Engineering researchers in the College of Science and Engineering at the University of Minnesota have recently discovered a new alloy material that converts heat directly into electricity. This revolutionary new energy conversion method is in the early stages of development, but it could have a wide-sweeping impact on the process of creating environmentally friendly electricity from waste heat sources.

Researchers stated that the material could potentially be utilized to capture waste heat from a car’s exhaust that would heat the material and produce electricity for charging the battery in a hybrid car. Other potential future uses include capturing rejected heat from industrial and power plants or temperature variations in the ocean to create electricity. The research team is looking into the possible commercialization of the technology.

“This research is very encouraging as it provides a totally new method of energy conversion that has never been performed before,” said University of Minnesota aerospace engineering and mechanics professor Richard James, who led the research team.”It’s also the ultimate ‘green’ way to create electricity because it uses waste heat to create electricity with no carbon dioxide.”

The research team combined elements at the atomic level in order to generate a new multiferroic alloy, Ni45Co5Mn40Sn10. Multiferroic materials combine unusual elastic, magnetic and electric attributes. The alloy Ni45Co5Mn40Sn10 attains multiferroism by experiencing a highly reversible phase transformation where one solid transforms into another solid. During this phase transformation the alloy experiences alterations to its magnetic properties that are utilized in the energy conversion device.

During a small-scale demonstration in the lab, University of Minnesota researchers showed how their new material can spontaneously produce electricity when the temperature is raised a small amount. Pictured (from left) are aerospace engineering and mechanics professor Richard James, Ph.D. student Yintao Song and post-doctoral researchers Kanwal Bhatti and Vijay Srivastava. (Credit: Image courtesy of University of Minnesota)

In the course of a small-scale demonstration in a University of Minnesota lab, the new material created by the researchers starts as a non-magnetic material, then abruptly becomes strongly magnetic when the temperature is increased by a small amount. When this occurs, the material absorbs heat and automatically generates electricity in a surrounding coil. Some of this heat energy is dissipated in a process called hysteresis. A significant discovery of the team is a systematic method to minimize hysteresis in phase transformations. The team’s research was recently published in the first issue of the new scientific journal Advanced Energy Materials.

In addition to Professor James, fellow members of the research team include University of Minnesota aerospace engineering and mechanics post-doctoral researchers Vijay Srivastava and Kanwal Bhatti, and Ph.D. student Yintao Song. The team is also working together with University of Minnesota chemical engineering and materials science professor Christopher Leighton to produce a thin film of the material that could be used, for example, to convert some of the waste heat from computers into electricity.

“This research crosses all boundaries of science and engineering,” James said. “It includes engineering, physics, materials, chemistry, mathematics and more. It has required all of us within the university’s College of Science and Engineering to work together to think in new ways.”

Funding for early research on the alloy came from a Multidisciplinary University Research Initiative (MURI) grant from the U.S. Office of Naval Research (involving other universities including the California Institute of Technology, Rutgers University, University of Washington and University of Maryland), and research grants from the U.S. Air Force and the National Science Foundation. The research is also tentatively financed by a small seed grant from the University of Minnesota’s Initiative for Renewable Energy and the Environment.

The Original Post is Located Here: Waste Heat Converted to Electricity Using New Alloy

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‘Tall Order’ Sunlight-to-Hydrogen System Works, Neutron Analysis Confirms

Researchers at the Department of Energy’s Oak Ridge National Laboratory have developed a biohybrid photoconversion system – based on the interaction of photosynthetic plant proteins with synthetic polymers – that can convert visible light into hydrogen fuel.

Photosynthesis, the natural process carried out by plants, algae and some bacterial species, converts sunlight energy into chemical energy and sustains much of the life on earth. Researchers have long sought inspiration from photosynthesis to develop new materials to harness the sun’s energy for electricity and fuel production.

In a step toward synthetic solar conversion systems, the ORNL researchers have demonstrated and confirmed with small-angle neutron scattering analysis that light harvesting complex II (LHC-II) proteins can self-assemble with polymers into a synthetic membrane structure and produce hydrogen.

The researchers envision energy-producing photoconversion systems similar to photovoltaic cells that generate hydrogen fuel, comparable to the way plants and other photosynthetic organisms convert light to energy.

Neutron scattering analysis performed at DOE's Oak Ridge National Laboratory reveals the lamellar structure of a hydrogen-producing, biohybrid composite material formed by the self-assembly of naturally occurring, light harvesting proteins with polymers. (Credit: Image courtesy of DOE/Oak Ridge National Laboratory)

“Making a, self-repairing synthetic photoconversion system is a pretty tall order. The ability to control structure and order in these materials for self-repair is of interest because, as the system degrades, it loses its effectiveness,” ORNL researcher Hugh O’Neill, of the lab’s Center for Structural Molecular Biology, said.

“This is the first example of a protein altering the phase behavior of a synthetic polymer that we have found in the literature. This finding could be exploited for the introduction of self-repair mechanisms in future solar conversion systems,” he said.

Small angle neutron scattering analysis performed at ORNL’s High Flux Isotope Reactor (HFIR) showed that the LHC-II, when introduced into a liquid environment that contained polymers, interacted with polymers to form lamellar sheets similar to those found in natural photosynthetic membranes.

The ability of LHC-II to force the assembly of structural polymers into an ordered, layered state — instead of languishing in an ineffectual mush — could make possible the development of biohybrid photoconversion systems. These systems would consist of high surface area, light-collecting panes that use the proteins combined with a catalyst such as platinum to convert the sunlight into hydrogen, which could be used for fuel.

The research builds on previous ORNL investigations into the energy-conversion capabilities of platinized photosystem I complexes — and how synthetic systems based on plant biochemistry can become part of the solution to the global energy challenge.

“We’re building on the photosynthesis research to explore the development of self-assembly in biohybrid systems. The neutron studies give us direct evidence that this is occurring,” O’Neill said.

The researchers confirmed the proteins’ structural behavior through analysis with HFIR’s Bio-SANS, a small-angle neutron scattering instrument specifically designed for analysis of biomolecular materials.

“Cold source” neutrons, in which energy is removed by passing them through cryogenically chilled hydrogen, are ideal for studying the molecular structures of biological tissue and polymers.

The LHC-II protein for the experiment was derived from a simple source: spinach procured from a local produce section, then processed to separate the LHC-II proteins from other cellular components. Eventually, the protein could be synthetically produced and optimized to respond to light.

O’Neill said the primary role of the LHC-II protein is as a solar collector, absorbing sunlight and transferring it to the photosynthetic reaction centers, maximizing their output. “However, this study shows that LHC-II can also carry out electron transfer reactions, a role not known to occur in vivo,” he said.

The research team, which came from various laboratory organizations including its Chemical Sciences Division, Neutron Scattering Sciences Division, the Center for Structural Molecular Biology and the Center for Nanophase Materials Sciences, consisted of O’Neill, William T. Heller, and Kunlun Hong, all of ORNL; Dimitry Smolensky of the University of Tennessee; and Mateus Cardoso, a former postdoctoral researcher at ORNL now of the Laboratio Nacional de Luz Sincrotron in Brazil.

“That’s one of the nice things about working at a national laboratory. Expertise is available from a variety of organizations,” O’Neill said.

The work, published in the journal Energy & Environmental Science, was supported with Laboratory-Directed Research and Development funding. HFIR is supported by the DOE Office of Science.

DOE/Oak Ridge National Laboratory (2011, February 3). ‘Tall order’ sunlight-to-hydrogen system works, neutron analysis confirms. ScienceDaily. Retrieved February 03, 2011, from http://www.sciencedaily.com­ /releases/2011/02/110203152544.htm

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The Original Post is Located Here: Sunlight-to-Hydrogen System Works

World Can Be Powered by Alternative Energy, Using Today’s Technology, in 20-40 Years, Experts Say

If someone told you there was a way you could save 2.5 million to 3 million lives a year and simultaneously halt global warming, reduce air and water pollution and develop secure, reliable energy sources — nearly all with existing technology and at costs comparable with what we spend on energy today — why wouldn’t you do it?

According to a new study coauthored by Stanford researcher Mark Z. Jacobson, we could accomplish all that by converting the world to clean, renewable energy sources and forgoing fossil fuels.

“Based on our findings, there are no technological or economic barriers to converting the entire world to clean, renewable energy sources,” said Jacobson, a professor of civil and environmental engineering. “It is a question of whether we have the societal and political will.”

He and Mark Delucchi, of the University of California-Davis, have written a two-part paper in Energy Policy in which they assess the costs, technology and material requirements of converting the planet, using a plan they developed.

The world they envision would run largely on electricity. Their plan calls for using wind, water and solar energy to generate power, with wind and solar power contributing 90 percent of the needed energy.

Geothermal and hydroelectric sources would each contribute about 4 percent in their plan (70 percent of the hydroelectric is already in place), with the remaining 2 percent from wave and tidal power.

Vehicles, ships and trains would be powered by electricity and hydrogen fuel cells. Aircraft would run on liquid hydrogen. Homes would be cooled and warmed with electric heaters — no more natural gas or coal — and water would be preheated by the sun.

Commercial processes would be powered by electricity and hydrogen. In all cases, the hydrogen would be produced from electricity. Thus, wind, water and sun would power the world.

The researchers approached the conversion with the goal that by 2030, all new energy generation would come from wind, water and solar, and by 2050, all pre-existing energy production would be converted as well.

“We wanted to quantify what is necessary in order to replace all the current energy infrastructure — for all purposes — with a really clean and sustainable energy infrastructure within 20 to 40 years,” said Jacobson.

One of the benefits of the plan is that it results in a 30 percent reduction in world energy demand since it involves converting combustion processes to electrical or hydrogen fuel cell processes. Electricity is much more efficient than combustion.

That reduction in the amount of power needed, along with the millions of lives saved by the reduction in air pollution from elimination of fossil fuels, would help keep the costs of the conversion down.

“When you actually account for all the costs to society — including medical costs — of the current fuel structure, the costs of our plan are relatively similar to what we have today,” Jacobson said.

One of the biggest hurdles with wind and solar energy is that both can be highly variable, which has raised doubts about whether either source is reliable enough to provide “base load” energy, the minimum amount of energy that must be available to customers at any given hour of the day.

Jacobson said that the variability can be overcome.

“The most important thing is to combine renewable energy sources into a bundle,” he said. “If you combine them as one commodity and use hydroelectric to fill in gaps, it is a lot easier to match demand.”

Wind and solar are complementary, Jacobson said, as wind often peaks at night and sunlight peaks during the day. Using hydroelectric power to fill in the gaps, as it does in our current infrastructure, allows demand to be precisely met by supply in most cases. Other renewable sources such as geothermal and tidal power can also be used to supplement the power from wind and solar sources.

“One of the most promising methods of insuring that supply matches demand is using long-distance transmission to connect widely dispersed sites,” said Delucchi. Even if conditions are poor for wind or solar energy generation in one area on a given day, a few hundred miles away the winds could be blowing steadily and the sun shining.

“With a system that is 100 percent wind, water and solar, you can’t use normal methods for matching supply and demand. You have to have what people call a supergrid, with long-distance transmission and really good management,” he said.

Another method of meeting demand could entail building a bigger renewable-energy infrastructure to match peak hourly demand and use the off-hours excess electricity to produce hydrogen for the industrial and transportation sectors.

Using pricing to control peak demands, a tool that is used today, would also help.

Jacobson and Delucchi assessed whether their plan might run into problems with the amounts of material needed to build all the turbines, solar collectors and other devices.

They found that even materials such as platinum and the rare earth metals, the most obvious potential supply bottlenecks, are available in sufficient amounts. And recycling could effectively extend the supply.

“For solar cells there are different materials, but there are so many choices that if one becomes short, you can switch,” Jacobson said. “Major materials for wind energy are concrete and steel and there is no shortage of those.”

Jacobson and Delucchi calculated the number of wind turbines needed to implement their plan, as well as the number of solar plants, rooftop photovoltaic cells, geothermal, hydroelectric, tidal and wave-energy installations.

They found that to power 100 percent of the world for all purposes from wind, water and solar resources, the footprint needed is about 0.4 percent of the world’s land (mostly solar footprint) and the spacing between installations is another 0.6 percent of the world’s land (mostly wind-turbine spacing), Jacobson said.

One of the criticisms of wind power is that wind farms require large amounts of land, due to the spacing required between the windmills to prevent interference of turbulence from one turbine on another.

“Most of the land between wind turbines is available for other uses, such as pasture or farming,” Jacobson said. “The actual footprint required by wind turbines to power half the world’s energy is less than the area of Manhattan.” If half the wind farms were located offshore, a single Manhattan would suffice.

Jacobson said that about 1 percent of the wind turbines required are already in place, and a lesser percentage for solar power.

“This really involves a large scale transformation,” he said. “It would require an effort comparable to the Apollo moon project or constructing the interstate highway system.”

“But it is possible, without even having to go to new technologies,” Jacobson said. “We really need to just decide collectively that this is the direction we want to head as a society.”

Jacobson is the director of Stanford’s Atmosphere/Energy Program and a senior fellow at Stanford’s Woods Institute for the Environment and the Precourt Institute for Energy.

Stanford University (2011, January 27). World can be powered by alternative energy, using today’s technology, in 20-40 years, experts say. ScienceDaily. Retrieved January 27, 2011, from http://www.sciencedaily.com­ /releases/2011/01/110126091443.htm

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The Original Post is Located Here: World Can Be Powered by Alternative Energy

Have a read of the article below... we are sure you will find it dots all the 'i's', and crosses all the 't's'. On our site we strive to provide the most up-to-date information. Remember that you read it here first, and please tell your friends.

Carsten Beier from the Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT in Oberhausen, Germany does not believe that “anyone would burn a 50-dollar bill just to keep warm. It’s obvious that it simply is too valuable for that.” But, in contrast to dollar bills, most energy carriers are all too frequently burned for less than they are worth. Take wood, for example. Beier and his colleagues have analyzed the efficiency of heat supply systems and he explains that “wood is a high-quality fuel that can be compared to natural gas. With adequate technologies we could utilize it for power generation. As a fuel, there’s a lot more in wood that we are taking advantage of at the moment.”

Beyond this, the researchers at the Fraunhofer Institute for Environmental, Safety and Energy Technology have come up with a model for comparing various systems and technologies in heat supply ranging from heating boilers for single-family dwellings right down to district heating networks for whole cities. They apply exergy as a criterion of analysis which is a thermodynamic parameter defined by the quantity and quality of an energy. In contrast to the CO2 balance sheet and primary energy consumption, the exergy analysis indicates whether we are sufficiently taking advantage of the potential lying dormant in the energies we use. Carsten Beier has come to the conclusion that “if we used fuels such as natural gas or wood for power generation and only use the waste heat for heating, we would be able to save large quantities of primary energy and avoid generating CO2 emissions.”

Cogeneration plants are taking advantage of these potentials. While large-scale power plants lose an average of 60 percent of the energy as waste heat through the cooling tower, cogeneration plants use this flow of heat for heating purposes, which means that they achieve overall efficiency of more than 80 percent. The researchers distinguished four categories of heat generation in their analyses: burning, cogeneration and using heat pumps or waste heat from industrial processes. Comparing these categories, using waste heat was particularly good in connection with heat networks. That said, it also became apparent that the way drinking water was heated was a key factor in exergy efficiency. Beier reveals that “even heating a room with waste heat has a poor overall exergy balance sheet if the service water for the household is electrically heated.”

Researchers derived one basic recommendation from their comparison of systems and technologies. Beier demands “we should take advantage of all sources of heat whose temperature level corresponds to our heating requirements.” And we could take advantage of the fact that there are a whole series of applications where heat is needed at different temperature levels. Beier explains how. “Any type of cascade is very efficient. For instance, if you use fuel for power generation first, then the waste heat for water heating and finally the remaining heat for space heating.” He confesses that there might be discussions on the economic efficiency of these scenarios, especially because the initial investments are rather high. “But, on the other hand, it is essential to restructure our energy system quickly and an exergy analysis is an excellent tool for identifying how power supply should be designed in future.”

Fraunhofer-Gesellschaft (2010, December 19). Which methods of heating are most efficient?. ScienceDaily. Retrieved December 19, 2010, from http://www.sciencedaily.com­ /releases/2010/12/101213121706.htm

Obviously, there is a lot more to know about heating. This brief article is just a start, and the next step is to do some more research. In any case, the tips in the article set the stage for a more detailed treatment of heating.

The Original Post is Located Here: Which Methods of Heating Are Most Efficient?

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Green energy too comes out of the electricity socket, but to get there it has to travel a long journey – from wind turbines in the North Sea or regional solar, wind and biogas power plants. On the way to the consumer lots of energy is lost. New electronic components will change things in future.

Cars and trucks race down the highway, turn off into town, wait at traffic lights and move slowly through side streets. Electricity flows in a similar way – from the power plant via high voltage lines to transformer substations. The flow is controlled as if by traffic lights. Cables then take the electricity into the city centre. Numerous switching points reduce the voltage, so that equipment can tap into the electricity at low voltage. Thanks to this highly complex infrastructure, the electricity customer can use all kinds of electrical devices just by switching them on.

Explosion protection reduces the risk of a chain reaction in the event of a fault, which could cause the entire converter station to fail. (Credit: © Fraunhofer IISB)

In major projects such as Desertec, solar thermal power plants in sun-rich regions of North Africa and the Middle East will in the future produce electricity for Europe. The energy will then flow to the consumer via long high-voltage power lines or undersea cables. The existing cables, systems and components need to be adapted to the future energy mix now, so that the electricity will get to the consumer as reliably and with as few losses as possible. The power electronics experts at the IISB are working on technological solutions, and are developing components for the efficient conversion of electrical energy.

For energy transmission over distances of more than 500 kilometers or for undersea cables direct current is being increasingly used. This possesses a constant voltage and only loses up to seven percent of its energy over long distances. By comparison, the loss rate for alternating current can reach 40 percent. Additional converter stations are, however, required to convert the high voltage of the direct current into the alternating current needed by the consumer.

“In cooperation with Siemens Energy we are developing high-power switches. These are necessary for transmitting the direct voltage in the power grid and are crucial for projects like Desertec. The switches have to be more reliable, more scaleable and more versatile than previous solutions in order to meet the requirements of future energy supply networks,” says Dipl.-Ing. Markus Billmann from the IISB. To this end, the research scientists are using low-cost semiconductor cells which with previous switching techniques could not be used for high-voltage direct-current transmission (HVDCT).

“At each end of a HVDCT system there is a converter station,” explains the research scientist. “For the converters we use interruptible devices which can be operated at higher switching frequencies, resulting in smaller systems that are easier to control.” A major challenge is to protect the cells from damage. Each converter station will contain about 5,000 modules, connected in series, and if more than a few of them failed at the same time and affected their neighboring modules a chain reaction could be triggered which would destroy the entire station. “We have now solved this problem. With our cooperation partners we are working on tailor-made materials and components so that in future the equipment will need less energy,” says Billmann.

Fraunhofer-Gesellschaft (2010, November 8). Power grid of the future saves energy. ScienceDaily. Retrieved November 08, 2010, from http://www.sciencedaily.com­ /releases/2010/11/101108140636.htm

You can never have too much information about such an important issue. Do you agree? Are you feeling better informed about the green energy? When all around you are scratching their heads, it's a great feeling to have clear vision and know which direction you are heading.

The Original Post is Located Here: Power Grid of the Future Saves Energy

The article below goes directly to the heart of the matter and explains some of the issue, so we hope it answers your particular questions.

The Technische Universität Darmstadt has dedicated a pilot plant for capturing carbon dioxide contained in flue gases of power plants. Its Institute for Energy Systems and Technology plans to utilize the plant for investigating two innovative methods for CO2 capture that require less energy and lower operating costs than earlier approaches.

Combustion of fossil fuels, such as coal, fuel oil, or natural gas, liberates large quantities of carbon dioxide, a gas that significantly affects global climate. A key technology that would reduce emissions and lead to more environmentally friendly power plants is the capture and storage of carbon dioxide from flue gases of power plants (carbon capture and storage (CCS)). CCS might be able to reduce CO2 emissions resulting from the employment of fossil fuels for power generation and other uses in industry to near zero and thereby contribute to reducing greenhouse-gas emissions. Earlier approaches to CO2‑capture require expending significantly more energy and entail greatly increased operating costs, which raises questions regarding their efficiency and acceptance. The TU Darmstadt’s Institute for Energy Systems and Technology’s new pilot plant will be utilized for investigating two new methods for CO2 capture that will allow nearly totally eliminating CO2 emissions and require virtually no additional energy input and entail only slight increases in operating costs.

In the experimental plant, scientists at TU Darmstadt will explore two novel processes for CO2 capture. (Credit: © Thomas Ott / TU Darmstadt)

The carbonate looping method involves utilizing naturally occurring limestone to initially bind CO2 from the stream of flue gases transiting power plants’ stacks in a first-stage reactor. The resultant pure CO2 is reliberated in a second reactor and can then be stored. The advantage of the carbonate-looping method is that even existing power plants can be retrofitted with this new method.

On new power plants, the chemical looping method will even allow capturing CO2 with hardly any loss of energy efficiency. Under this method, a dual-stage, flameless, combustion yields a stream of exhaust gases containing only CO2 and water vapor. The CO2 can then be captured and stored.

The investigations of these new methods are being supported with grants totaling seven million Euros from the European Union, the German Federal Ministry for Economic Affairs, and various industrial partners. Due to the pilot plant’s height, the TU‑Darmstadt has built a new, twenty-meter high experimentation hall on its “Lichtwiese” campus to house it. Construction of the new hall and pilot plant took twenty months. The plant has already demonstrated its ability to bind CO2 in conjunction with initial trial runs.

Technische Universität Darmstadt (2010, November 7). On the way to CO2-free power plants. ScienceDaily. Retrieved November 11, 2010, from http://www.sciencedaily.com­ /releases/2010/11/101103082306.htm

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The Original Post is Located Here: On the Way to CO2-Free Power Plants

Every living cell in our body can do it: covered with a thin membrane known as a cell membrane or nanomembrane, the cells can deliberately let specific substances in and out. Although it is thousands of times thinner than a human hair, this nanomembrane has an extremely complex structure and function. Three Nobel prizes have already been awarded for improving our understanding of these nanomembranes.

Microscopic ducts convey water, electrical charges and nutrients around and in doing so, create an equilibrium within the cell. However, we still do not know about many of the functions and structural details, as it is only the water and proton exchange that has been researched in depth. “These extremely fine cell membrane ducts, with the ability to selectively convey protons, function in exactly the same way as fuel cells created by humans,” explains Dr Werner Brenner, “only this naturally occurring process is considerably more efficient.”

Fuel cells: an alternative to oil

Today, fuel cells are seen as a serious alternative to oil, which until now has been the basis for electrical energy and mobility. However, the earth’s oil reserves are rapidly running out, under economic pressure to drill ever deeper into the seabed. Oil combustion also generates CO2, soot and other residues. The only waste product from a fuel cell is water.

The EU project focuses on the design of the main component of every fuel cell — i.e. the membrane — with the intention of conveying protons more efficiently than in previous solutions. “The first results have been encouraging. It will not be easy, but it is possible. Nature has been producing these structures for billions of years and their effectiveness can be seen in every living organism. Our task is to transfer the structure of these natural nanoducts to an artificial nanomembrane, which is itself only a few hundred nanometres thick,” explains Dr Jovan Matovic.

A wide range of scientific approaches are required for this project, ranging from solid state physics and nanotechnology through to chemistry. Therefore, international cooperation with six universities, research institutes and businesses is also of great importance. The EU project is being coordinated by the TU Vienna research team of Assist Prof Dr Werner Brenner, Dr Jovan Matovic and Dr Nadja Adamovic at the Institute of Sensor and Actuator Systems.

The University research team is confident: “The results of this project should have far-reaching significance for our society. If we succeed in creating the nanoducts exactly as planned, then completely different fields of application will open up, such as the accurately controlled delivery of medicine, water desalination or even new types of sensors,” explains Dr Nadja Adamovic, “In this project, the boundaries between “artificial and “natural” are becoming even more blurred.”

Vienna University of Technology (2010, October 6). Nano design, just like in nature. ScienceDaily http://www.sciencedaily.com­ /releases/2010/06/100615151705.htm

The Original Post is Located Here: Nano Design, Just Like in Nature

In the smooth, white, bunny-suited clean-room world of silicon wafers and solar cells, it turns out that a little roughness may go a long way, perhaps all the way to making solar power an affordable energy source, say Stanford engineers.

Their research shows that light ricocheting around inside the polymer film of a solar cell behaves differently when the film is ultra thin. A film that’s nanoscale-thin and has been roughed up a bit can absorb more than 10 times the energy predicted by conventional theory.

This schematic diagram of a thin film organic solar cell shows the top layer, a patterned, roughened scattering layer, in green. The organic thin film layer, shown in red, is where light is trapped and electrical current is generated. The film is sandwiched between two layers that help keep light contained within the thin film. (Credit: Reproduced with permission from Proceedings of the National Academy of Sciences USA)

The key to overcoming the theoretical limit lies in keeping sunlight in the grip of the solar cell long enough to squeeze the maximum amount of energy from it, using a technique called “light trapping.” It’s the same as if you were using hamsters running on little wheels to generate your electricity — you’d want each hamster to log as many miles as possible before it jumped off and ran away.

“The longer a photon of light is in the solar cell, the better chance the photon can get absorbed,” said Shanhui Fan, associate professor of electrical engineering. The efficiency with which a given material absorbs sunlight is critically important in determining the overall efficiency of solar energy conversion. Fan is senior author of a paper describing the work published online by Proceedings of the National Academy of Sciences.

Light trapping has been used for several decades with silicon solar cells and is done by roughening the surface of the silicon to cause incoming light to bounce around inside the cell for a while after it penetrates, rather than reflecting right back out as it does off a mirror. But over the years, no matter how much researchers tinkered with the technique, they couldn’t boost the efficiency of typical “macroscale” silicon cells beyond a certain amount.

Eventually the scientists realized that there was a physical limit related to the speed at which light travels within a given material.

But light has a dual nature, sometimes behaving as a solid particle (a photon) and other times as a wave of energy, and Fan and postdoctoral researcher Zongfu Yu decided to explore whether the conventional limit on light trapping held true in a nanoscale setting. Yu is the lead author of the PNAS paper.

“We all used to think of light as going in a straight line,” Fan said. “For example, a ray of light hits a mirror, it bounces and you see another light ray. That is the typical way we think about light in the macroscopic world.

“But if you go down to the nanoscales that we are interested in, hundreds of millionths of a millimeter in scale, it turns out the wave characteristic really becomes important.”

Visible light has wavelengths around 400 to 700 nanometers (billionths of a meter), but even at that small scale, Fan said, many of the structures that Yu analyzed had a theoretical limit comparable to the conventional limit proven by experiment.

“One of the surprises with this work was discovering just how robust the conventional limit is,” Fan said.

It was only when Yu began investigating the behavior of light inside a material of deep subwavelength-scale — substantially smaller than the wavelength of the light — that it became evident to him that light could be confined for a longer time, increasing energy absorption beyond the conventional limit at the macroscale.

“The amount of benefit of nanoscale confinement we have shown here really is surprising,” said Yu. “Overcoming the conventional limit opens a new door to designing highly efficient solar cells.”

Yu determined through numerical simulations that the most effective structure for capitalizing on the benefits of nanoscale confinement was a combination of several different types of layers around an organic thin film.

He sandwiched the organic thin film between two layers of material — called “cladding” layers — that acted as confining layers once the light passed through the upper one into the thin film. Atop the upper cladding layer, he placed a patterned rough-surfaced layer designed to send the incoming light off in different directions as it entered the thin film.

By varying the parameters of the different layers, he was able to achieve a 12-fold increase in the absorption of light within the thin film, compared to the macroscale limit.

Nanoscale solar cells offer savings in material costs, as the organic polymer thin films and other materials used are less expensive than silicon and, being nanoscale, the quantities required for the cells are much smaller.

The organic materials also have the advantage of being manufactured in chemical reactions in solution, rather than needing high-temperature or vacuum processing, as is required for silicon manufacture.

“Most of the research these days is looking into many different kinds of materials for solar cells,” Fan said. “Where this will have a larger impact is in some of the emerging technologies; for example, in organic cells.”

“If you do it right, there is enormous potential associated with it,” Fan said.

Aaswath Raman, a graduate student in applied physics, also worked on the research and is a coauthor of the paper.

The project was supported by funding from the King Abdullah University of Science and Technology, which supports the Center for Advanced Molecular Photovoltaics at Stanford, and by the U.S. Department of Energy.

Stanford University (2010, September 28). Solar cells thinner than wavelengths of light hold huge power potential. ScienceDaily http://www.sciencedaily.com­ /releases/2010/09/100928092841.htm

The Original Post is Located Here: Solar Cells Thinner Than Wavelengths of Light Hold Huge Power Potential

Electric & petrol Unit in tandem:
Reports indicate that Fit will be fitted with Honda’s 1.3 litre/4-cylinder petrol unit to work in tandem with a 9.7kW electric motor and is expected to generate about 97hp. Plans are afoot to launch the automatic (CVT) version as well as the manual Fit Hybrid version.

Usual features:
All features like brake-energy regeneration that are usually found in Honda hybrids are found along with an Economy button for maximum fuel efficiency. As usual with the hybrid cars – which are known for not being very fast – Honda Fit Hybrid is also projected more for its efficiency rather than for its speed.

Hybrid system – Japanese favourite:
While European market still looks at diesel-driven small cars, Japan leads in going for smaller, more compact and more energy-efficient hybrid models. This has been more due to considerable government subsidies on green-car models. But the Japanese customers will benefit more than before thanks to the competitive deals that will certainly be offered even if subsidies are lifted.

Sales expectations:
Making its advent in the 2010 Auto Show at Paris, the sales are expected to start by 2010 end or early 2011. The car priced at a premium is expected to have the additional attraction of mileage – which in the upper sixties makes it a good buy.

Honda’s future goals:
Honda is firm in its conviction that future market in automobiles will be in small cars – that too in hybrid versions of small cars. The firm is going ahead with its plans accordingly and is busy with the production of 2011 CR-Z vehicles. Seeing that the hybrids have advantages like low price, cost competitiveness, and fuel efficiency, their hopes seem to be well founded.

The Original Post is Located Here: Cheapest Green Car – Honda Fit Hybrid

Processes which lend materials new characteristics are generally complicated and therefore often rather difficult to reproduce. So surprise turns to astonishment when scientists report on new methods which not only produce outstanding results despite the fact that they use economically priced starting materials but also do not need expensive instrumentation.

Just a simple framework made of polystyrene

These are "sea urchins" made of tiny polystyrene balls, with zinc oxide nanowire "spines" are created using a simple electrochemical process. (Credit: Empa)

This is exactly what Jamil Elias and Laetitia Philippe of Empa’s Mechanics of Materials and Nanostructures Laboratory in Thun have succeeded in doing. They used polystyrene spheres as a sort of scaffolding to create three-dimensional nanostructures of semiconducting zinc oxide on various substrates. The two scientists are convinced that the (nanostructured) “rough” but regularly-structured surfaces they have produced this way can be exploited in a range of electronic and optoelectronic devices such as solar cells and also short wave lasers, light emitting diodes and field emission displays.

The scientific world reacted promptly. The paper in which the results were reported was published in January 2010 in the on line edition of Advanced Materials. In the same month it became the most frequently downloaded article, and in April it was selected to appear on the Inside Front Cover of the journal.

The principle behind the process is quite simple. Little spheres of polystyrene a few micrometers in diameter are placed on an electrically conducting surface where they orient themselves in regular patterns. Polystyrene is cheap and ubiquitous — it is widely used as a packaging material (for example for plastic yoghurt pots) or as insulating material in expanded form as a solidified foam.

Hollow bodies with prickles for photovoltaic applications

The tiny balls of polystyrene anchored in this way form the template on which the nanowires are desposited. Jamil Elias has succeeded in using an electrochemical method which himself has developed to vary the conductivity and electrolytic properties of the polystyrene balls in such way that the zinc oxide is deposited on the surface of the microspheres. Over time regular nanowires grow from this surface, and when this process is complete the polystyrene is removed, leaving behind hollow spherical structures with spines — little sea-urchins, as it were! Tightly packed on the underlying substrate, the sea-urchins lend it a three-dimensional structure, thereby increasing considerably its surface area.

This nanostructured surface is predestined for use in photovoltaic applications. The researchers expect that it will have excellent light scattering properties. This means the surface will be able to absorb significantly more sunlight and therefore be able to convert radiated energy into electricity more efficiently. In a project supported by the Swiss Federal Office of Energy (SFOE), Laetitia Philippe and her research team are developing extremely thin absorbers (ETAs) for solar cells, based these zinc oxide nanostructures.

Swiss Federal Laboratories for Materials Science and Technology (EMPA) ‘Sea urchin’-shaped nanostructures grown in the lab. ScienceDaily http://www.sciencedaily.com­ /releases/2010/07/100729074910.htm

The Original Post is Located Here: ‘Sea Urchin’-Shaped Nanostructures Grown in the Lab