to the avoid global mean temperature rising by more than 2°C.

"To better understand the global climate change response and emissions reduction actions, we recommend the establishment of an international database of mitigation and adaptation options that builds upon this European study," writes Reckien.


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Climate change: Procrastination over mitigation measures could prove costly


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Wednesday, December 11, 2013

Power boosting self-cleaning solar panels

Nov. 21, 2013 — High-power, self-cleaning solar panels might be coming soon to a roof near you. There are two obvious problems with photovoltaic cells, solar panels. First, they are very shiny and so a lot of the incident sunlight is simply reflected back into the sky rather than being converted into electricity. Secondly, they get dirty with dust and debris caught on the wind and residues left behind by rain and birds.

Now, research published in the International Journal of Nanomanufacturing suggests that it might be possible to add a nanoscopic relief pattern to the surface of solar cells that makes them non-reflective significantly boosting efficiency and at the same time making them highly non-stick and self-cleaning.

Zuobin Wang of Changchun University of Science and Technology (China), Jin Zhang of Xi'an Technological University (China) and colleagues at Cardiff University (UK), who are partners of the EU FP7 LaserNaMi project, have devised an approach to lithography, the process used to "print" microelectronic circuits, that allows them to add a pattern to the surface of a solar cell. The features of the pattern are so small that individual parts are shorter than the wavelength of light. This means that incident sunlight becomes trapped rather than reflected passing on more of its energy to electricity-generation process that takes place within the panel.

The same pattern also makes the surface of the solar cell behave like the surface of a lotus leaf, a natural material that is known to be very water repellant, or hydrophobic, so that particles and liquids that land on it do not become stuck as there is no surface to which the droplets can grip. When it rains any deposits are sloughed away and the rainwater runs off efficiently leaving the panel clean and dry after the downpour.

The team's work indicates that a patterned layer on top of the active part of the panel can avoid the energy losses due to reflection from the surface. It directly boosts absorption of sunlight in the visible spectrum and into the near-infrared part of the spectrum, all of which contributes to a boost to the overall electrical efficiency of the panel. The team suggests that printing the surface of the photovoltaic cell so that it is covered with nanoscopic cones would provide the optimal combination of making the panel non-reflective and hydrophobic and so self-cleaning.

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Story Source:

The above story is based on materials[1] provided by Inderscience[2], via AlphaGalileo.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.


Journal Reference:

  1. Zuobin Wang, Jin Zhang, Lingxia Hang, Shilei Jiang, Guoqiang Liu, Ze Ji, Chunlei Tan, Huan Sun. Nanoscale structures for implementation of anti-reflection and self-cleaning functions. International Journal of Nanomanufacturing, 2013; 9 (5/6): 520 DOI: 10.1504/IJNM.2013.057596[3]

Note: If no author is given, the source is cited instead.

References

  1. ^ materials (www.alphagalileo.org)
  2. ^ Inderscience (www.inderscience.com)
  3. ^ 10.1504/IJNM.2013.057596 (dx.doi.org)

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Two for one in solar power: New process could revolutionize solar energy harvesting

Nov. 17, 2013 ? Solar cells offer the opportunity to harvest abundant, renewable energy. Although the highest energy light occurs in the ultraviolet and visible spectrum, most solar energy is in the infrared. There is a trade-off in harvesting this light, so that solar cells are efficient in the infrared but waste much of the energy available from the more energetic photons in the visible part of the spectrum.

When a photon is absorbed it creates a single electronic excitation that is then separated into an electron and a positively charged hole, irrespective of the light energy. One way to improve efficiency is to split energy available from visible photons into two, which leads to a doubling of the current in the solar cell.

Researchers in Cambridge and Mons have investigated the process in which the initial electronic excitation can split into a pair of half-energy excitations. This can happen in certain organic molecules when the quantum mechanical effect of electron spin sets the initial spin 'singlet' state to be double the energy of the alternative spin 'triplet' arrangement.

The study, published today in the journal Nature Chemistry, shows that this process of singlet fission to pairs of triplets depends very sensitively on the interactions between molecules. By studying this process when the molecules are in solution it is possible to control when this process is switched on.

When the material is very dilute, the distance between molecules is large and singlet fission does not occur. When the solution is concentrated, collisions between molecules become more frequent. The researchers find that the fission process happens as soon as just two of these molecules are in contact, and remarkably, that singlet fission is then completely efficient -- so that every photon produces two triplets.

This fundamental study provides new insights into the process of singlet fission and demonstrates that the use of singlet fission is a very promising route to improved solar cells. Chemists will be able to use the results to make new materials, say the team from Cambridge's Cavendish Laboratory, who are currently working on ways to use these solutions in devices.

"We began by going back to fundamentals; looking at the solar energy challenge from a blue skies perspective," said Dr Brian Walker, a research fellow in the Cavendish Lab's Optoelectronics group, who led the study.

"Singlet fission offers a route to boosting solar cell efficiency using low-cost materials. We are only beginning to understand how this process works, and as we learn more we expect improvements in the technology to follow."

The team used a combination of laser experiments -- which measure timings with extreme accuracy -- with chemical methods used to study reaction mechanisms. This dual approach allowed the researchers to slow down fission and observe a key intermediate step never before seen.

"Very few other groups in the world have laser apparatus as versatile as ours in Cambridge," added Andrew Musser, a researcher who collaborated in the study. "This enabled us to get a step closer to working out exactly how singlet fission occurs."


View the original article here

Paradigm shift in organic solar cell research?

Nov. 19, 2013 — Organic solar cells have long been touted as lightweight, low-cost alternatives to rigid solar panels made of silicon. Dramatic improvements in the efficiency of organic photovoltaics have been made in recent years, yet the fundamental question of how these devices convert sunlight into electricity is still hotly debated.

Now a Stanford University research team is weighing in on the controversy. Their findings, published in the Nov. 17 issue of the journal Nature Materials, indicate that the predominant working theory is incorrect, and could steer future efforts to design materials that boost the performance of organic cells.

"We know that organic photovoltaics are very good," said study coauthor Michael McGehee, a professor of materials science and engineering at Stanford. "The question is, why are they so good? The answer is controversial."

A typical organic solar cell consists of two semiconducting layers made of plastic polymers and other flexible materials. The cell generates electricity by absorbing particles of light, or photons.

When the cell absorbs light, a photon knocks out an electron in a polymer atom, leaving behind an empty space, which scientists refer to as a hole. The electron and the hole immediately form a bonded pair called an exciton. The exciton splits, allowing the electron to move independently to a hole created by another absorbed photon. This continuous movement of electrons from hole to hole produces an electric current.

In the study, the Stanford team addressed a long-standing debate over what causes the exciton to split.

"To generate a current, you have to separate the electron and the hole," said senior author Alberto Salleo, an associate professor of materials science and engineering at Stanford. "That requires two different semiconducting materials. If the electron is attracted to material B more than material A, it drops into material B. In theory, the electron should remain bound to the hole even after it drops.

"The fundamental question that's been around a long time is, how does this bound state split?"

Some like it hot

One explanation widely accepted by scientists is known as the "hot exciton effect." The idea is that the electron carries extra energy when it drops from material A to material B. That added energy gives the excited ("hot") electron enough velocity to escape from the hole.

But that hypothesis did not stand up to experimental tests, according to the Stanford team.

"In our study, we found that the hot exciton effect does not exist," Salleo said. "We measured optical emissions from the semiconducting materials and found that extra energy is not required to split an exciton."

So what actually causes electron-hole pairs to separate?

"We haven't really answered that question yet," Salleo said. "We have a few hints. We think that the disordered arrangement of the plastic polymers in the semiconductor might help the electron get away."

In a recent study, Salleo discovered that disorder at the molecular level actually improves the performance of semiconducting polymers in solar cells. By focusing on the inherent disorder of plastic polymers, researchers could design new materials that draw electrons away from the solar cell interface where the two semiconducting layers meet, he said.

"In organic solar cells, the interface is always more disordered than the area further away," Salleo explained. "That creates a natural gradient that sucks the electron from the disordered regions into the ordered regions."

Improving energy efficiency

The solar cells used in the experiment have an energy-conversion efficiency of about 9 percent. The Stanford team hopes to improve that performance by designing semiconductors that take advantage of the interplay between order and disorder.

"To make a better organic solar cell, people have been looking for materials that would give you a stronger hot exciton effect," Salleo said. "They should instead try to figure out how the electron gets away without it being hot. This idea is pretty controversial. It's a fundamental shift in the way people think about photocurrent generation."

Other authors of the paper are Koen Vandewal (lead author), Erik Hoke, William Mateker, Jason Bloking and George Burkhard of Stanford; Steve Albrecht, Marcel Schubert and Dieter Neher of the University of Potsdam; Johannes Widmer and Moritz Riede of the Institute for Applied Photophysics (IAPP); Jessica Douglas and Jean Frechet of the University of California-Berkeley; Aram Amassian of the King Abdullah University of Science and Technology (KAUST); and Alan Sellinger of the Colorado School of Mines and the University of Oxford. Author Kenneth Graham has a joint postdoctoral fellowship with Stanford and KAUST.

Support for the study was provided by the Stanford Center for Advanced Molecular Photovoltaics and the U.S. Department of Energy.


View the original article here

Tuesday, December 10, 2013

Specially designed nanostructured materials can increase the light-absorbing efficiency of solar cells

Nov. 20, 2013 — The Sun is our most promising source of clean and renewable energy. The energy that reaches Earth from the Sun in an hour is almost equivalent to that consumed by humans over a year. Solar cells can tap this massive source of energy by converting light into an electrical current. However, these devices still require significant improvements in efficiency before they can compete with more traditional energy sources.

Xiaogang Liu, Alfred Ling Yoong Tok and their co-workers at the A*STAR Institute of Materials Research and Engineering, the National University of Singapore and Nanyang Technological University, Singapore, have now developed a method for using nanostructures to increase the fraction of incoming light that is absorbed by a light-harvesting material1. The method is ideal for use with high-efficiency solar cells.

Solar cells absorb packets of optical energy called photons and then use the photons to generate electrons. The energy of some photons from the Sun, however, is too small to create electrons in this way and so is lost. Liu, Tok and their co-workers circumvented this loss using an effect known as upconversion. In this process, two low-energy photons are combined to produce a single high-energy photon. This energetic photon can then be absorbed by the active region of the solar cell.

The researchers' device comprised a titanium oxide frame filled with a regular arrangement of air pores roughly half a micrometer across -- a structure called an inverse opal (see image). Spheres of the upconversion material, which were 30 nanometers in diameter, sat on the surface of these pores. Tiny light-sensitive quantum dots made of crystals of cadmium selenide coated these nanospheres.

The quantum dots efficiently absorbed incoming light, either directly from an external source or from unconverted photons from the nanospheres, and converted it to electrons. This charge then flowed into the titanium oxide frame. "The titanium oxide inverse opal creates a continuous electron-conducting pathway and provides a large interfacial surface area to support the upconversion nanoparticles and the quantum dots," explains Liu.

Liu, Tok and the team tested the device by firing laser light at it with a wavelength of 980 nanometers, which is not normally absorbed by cadmium selenide quantum dots. As expected, they were able to measure a much higher electrical current than the same experiment performed with a device without the upconversion nanospheres. "We believe that the enhanced energy transfer and light harvesting may afford a highly competitive advantage over conventional silicon solar cells," says Liu.


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New energy model offers transparency to let others replicate findings


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Let's just harvest invasive species -- problem solved?

Nov. 20, 2013 — Although invasive Asian carp have been successfully harvested and served on a dinner plate, harvesting invasive plants to convert into ethanol isn't as easy.

According to a recent study at the University of Illinois, harvesting invasive plants for use as biofuels may sound like a great idea, but the reality poses numerous obstacles and is too expensive to consider, at least with the current ethanol pathways.

"When the topic of potential invasion by non-native biofuel crops has been raised at conferences I've attended, the ecologists in the room have suggested we use biomass from existing invaders instead," said Lauren Quinn, an invasive plant ecologist in U of I's Energy Biosciences Institute. "They worry about the potential deployment of tens of thousands of acres of known invaders like Arundo donax for ethanol production. They'd say, 'we have all of these invasive plants. Let's just harvest them instead of planting new ones!' But when I analyzed the idea from a broader perspective, it just didn't add up."

Quinn explored the idea of harvesting invasive plants from many angles but said that the overarching problem is the non-sustainability of the profit stream. "From a business person's perspective, it just doesn't function like a typical crop that is harvested and then replanted or harvested again the following year," she said. "Here, land managers are trying to get rid of an invasive plant using an array of methods, including herbicides, so there wouldn't necessarily be multiple years of harvest."

Other obstacles Quinn examined are the need for specially designed harvesting equipment, the development of new conversion technologies for these unique plants, and even the problems associated with transportation.

"One of the biggest issues is the absence of appropriate biorefineries in any given area," Quinn said. "If there isn't one nearby, growers would have to transport the material long distances, and that's expensive."

Perhaps more important, Quinn discussed the issues with the high variability of the cell wall composition across different species. "Most existing or planned biorefineries can process only a single, or at best, a small handful of conventional feedstocks, and are not likely to be flexible enough to handle the variety of material brought in from invasive plant control projects," Quinn said. "The breakdown and processing of plant tissues to ethanol requires different temperatures, enzymes, and equipment that are all highly specific. The proportion of cellulose, lignin, and other fractionation products can differ even within a single genotype if it is grown in multiple regions so the variations between completely different plant types would be an even greater hurdle."

Quinn isn't discounting the idea of harvesting invasive plants, however. She encourages control of invasive populations and subsequent ecological restoration but does not believe that invasive biomass can replace dedicated energy crops at present.

"One day there might be a pathway toward ethanol conversion of invasive biomass," Quinn said. "But until we do get to that point, there may be possibilities to use invasive plants as alternative sources of energy, like combustion for electricity. Invasive biomass could drop into the existing supply of biomass being co-fired with coal in the already huge network of electrical power plants across the country. That would eliminate the technological barriers that conversion to ethanol presents.

"I'm not saying that we shouldn't continue to look at ethanol conversion processes eventually, I'm just saying that right now, it doesn't seem to make a lot of economic sense."

"Why not harvest existing invaders for bioethanol?" was published in a recent issue of Biological Invasions. A. Bryan Endres and Thomas B. Voigt contributed. The research was funded by the Energy Biosciences Institute.


View the original article here

Monday, December 9, 2013

Specially designed nanostructured materials can increase the light-absorbing efficiency of solar cells

Nov. 20, 2013 ? The Sun is our most promising source of clean and renewable energy. The energy that reaches Earth from the Sun in an hour is almost equivalent to that consumed by humans over a year. Solar cells can tap this massive source of energy by converting light into an electrical current. However, these devices still require significant improvements in efficiency before they can compete with more traditional energy sources.

Xiaogang Liu, Alfred Ling Yoong Tok and their co-workers at the A*STAR Institute of Materials Research and Engineering, the National University of Singapore and Nanyang Technological University, Singapore, have now developed a method for using nanostructures to increase the fraction of incoming light that is absorbed by a light-harvesting material1. The method is ideal for use with high-efficiency solar cells.

Solar cells absorb packets of optical energy called photons and then use the photons to generate electrons. The energy of some photons from the Sun, however, is too small to create electrons in this way and so is lost. Liu, Tok and their co-workers circumvented this loss using an effect known as upconversion. In this process, two low-energy photons are combined to produce a single high-energy photon. This energetic photon can then be absorbed by the active region of the solar cell.

The researchers' device comprised a titanium oxide frame filled with a regular arrangement of air pores roughly half a micrometer across -- a structure called an inverse opal (see image). Spheres of the upconversion material, which were 30 nanometers in diameter, sat on the surface of these pores. Tiny light-sensitive quantum dots made of crystals of cadmium selenide coated these nanospheres.

The quantum dots efficiently absorbed incoming light, either directly from an external source or from unconverted photons from the nanospheres, and converted it to electrons. This charge then flowed into the titanium oxide frame. "The titanium oxide inverse opal creates a continuous electron-conducting pathway and provides a large interfacial surface area to support the upconversion nanoparticles and the quantum dots," explains Liu.

Liu, Tok and the team tested the device by firing laser light at it with a wavelength of 980 nanometers, which is not normally absorbed by cadmium selenide quantum dots. As expected, they were able to measure a much higher electrical current than the same experiment performed with a device without the upconversion nanospheres. "We believe that the enhanced energy transfer and light harvesting may afford a highly competitive advantage over conventional silicon solar cells," says Liu.


View the original article here

Cost gap for Western renewables could narrow by 2025


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Sunday, December 8, 2013

Coal continues to dominate global carbon emissions

Nov. 18, 2013 ? Despite explosive growth in renewable energy consumption, continued strong growth in coal consumption has further consolidated coal as the dominate source of carbon dioxide emissions.

In its annual analysis of global carbon emissions production published online Tuesday 19 November, the Global Carbon Project (GCP) found that global emissions from fossil fuel combustion and cement production reached a record high of 35 billion tonnes CO2 in 2012, 58 per cent above the level of 1990.

In 2012 global carbon dioxide emissions were 2.2 per cent higher1 than in 2011, and based on estimates of economic activity in 2013, emissions are set to rise 2.1 per cent in 2013 to reach 36 billion tonnes CO2. These growth rates are slightly lower than the average growth of 2.7 per cent per year in the last 10 years.

In 2012 many countries increased dependence on coal. German emissions increased 1.8 per cent in 2012, with coal growing at 4.2 per cent.Japanese emissions increased 6.9 per cent in 2012, with coal growing at 5.6 per cent. EU28 emissions decreased 1.3 per cent, but emissions from coal grew 3.0 per cent. Indian emissions increased 7.7 per cent, with coal growing at 10.2 per cent.

Poland, host of the 19th Conference of the Parties to the UNFCCC, recorded a 3.1 per cent decrease in emissions in 2012, but it is still one of Europe's most coal-reliant economies.

"While society is seeing many positive developments in renewable energy, this increased production capacity is not simply displacing coal consumption," said Peters, an author of the study based at CICERO, a climate research institute in Norway.

Seventy per cent of the growth in global emissions was due to increased emissions in China.Chinese emissions grew 5.9 per cent in 2012, lower than the average of 7.9 per cent per year over the last 10 years.

Coal accounted for about 68 per cent of Chinese energy consumption, while hydropower and renewables accounted for about 8 per cent.

"Even though renewable and hydro energy consumption in China grew around 25 per cent in 2012, this growth is from a low baseline. The growth in low-carbon energy sources was more than offset by a 6.4 per cent increase on coal consumption which has a higher baseline," said Dr Peters.

Carbon dioxide emissions in the USA continued their decline with a 3.7 per cent decrease in 2012, with emissions from coal consumption decreasing 12 per cent.

"If US emissions continue to decline as in the last five years, and Chinese emissions continue to increase, then China will emit more than the US on a per capita basis in the period 2020-2025," said Peters.

China already emits the same as the EU on a per capita basis, 7.0 tonnes CO2 per person.

"China has had rapid economic growth in the last decades bringing lasting benefits to its citizens, but this has come at a great cost to the environment. The conventional view is that China still lags behind developed countries, but China is actually comparable to many developed countries in terms of per capita CO2 emissions," said Peters.

Growing cumulative emissions increases chance of exceeding two degrees The latest IPCC assessment report suggests that cumulative emissions must not exceed 2900 billion tonnes CO2 to have a "likely" chance of keeping global average temperatures below two degrees. Society has already emitted 69 per cent of this amount.

"Trends need to reverse and emissions to fall to limit global climate change below two degrees" says Prof Corinne Le Quéré of the Tyndall Centre for Climate Change Research at the University of East Anglia, who led the study involving 49 authors from 10 countries.

In May this year, carbon dioxide in the atmosphere ominously exceeded 400 parts per million for the first time since measurements started in 1958 at the Mauna Loa observatory.

Including an estimate of land-use change, emissions in 2012 were 39 billion tonnes of CO2 with land use change 8 per cent of the total.


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Saturday, December 7, 2013

The reality behind Europe's response to climate change

Nov. 25, 2013 ? British cities -- unlike their counterparts on the mainland -- are taking the lead in making plans to curb and handle the impact of climate change. So says Diana Reckien, of Columbia University in the US, in a study published in Springer's journal Climatic Change that analysed the relevant strategic policies and planning documents of 200 urban areas in eleven European countries. They found that one in every three European cities has no plans on the table to reduce greenhouse gas emissions, while seven in every ten urban areas have no formal adaptation plans in place.

How cities respond to climate change is important as they are responsible for 31 to 80 percent of global greenhouse gas emissions. Cities are particularly vulnerable to climate hazards due to their high density of people, their assets and infrastructure. On the other hand, such urban areas are unencumbered by the complicated international negotiations that hamper climate change action at the international level.

Reckien's team, funded by the European Science Foundation COST Action TU0902, studied the response to climate change issues of 200 large and medium-sized cities in eleven European countries. Their analysis is the first to look objectively at strategic policy and planning documents rather than relying on self-reported measures such as questionnaires and interviews of city representatives. They scrutinized adaptation plans which incorporate urban planning and development actions that lead to the abatement or reduction of vulnerability to climate change, and mitigation plans that include actions such as improved energy efficiency and renewable energy generation to reduce greenhouse gas emissions.

Overall, 130 cities (65 percent) have at least a mitigation plan, and less than a third (28 percent) also an adaptation plan. More than one in every three cities (35 percent) has no plan whatsoever in place. Only one in every four cities (25 percent) had both, and also set quantitative targets to reduce greenhouse gas emissions. Most (88 percent) mitigation plans quantify targets for carbon dioxide or greenhouse gas emission reduction.

Countries vary in their planning: 93 percent of UK cities studied have a mitigation plan whereas only 43 percent of French and 42 percent of Belgian cities do. The highest proportion of cities with an adaptation plan are in the UK (80 percent of 30 cities), Finland (50 percent of 4 cities) and Germany (33 percent of 40 cities). Dutch cities are the most ambitious aiming to be 'carbon-', 'climate-' or 'energy-neutral' (100 percent reduction target) by 2050 or earlier.

If the planned actions within cities are nationally representative, the European Union would achieve its 20 percent reduction target, but fall short of the 80 percent emission reduction recommended to the avoid global mean temperature rising by more than 2°C.

"To better understand the global climate change response and emissions reduction actions, we recommend the establishment of an international database of mitigation and adaptation options that builds upon this European study," writes Reckien.


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Thursday, December 5, 2013

Let's just harvest invasive species -- problem solved?

Nov. 20, 2013 ? Although invasive Asian carp have been successfully harvested and served on a dinner plate, harvesting invasive plants to convert into ethanol isn't as easy.

According to a recent study at the University of Illinois, harvesting invasive plants for use as biofuels may sound like a great idea, but the reality poses numerous obstacles and is too expensive to consider, at least with the current ethanol pathways.

"When the topic of potential invasion by non-native biofuel crops has been raised at conferences I've attended, the ecologists in the room have suggested we use biomass from existing invaders instead," said Lauren Quinn, an invasive plant ecologist in U of I's Energy Biosciences Institute. "They worry about the potential deployment of tens of thousands of acres of known invaders like Arundo donax for ethanol production. They'd say, 'we have all of these invasive plants. Let's just harvest them instead of planting new ones!' But when I analyzed the idea from a broader perspective, it just didn't add up."

Quinn explored the idea of harvesting invasive plants from many angles but said that the overarching problem is the non-sustainability of the profit stream. "From a business person's perspective, it just doesn't function like a typical crop that is harvested and then replanted or harvested again the following year," she said. "Here, land managers are trying to get rid of an invasive plant using an array of methods, including herbicides, so there wouldn't necessarily be multiple years of harvest."

Other obstacles Quinn examined are the need for specially designed harvesting equipment, the development of new conversion technologies for these unique plants, and even the problems associated with transportation.

"One of the biggest issues is the absence of appropriate biorefineries in any given area," Quinn said. "If there isn't one nearby, growers would have to transport the material long distances, and that's expensive."

Perhaps more important, Quinn discussed the issues with the high variability of the cell wall composition across different species. "Most existing or planned biorefineries can process only a single, or at best, a small handful of conventional feedstocks, and are not likely to be flexible enough to handle the variety of material brought in from invasive plant control projects," Quinn said. "The breakdown and processing of plant tissues to ethanol requires different temperatures, enzymes, and equipment that are all highly specific. The proportion of cellulose, lignin, and other fractionation products can differ even within a single genotype if it is grown in multiple regions so the variations between completely different plant types would be an even greater hurdle."

Quinn isn't discounting the idea of harvesting invasive plants, however. She encourages control of invasive populations and subsequent ecological restoration but does not believe that invasive biomass can replace dedicated energy crops at present.

"One day there might be a pathway toward ethanol conversion of invasive biomass," Quinn said. "But until we do get to that point, there may be possibilities to use invasive plants as alternative sources of energy, like combustion for electricity. Invasive biomass could drop into the existing supply of biomass being co-fired with coal in the already huge network of electrical power plants across the country. That would eliminate the technological barriers that conversion to ethanol presents.

"I'm not saying that we shouldn't continue to look at ethanol conversion processes eventually, I'm just saying that right now, it doesn't seem to make a lot of economic sense."

"Why not harvest existing invaders for bioethanol?" was published in a recent issue of Biological Invasions. A. Bryan Endres and Thomas B. Voigt contributed. The research was funded by the Energy Biosciences Institute.


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Wednesday, December 4, 2013

Let's just harvest invasive species -- problem solved?

Nov. 20, 2013 — Although invasive Asian carp have been successfully harvested and served on a dinner plate, harvesting invasive plants to convert into ethanol isn't as easy.

According to a recent study at the University of Illinois, harvesting invasive plants for use as biofuels may sound like a great idea, but the reality poses numerous obstacles and is too expensive to consider, at least with the current ethanol pathways.

"When the topic of potential invasion by non-native biofuel crops has been raised at conferences I've attended, the ecologists in the room have suggested we use biomass from existing invaders instead," said Lauren Quinn, an invasive plant ecologist in U of I's Energy Biosciences Institute. "They worry about the potential deployment of tens of thousands of acres of known invaders like Arundo donax for ethanol production. They'd say, 'we have all of these invasive plants. Let's just harvest them instead of planting new ones!' But when I analyzed the idea from a broader perspective, it just didn't add up."

Quinn explored the idea of harvesting invasive plants from many angles but said that the overarching problem is the non-sustainability of the profit stream. "From a business person's perspective, it just doesn't function like a typical crop that is harvested and then replanted or harvested again the following year," she said. "Here, land managers are trying to get rid of an invasive plant using an array of methods, including herbicides, so there wouldn't necessarily be multiple years of harvest."

Other obstacles Quinn examined are the need for specially designed harvesting equipment, the development of new conversion technologies for these unique plants, and even the problems associated with transportation.

"One of the biggest issues is the absence of appropriate biorefineries in any given area," Quinn said. "If there isn't one nearby, growers would have to transport the material long distances, and that's expensive."

Perhaps more important, Quinn discussed the issues with the high variability of the cell wall composition across different species. "Most existing or planned biorefineries can process only a single, or at best, a small handful of conventional feedstocks, and are not likely to be flexible enough to handle the variety of material brought in from invasive plant control projects," Quinn said. "The breakdown and processing of plant tissues to ethanol requires different temperatures, enzymes, and equipment that are all highly specific. The proportion of cellulose, lignin, and other fractionation products can differ even within a single genotype if it is grown in multiple regions so the variations between completely different plant types would be an even greater hurdle."

Quinn isn't discounting the idea of harvesting invasive plants, however. She encourages control of invasive populations and subsequent ecological restoration but does not believe that invasive biomass can replace dedicated energy crops at present.

"One day there might be a pathway toward ethanol conversion of invasive biomass," Quinn said. "But until we do get to that point, there may be possibilities to use invasive plants as alternative sources of energy, like combustion for electricity. Invasive biomass could drop into the existing supply of biomass being co-fired with coal in the already huge network of electrical power plants across the country. That would eliminate the technological barriers that conversion to ethanol presents.

"I'm not saying that we shouldn't continue to look at ethanol conversion processes eventually, I'm just saying that right now, it doesn't seem to make a lot of economic sense."

"Why not harvest existing invaders for bioethanol?" was published in a recent issue of Biological Invasions. A. Bryan Endres and Thomas B. Voigt contributed. The research was funded by the Energy Biosciences Institute.


View the original article here

Tuesday, December 3, 2013

Power boosting self-cleaning solar panels

Nov. 21, 2013 ? High-power, self-cleaning solar panels might be coming soon to a roof near you. There are two obvious problems with photovoltaic cells, solar panels. First, they are very shiny and so a lot of the incident sunlight is simply reflected back into the sky rather than being converted into electricity. Secondly, they get dirty with dust and debris caught on the wind and residues left behind by rain and birds.

Now, research published in the International Journal of Nanomanufacturing suggests that it might be possible to add a nanoscopic relief pattern to the surface of solar cells that makes them non-reflective significantly boosting efficiency and at the same time making them highly non-stick and self-cleaning.

Zuobin Wang of Changchun University of Science and Technology (China), Jin Zhang of Xi'an Technological University (China) and colleagues at Cardiff University (UK), who are partners of the EU FP7 LaserNaMi project, have devised an approach to lithography, the process used to "print" microelectronic circuits, that allows them to add a pattern to the surface of a solar cell. The features of the pattern are so small that individual parts are shorter than the wavelength of light. This means that incident sunlight becomes trapped rather than reflected passing on more of its energy to electricity-generation process that takes place within the panel.

The same pattern also makes the surface of the solar cell behave like the surface of a lotus leaf, a natural material that is known to be very water repellant, or hydrophobic, so that particles and liquids that land on it do not become stuck as there is no surface to which the droplets can grip. When it rains any deposits are sloughed away and the rainwater runs off efficiently leaving the panel clean and dry after the downpour.

The team's work indicates that a patterned layer on top of the active part of the panel can avoid the energy losses due to reflection from the surface. It directly boosts absorption of sunlight in the visible spectrum and into the near-infrared part of the spectrum, all of which contributes to a boost to the overall electrical efficiency of the panel. The team suggests that printing the surface of the photovoltaic cell so that it is covered with nanoscopic cones would provide the optimal combination of making the panel non-reflective and hydrophobic and so self-cleaning.

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Story Source:

The above story is based on materials[1] provided by Inderscience[2], via AlphaGalileo.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.


Journal Reference:

  1. Zuobin Wang, Jin Zhang, Lingxia Hang, Shilei Jiang, Guoqiang Liu, Ze Ji, Chunlei Tan, Huan Sun. Nanoscale structures for implementation of anti-reflection and self-cleaning functions. International Journal of Nanomanufacturing, 2013; 9 (5/6): 520 DOI: 10.1504/IJNM.2013.057596[3]

Note: If no author is given, the source is cited instead.

References

  1. ^ materials (www.alphagalileo.org)
  2. ^ Inderscience (www.inderscience.com)
  3. ^ 10.1504/IJNM.2013.057596 (dx.doi.org)

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Monday, December 2, 2013

Refined materials provide booster shot for solar energy conversion

Nov. 18, 2013 ? If you want to get the most out of the sun, you have to improve the performance of the materials used.

An interdisciplinary team of Engineering at Illinois researchers has set its sights on improving the materials that make solar energy conversion/photocatalysis possible. Together, they have developed a new form of high-performance solar photocatalyst based on the combination of the TiO2 (titanium dioxide) and other "metallic" oxides that greatly enhance the visible light absorption and promote more efficient utilization of the solar spectrum for energy applications.

"This is a fundamentally new way of approaching these matters," explained Lane Martin, who is an assistant professor in the Department of Materials Science and Engineering at Illinois. "Our research group incorporates aspects of condensed matter physics, semiconductor device engineering, and photochemistry to make new performance possible. From these materials we can imagine carbon-neutral energy production of clean-burning fuels, waste water purification and remediation, and much more.

"As a follow-up to our prior work, we expanded our discovery of new strongly absorbing energy materials," Martin added. "The overall concept is that we have developed a new form of high-performance solar photocatalyst based on the combination of the TiO2 and 'metallic' oxides." The group's paper "Enhanced photoelectrochemical activity in all-oxide heterojunction devices based on correlated 'metallic' oxides," appears in the journal, Advanced Materials (Volume 25, Issue 43, pages 6201-6206). The researchers also have a patent application pending for this work.

According to Martin the research paper addresses the most pressing limiting factor of these materials for applications -- their poor absorption of light.

"This paper covers several new variations where we integrate chemically compatible correlated 'metallic' oxides with the model n-type, wide band gap oxide semiconductor TiO2 to produce high-performance photocatalytic heterojunctions. These composite structures operate on the principle of hot carrier injection from the 'metallic' oxide into the TiO2. "

These effects are made possible by harnessing the diverse range of correlated electron physics of common metallic oxide materials including n-type LaNiO3 (lanthanum nickelate), SrRuO3 (strontium ruthenate), and SrVO3 (strontium vanadate) and p-type La0.5Sr0.5CoO3 (lanthanum strontium cobaltite) and La0.7Sr0.3MnO3 (lanthanum strontium manganite). These materials have been extensively explored (individually) for their novel electronic transport, magnetic properties, and other exotic physical phenomena and are widely utilized as epitaxial bottom electrodes in ferroic heterostructures.

Martin noted that one of the new materials studied (La 0.5Sr0.5CoO3-based devices) demonstrated photocatalytic activities that are 27-, 6.2-, and 3-times larger than that for a single-layer TiO2 film, nanopowder Degussa P25 samples, and the prior report of devices based on SrRuO3, respectively.

This work is partially supported by the College of Engineering's Strategic Research Initiatives (SRI) program which invests in promising new and emerging areas of engineering research.

"This project reflects the kinds of research endeavors that the SRI program is designed to support," explained Jennifer Bernhard, the College's associate dean for research. "It addresses key challenges in energy and the environment that face our society. The momentum of this work is tremendous. It cuts across disciplines and it has tremendous impact potential. We're all excited to see where the team takes it from here."


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Friday, November 29, 2013

Hydrogen fuel from sunlight? Low-cost, long-lasting water splitter made of silicon and nickel

Nov. 14, 2013 ? Stanford University scientists have created a silicon-based water splitter that is both low-cost and corrosion-free. The novel device -- a silicon semiconductor coated in an ultrathin layer of nickel -- could help pave the way for large-scale production of clean hydrogen fuel from sunlight, according to the scientists.
Their results are published in the Nov. 15 issue of the journal Science.
"Solar cells only work when the sun is shining," said study co-author Hongjie Dai, a professor of chemistry at Stanford. "When there's no sunlight, utilities often have to rely on electricity from conventional power plants that run on coal or natural gas."
A greener solution, Dai explained, is to supplement the solar cells with hydrogen-powered fuel cells that generate electricity at night or when demand is especially high.
To produce clean hydrogen for fuel cells, scientists have turned to an emerging technology called water splitting. Two semiconducting electrodes are connected and placed in water. The electrodes absorb light and use the energy to split the water into its basic components, oxygen and hydrogen. The oxygen is released into the atmosphere, and the hydrogen is stored as fuel.
When energy is needed, the process is reversed. The stored hydrogen and atmospheric oxygen are combined in a fuel cell to generate electricity and pure water.
The entire process is sustainable and emits no greenhouse gases. But finding a cheap way to split water has been a major challenge. Today, researchers continue searching for inexpensive materials that can be used to build water splitters efficient enough to be of practical use.
Silicon solution
"Silicon, which is widely used in solar cells, would be an ideal, low-cost material," said Stanford graduate student Michael J. Kenney, co-lead author of the Science study. "But silicon degrades in contact with an electrolyte solution. In fact, a submerged electrode made of silicon corrodes as soon as the water-splitting reaction starts."
In 2011, another Stanford research team addressed this challenge by coating silicon electrodes with ultrathin layers of titanium dioxide and iridium. That experimental water splitter produced hydrogen and oxygen for eight hours without corroding.
"Those were inspiring results, but for practical water splitting, longer-term stability is needed," Dai said. "Also, the precious metal iridium is costly. A non-precious metal catalyst would be desirable."
To find a low-cost alternative, Dai suggested that Kenney and his colleagues try coating silicon electrodes with ordinary nickel. "Nickel is corrosion-resistant," Kenney said. "It's also an active oxygen-producing catalyst, and it's earth-abundant. That makes it very attractive for this type of application."
Nickel nanofilm
For the experiment, the Dai team applied a 2-nanometer-thick layer of nickel onto a silicon electrode, paired it with another electrode and placed both in a solution of water and potassium borate. When light and electricity were applied, the electrodes began splitting the water into oxygen and hydrogen, a process that continued for about 24 hours with no sign of corrosion.
To improve performance, the researchers mixed lithium into the water-based solution. "Remarkably, adding lithium imparted superior stability to the electrodes," Kenney said. "They generated hydrogen and oxygen continuously for 80 hours -- more than three days -- with no sign of surface corrosion."
These results represent a significant advance over previous experimental efforts, added Dai. "Our lab has produced one of the longest lasting silicon-based photoanodes," he said. "The results suggest that an ultrathin nickel coating not only suppresses corrosion but also serves as an electrocatalyst to expedite the otherwise sluggish water-splitting reaction.
"Interestingly, a lithium addition to electrolytes has been used to make better nickel batteries since the Thomas Edison days. Many years later we are excited to find that it also helps to make better water-splitting devices."
The scientists plan to do additional work on improving the stability and durability of nickel-treated electrodes of silicon as well as other materials.
Other authors of the study are Ming Gong and Yanguang Li (co-lead authors), Justin Z. Wu, Ju Feng and Mario Lanza, all formerly or currently affiliated with the Dai Lab at Stanford.
Support was provided by the Precourt Institute for Energy and the Global Climate and Energy Project at Stanford and the National Science Foundation.

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Solar cells utilize thermal radiation

Nov. 13, 2013 ? Thermal radiation from the sun is largely lost on most silicon solar cells. Up-converters transform the infrared radiation into usable light, however. Researchers have now for the first time successfully adapted this effect for use in generating power.

There is more to solar radiation than meets the eye: sun- burn develops from unseen UV radiation, while we sense infrared radiation as heat on our skin, though invisible to us. Solar cells also 'see' only a portion of solar radiation: ap- proximately 20 percent of the energy contained in the solar spectrum is unavailable to cells made of silicon -- they are unable to utilize a part of the infrared radiation, the short-wavelength IR radiation, for generating power.

Researchers of the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg, together with their colleagues at the University of Bern, Switzerland, and the Heriot-Watt University in Edinburgh, Scotland, have now for the first time made a portion of this radiation usable with the assistance of a practical up-converter. The technology that transforms infra- red into usable light has been known about since the 1960s. However, it has only been investigated in connection with solar cells since 1996. "We have been able to adapt both the solar cells and the up-converter so as to obtain the biggest improvement in efficiency so far," reports Stefan Fischer happily, a scientist at ISE. The potential is big: silicon solar cells theoretically convert about thirty percent of sunlight falling upon them into electrical power. Up-converters could increase this portion to a level of forty percent.

A ladder for light particles

However, how does the up-converter manage to utilize the infrared radiation for the solar cells? As solar radiation falls on the solar cells, they absorb the visible and near-infrared light. The infrared portion is not absorbed, however, it goes right through them. On the back- side, the radiation runs into the up-converter -- essentially a microcrystalline powder made of sodium yttrium fluoride embedded in a polymer. Part of the yttrium has been replaced by the scientists with the element erbium, which is active in the optical range and responsible in the end for the up-conversion.

As the light falls on this up-converter, it excites the erbium ions. That means they are raised to a higher energy state. You can imagine this reaction like climbing up a ladder: an electron in the ion uses the energy of the light particle to climb up the first step of the ladder. A sec- ond light particle enables the electron to climb to the second step, and so on. An ion that has been excited in this manner can "jump down" from the highest step or state. In doing so, it emits light with an energy equal to all of the light particles that have helped the elec- tron to climb on up. The up-converter collects, so to speak, the energy of several of these particles and transfers it to a single one. This has so much energy then that the solar cells "see" it and can utilize it.

Researchers had to adapt the solar cells in order to be able to employ an up-converter such as this. Normally, metal is vapour-deposited on the backside, enabling current to flow out of the solar cells -- so no light can shine through normally. "We equipped the solar cells with metal lattices on the front and rear sides so that IR light can pass through the solar cells. In addition, the light can be used by both faces of the cell -- we call this a bi-facial solar cell," explains Fischer. Scientists have applied specialized anti-reflection coatings to the front and rear sides of the solar cell. These cancel reflections at the surfaces and assure that the cells absorb as much light as possible. "This is the first time we have adapted the anti- reflection coating to the backside of the solar cell as well. That could increase the efficiency of the modules and raise their energy yields. The first companies are already trying to accomplish this by implementing bi-facial solar cells," says Fischer, emphasizing the potential of the approach.


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Blue-green algae a five-tool player in converting waste to fuel


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Tuesday, November 19, 2013

HOMEMADE SOLAR PANEL

The present economic scenario and the ever-shrinking state of the global oil reserves is not good news for everyone. But on a positive note it makes us investigate for alternative energy sources that is become the solution of cutting down present and the future energy consumption, particularly in terms of fossil fuel usage like oil. For example, it has become more and more economical to build homemade solar energy system. Building the home made solar panels that utilize deep cell storage batteries produce the electricity upon consumer demand and reduce the their individual dependence on the country’s energy grid.
Who is there in the world who does not wish to have the energy bills get reduced by 80% or more? Many of us shall want to take advantage of such a great deal. If such is the demand then follow the guide Earth4Energy that offers lot of fantastic homemade solar solutions on their site, which can be built easily, for the low cost of less than $200. Click Here!

Cheaper Chinese solar panels are not due to low-cost labor


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Friday, November 8, 2013

Laying down a discerning membrane

One of the thinnest membranes ever made is also highly discriminating when it comes to the molecules going through it. Engineers have constructed a graphene oxide membrane less than 2 nanometers thick with high permeation selectivity between hydrogen and carbon dioxide gas molecules.

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First uses of new solar energy technology: Killing germs on medical, dental instruments


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Thursday, November 7, 2013

Charge your mobile phone with formic acid?

With the technology of today it is possible to use environmental friendly formic acid in fuel cell powering your mobile phone or laptop. A physicist in Sweden has developed new catalysts to improve the capacity of these fuel cells.

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Sunday, September 1, 2013

New Page http://adairsalternativeenergyblog.blogspot.com/p/get-prepared.html

Have you been watching the news lately? You can stick your head in the sand and hope it all goes away, or you can Get Prepared Now. I always pray for peace. I pray for the victims. I also do what I can to prepare my family for whatever may come.

New solar-cell coating could enable a major boost in efficiency


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