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

Introducing plug-and-play nanoelectromechanical systems (NEMS)

Engineerblogger
March 8, 2012

Silicon nitride beam flanked by two gold electrodes.  Schematic illustration of the 55-µm long silicon nitride beam (green) flanked by two gold electrodes (yellow). Artwork by Christoph Hohmann, Nanosystems Initiative Munich (NIM).

The measurement of very low concentrations of various agents plays an important role in medicine, pharmacology and food technology. So-called “nanomechanical resonators” – vibrating nanostrings – represent promising candidates for suitable detectors, because their oscillating motion is extremely sensitive to the binding of substances of interest. In recent years scientists have refined these techniques to the point where single atoms can now be detected. These analyses, however, have their shortcomings. They tend to be time-consuming, require expensive instrumentation and frequently operate only at temperatures near absolute zero. Recently, a group of physicists at the LMU developed a compact sensor architecture on the nanometer scale, which is easy to handle and works at room temperature.

The group is led by Dr. Eva Weig, who is also a member of the Nanosystems Initiative Munich (NIM). The new work builds on their initial demonstration of an efficient electrical interface for nanomechanical resonators which was published in Nature in 2009. They now describe a fully integrated nanomechanical sensor platform that permits robust and sensitive detection of tiny displacements.

The most important part of the nanosensor is a thin beam of highly stressed silicon nitride, about 50 micrometers in length and 200 nanometers wide, suspended between two silica supports. The large pre-stress on this “nano guitar string” allows one to drive its resonant motion with low excitation energy and gives rise to a high mechanical quality factor. The beam is flanked on each side by slightly elevated, parallel gold electrodes. An electric voltage is applied to the two gold electrodes, which act as a capacitor. The resulting electric field couples to the resonator. In the preceding 2009 Nature publication, this effect was employed to control and drive the vibration of the beam. In the new work, it is utilized to sense its motion. The measurement scheme is based on a simple effect: when the nanobeam oscillates up and down within the electric field, the capacitance between the two electrodes varies slightly. In order to pick up this tiny signal, the scientists devised an elegant extension of the existing setup. They incorporated a so-called microwave cavity into the design, which allows them to detect even the thermal motion of the suspended nanobeam.
The microwave cavity can be described as an electrical circuit formed by an inductor and a capacitor, which is connected to the gold electrodes. It is powered by a microwave signal and transmits the combined response of nanobeam and microwave cavity. This effectively allows one to employ the microwave cavity as an amplifier to enhance the signal generated by the moving nanoresonator. The measurement scheme combines two major advantages. Besides considerably enhancing the sensitivity, the microwave cavity can be easily connected to a whole set of nanobeams, which dramatically simplifies operation.

“This will enable the development of highly integrated sensors in the future,” says Thomas Faust, who is first author of the publication. In addition, the scientists have also demonstrated a back-action of the microwave cavity field on the oscillation of the nanomechanical resonator. In this way it is possible to directly drive the resonator motion into self-oscillation and to narrow the width of the peak down to only a few Hz. This offers a means of further enhancing the sensitivity of any future sensor. Furthermore, this latest version of the device is much easier to utilize than other existing solutions. “You only need to connect two cables and, in principle, you can obtain the read-out from thousands of resonators at the touch of a button.” explains Eva Weig. Because the system is simple to operate and is not susceptible to external influences, the new method should be suitable for use even under the non-ideal conditions found outside physics labs. (bige, NIM)

The work has been funded by the German Research Foundation (DFG) and the FET-Open project QNEMS of the European Commission.

Source:  Nanosystems Initiative Munich

Additional Information:

• Microwave cavity-enhanced transduction for plug and play nanomechanics at room temperature. T. Faust, P. Krenn, S. Manus, J.P. Kotthaus, and E.M. Weig. Nature Communications

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Fuel cell technology could be under your car bonnet by 2017

Engineerblogger
March 8, 2012

Credit: Carbon Trust

Carbon Trust has given a £1m boost to four UK fuel cell pioneers. Their cutting-edge technology could be used under the bonnet of mass-produced hydrogen-powered cars as early as 2017. Major manufacturers have already built hydrogen-powered fuel cell cars, but the real challenge is to bring down the costs and, in the global race to do this, UK technologies are now in pole position.

Having identified an opportunity to combine innovative technology from Runcorn-based ACAL Energy and Sheffield-based ITM Power, the Carbon Trust is providing £500k of funding to the companies to develop a new hybrid high-power, low-cost fuel cell design.

Carbon Trust is also backing a project based at Imperial College London (Imperial) and University College London (UCL) with £500k to develop a fuel cell that could offer significant cost savings by using existing high-volume manufacturing techniques employed in the production of printed circuit boards.

The funding comes from the Carbon Trust’s Polymer Fuel Cells Challenge (PFCC) which was launched in 2009 to support the Department for Energy and Climate Change’s objectives to develop lower cost fuel cells and coincides with the recent launch of the Government’s UKH2Mobility project to ensure the UK is well positioned for the commercial roll-out of hydrogen fuel cell vehicles.

Dr Ben Graziano, Technology Commercialisation Manager at the Carbon Trust, said:

“The UK’s home-grown automotive industry hasn’t been the runaway success story many would have hoped for, but British technology is in pole position to be under the bonnet of a next generation of mass-produced hydrogen-powered cars. After a lot of hype, fuel cell technology is now a great growth opportunity for the UK. The funding that we have received from the Department for Energy and Climate Change has enabled us to support the development of some truly world-class British technologies that could slash the costs of fuel cells and transform how we all get about; by 2017 British fuel cell technologies could be powering your car.”

Simon Bourne, CTO, ITM Power Plc, said:

“The PFCC has afforded ITM the opportunity to build on its ground breaking laboratory results via a structured programme to de-risk its membrane technology. With the high level introductions the Carbon Trust has made with commercial end users and the continued success of subsequent material evaluation studies, ITM is in a very strong position to exploit this exciting new fuel cell technology.”

Amanda Lyne, VP of Strategic Business Development and Marketing, ACAL Energy Ltd said:

"It is excellent news that automotive OEMs are committed to the launch of hydrogen fuel cell electric vehicles in 2015 timescales, and that the UK will be among the early adopters. However it is clear that continuous efforts to reduce cost will be necessary to ensure that H2FC vehicles are affordable for mass markets. This funding from the Carbon Trust PFCC is perfectly targeted to ensure that British innovation can be at the forefront of the process to get the economics of the technology right."

Carbon Trust’s Polymer Fuel Cells Challenge aims to speed the UK towards world-beating fuel cell solutions that can grab a significant share of a market that the Carbon Trust has estimated to be worth $26bn in 2020. About the projects:

ACAL Energy/ITM Power

Carbon Trust, which has already supported ACAL Energy and ITM Power in de-risking their unique technologies, saw an opportunity to combine these innovations to demonstrate a fuel cell that could be far cheaper to manufacture, more efficient, produce the required power and be compact enough to fit under the bonnet of tomorrow’s cars. ACAL Energy brings a revolutionary new design of fuel cell inspired by the human lung and bloodstream that is highly durable, virtually platinum-free and also significantly cheaper to produce. ITM Power brings a unique membrane technology (which has been evaluated by several global companies), proven to produce world-beating power density (widely recognised as the single most important factor in reducing fuel cell costs), which could be in fuel cell cars by as early as 2017.

ITM’s current order book for delivery in the current financial year is £0.5m. The company has recruited seven staff in the last 12 months and is currently seeking to recruit ten more. ACAL Energy has raised £6.1m of investment since March 2010 and its staff is set to increase from 25 at that time to 35 by April 2012.

Imperial/UCL

The Imperial and UCL project is developing a fuel cell stack that could offer significant cost savings by using existing high-volume manufacturing techniques employed in the production of printed circuit boards. By simplifying the design and manufacture, this could reduce the costs of a fuel cell stack by more than 20%. Imperial Innovations and UCL Business are collaborating with the project to assist commercialisation of the technology.

Source:  Carbon Trust

Related Information:

• Fuel Cell

• Polymer Fuel Cells

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.

Exotic Material Shows Promise as Flexible, Transparent Electrode

Engineerblogger
March 8, 2012

An array of microcircuits made of a 10-nanometer-thick film of bismuth sulfide, an exotic material called a topological insulator, on an insulating mica substrate can be flexed without damaging its electrical properties.

Photo by Hailin Peng, Peking University.

An international team of scientists with roots at SLAC and Stanford has shown that ultra-thin sheets of an exotic material remain transparent and highly conductive even after being deeply flexed 1,000 times and folded and creased like a piece of paper.

The result could open this class of unusual materials, called topological insulators, to its first practical applications: flexible, transparent electrodes for solar cells, sensors and optical communications devices.

“It’s rare for a good conductor to be both transparent and durable as well,” said Zhi-Xun Shen of SLAC and Stanford’s Institute for Materials and Energy Sciences (SIMES).

Researchers led by Shen, Zhongfan Liu and Hailin Peng of Peking University in China, and Yulin Chen of Oxford University in England published their results last week in Nature Chemistry. Until recently, Peng and Chen were graduate students and postdoctoral researchers at Stanford and SIMES. They have continued to collaborate with Shen’s research team after being named professors at their current universities.

The researchers made and tested samples of a compound in which sheets of bismuth and selenium, each just one atom thick, alternate to form five-layer units. The bonds between the units are weak, allowing the overall material to flex while retaining its durability. And as a topological insulator – a new state of quantum matter – the material conducts electricity only on its surface while its interior remains insulating, an unexpected property with unknown potential for fundamental research and practical applications.

Since surface atoms dominate the structure of bismuth selenide, it is an exceptionally good electrical conductor – as good as gold. Unlike gold, however, bismuth selenide is transparent to infrared light, which we know as heat. While about half the solar energy that hits the Earth comes in the form of infrared light, few of today’s solar cells are able to collect it. The transparent electrodes on the surfaces of most cells are either too fragile or not transparent or conducting enough. The new material could get around that problem and allow cells to harvest more of the sun’s spectrum of wavelengths.

The researchers’ experiments also showed that bismuth selenide does not degrade significantly in humid environments or when exposed to oxygen treatments that are common in manufacturing.

“In addition to being a scientific success,” Chen said, “this demonstration should alert engineers and companies that topological insulators can also be important commercially.”

Peng added, “Infrared light pulses carry phone calls and data through optical fiber networks, so bismuth selenide may be useful in communications devices. This material could also improve infrared sensors common in scientific equipment and aerospace systems.”

Peng and colleagues made the bismuth selenide samples and conducted the flexing, conductivity and transparency tests in China. The researchers confirmed that the samples were topological insulators at the Stanford Synchrotron Radiation Lightsource’s Beam Line 5-4 at SLAC.

Theorists first proposed topological insulators in 2004, and experimentalists made the first examples, using mercury telluride at very low temperatures, two years later. Guided by theory, Chen, Shen and colleagues proved in 2009 that cheaper, more abundant and easier-to-handle bismuth telluride and similar compounds containing antimony and selenium are topological insulators at room temperature. Also in 2009, Peng, Shen and colleagues discovered important electrical conduction behavior in bismuth selenide nanoribbons.





Source:  SLAC National Accelerator Laboratory

Engineering research and development spurring U.S. toward energy security

Engineerblogger
March 8, 2012

Breakthroughs in engineering research and development have helped launch the U.S. on the path toward elusive energy independence, NPR reports.

With gas prices continuing to spike throughout the U.S, Americans have increasingly called on the Obama Administration to support policies that would bolster the nation's fuel production. While President Obama has publicly championed an "all of the above" energy strategy – one that promotes domestic drilling, improves fuel efficiency and develops alternative energy technologies – energy experts contend the U.S. has made significant strides over the past decade in reducing its reliance on foreign countries for oil, natural gas and other fossil fuels.

"Energy self-sufficiency is now in sight," energy economist Phil Verleger told the news provider.

Verleger and other experts assert that engineering tools and breakthroughs in industrial engineering research have helped augment oil and gas supplies in the U.S. He and other scientists contend that hydraulic fracturing – more commonly known as fracking – and other advanced drilling techniques have allowed the U.S. to tap into previously unattainable natural gas and oil reserves throughout the U.S.

Though fracking remains exceedingly controversial, such drilling wells have fueled U.S. natural gas production over the past few years, as companies have increasingly exploited resources in states such as Pennsylvania, West Virginia, North Dakota and Texas. Verleger said that the uptick in the nation's energy supplies results from the success of private research and development.

"This is really the classic success of American entrepreneurs," Verleger noted. "These were people who saw this coming, managed to assemble the capital and go ahead."

While the U.S. has historically relied upon other countries for the majority of its energy needs, it could become the world's largest producer of natural gas and oil by the end of the decade, according to PFC Energy chief executive Robin West.

"This shale gale, I describe it as the energy equivalent of the Berlin Wall coming down. This is a big deal," West said, referring to the widespread use of fracking and advanced drilling techniques. "We estimate that by 2020, the U.S. overall will be the largest hydrocarbon producer in the world; bigger than Russia or Saudi Arabia."

Though many experts caution against estimating when the U.S. will achieve the nebulous goal of energy independence, experts such as West and Verleger contend the uptick in domestic hydrocarbon production will ultimately increase energy security. If the U.S. continues on its current energy course, it would enable the country to reduce its reliance on unstable oil and natural gas producers in the Middle East, experts say.

Source: Knovel