Power Grid of the Future Saves Energy

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.

"A reliable power supply is the key to all this, and major changes will take place in the coming years to safeguard this reliability. The transport and power networks will grow together more strongly as a result of electromobility, because electric vehicles will not only tank up on electricity but will also make their batteries available to the power grid as storage devices. Renewable energy sources will become available on a wider scale, with individual households also contributing electricity they have generated," says Professor Lothar Frey, Director of the Fraunhofer Institute for Integrated Systems and Device Technology IISB in Erlangen.

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.

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'Green' Way to Generate Heat and Electricity With Use of Fuel Cells

An SOFC fuel cell produces electricity and heat with a very high efficiency. That means less carbon emissions for each kW produced. Furthermore, the production of electricity happens with nearly no emissions of pollutants such as nitrogen and sulphur oxides. Thus, SOFC fuel cells are a strong card in the future climate-friendly energy supply. SOFC fuel cells are flat and thin as a piece of paper, providing a voltage of approx. 1 volt. They are put together in stacks to achieve the desired voltage and wattage.

The results from the research at Risø DTU are known internationally and have spread in ever-widening circles. Risø DTU entered into a long-term strategic cooperation agreement with Topsoe Fuel Cell, which developed fuel cell stacks into a commercial stage and is now marketing them under the name Topsoe PowerCores™. Topsoe Fuel Cell has subsequently entered into a long-term cooperation agreement with the Danish company Dantherm Power, which is selling small CHP plants, among other things. So long-term research conducted in Risø DTU's laboratories is now turning into concrete revolutionary products to be used in the supply of power and heat.

Each home will have a micro CHP plant of its own

To accommodate more renewable energy, the future electricity system will look significantly different from now. E.g. it is believed that today's large, central CHP plants will be supplemented with numerous quite small CHP plants of a few kW, in each home. These micro CHP plants in homes can help balance energy in the future energy system, where more energy will be coming from renewable energy sources such as the wind and the sun. The micro CHP plants will be taking over energy production, for example, when there is no wind, and when the sun is hiding behind a cloud.

"Topsoe Fuel Cell provides the engine, we produce the rest of what is to surround the engine in order to finally end up having a fully operational micro CHP plant," says Jesper Themsen from Dantherm Power. The core technology at Topsoe Fuel Cell is based on fuel cells developed at Risø DTU.

"At the moment, we are developing compact micro CHP plants, similar to a conventional oil or gas furnace when it comes to generating heat for the home. What's new about micro CHP plants, is that they also produce the power the home needs. In this way, you avoid transmission loss in the electricity and district heating network," says Jesper Themsen, technical director at Dantherm Power. Simultaneously, the micro CHP plants emit no or very little pollution and less carbon.

"In the spring of 2010 we produced a few micro CHP plants as part of the project 'Danish micro cogeneration'. Now we're doing tomorrow's micro CHP plant in cooperation with Topsoe Fuel Cell, and in October 2010, we produced two systems that we will put into operation among professional users, for example plumbers or electricians. People with craftsman experience who can help us solve the problems that naturally arise with the plants during the first phase,"says Jesper Themsen. The first plants will generate 1 kW of power and 1 kW of heat and will be powered by natural gas.

"Subsequently, we will produce five micro CHP plants, which will also be put into operation among professional users. We are still in the early process of the technological launch and need to gather as much experience with these systems as possible," says Jesper Themsen.

The micro CHP plants are based on Topsoe PowerCores™. Dantherm Power will build the rest around them. It should be possible to add natural gas purified of sulphur and with the correct pressure. There must be supply of fresh air, a heat exchanger and a heat store. The necessary electronic control for the micro CHP plant to be connected to the grid will be incorporated. Last but not least, the micro CHP plants will have to gain security clearance.

Currently, micro CHP plants are the size of an overgrown American fridge."It's not that we cannot make them smaller, but here to start with it should not be too compact, but easy for one to supervise and maintain the various parts of the plant," says Jesper Themsen.

Dantherm Power expects to have seven micro CHP plants in operation in early 2011, which will be in operation throughout the entire heating season and well into spring 2011.

In September 2011, Dantherm Power plans to produce 15 new micro CHP plants based on experiences from the first seven."They'll be so reliable that we can install them in private homes in Southern Jutland," says Jesper Themsen and continues:"In 2012, we believe that SOFC micro CHP plants will be affordable and have the desired properties, allowing ordinary people to easily replace their old furnace with a SOFC micro CHP plant."

Jesper Themsen expects a major breakthrough to happen in 2013 -- 2015 and that many Danish families in 2015 will be having a SOFC micro CHP plant, which will not take up more space than a dishwasher. Fuels will initially be natural gas, later it could be methanol and liquefied petroleum gas. In the long term, biofuels could also prove useful.

"We are having a long-term strategic cooperation with Topsoe Fuel Cell on SOFC micro CHP plants, and we are working mutually to make SOFC fuel cell power plants a commercial success," says Jesper Themsen.

In the long term, he imagines that fuel cell power plants will replace generators powered by diesel or gas. They are used as backup in countries where the grid is not as stable as in Denmark. Here they are in operation continuously for many hours with the purpose of using the fuel efficiently.

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More Efficient Polymer Solar Cells Fabricated

"Our technology efficiently utilizes the light trapping scheme," said Sumit Chaudhary, an Iowa State assistant professor of electrical and computer engineering and an associate of the U.S. Department of Energy's Ames Laboratory."And so solar cell efficiency improved by 20 percent."

Details of the fabrication technology were recently published online by the journalAdvanced Materials.

Chaudhary said the key to improving the performance of solar cells made from flexible, lightweight and easy-to-manufacture polymers was to find a textured substrate pattern that allowed deposition of a light-absorbing layer that's uniformly thin -- even as it goes up and down flat-topped ridges that are less than a millionth of a meter high.

The result is a polymer solar cell that captures more light within those ridges -- including light that's reflected from one ridge to another, he said. The cell is also able to maintain the good electrical transport properties of a thin, uniform light-absorbing layer.

Tests indicated the research team's light-trapping cells increased power conversion efficiency by 20 percent over flat solar cells made from polymers, Chaudhary said. Tests also indicated that light captured at the red/near infrared band edge increased by 100 percent over flat cells.

Researchers working with Chaudhary on the solar cell project are Kai-Ming Ho, an Iowa State Distinguished Professor of Physics and Astronomy and an Ames Laboratory faculty scientist; Joong-Mok Park, an assistant scientist with the Ames Laboratory; and Kanwar Singh Nalwa, a graduate student in electrical and computer engineering and a student associate of the Ames Laboratory. The research was supported by the Iowa Power Fund, the Ames Laboratory and the Department of Energy's Office of Basic Energy Sciences.

The idea of boosting the performance of polymer solar cells by using a textured substrate is not a new one, Chaudhary said. The technology is commonly used in traditional, silicon-based solar cells.

But previous attempts to use textured substrates in polymer solar cells have failed because they require extra processing steps or technically challenging coating technologies. Some attempts produced a light-absorbing layer with air gaps or a too-thin layer over the ridges or a too-thick layer over the valleys. The result was a loss of charges and short circuiting at the valleys and ridges, resulting in poor solar cell performance.

But, get the substrate texture and the solution-based coating just right,"and we're getting more power out," Nalwa said.

The Iowa State University Research Foundation Inc. has filed a patent for the substrate and coating technology and is working to license the technology to solar cell manufacturers.

"This may be an old idea we're using," Chaudhary said,"but it's never before been successfully implemented in polymer solar cells."

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Electrocution of Birds and Collision With Power Lines: Solutions to a Global Problem

Bird death by electrocution is a global problem that has been aggravated by increases in the energy demand of certain regions and is particularly prevalent in natural areas where the introduction of power lines is a cause of significant disruption to local species. In Catalonia, electrocution is the primary cause of death of the Bonelli's Eagle (Aquila fasciata), and across the rest of the Iberian Peninsula it affects particularly large numbers of the endangered Iberian Imperial Eagle (Aquila adalberti) and many other ecologically valuable species. In the United States, the problem has a particular impact on the highly symbolic Bald Eagle (Haliaeetus leucocephalus). In Africa, common victims include the Cape Vulture (Gyps coprotheres) and the Egyptian Vulture (Neophron percnopterus).

Electrocution: Threats and solutions

Electrocution occurs when a bird comes into contact with two wires or when it perches on a conductive pylon (for example, a metal structure) and comes into simultaneous contact with a wire. In Catalonia, there are more than 1000 different models of electricity pylons, which pose different levels of threat to birds. The article published in theJournal of Wildlife Managementconfirms the validity of the predictive model designed by the UB research group to determine the risk of electrocution according to pylon design and location, as well as verifying the effectiveness of corrective measures implemented at electrocution blackspots.

Joan Real explains that,"The threat posed by a pylon depends on the electrotechnical design and the natural features around it. If we apply the predictive model we can correct power lines more effectively without having to apply measures to entire spans of the transmission network." The model makes it possible to select and act on the most dangerous pylons and correct them effectively. According to Joan Real, applying correction measures"to only 6% of the most dangerous pylons could reduce bird mortality by up to 70%."

Effectiveness of corrective measures

The article reviews more than ten years of pioneering work by the UB team on the detection and correction of potentially dangerous pylons and the evaluation of anti-electrocution measures over an area of 210,000 hectares in the Barcelona pre-littoral mountains. In the design of the predictive tool, the team modelled the risk of bird electrocution posed by 3,869 electricity pylons. Next, the team worked with power companies to apply corrective measures to the most dangerous pylons identified by the model (those with wires or connectors above the cross-arms and located in natural habitats or areas selected by bird species for specific activities). The study confirms that these anti-electrocution measures are effective and reduce the number of birds electrocuted in their natural habitats.

As Joan Real explains,"The predictive model is effective in identifying the pylons that present the greatest risk of electrocution. The results also show the effectiveness of corrective measures in preventing bird death through electrocution." Through its research, the Conservation Biology Group has developed a strategic analytical tool that will be of use to any public or private body involved in environment management in areas where transmission infrastructures have had adverse effects on bird life -- a specific environmental problem recognized by the Convention on Migratory Species (Bonn Convention, 2002) and in many EU conservation directives, as well as receiving specific mention in the recent decree on power transmission lines announced by the Spanish government.

Collision: A hidden threat

Electrocution is not the only threat that power lines pose to bird species. Collision also has an impact on the survival of birds, in particular endangered species and those with wider home ranges, which include various species of eagles. The findings of an article produced by the UB's Conservation Biology Group, published in the journalBird Conservation International, suggest that the problem is more serious than previously thought.

"Collision with power lines is a lesser-known problem than electrocution and is harder to detect because it can occur at any point along the transmission line," exaplins Joan Real. In the case of power lines, the bird collides with one of the wires, generally the earth wire, which is less visible. In the study, the UB team presents a predictive model for determining which lines and spans create the greatest risk of collision, describing the most effective strategies for reducing the number of accidents caused by transmission lines. The results of the article, based on a radio-tracking study of Bonelli's eagle populations in the Barcelona and Tarragona area, suggest that collision risk is influenced by a number of factors, including the topography of surrounding terrain and the proximity of lines and pylons to nests and other areas used frequently by local species.

Since 1980, the Conservation Biology Group has carried out applied research for the conservation of endangered species aimed at identifying effective preventive measures which can be applied by conservation managers and other stakeholders. The group is supported by the Miquel Torres Foundation in Vilafranca Penedès, and funding for its most recent studies has been provided by Barcelona Regional Council and the companies FECSA-ENDESA, Estabanell i Paysa S.A., Electra Caldense S.A. and Red Eléctrica de España, S.A.

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Manufacturing 'Made to Measure' Atomic-Scale Electrodes

Results were published in the journalNature Nanotechnology.

One of the key problems in nanotechnology is the formation of electrical contacts at an atomic scale. This demands the detailed characterisation of the current flowing through extremely small circuits– so small that their components can be individual atoms or molecules. It is precisely this miniature nature of the system, of typically nanometric dimensions (1 metro = a thousand million nanometers), where the difficulty of this yet unresolved problem arises. In particular, in unions formed by a single molecule, it has been shown that the number of individual atoms making up the contact and their positions are crucial when determining the electric current that is flowing. To date, there has been no experiment where it has been possible to control these parameters with sufficient precision.

In the research published in theNature Nanotechnologyjournal, however, these scientists have revealed and explained the changes that the electric current flowing through a molecular union (metal/molecule/metal) undergoes, depending on the area of contact uniting the molecule to the metallic electrodes. Basically, changing the number of atoms in contact with the molecule, one by one, it goes from a low state (bad contact) to another, higher one (good contact) of conduction. With bad contact the current is limited by the area of contact, while with good contact the current is limited by the intrinsic properties of the molecule.

Taking part in this collaboration project were scientists from the Donostia International Physics Center (DIPC), from the Physics of Materials Centre at the CSIC-University of the Basque Country (UPV/EHU) Mixed Centre and from the Department of the Physics of Materials at the Chemistry Faculty of the UPV/EHU.

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Electron 'Pairing': Triplet Superconductivity Proven Experientially for First Time

The researchers reported on their findings in the American Physical Society's journalPhysical Review B.

If it were possible to eliminate electrical resistance we could reduce our electric bill significantly and make a significant contribution to solving the energy problem, if it were not for a few other problems. Many metals as well as oxides demonstrate a superconductive state, however only at low temperatures. The superconductive effect results from Cooper pairs that migrate through the metal together"without resistance." The electrons in each Cooper pair are arranged so that their composite angular momentum is zero. Each electron has an angular momentum, the so-called spin, with a value of 1/2. When one electron spins counterclockwise (-1/2) and the other clockwise (+1/2), the total of the two spin values is zero. This effect, found only in superconductors, is called the singlet state.

If a superconductor is brought into contact with a ferromagnetic material, the Cooper pairs are broken up along the shortest path and the superconductor becomes a normal conductor. Cooper pairs cannot continue to exist in a singlet state in a ferromagnetic material. Researches at RUB (Prof. Konstantin Efetov, Solid State Physics) among others have, however, theoretically predicted a new type of Cooper pair, which has a better chance of survival in ferromagnetic materials. In such Cooper pairs the electrons spin in parallel with one another so that they have a finite spin with a value of 1. Since this angular momentum can have three orientations in space, it is also known as the triplet state."Obviously there can also be only one certain, small fraction of Cooper pairs in a triplet state, which then quickly revert to the singlet state" explained Prof. Kurt Westerholt."The challenge was to verify these triplet Cooper pairs experimentally."

Superconductors allow us to produce highly sensitive detectors for magnetic fields, which even allow detection of magnetic fields resulting from brain waves. These detectors are called SQUID's (superconducting quantum interference devices) -- components which use the superconductive quantum properties. The central feature in these components consists of so-called tunnel barriers with a series of layers made up of a superconductor, insulator and another superconductor. Quantum mechanics allows a Cooper pair to be"tunneled" through a very thin insulating layer. Tunneling of a large number of Cooper pairs results in a tunnel current."Naturally the barrier cannot be too thick, otherwise the tunnel current subsides. A thickness of one to two nanometers is ideal," according to Prof. Hermann Kohlstedt (CAU).

If part of the tunnel barrier is replaced by a ferromagnetic layer, the Cooper pairs are broken up while they are still in the barrier and do not reach the superconductor on the other side. The tunnel current decreases drastically."Triplet Cooper pairs can, however, be tunneled much better through such a ferromagnetic barrier," says Dirk Sprungmann, who was involved as Ph.D. student. If we are successful in converting a portion of the singlet Cooper pairs to triplet Cooper pairs, the tunnel current should be significantly stronger and be able to pass through a thicker ferromagnetic layer. This is precisely what the physicists in Bochum and Kiel tested. They allowed the Cooper pairs to pass through ferromagnetic barriers with thicknesses of up to 10 nanometers. With this attempt the physicists achieved a double success. On the one hand they were able to experimentally verify the existence of triplet Cooper pairs, and, on the other, they demonstrated that the tunnel current is greater than for singlet Cooper pairs in conventional tunnel contacts."These new ferromagnetic tunnel barriers may possibly be used for new types of components," states Dr. Martin Weides (Santa Barbara). With their research findings the scientists confirmed, among other things, the theoretical work of a Norwegian research team published only a few weeks before.

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