Shift to green energy sources could mean crunch in supply of scarce metals

Engineerblogger
March 8, 2012

A large-scale shift from coal-fired electric power plants and gasoline-fueled cars to wind turbines and electric vehicles could increase demand for two already-scarce metals — available almost exclusively in China — by 600-2,600 percent over the next 25 years, a new study has concluded. Published in the ACS journal Environmental Science & Technology, it points out that production of the two metals has been increasing by only a few percentage points per year.

Randolph E. Kirchain, Ph.D., and colleagues explain that there has been long-standing concern about a secure supply of the so-called rare earth elements, 17 elements adjacent on the periodic table of elements. These metals are used to make airplane components and lasers for medical imaging. Two of the rare earths, dysprosium and neodymium, are critical for current technologies for manufacturing wind turbines that generate electricity and electric vehicles. Those green technologies, Kirchain notes, would be essential in carrying out a proposed stabilization in atmospheric levels of carbon dioxide, the main greenhouse gas, at 450 parts per million. Kirchain’s team analyzed the supply of lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium and yttrium under various scenarios.

They projected the demand for these 10 rare earth elements through 2035. In one scenario, demand for dysprosium and neodymium could be higher than 2,600 and 700 percent respectively. To meet that need, production of dysprosium would have to grow each year at nearly twice the historic growth rate for rare earth supplies. “Although the RE [rare earth] supply base has demonstrated an impressive ability to expand over recent history, even the RE industry may struggle to keep up with that pace of demand growth,” the authors said. But they also point out that shortfalls in future supply could be mitigated “through materials substitution, improved efficiency, and the increased reuse, recycling, and use of scrap.”

Source:  American Chemical Society


Additional Information:

• Evaluating Rare Earth Element Availability: A Case with Revolutionary Demand from Clean Technologies

Related Information:

• DOE: Rare earth shortages may damage clean tech growth 

• Broad scientific approach to studying rare earth materials needed to ensure continued deployment of clean energy technologies

• The Rare-Earth Crisis 

• No future without scarce metals: the scarcity of raw materials 

• Bloomberg articles, "Rare Earth Prices Double in Two Weeks as China Seeks to Increase Control" and "BMW Carbon Factory Lets Motor Vehicles Follow Road Bike to Lightness: Cars

NIST Measurements May Help Optimize Organic Solar Cells

Engineerblogger
March 8, 2012

Light that strikes this organic solar cell causes electrons to flow between its layers, creating an electric current. Measurements made by the NIST/NRL research team determined the best thickness for the layers, a finding that could help optimize the cells performance.  Credit: NIST

Organic solar cells may be a step closer to market because of measurements taken at the National Institute of Standards and Technology (NIST) and the U.S. Naval Research Laboratory (NRL), where a team of scientists has developed a better fundamental understanding of how to optimize the cells’ performance.

Prototype solar cells made of organic materials currently lag far behind conventional silicon-based photovoltaic cells in terms of electricity output. But if even reasonably efficient organic cells can be developed, they would have distinct advantages of their own: They would cost far less to produce than conventional cells, could cover larger areas, and conceivably could be recycled far more easily.

The cells the team studied are made by stacking up hundreds of thin layers that alternate between two different organic materials—zinc pthalocyanine and C60, the soccer-ball shaped carbon molecules sometimes called buckminsterfullerenes, or “buckyballs.” Light that strikes this multilayered film excites all its layers from top to bottom, causing them to give up electrons that flow between the buckyball and pthalocyanine layers, creating an electric current.

Each layer is only a few nanometers thick, and varying their thickness has a dramatic effect on how much electrical current the overall cell puts out. According to NIST chemist Ted Heilweil, determining the ideal thickness of the layers is crucial to making the best-performing cells.

“In essence, if the layers are too thin, they don’t generate enough electrons for a substantial current to flow, but if they are too thick, many of the electrons get trapped in the individual layers,” says Heilweil. “We wanted to find the sweet spot.”

Finding that “sweet spot” involved exploring the relationship between layer thickness and two different aspects of the material. When light strikes the film, the layers generate an initial “spike” in current that then decays fairly quickly; the ideal cell would generate electrons as steadily as possible. Changing the layer thickness affects the initial decay rate, but it also affects the overall capacity of the material to carry electrons, so the team wanted to find the optimum combination of these two factors.

Paul Lane of NRL grew a number of films that had layers of different thickness, and the team made measurements at both labs that took the two factors into account, finding that layers of roughly two nanometers thick give the best performance. Heilweil says the results encourage him to think prototype cells based on this geometry can be optimized, though one engineering hurdle remains: finding the best way to get the electricity out.

“It’s still unclear how to best incorporate such thin nanolayers in devices,” he says. “We hope to challenge engineers who can help us with that part.”

Source: NIST

Additional Information:

• P.A. Lane, P.D. Cunningham, J.S. Melinger, G.P. Kushto, O. Esenturk and E.J. Heilweil. Photoexcitation dynamics in films of C60 and Zn-Phthalocyanine with a layered nanostructure. Physical Review Letters, DOI: 10.1103/PhysRevLett.108.077402. Published 15 Feb 2012.

The Future of Nuclear Energy

Engineerblogger
March 7, 2012

Aerial photograph of Vogtle nuclear power plant site, just outside Augusta, Georgia. The existing Vogtle 1 adn 2 operating units to the left and the Vogtle 3 and 4 construction site to the right. Courtesy: Southern Company 2011

Last March, the world watched closely as Japan struggled to contain a series of equipment failures, hydrogen explosions and releases of radioactive materials at the Fukushima Daiichi Nuclear Power Plant.

The historic tsunami following the 9.0-magnitude earthquake destroyed the reactors’ connection to the power grid, causing them to overheat. Hundreds of people were exposed to increased levels of radiation. Thousands more were evacuated. Although Japanese officials have since declared the plant stable, the cleanup will be expensive and is expected to take decades.

A year later, however, the United States is moving forward with nuclear power. For the first time since 1978, the National Regulatory Commission has approved two new plants. The $14 billion facilities will be built just outside Augusta and operated by Atlanta-based Southern Company. They’re scheduled to be up and running by 2016 and 2017 and should produce about 10 percent of Georgia’s power.

“It’s smart to continue generating nuclear power in the United States,” said Marilyn Brown, professor in Georgia Tech’s School of Public Policy. “It is a reliable, cost-competitive option that doesn’t contribute to air pollution or contribute to greenhouse gas emissions.” Brown helps shape the nation’s energy policies as a board member of the Tennessee Valley Authority (TVA) and chair of the company’s Nuclear Oversight Committee.

Brown said that nuclear power plants are expensive to build, compared to natural gas facilities.

“But they are clearly worth the investment,” she said. “A nuclear plant produces no carbon dioxide emissions and four times the power of a typical natural gas facility. Fourteen billion is a big number, but the plants should stay online for 50 to 70 years.”

Despite the benefits, critics will always point to the risk of a nuclear catastrophe. These are the nation’s first approved nuclear facilities since Pennsylvania’s Three Mile Island accident in 1979. Experts contend that modern plant designs are much safer than those built previously.

“The new plant designs are passively safe, so there are far fewer issues to worry about, like those that occurred with the older plants at Fukushima with the loss of off-site power,” said Glenn Sjoden, Georgia Tech professor of nuclear and radiological engineering. “With the new plants, you have a convection cooling loop that uses gravity and runs by itself for days in the event of lost power. There would be no active pumping required. . . . The more modern designs and precautions taken make nuclear the best option to satisfy our energy needs.”

Since last year’s incident, the Nuclear Regulatory Commission has been reviewing existing U.S. plants to ensure that they can withstand earthquakes, floods and other natural disasters and making retrofit upgrades when necessary, Sjoden said.

Critics point to nuclear waste as another challenge with nuclear power. Each of the nation’s 104 plants store the radioactive waste on-site in steel casks protected by concrete and other safety systems. These are safe too, Brown said, because of careful construction and maintenance.

Nuclear waste would be a nonissue if the U.S. reprocessed its spent fuel like other nations such as France, Sjoden said.

“Like most nations, they recycle their used fuel, since 95 percent of the fuel can be recycled back into the reactor and used again, making nuclear power the most ‘green’ energy source out there,” Sjoden said. “Burying the waste, as we do in the United States, is completely wasteful.”

The United States generates almost 20 percent of its energy from nuclear plants, the same amount as natural gas. Coal supplies 50 percent. The remainder is generated from hydropower and other natural sources.

“We must develop more renewables sources, such as wind, solar and biopower,” says Brown. “Industry leaders, business and the general public must also become more energy efficient. That is the key to our future.”

Source:  Georgia Institute of Technology

Graphene Battery Turns Ambient Heat Into Electric Current

Engineerblogger
March 7, 2012

Credit: Technology Review

Here's an interesting idea for a battery. The thermal velocity of ions in aqueous solution is huge--hundreds of metres per second at room temperature. And yet few people have studied this process or its potential to generate current.

Step forward Zihan Xu at The Hong Kong Polytechnic University and a few buddies who have not only studied this process but seemingly mastered it too.

These guys have created a circuit consisting of an LED connected to a strip of graphene by some wire. They simply placed the graphene in a solution of copper chloride and watched. Sure enough, the LED lights up. (Actually, they needed six of these graphene circuits in series to generate the 2V needed to make the LED light up but you get the picture.)

Here's what's going on, according to Zihan and co. The copper ions, which have a double positive charge, move through the solution at a rate of about 300 metres per second thanks to the thermal energy of the solution at room temperature.

When an ion smashes into the graphene strip, the collision generates enough energy to kick a delocalised electron out of the graphene.

The electron then has two options: it can either leave the graphene strip and combine with the copper ion or it can travel through the graphene strip and into the circuit.

It turns out that the mobility of electrons is much higher in graphene than it is through the solution, so the electron naturally chooses the route through the circuit. It is this that lights up the LED.

"The released electrons prefer to travel across the graphene surface...instead of going into the electrolyte solution. That is how the voltage was produced by our device," say Zihan and co.

So the energy generated by this device comes from ambient heat. These guys say there were able to increase the current by heating the solution and also by accelerating the copper ions with ultrasound. They even claim to have kept their graphene battery running for 20 days on nothing but ambient heat.

But there's an important question mark. One alternative hypothesis is that some kind of chemical reaction is generating the current, just as in an ordinary battery.

However, Zihan and co say they ruled this out with a couple of control experiments. However, these are described in some supplementary material that they do not appear to have put on the arXiv. They'll need to make this available before others will take the claim seriously, of course.

Taken at face value, however, this looks to be a hugely important result. Others have generated current in graphene simply by passing moving water over it, so it's not really a surprise that moving ions can do the job as well.

It raises the prospect of clean, green batteries powered by nothing but ambient heat. As Zihan and co modestly put it: "it represents a huge breakthrough for the research of self-powered technology".

Let's hope they're right. But for the moment at least, the jury must remain undecided.

Source: Technology Review

Additional Information:

•  To read the abstract"Self-Charged Graphene Battery Harvests Electricity from Thermal Energy of the Environment" in the Cornell University Library.

Nanotrees harvest the sun's energy to turn water into hydrogen fuel

Engineerblogger
March 7, 2012

Schematic shows the light trapping effect in nanowire arrays. Photons on are bounced between single nanowires and eventually absorbed by them (R). By harvesting more sun light using the vertical nanotree structure, Wang’s team has developed a way to produce more hydrogen fuel efficiently compared to planar counterparts (L) where light is simply reflected off the surface. Image Credit: Wang Research Group, UC San Diego Jacobs School of Engineering.

University of California, San Diego electrical engineers are building a forest of tiny nanowire trees in order to cleanly capture solar energy without using fossil fuels and harvest it for hydrogen fuel generation. Reporting in the journal Nanoscale, the team said nanowires, which are made from abundant natural materials like silicon and zinc oxide, also offer a cheap way to deliver hydrogen fuel on a mass scale.

“This is a clean way to generate clean fuel,” said Deli Wang, professor in the Department of Electrical and Computer Engineering at the UC San Diego Jacobs School of Engineering.

The trees’ vertical structure and branches are keys to capturing the maximum amount of solar energy, according to Wang. That’s because the vertical structure of trees grabs and adsorbs light while flat surfaces simply reflect it, Wang said, adding that it is also similar to retinal photoreceptor cells in the human eye. In images of Earth from space, light reflects off of flat surfaces such as the ocean or deserts, while forests appear darker.

Wang’s team has mimicked this structure in their “3D branched nanowire array” which uses a process called photoelectrochemical water-splitting to produce hydrogen gas. Water splitting refers to the process of separating water into oxygen and hydrogen in order to extract hydrogen gas to be used as fuel. This process uses clean energy with no green-house gas byproduct. By comparison, the current conventional way of producing hydrogen relies on electricity from fossil fuels

“Hydrogen is considered to be clean fuel compared to fossil fuel because there is no carbon emission, but the hydrogen currently used is not generated cleanly,” said Ke Sun, a PhD student in electrical engineering who led the project.

By harvesting more sun light using the vertical nanotree structure, Wang’s team has developed a way to produce more hydrogen fuel efficiently compared to planar counterparts. Wang is also affiliated with the California Institute of Telecommunications and Information Technology and the Material Science and Engineering Program at UC San Diego.

The vertical branch structure also maximizes hydrogen gas output, said Sun. For example, on the flat wide surface of a pot of boiling water, bubbles must become large to come to the surface. In the nanotree structure, very small gas bubbles of hydrogen can be extracted much faster. “Moreover, with this structure, we have enhanced, by at least 400,000 times, the surface area for chemical reactions,” said Sun.

In the long run, what Wang’s team is aiming for is even bigger: artificial photosynthesis. In photosynthesis, as plants absorb sunlight they also collect carbon dioxide (CO2) and water from the atmosphere to create carbohydrates to fuel their own growth. Wang’s team hopes to mimic this process to also capture CO2 from the atmosphere, reducing carbon emissions, and convert it into hydrocarbon fuel.

In this experiment, nanotree electrodes are submersed in water and illuminated by simulated sun light to measure electricity output of the device. Photo Credit: Joshua Knoff, UC San Diego Jacobs School of Engineering.

“We are trying to mimic what the plant does to convert sunlight to energy,” said Sun. “We are hoping in the near future our ‘nanotree’ structure can eventually be part of an efficient device that functions like a real tree for photosynthesis."

The team is also studying alternatives to zinc oxide, which absorbs the sun’s ultraviolet light, but has stability issues that affect the lifetime usage of the nanotree structure.

Source: University of California, San Diego

Is Seaweed the Future of Biofuel?

Engineerblogger
March 6, 2012

Credit: TAU

As scientists continue the hunt for energy sources that are safer, cleaner alternatives to fossil fuel, an ever-increasing amount of valuable farmland is being used to produce bioethanol, a source of transportation fuel. And while land-bound sources are renewable, economists and ecologists fear that diverting crops to produce fuel will limit food resources and drive up costs.

Now, Prof. Avigdor Abelson of Tel Aviv University's Department of Zoology and the new Renewable Energy Center, and his colleagues Dr. Alvaro Israel of the Israel Oceanography Institute, Prof. Aharon Gedanken of Bar-Ilan University, Dr. Ariel Kushmaro of Ben-Gurion University, and their Ph.D. student Leor Korzen, have gone to the seas in the quest for a renewable energy source that doesn't endanger natural habitats, biodiversity, or human food sources.He says that marine macroalgae — common seaweed — can be grown more quickly than land-based crops and harvested as fuel without sacrificing usable land. It's a promising source of bioethanol that has remained virtually unexplored until now.

The researchers are now developing methods for growing and harvesting seaweed as a source of renewable energy. Not only can the macroalgae be grown unobtrusively along coastlines, Prof. Abelson notes, they can also clear the water of excessive nutrients — caused by human waste or aquaculture — which disturb the marine environment.

A man-made "ecosystem"

While biomasses grown on land have the potential to inflict damage on the environment, the researchers believe that producing biofuel from seaweed-based sources could even solve problems that already exist within the marine environment. Many coastal regions, including the Red Sea in the south of Israel, have suffered from eutrophication — pollution caused by human waste and fish farming, which leads to excessive amounts of nutrients and detrimental algae, ultimately harming endangered coral reefs.

Encouraging the growth of seaweed for eventual conversion into biofuel could solve these environmental problems. The system that the researchers are developing, called the "Combined Aquaculture Multi-Use Systems" (CAMUS), takes into account the realities of the marine environment and human activity in it. Ultimately, all of these factors function together to create a synthetic "man-made ecosystem," explains Prof. Abelson.

Man-made fish feeders, which produce pollution in the form of excess nutrients and are generally considered harmful to the marine environment, would become a positive link in this chain. Used alongside an increased population of filter feeders such as oysters, which suck in extra particles and convert them food that the microalgae can consume, this "pollution" could be used to sustain a much greater yield of seaweed, which is needed for seaweed to become a sustainable source of fuel.

"By employing multiple species, CAMUS can turn waste into productive resources such as biofuel, at the same time reducing pollution's impact on the local ecosystem," he says.

Turning waste into opportunity

The researchers are now working to increase the carbohydrate and sugar contents of the seaweed for efficient fermentation into bioethanol, and they believe that macroalgae will be a major source for biofuel in the future. The CAMUS system could turn seaweed into a sustainable bioethanol source that is productive, efficient, and cost-effective.

Source: Tel Aviv University

Battery 500 Project: 800 km range for electrovehicles

Engineerblogger
March 5, 2012

IBM's Battery 500 project, led by scientists at IBM Research – Almaden in California, is an interdisciplinary consortium to develop a lithium–air battery that aims to increase the range of electrovehicles to 500 miles (approximately 800 km). This is more than five times the range of today's batteries, which average some 150 km per charge. If the project is successful, battery-powered vehicles could finally become a practical reality and thus overcome the main obstacle to becoming generally accepted and widespread: In a recent survey conducted by IBM, 64% of consumers said that the limited range was their strongest objection to driving electrovehicles.

Changing from gasoline to electricity as the main energy source for vehicles could be one of the most significant technological turning points in the history of our modern industrial society. However, progress has been slow in developing high-performance batteries. High manufacturing costs are another major factor that has limited the widespread acceptance and large-scale development of electrovehicles. Consumers' greatest fear is being stranded somewhere with an empty battery, and this fear is justified, as the range of most current battery-operated vehicles is only some 150 km. It appears unlikely that a realistic range can be achieved with today's battery technology, which must also have an acceptable weight and be available at reasonable prices.

Rechargeable lithium–ion storage batteries like the ones used in cell phones or notebook computers offer only a fraction of the energy density—the amount of energy that can be stored per mass unit or volume unit—achieved by fossil fuels such as gasoline or diesel. Therefore this battery technology for electrovehicles is only of interest today for short distances or in hybrid-engine vehicles. If this situation is to be fundamentally changed, new types of batteries with significantly higher energy densities must replace today's lithium–ion batteries. IBM, world patent leader and active for decades in fundamental research, has launched a new project dubbed Battery 500 to tackle this problem. For this new project, IBM is leveraging its recent progress in the fields of materials science, nanotechnology, chemistry and supercomputing.

An interdisciplinary team of scientists at IBM Research – Almaden in California and IBM Research – Zurich, together with leading universities, corporations and research institutes has been exploring a so-called lithium–air battery since mid-2009. The aim of this project is to develop a battery whose energy density is up to ten times higher than that of today's rechargeable lithium–ion batteries, thus providing electrovehicles with a range of up to 500 miles or 800 km. "With our lithium–air battery technology we hope to achieve a quantum leap that could be a breakthrough in electromobility," explains Dr. Winfried Wilcke, initiator and head of the Battery 500 project at IBM Research – Almaden. "This is yet another project of IBM's 'Smarter Planet' vision in which new mobility concepts play a vital role."

"Airy" bundle of energy

A major advantage of the lithium–air battery is that it takes oxygen from the atmosphere as its reacting agent. The oxygen is stored in light carbon nanostructures in the cathode, meaning that significantly more energy per kilogram battery weight can be stored than in today's batteries. A numerical example illustrates this advantage: a conventional lithium–ion battery with an energy content of 50 kilowatt hours (kWh) weighs about 500 kg. A range of 800 km would require an energy content of 150 kWh, which would mean a weight of 1.5 tons, which is clearly unrealistic for practical use in electrovehicles. In contrast, IBM scientists estimate that a 150 kWh lithium–air battery would weigh "only" about 150–300 kg.
The theoretically achievable specific energy of a lithium–air battery (without the weight of the ambient oxygen) is greater than 11 kWh per kilogram (kWh/kg). Scientists predict that, in practice, a lithium–air battery could achieve about one-tenth of the theoretical specific energy. Taking the relative efficiency of combustion motors and electromotors into account, the difference in "practical" energy densities between electromotors and gasoline or diesel-powered motors is actually very small because electromotors have a very high efficiency of 85%. The lithium–air technology thus exhibits the greatest potential of all battery types researched to date.

A battery that "breathes"

Like all batteries, the basic construction of a lithium–air battery consists of two electrodes, in this case a metal electrode of lithium (the anode) and an oxygen-permeable electrode of a light carbon structure (the cathode). When the battery is discharged, the lithium atoms of the anode lose electrons and proceed as lithium ions through an electrically conducting electrolyte to the cathode, where they react with oxygen from the atmosphere. The product of this reaction is then deposited in the cathode. When the battery is charged, it releases the oxygen collected while the vehicle was being driven (discharged) back into the atmosphere. Metaphorically speaking, the battery "inhales" oxygen while discharging and "exhales" it again while being recharged.
IBM scientists are focusing on so-called aprotic (non-watery) lithium–air batteries, which use organic liquids and lithium salts as electrolytes. Discharging the battery produces lithium peroxide (Li2O2)—but only when the right electrolytes are used—which is stored in the battery's cathode. During the charging process, the lithium peroxide breaks down into oxygen, which is released into the atmosphere, and lithium, which is stored in the battery's anode.

From simulations and experiments to success

The members of this project have already achieved major breakthroughs toward achieving their ambitious goal. For example, the functionality of this technology has been proved in principle on laboratory-scale models that unequivocally demonstrated the rechargeability of lithium–air batteries. The key to this first success was a combination of computer-based simulations and practical experiments. The team at the IBM Research – Zurich Laboratory performed so-called ab initio simulations to obtain new insights into the molecular-level processes that take place in lithium–air batteries. These highly complex simulations draw exclusively on basic laws of physics and physics models. In this way, interactions between atoms and molecules in a given system can be computed exactly. Performed on a petaflop IBM BlueGene/P supercomputer at Argonne National Laboratory, these simulations showed for the first time that the electrolytes used in conventional lithium–ion batteries do not work in lithium–air batteries, contrary to what was previously thought.

"Our simulations allowed us to demonstrate the processes that actually take place during discharge. The carbon-based electrolyte reacts in an undesirable manner with the lithium peroxide and decompose as a result. This effectively destroys the lithium–air battery," explains Dr. Alessandro Curioni, head of the Computational Sciences research group at IBM Research – Zurich.
Using a mass spectrometer developed specifically for the Battery 500 project, scientists were able to perform laboratory experiments that clearly confirm the electrolyte decomposition predicted by the simulations. "Simulations and experimental results have allowed us to identify stable electrolytes with which we were able to demonstrate the basic functionality of the charging and discharging processes," says project leader Wilcke. In addition, very high charge capacities have been demonstrated in the laboratory. A further fundamental result is the fact that, contrary to long-held assumptions, catalyzers are not kinetically necessary because the so-called overvoltage of the fundamental electrochemical reaction 2Li+ + O2 + 2- <=> Li2O2 is much smaller than originally thought. Nevertheless, the very low conductivity of lithium peroxide is a problem that is yet to be resolved.

Still a "Grand Challenge"

Several other veritable challenges remain for scientists to solve before lithium–air batteries can be implemented for practical purposes or fabricated industrially. It is therefore one of IBM Research's so-called "Grand Challenges"—ambitious and risky research projects with uncertain outcomes but very high potentials, such as the development of the WATSON supercomputer.
Currently, scientists are seeking to increase the energy density of the battery, which is still far too low for real-life electromobility. Another challenge is the charging process, which is currently too slow. But even assuming that this can be improved markedly, it will not be possible, say, to charge the battery quickly during one's coffee break. Scientists are currently aiming for the capability to charge the battery overnight, which, based on the considerable range, should be sufficient. To solve the problem posed by lithium's susceptibility to humidity, the IBM team is also developing novel nanomembranes, which will be required in order to protect the sensitive lithium anode from steam and carbon dioxide in the atmosphere. Additional challenges are the long-term stability of the components' materials and the improved ability to suppress undesirable secondary reactions.

Upon successful completion of the current research phase, the Battery 500 project could possibly be pursued with industrial partners to develop commercial models of the lithium–air battery in the timeframe of 2020 to 2030. Participants of the Battery 500 project include several other top-notch partners of German, Japanese and Korean corporations as well as additional American research institutions.


Source: IBM

Heart-powered pacemaker could one day eliminate battery-replacement surgery

Engineerblogger
March 5, 2012

An artificial pacemaker from St. Jude Medical, with electrode.

A new power scheme for cardiac pacemakers turns to an unlikely source: vibrations from heartbeats themselves.

Engineering researchers at the University of Michigan designed a device that harvests energy from the reverberation of heartbeats through the chest and converts it to electricity to run a pacemaker or an implanted defibrillator. These mini-medical machines send electrical signals to the heart to keep it beating in a healthy rhythm. By taking the place of the batteries that power them today, the new energy harvester could save patients from repeated surgeries. That's the only way today to replace the batteries, which last five to 10 years.

"The idea is to use ambient vibrations that are typically wasted and convert them to electrical energy," said Amin Karami, a research fellow in the U-M Department of Aerospace Engineering. "If you put your hand on top of your heart, you can feel these vibrations all over your torso."

The researchers haven't built a prototype yet, but they've made detailed blueprints and run simulations demonstrating that the concept would work. Here's how: A hundredth-of-an-inch thin slice of a special "piezoelectric" ceramic material would essentially catch heartbeat vibrations and briefly expand in response. Piezoelectric materials' claim to fame is that they can convert mechanical stress (which causes them to expand) into an electric voltage.

Karami and his colleague Daniel Inman, chair of Aerospace Engineering at U-M, have precisely engineered the ceramic layer to a shape that can harvest vibrations across a broad range of frequencies. They also incorporated magnets, whose additional force field can drastically boost the electric signal that results from the vibrations.

The new device could generate 10 microwatts of power, which is about eight times the amount a pacemaker needs to operate, Karami said. It always generates more energy than the pacemaker requires, and it performs at heart rates from 7 to 700 beats per minute. That's well below and above the normal range.

Karami and Inman originally designed the harvester for light unmanned airplanes, where it could generate power from wing vibrations.

A paper on the research, titled "Powering pacemakers from heartbeat vibrations using linear and nonlinear energy harvesters," is published in the current print edition of Applied Physics Letters.

The research is funded by the National Institute of Standards and Technology and the Institute for Critical Technology and Applied Science at Virginia Tech.

Source: University of Michigan

Unique salt allows energy production to move inland

Engineerblogger
March 2, 2012

Microbial reverse dialysis test cell. Credit PSU

Production of energy from the difference between salt water and fresh water is most convenient near the oceans, but now, using an ammonium bicarbonate salt solution, Penn State researchers can combine bacterial degradation of waste water with energy extracted from the salt-water fresh-water gradient to produce power anywhere.

"We are taking two technologies, each having limitations, and putting them together," said Bruce E. Logan, Kappe Professor of Environmental Engineering. "Combined, they overcome the limitations of the individual technologies."

The technologies Logan refers to are microbial fuel cells (MFC) -- which use wastewater and naturally occurring bacteria to produce electricity -- and reverse electrodialysis (RED) -- which produces electricity directly from the salinity gradient between salty and fresh water. The combined technology creates a microbial reverse-electrodialysis cell (MRC). The researchers describe MRCs in today's (March 1) edition of Science Express.

RED stacks extract energy from the ionic difference between fresh water and salt water. A stack consists of alternating ion exchange membranes -- positive and negative -- with each RED membrane pair contributing additively to the electrical output. Unfortunately, using only RED stacks to produce electricity is difficult because a large number of membranes is required when using water at the electrodes, due to the need for water electrolysis.

Using exoelectrogenic bacteria -- bacteria found in wastewater that consume organic material and produce an electric current -- reduces the number of stacks needed and increases electric production by the bacteria.

Logan, working with Roland Cusick, graduate student in environmental engineering, and postdoctoral fellow Younggy Kim, placed a RED stack between the electrodes of an MFC to form the MRC.

While the researchers previously showed that an MRC can work with natural seawater, the organic matter in water will foul the membranes without extensive precleaning and treatment of the water. Seawater use restricts MRC operation to coastal areas, but food waste, domestic waste and animal waste contain about 17 gigawatts of power throughout the U.S. One nuclear reactor typically produces 1 gigawatt.

Rather than rely on seawater, the researchers used ammonium bicarbonate, an unusual salt. An ammonium bicarbonate solution works similarly to seawater in the MRC and will not foul the membranes. The ammonium bicarbonate is also easily removed from the water above 110 degrees Fahrenheit. The ammonia and carbon dioxide that make up the salt boil out, and are recaptured and recombined for reuse.

"Waste heat makes up 7 to 17 percent of energy consumed in industrial processes," said Logan. "There is always a source of waste heat near where this process could take place and it usually goes unused."

The researchers tested their ammonium bicarbonate MRC and found that the initial production of electricity was greater than that from an MRC using seawater.

"The bacteria in the cell quickly used up all the dissolved organic material," said Logan. "This is the portion of wastewater that is usually the most difficult to remove and requires trickling filters, while the particulate portion which took longer for the bacteria to consume, is more easily removed."

The researchers tested the MRC only in a fill and empty mode, but eventually a stream of wastewater would be run through the cell. According to Logan, MRCs can be configured to produce electricity or hydrogen, making both without contributing to greenhouse gases such as carbon dioxide. The MRC tested produced 5.6 watts per square meter.

Logan also said not having to process wastewater would save about 60 gigawatts.

The King Abdullah University of Science and Technology supported this work.

Source: Pennsylvania State University

Jump in Battery Capacity: Technology could cut the cost of electric-car batteries

Technology Review
March 2, 2012

Battery packs can cost more than $10,000, which is one of the biggest reasons electric cars cost more than conventional gas-powered cars.

Envia, a startup funded by GM and the U.S. government's Advanced Research Projects Agency for Energy (ARPA-E), says it has built batteries that store more than twice as much energy as the ones in electric cars now. If the technology comes to fruition, it could halve the cost of batteries—the most expensive part on an electric vehicle.

Much work remains, however, before the batteries can be used in commercial electric vehicles. Among other things, the number of times they can be charged and recharged must be more than doubled.

The technology was highlighted at the annual ARPA-E summit in Washington, D.C., this week, in part to demonstrate the progress in energy technology being made by the Department of Energy, which oversees ARPA-E. The DOE has come under fire after giving loan guarantees to some companies that later declared bankruptcy.

Envia's technology is based on work originating in the DOE's Argonne National Lab, which identified a material with a novel microscopic structure that could help improve the storage capacity of one of the battery electrodes.

GM and battery maker LG Chem, which is using some aspects of the technology in the Chevrolet Volt, may incorporate other technology from Argonne in batteries for the next generation of the car. Envia modified the original Argonne technology to get higher energy densities.
To read more click here...

Additional Information:

• Envia Systems Achieves World Record Energy Density for Rechargeable Lithium-Ion Batteries  

Generating electricity from vibrations in road surface works

Engineerblogger
March 1, 2012

Credit: University of Twente

A pilot research project into vibration energy on the N34 provincial motorway near Hardenberg in the eastern Netherlands has shown that vibration energy as a local energy source is a sustainable alternative for the batteries of roadside sensors and other applications. The trial project has provided valuable insights into this innovative form of energy production.

In the autumn of 2011, a piezoelectric material that converts vibrations from passing vehicles into energy was applied to the surface of the N34 motorway. The piezoelectric material was applied to the road surface in a rural area where the speed limit is 100 km per hour. The aim of the pilot project was to investigate the feasibility of piezo technology in road construction. The research was carried out by the Tauw advice and engineering agency and the University of Twente in partnership with the Dutch province of Overijssel.

The aim of the pilot project was to establish whether electrical energy can be generated from traffic vibrations using piezoelectric material and, if so, how much energy can be generated. The trial system was tested in various weather conditions between October and December 2011. A measurement device was used to continually monitor the system and collect data.

Results
Tauw and the University of Twente have concluded that energy can indeed be generated using piezoelectric material in the road surface. The amount of energy generated depends on the number of passing vehicles and the number of piezo elements in the road. Vehicles that are moving more slowly appear to generate slightly more energy than faster-moving vehicles, but further research is needed to confirm this.

The amount of energy generated during the pilot project was too small to be used for traffic lights or street lighting, but it was enough for devices that need less energy, such as wireless motion sensors, which detect vehicles and send a signal to, for example, traffic lights. Currently these are mainly powered by batteries or solar panels. Vibration energy is a sustainable alternative for these power sources.

The project partners also concluded that integrating piezo elements in an existing road surface is problematic. For the pilot research, a narrow groove was cut into the road and a steel housing containing the piezo elements was fitted into it. Ultimately it turned out that the housing was not strong enough to withstand the forces of the passing traffic, and it came loose in December. This did not cause a traffic hazard, but it did mean that the research ended a few weeks earlier than planned.

Applications
The project partners are hopeful about other applications. Project leader Simon Bos says: “The application of vibration energy in existing roads did turn out to be difficult, but we do see possibilities for existing and new bridges and viaducts, for example at expansion joints. Of course further research into a good, strong design has to be carried out before this can be applied on a large scale.”

Next steps
Following the pilot project, various interested parties have contacted Tauw and the University of Twente to carry out further research into vibration energy. Piezo elements can not only be fitted under bridges and viaducts, but also under concrete road slabs and speed bumps, or alongside railway lines or water drainage channels. The application of piezo elements beneath concrete slabs is at an advanced stage, while the other possible applications are still in the research phase.

Source: University of Twente

National Grid, Advanced Plasma Power and Progressive Energy announce new project to transform waste into Bio Substitute Natural Gas

Engineerblogger
March 1, 2012

Project will deliver an end-to-end process for converting waste to Bio-SNG, using Gasplasma® technology

The first pilot project that demonstrates the use of waste to produce bio-substitute natural gas (Bio-SNG) has today been announced by National Grid, Advanced Plasma Power and Progressive Energy.

The project, which uses waste as a feedstock to produce Bio-SNG, will be based at the Advanced Plasma Power Gasplasma® facility in Swindon, UK. It will demonstrate the technical feasibility and commercial viability of the waste to Bio-SNG process. The three partners will work together to design, install and test the operation of a demonstration plant.

The plant will take the waste-derived and energy rich synthesis gas from the existing Gasplasma® process, and convert it to meet the specification for injecting it into the gas network. Bio-SNG could play a crucial role in the decarbonisation of heating and help reach the UK's binding carbon reduction targets. As part of its work on future energy scenarios, National Grid has forecast that renewable gas could be a vital part of the energy mix in the coming decades.

APP’s process converts commercial waste into high-quality syngas, which can then be converted into methane. Credit: APP

Marcus Stewart, Future Distribution Networks Manager at National Grid said, “This project is a great opportunity to look at the potential of Bio-SNG from both a technical and commercial perspective. The project underlines our commitment to seeking economic and innovative ways to decarbonise energy, while making the best use of the existing network. ”

It is estimated that renewable gas, of which Bio-SNG may be a major source, could account for as much as one fifth of the UK’s heat requirement by 2050.

Rolf Stein, Chief Executive, Advanced Plasma Power said, “The development and implementation of a process to derive Bio-SNG from waste using our unique Gasplasma® process has significant global implications for sustainable waste management and low carbon energy solutions. We look forward to demonstrating the process on our plant in Swindon.”

Phillip Cozens, Progressive Energy said, “"This project is a significant step towards greater resource efficiency in our economy, exploiting the capacity of the existing gas infrastructure and demonstrating the potential to deliver renewable heat at a cost that is competitive with other renewable heat options. The partnership has put together a strong project execution team to deliver a practical demonstration of Bio-SNG production from residual wastes. Successful demonstration would provide a blue-print for general deployment.”

National Grid:
National Grid is an electricity and gas company that connects consumers to energy sources through its networks. The company is at the heart of one of the greatest challenges facing our society - to create new, sustainable energy solutions for the future and developing an energy system that underpins economic prosperity in the 21st century. National Grid holds a vital position at the centre of the energy system and we ‘join everything up’. In Britain, we run the gas and electricity systems that our society is built on, delivering gas and electricity across the country. In the North Eastern US, we connect more than seven million gas and electric customers to vital energy sources, essential for our modern lifestyles.

Advanced Plasma Power:
Advanced Plasma Power Limited (APP) is a leading technology provider for advanced waste to energy plants, showcasing its globally patented Gasplasma® technology. After the removal of valuable recyclates, the Gasplasma® process treats a wide range of feedstocks including residual municipal solid waste and commercial/industrial waste converting it all into two high value outputs: a clean, high quality, energy rich synthesis gas (syngas) and a solid, vitrified product each with multiple applications. The syngas can be used to generate electricity directly in gas engines, gas turbines and fuel cells or it can be converted to Bio-SNG or liquid fuels. The solid product, Plasmarok®, has a variety of valuable end uses, for instance, as a building material. The process is clean, modular and scalable, delivering high efficiency and maximising landfill diversion whilst minimising visual and environmental impact.

Progressive Energy:
Progressive Energy is a market leading project development company, specialising in clean energy and carbon abatement in the energy sector through the deployment of carbon capture and storage and renewable energy technologies. 

Source: National Grid

Battery to Take On Diesel and Natural Gas

Technology Review
Feb 29, 2012

Battery building: Aquion Energy recently announced plans to retrofit this factory—which used to make Sony televisions—to make large batteries for use with solar power plants. Credit: RIDC Westmoreland

Aquion Energy, a company that's making low-cost batteries for large-scale electricity storage, has selected a site for its first factory and says it's lined up the financing it needs to build it.

The company hopes its novel battery technology could allow some of the world's 1.4 billion people without electricity to get power without having to hook up to the grid.

The site for Aquion's factory is a sprawling former Sony television factory near Pittsburgh. The initial production capacity will be "hundreds" of megawatt-hours of batteries per year—the company doesn't want to be specific yet. It also isn't saying how much funding it's raised or where the money comes from, except to mention that some of it comes from the state of Pennsylvania, and that $5 million, in the form of an R&D grant, comes from the federal government.

The first applications are expected to be in countries like India, where hundreds of millions of people in communities outside major cities don't have a connection to the electrical grid or any other reliable source of electricity. Most of these communities use diesel generators for power, but high prices for oil and low prices for solar panels are making it cheaper to install solar in some cases.

To store power generated during the day for use at night, these communities need battery systems that can handle anything from tens of kilowatt-hours to a few megawatt-hours, says Scott Pearson, Aquion's CEO. Such a system could make long-distance transmission lines unnecessary, in much the same way that cell-phone towers have allowed such communities access to cellular service before they had land lines.

Eventually Aquion plans to sell stacks of batteries in countries that have electrical grids. They could provide power during times of peak demand and make up for fluctuations in power that big wind farms and solar power plants contribute to the grid. Those applications require tens to hundreds of gigawatt-hours' worth of storage, so to supply them, Aquion needs to increase its manufacturing capacity. Competing with natural-gas power plants—especially in the United States, where natural gas is so cheap—will mean waiting until economies of scale bring costs down.

The company has said that it initially hopes to make batteries for under $300 per kilowatt-hour, far cheaper than conventional lithium-ion batteries. Lead-acid batteries can be cheaper than Aquion's, but they last only two or three years. Aquion's batteries, which can be recharged 5,000 times, could last for over a decade in situations in which they're charged once a day (the company has tested the batteries for a couple of years so far).
To read more click here...

New laser can point the way to new energy harvesting

Engineerblogger
Feb 29, 2012

Ismael Heisler next to a diffractive optic polarisation spectrometer. Credit: EPRSC

New ultrafast laser equipment, capable of generating intense pulses of light as short as a few femtoseconds from the UV to the Infra Red, will help scientists at the University of East Anglia (UEA) measure how energy is transferred from molecule to molecule and point the way to molecular structures for exploiting solar radiation.

Funded by a £466,000 grant from the Engineering and Physical Sciences Research Council, the new laser will be used for 2D electronic spectroscopy experiments that look at the very fastest reactions. By studying how energy transfers in natural and artificial systems such as proteins and molecular materials, researchers will in turn be able to help the design of new nanomachines and solar power collectors.

Steve Meech, Professor of Chemistry at UEA’s said:

"With this equipment we will be able to develop experiments which probe in exquisite detail the link between the efficiency of light driven processes in natural and synthetic systems and the underlying molecular architecture."

2D electronic spectroscopy is in many ways analogous to the much better known 2D Nuclear Magnetic Resonance method. It uses ultra fast visible light pulses to reveal coupling between electronic states whereas NMR uses radio frequency pulses to measure couplings between nuclear spins.

Twenty years ago most ultrafast experiments relied upon amplified dye lasers. These difficult to use and unstable devices severely limited the range of experiments possible. Starting with the discovery of the Titanium Sapphire laser, a whole new family of experiments became possible.

"It is because of the amazing stability and reliability of these modern devices that we can even consider 2D optical experiments, which may take days to run", added Meech.

Lesley Thompson, EPSRC’s Director of Research Base, said:

"The grant for equipment made by our strategic equipment panel will give UEA the tools they need, but EPSRC has also allocated a further £613,000 for staff and collaborations to drive this research forward."

The announcement coincides with the inaugural lecture by Professor Alf Adams at the Royal Society in London, to mark the 25th anniversary of his work on strained quantum well lasers, recently named as one of the Top Ten greatest UK scientific breakthroughs of all time.

The lecture, entitled Semiconductor Lasers TakeThe Strain, is the first in a series named in his honour.

Source: Engineering and Physical Sciences Research Council (EPSRC)

How to measure solar cell efficiency correctly

Engineerblogger
Feb 29, 2012

Photographs of liquid electrolyte-based dye-sensitised solar cells with different masking configurations, including no mask and set on its side. The active area of None is taken to be the area of the screen printed dye-sensitised TiO2 dot, Mask and Mask + Edge are taken to be the area of the square mask aperture and Side-on is the same as None

The significance of new solar cell technologies tends to rest heavily on their measured efficiency. But compounding small mistakes in measuring that efficiency can lead to values up to five times higher than the true reading, says Henry Snaith from the University of Oxford, UK.

Snaith has therefore set out a guide that illustrates the factors that should be taken into consideration when measuring efficiency, and outlines the potential sources of error. It is an attempt to restore confidence in literature claims and make them more easily comparable - both within fields and across different types of cells including dye-sensitised solar cells (DSSCs), organic photovoltaics and hybrid solar cells. The guidance includes how to mask cells to get an accurate measure of the test area; the type of lamps to use and how to calibrate them; and the importance of positioning the cell in exactly the same place as the calibration reference.

'There's an ongoing stream of papers in which it's not entirely clear exactly how the measurements have been made,' says Snaith. And worse than that, some papers claim values that appear to be grossly overinflated. That has an impact on genuine claims, Snaith explains. 'If, for example, someone claims their hybrid solar cell has an efficiency of 4% when it's really more like 1%, that makes it problematic for someone else to write an exciting paper when they've genuinely improved something to 1.5%.'

However, Snaith is quick to point out that his intention is not to point the finger of blame. 'The field has grown rapidly, so there are a lot of people coming in - without much device experience - who want to be able to make a solar cell and test it to see if their systems have made improvements,' he adds. This influx brings new ideas and approaches, which is definitely to be encouraged. Unfortunately, there are some easy-to-make mistakes that can have drastic effects on measurements. 'There's nothing particularly new or complex in the paper - the idea is to provide a clear protocol for how to get a value that accurately reflects the efficiency of the solar cell, and to point out the common pitfalls that can occur.'

Nicolas Tétreault, who develops DSSCs at the Swiss Federal Polytechnic School in Lausanne, agrees that having a single reference point for best practice will be very useful, especially one showing the possibility of such huge variations and illustrating how they relate to what's going on in the cell. 'One of the benefits of showing these extremes is that it shows that the consequence of not doing it correctly can introduce errors that border on cheating!' Tétreault adds that accurate measurements are even more important when trying to claim a new efficiency record. Snaith agrees, although in that case, he says, measurements should be independently certified by one of the national laboratories such as the US National Renewable Energy Laboratory.

Source: Royal Society of Chemistry - Chemistry World


Additional Information:

• H J Snaith, Energy Environ. Sci., 2012, "How should you measure your excitonic solar cells?"
  

New energy storage device based on water: Solution for increasing energy demand

Engineerblogger
Feb 27, 2012

Semiconductor and Energy Conversion”-group (pictured left to right): Alberto Battistel (Ph.D. Student), Dr. Edyta Madej (PostDoc), Dr. Fabio La Mantia (Junior Group Leader), Dr. Jelena Stojadinovic (PostDoc), Mu Fan (Ph.D. Student)

The global energy demand is still increasing. However, today's concepts for power generation aren't able to deliver the amount of electricity, which is needed in the future. Dr. Fabio La Mantia, junior group leader of the “Semiconductor and Energy Conversion”-group (Center for Electrochemical Sciences) of the Ruhr-Universität Bochum, is working on a solution for the problem. In March he and his team are going to start a project, with the ambition to develop an aqueous lithium-ion battery. They want to produce an accumulator, which is working at two volt with a three times decreased cost, compared to conventional ones. The Federal Ministry of Education and Research is going to support the project with 1.424.000 Euro for a duration of five years.

Renewable energies fall short

The current world-wide consumption is predicted by experts to rise up from 13 to 25 terawatt by 2050. Renewable energies are only able to supply ten percent of the need, because they are expensive and not always available in the same extent. This applies especially for solar and wind energy. “Fast and economical systems, to cache the current, are in demand”, explains La Mantia. The idea is to produce batteries, which are appropriate for the application in the power grid.

Higher performance and lifespan

General lithium-ion batteries are based on organic solvents. They are the standard for all portable devices. However, for the use in power supply systems, they are too expensive and unsafe. They overheat too quickly, which can cause short circuits. To improve the performance, lifespan, energy density and the price-performance ratio, the young scientists concentrate themselves on the combination of appropriate materials, separators, cells and aqueous electrolytes (liquid conductor of electricity).

Source: Ruhr-University Bochum

Reduction in U.S. carbon emissions attributed to cheaper natural gas

Harvard University
Feb 27, 2012

Changes in carbon dioxide emissions from the power sector in the nine census regions of the contiguous United States, 2008-2009. Image courtesy of Xi Lu.

In 2009, when the United States fell into economic recession, greenhouse gas emissions also fell, by 6.59 percent relative to 2008.

In the power sector, however, the recession was not the main cause.

Researchers at the Harvard School of Engineering and Applied Sciences (SEAS) have shown that the primary explanation for the reduction in CO2 emissions from power generation that year was that a decrease in the price of natural gas reduced the industry's reliance on coal.

According to their econometric model, emissions could be cut further by the introduction of a carbon tax, with negligible impact on the price of electricity for consumers.

A regional analysis, assessing the long-term implications for energy investment and policy, appears in the journal Environmental Science and Technology.

In the United States, the power sector is responsible for 40 percent of all carbon emissions. In 2009, CO2 emissions from power generation dropped by 8.76 percent. The researchers attribute that change to the new abundance of cheap natural gas.

"Generating 1 kilowatt-hour of electricity from coal releases twice as much CO2 to the atmosphere as generating the same amount from natural gas, so a slight shift in the relative prices of coal and natural gas can result in a sharp drop in carbon emissions," explains Michael B. McElroy, Gilbert Butler Professor of Environmental Studies at SEAS, who led the study.

"That's what we saw in 2009," he says, "and we may well see it again."

Patterns of electricity generation, use, and pricing vary widely across the United States. In parts of the Midwest, for instance, almost half of the available power plants (by capacity) were built to process coal. Electricity production can only switch over to natural gas to the extent that gas-fired plants are available to meet the demand. By contrast, the Pacific states and New England barely rely on coal, so price differences there might make less of an impact.

To account for the many variables, McElroy and his colleagues at SEAS developed a model that considers nine regions separately.
To read more click here...

Mechanism Behind Capacitor’s High-Speed Energy Storage Discovered

Engineerblogger
Feb 27, 2012

Researchers at North Carolina State University have discovered the means by which a polymer known as PVDF enables capacitors to store and release large amounts of energy quickly. Their findings could lead to much more powerful and efficient electric cars.

Capacitors are like batteries in that they store and release energy. However, capacitors use separated electrical charges, rather than chemical reactions, to store energy. The charged particles enable energy to be stored and released very quickly. Imagine an electric vehicle that can accelerate from zero to 60 miles per hour at the same rate as a gasoline-powered sports car. There are no batteries that can power that type of acceleration because they release their energy too slowly. Capacitors, however, could be up to the job – if they contained the right materials.

NC State physicist Dr. Vivek Ranjan had previously found that capacitors which contained the polymer polyvinylidene fluoride, or PVDF, in combination with another polymer called CTFE, were able to store up to seven times more energy than those currently in use.

“We knew that this material makes an efficient capacitor, but wanted to understand the mechanism behind its storage capabilities,” Ranjan says.

In research published in Physical Review Letters, Ranjan, fellow NC State physicist Dr. Jerzy Bernholc and Dr. Marco Buongiorno-Nardelli from the University of North Texas, did computer simulations to see how the atomic structure within the polymer changed when an electric field was applied. Applying an electric field to the polymer causes atoms within it to polarize, which enables the capacitor to store and release energy quickly. They found that when an electrical field was applied to the PVDF mixture, the atoms performed a synchronized dance, flipping from a non-polar to a polar state simultaneously, and requiring a very small electrical charge to do so.

“Usually when materials change from a polar to non-polar state it’s a chain reaction – starting in one place and then moving outward,” Ranjan explains. “In terms of creating an efficient capacitor, this type of movement doesn’t work well – it requires a large amount of energy to get the atoms to switch phases, and you don’t get out much more energy than you put into the system.

“In the case of the PVDF mixture, the atoms change their state all at once, which means that you get a large amount of energy out of the system at very little cost in terms of what you need to put into it. Hopefully these findings will bring us even closer to developing capacitors that will give electric vehicles the same acceleration capabilities as gasoline engines.”

Source: North Carolina State University

Additional Information:

• The abstract "Electric Field Induced Phase Transitions in Polymers: A Novel Mechanism for High Speed Energy Storage" published on February 23, 2012 in the American Physical Society (APS)

Aircraft of the future could capture and re-use some of their own power

Engineerblogger
Feb 25, 2012

Credit: Lincoln University

Tomorrow's aircraft could contribute to their power needs by harnessing energy from the wheel rotation of their landing gear to generate electricity, according to research by the University of Lincoln.

Planes could use this to power their taxiing to and from airport buildings, reducing the need to use their jet engines. This would save on aviation fuel, cut emissions and reduce noise pollution at airports.

The feasibility of this has been confirmed by a team of engineers from the University of Lincoln with funding from the Engineering and Physical Sciences Research Council (EPSRC).

The energy produced by a plane's braking system during landing – currently wasted as heat produced by friction in the aircraft's disc brakes - would be captured and converted into electricity by motor-generators built into the landing gear. The electricity would then be stored and supplied to the in-hub motors in the wheels of the plane when it needed to taxi.

'Engine-less taxiing' could therefore become a reality. ACARE (the Advisory Council for Aeronautics Research in Europe) has made engine-less taxiing one of the key objectives beyond 2020 for the European aviation industry.

"Taxiing is a highly fuel-inefficient part of any trip by plane with emissions and noise pollution caused by jet engines being a huge issue for airports all over the world," said Professor Paul Stewart, who led the research.
"If the next generation of aircraft that emerges over the next 15 to 20 years could incorporate this kind of technology, it would deliver enormous benefits, especially for people living near airports. Currently, commercial aircraft spend a lot of time on the ground with their noisy jet engines running. In the future this technology could significantly reduce the need to do that."

The University of Lincoln's research formed part of a project that aimed to assess the basic feasibility of as many ways of capturing energy from a landing aircraft as possible.

"When an Airbus 320 lands, for example, a combination of its weight and speed gives it around three megawatts peak available power," Professor Stewart explained. "We explored a wide variety of ways of harnessing that energy, such as generating electricity from the interaction between copper coils embedded in the runway and magnets attached to the underside of the aircraft, and then feeding the power produced into the local electricity grid."

Unfortunately, most of the ideas weren't technically feasible or simply wouldn't be cost-effective. But the study showed that capturing energy direct from a plane's landing gear and recycling it for the aircraft's own use really could work, particularly if integrated with new technologies emerging from current research related to the more-electric or all-electric aircraft.

A number of technical challenges would need to be overcome. For example, weight would be a key issue, so a way of minimising the amount of conductors and electronic power converters used in an on-board energy recovery system would need to be identified.

The project was carried out under the auspices of the EPSRC-funded Airport Energy Technologies Network (AETN) established in 2008 to undertake low-carbon research in the field of aviation, and was undertaken in collaboration with researchers at the University of Loughborough.

Source: Lincoln University

SPIDERS microgrid project secures military installations

Engineerblogger
Feb 23, 2012

Bill Waugaman is the SPIDERS operational lead at Sandia National Laboratories. Credit: Randy Montoya

When the lights go out, most of us find flashlights, dig out board games and wait for the power to come back. But that’s not an option for hospitals and military installations, where lives are on the line. Power outages can have disastrous consequences for such critical organizations, and it’s especially unsettling that they rely on the nation’s aging, fragile and fossil-fuel dependent grid.

A three-phase, $30 million, multi-agency project known as SPIDERS, or the Smart Power Infrastructure Demonstration for Energy Reliability and Security, is focused on lessening those risks by building smarter, more secure and robust microgrids that incorporate renewable energy sources.

Sandia was selected as the lead designer for SPIDERS, the first major project under a Memorandum of Understanding (MOU) signed by the Department of Energy (DOE) and the Department of Defense (DoD) to accelerate joint innovations in clean energy and national energy security. The effort builds on Sandia’s decade of experience with microgrids – localized, closed-circuit grids that both generate and consume power – that can be run connected to or independent of the larger utility grid.

The goal for SPIDERS microgrid technology is to provide secure control of on-base generation.

“If there is a disruption to the commercial utility power grid, a secure microgrid can isolate from the grid and provide backup power to ensure continuity of mission-critical loads. The microgrid can allow time for the commercial utility to restore service and coordinate reconnection when service is stabilized,” said Col. Nancy Grandy, oversight executive of the SPIDERS Joint Capability Technology Demonstration (JCTD). “This capability provides much-needed energy security for our vital military missions.”

SPIDERS is addressing the challenge of tying intermittent clean energy sources such as solar and wind to a grid. “People run single diesel generators all the time to support buildings, but they don’t run interconnected diesels with solar, hydrogen fuel cells and so on, as a significant energy source. It’s not completely unheard of, but it’s a real integration challenge,” said Jason Stamp, Sandia’s lead project engineer for SPIDERS.

Currently, when power is disrupted at a military base, individual buildings switch to backup diesel generators, but that approach has several limitations. Generators might fail to start, and if a building’s backup power system doesn’t start, there is no way to use power from another building’s generator. Most generators are oversized for the load and run at less-than-optimal capacity, and excess fuel is consumed. Furthermore, safety requirements state that all renewable energy sources on base must disconnect when off-site power is lost.

A smart, cybersecure microgrid addresses these issues by allowing renewable energy sources to stay connected and run in coordination with diesel generators, which can all be brought online as needed. Such a system would dramatically help the military increase power reliability, lessen its need for diesel fuel and reduce its “carbon bootprint.”

“The military has indicated it wants to be protected against disruptions, to integrate renewable energy sources and to reduce petroleum demand,” Stamp said. “SPIDERS is focused on accomplishing those tasks, and the end result is having better energy delivery for critical mission support, and that is important for every American.”

SPIDERS uses existing, commercially available technologies for implementation, so the individual technologies are not novel. “What’s novel is the system integration of the various technologies, and demonstrating them in an operational field environment. Microgrid concepts are still fairly new, and that’s where Sandia’s microgrid design expertise is coming into play,” said Sandia researcher Bill Waugaman, SPIDERS operational lead.

It is common practice to connect diesel generators to buildings, but integrating significant amounts of energy from intermittent clean sources such as solar and wind to that system is unique, and it is a challenge that Sandia and SPIDERS are working to address.

Such integration requires data to determine the most efficient and effective way to operate, but that can open system vulnerabilities, so cybersecurity is paramount. SPIDERS addresses that issue by incorporating an unprecedented level of cybersecurity into the system from the outset.

“Any perturbation of information flow by an adversary would possibly cause an interruption to electrical service, which can have significant consequences,” Stamp said. “It’s important that if we build a microgrid system that depends explicitly on greater information flow, that it operate as intended: reliably and securely.”

SPIDERS is funded and managed through the DoD’s JCTD, which joins the efforts of other government organizations and companies to rapidly develop, assess and transition needed capabilities to support DoD missions. With the DOE’s support, the SPIDERS transition plan includes civilian facilities.

“The SPIDERS approach has many applications beyond military uses. Our interest in SPIDERS extends to organizations, like hospitals, that are critical to our nation’s functionality, especially in times of emergency,” said Merrill Smith, DOE program manager.

Sandia’s microgrid expertise spans the past decade, beginning when Sandia designed microgrids for the DOE’s Federal Energy Management Program (FEMP) and the DOE’s Office of Electricity Delivery and Energy Reliability (OE). The DOE initially asked Sandia to develop a conceptual design for a microgrid at Fort Carson in Colorado Springs, Colo., and another for Camp H.M. Smith in Hawaii.

After Sandia conducted a feasibility analysis and modeling and simulation work for the two bases, U.S. Pacific Command (USPACOM) and U.S. Northern Command (USNORTHCOM) asked Sandia to prove the concept through field work under a JCTD. The two commands pulled together a team of national labs and defense organizations, and selected Sandia to lead the development of the initial designs for three separate microgrids, each more complex than the previous.

The Army Construction Engineering Research Laboratory will use the Sandia designs as a basis for developing contracts with potential system integrators, who will construct the actual microgrids. Other partners in the SPIDERS JCTD include National Renewable Energy Laboratory for renewable energy and electrical vehicle expertise, Pacific Northwest National Laboratory for testing and transition, Oak Ridge National Laboratory to assist with control system development and Idaho National Laboratory for cybersecurity.

The first SPIDERS microgrid will be implemented at Joint Base Pearl Harbor Hickam in Honolulu, and will take advantage of several existing generation assets, including a 146-kW photovoltaic solar power system, and up to 50 kW of wind power. The integrator for the project has been selected and the final design and construction process is underway.

The second installation, at Fort Carson, is much larger and more complex and will integrate an existing 2 MW of solar power, several large diesel generators and electric vehicles. Large-scale electrical energy storage will also be implemented to ensure microgrid stability and to reduce the effects of PV variability on the system. Camp H.M. Smith, the most ambitious project, will rely on solar and diesel generators to power the entire base, which will be its own self-sufficient 5 MW microgrid when the national grid is unavailable.

Integration and implementation are scheduled through 2014. The goal is to install the circuit level demonstration at Pearl Hickam and Fort Carson next year, with Camp Smith installed in 2013.

Source: Sandia National Laboratories