New device to generate electricity from human breathing

A simulated lung with the piezoelectric PVDF microband (in yellow) that vibrates as air flows past it 
One of the biggest hurdles facing the developers of biological implants is coming up with a power source to keep the implanted devices ticking. We've seen various technologies that could be used instead of traditional batteries (which require the patient to go under the knife so they can be replaced) such as wireless transmission of power from outside the body, biological fuel cells that generate electricity from a person's blood sugar, and piezoelectric devices that generate electricity from body movements or the beating of the heart. Now researchers have developed a device that could be used to generate electricity from a patient's breathing.
The device created by researchers at the University of Wisconsin-Madison relies on the piezoelectric effect - whereby an electrical charge accumulates in certain materials in response to mechanical stress. But instead of relying on body movements to create the mechanical stress, the UW-Madison team's device uses low speed airflow like that caused by normal human respiration to cause the vibration of a plastic microbelt engineered from a piezoelectric material called polyvinylidene fluoride (PVDF).
"Basically, we are harvesting mechanical energy from biological systems. The airflow of normal human respiration is typically below about two meters per second," says Materials Science and Engineering Assistant Professor Xudong Wang who created the device along with postdoctoral researcher Chengliang Sun and graduate student Jian Shi. "We calculated that if we could make this material thin enough, small vibrations could produce a microwatt of electrical energy that could be useful for sensors or other devices implanted in the face," said Wang.

To thin the PVDF material to micrometer scale while preserving its piezoelectric properties, Wang's team used an ion-etching process. Wang believes that, with improvements, the thickness of the material, which is biocompatible, can be controlled down to the submicron level and lead to the development of a practical micro-scale device that could harvest energy from the airflow in a person's nose.
Tests conducted by the team saw the device reach power levels in the millivolt range, but reached up to 6 volts with maximum airflow speeds. Wang and the UW-Madison team now plan to look for ways to improve the efficiency of the device. The team's research appears in the September issue of Energy and Environmental Science.

New material claimed to store more energy and cost less money than batteries

The low-cost, high-density energy-storage membrane, created at the National University of Singapore

Researchers from the National University of Singapore's Nanoscience and Nanotechnology Initiative (NUSNNI) have created what they claim is the world's first energy-storage membrane. Not only is the material soft and foldable, but it doesn't incorporate liquid electrolytes that can spill out if it's damaged, it's more cost-effective than capacitors or traditional batteries, and it's reportedly capable of storing more energy.
The membrane is made from a polystyrene-based polymer, which is sandwiched between two metal plates. When charged by those plates, it can store the energy at a rate of 0.2 farads per square centimeter - standard capacitors, by contrast, can typically only manage an upper limit of 1 microfarad per square centimeter.
Due in part to the membrane's low fabrication costs, the cost of storing energy in it reportedly works out to 72 cents US per farad. According to the researchers, the cost for standard liquid electrolyte-based batteries is more like US$7 per farad. This in turn translates to an energy cost of 2.5 watt-hours per US dollar for lithium-ion batteries, whereas the membrane comes in at 10-20 watt-hours per dollar.
Details on how the material works, along with data on factors such as charging/discharging times and longevity have not yet been released. Principle investigator Dr. Xie Xian Ning, however, has stated "The performance of the membrane surpasses those of rechargeable batteries, such as lithium ion and lead-acid batteries, and supercapacitors."
The NUSNNI team is now looking into opportunities for commercializing the technology.

Edible sponge captures and stores carbon dioxide

The Northwestern filter changes color when full of carbon dioxide, then changes back after being emptied

As concerns continue to rise over man-made carbon dioxide entering the atmosphere, various groups of scientists have begun developing filters that could remove some or all of the CO2 content from smokestack emissions. Many of these sponge-like filters incorporate porous crystals known as metal-organic frameworks (MOFs). Unfortunately, most MOFs are derived from crude oil, plus some of them contain toxic heavy metals. Researchers from Illinois' Northwestern University, however, recently announced that their nontoxic MOF sponge - made from sugar, salt and alcohol - is fully capable of capturing and storing CO2. As an added bonus, should you be really hungry, you can eat the thing.
The main ingredient in the edible MOF is gamma-cyclodextrin, which is a biorenewable naturally-occurring sugar derived from corn starch. Metals taken from salts such as potassium benzoate and rubidium hydroxide hold the sugar molecules in place, those molecules' precise arrangement within the crystals being essential to the capture of CO2.
"It turns out that a fairly unexpected event occurs when you put that many sugars next to each other in an alkaline environment - they start reacting with carbon dioxide in a process akin to carbon fixation, which is how sugars are made in the first place," said postdoctoral fellow Jeremiah J. Gassensmith. "The reaction leads to the carbon dioxide being tightly bound inside the crystals, but we can still recover it at a later date very simply."
Not only can the filters be emptied of CO2 and reused, but they also have a way of letting people know when they can't hold any more. Each crystal has an indicator molecule placed inside of it, which changes color according to the surrounding pH. When the whole sponge changes from yellow to red, that means that it has reached capacity. After being emptied, its color returns to yellow.
The Northwestern research was recently published in the Journal of the American Chemical Society.

Researchers turn wastewater into “inexhaustible” source of hydrogen

Penn State researchers have developed an electrolysis cell with RED stack that produces pure hydrogen from waste water
Currently, the world economy and western society in general runs on fossil fuels. We've known for some time that this reliance on finite resources that are polluting the planet is unsustainable in the long term. This has led to the search for alternatives and hydrogen is one of the leading contenders. One of the problems is that hydrogen is an energy carrier, rather than an energy source. Pure hydrogen doesn't occur naturally and it takes energy - usually generated by fossil fuels - to manufacture it. Now researchers at Pennsylvania State University have developed a way to produce hydrogen that uses no grid electricity and is carbon neutral and could be used anyplace that there is wastewater near sea water.
The researchers' work revolves around microbial electrolysis cells (MECs) - a technology related to microbial fuel cells (MFCs), which produce an electric current from the microbial decomposition of organic compounds. MECs partially reverse this process to generate hydrogen (or methane) from organic material but they require the some electrical input to do so.
Instead of relying on the grid to provide the electricity required for their MECs, Bruce E. Logan, Kappe Professor of Environmental Engineering, and postdoctoral fellow Younggy Kim, turned to reverse-electrodialysis (RED). We've previously looked at efforts to use RED to generate electricity using salt water from the North Sea and fresh water from the Rhine and the Penn State team's work follows the same principle - extracting energy from the ionic differences between salt water and fresh water.

A RED stack consists of alternating positive and negative ion exchange membranes, with each RED contributing additively to the electrical output. Logan says that using RED stacks to generate electricity has been proposed before but, because they are trying to drive an unfavorable reaction, many membrane pairs are required. To split water into hydrogen and oxygen using RED technology requires 1.8 volts, which would require about 25 pairs of membranes, resulting in increased pumping resistance.
But by combining RED technology with exoelectrogenic bacteria - bacteria that consume organic material and produce an electric current - the researchers were able to reduce the number of RED stacks required to five membrane pairs.
Previous work with MECs showed that, by themselves, they could produce about 0.3 volts of electricity, but not the 0.414 volts needed to generate hydrogen in these fuel cells. Adding less than 0.2 volts of outside electricity released the hydrogen. Now, by incorporating 11 membranes - five membrane pairs that produce about 0.5 volts - the cells produce hydrogen.
"The added voltage that we need is a lot less than the 1.8 volts necessary to hydrolyze water," said Logan. "Biodegradable liquids and cellulose waste are abundant and with no energy in and hydrogen out we can get rid of wastewater and by-products. This could be an inexhaustible source of energy."
While Logan and Kim used platinum as the catalyst on the cathode in their initial experiments, subsequent experimentation showed that a non-precious metal catalyst, molybdenum sulfide, had 51 percent energy efficiency.
The Penn State researchers say their results, which are published in the Sept. 19 issue of the Proceedings of the National Academy of Sciences, "show that pure hydrogen gas can efficiently be produced from virtually limitless supplies of seawater and river water and biodegradable organic matter."

Carbon nanotube-reinforced polyurethane could make for bigger and better wind turbines

Carbon nanotube-reinforced polyurethane could make for lighter and more durable wind turbine blades
In the effort to capture more energy from the wind, the blades of wind turbines have become bigger and bigger to the point where the diameter of the rotors can be over 100 m (328 ft). Although larger blades cover a larger area, they are also heavier, which means more wind is needed to turn the rotor. The ideal combination would be blades that are not only bigger, but also lighter and more durable. A researcher at Case Western Reserve University has built a prototype blade from materials that could provide just such a winning combination.
The new blade developed by Marcio Loos, a post-doctoral researcher in the Department of Macromolecular Science and Engineering, is the world's first polyurethane blade reinforced with carbon nanotubes. Using a small commercial blade as a template, Loos manufactured a 29-inch (73.6 cm) blade that is substantially lighter, more rigid and tougher than conventional blades. Rigidity is important because as a blade flexes in the wind it loses the optimal shape for catching air, so less energy is captured.
Working with colleagues at Case Western Reserve, and investigators from Bayer Material Science in Pittsburgh, and Molded Fiber Glass Co. in Ashtabula, Ohio, Loos compared the properties of the new materials with that of conventional blades manufactured using fiberglass resin.
"Results of mechanical testing for the carbon nanotube reinforced polyurethane show that this material outperforms the currently used resins for wind blades applications," said Ica Manas-Zloczower, professor of macromolecular science and engineering and associate dean in the Case School of Engineering.

Comparing reinforcing materials, the researchers found that the carbon nanotubes are lighter per unit of volume than carbon fiber and aluminum and had five times the tensile strength of carbon fiber and more than 60 times that of aluminum.
Meanwhile, fatigue testing showed the reinforced polyurethane composite lasts about eight times longer than epoxy reinforced with fiberglass, while delamination fracture tests showed it was also about eight times tougher. The performance of the material was even better when compared against vinyl ester reinforced with fiberglass, another material used to make wind turbine blades. Fracture growth rates were also a fraction of that found for traditional epoxy and vinyl ester composites.
Loos and her team are now working to determine the optimal conditions for the dispersion of the nanotubes, the ideal distribution within the polyurethane and the ways to achieve both.

Scientists claim that cars could run on old newspapers

Tulane associate professor David Mullin (right), postdoctoral fellow Harshad Velankar (center), and undergraduate student Hailee Rask have discovered a bacteria that converts the cellulose in newspapers to biofue
Hopefully, your old newspapers don't just end up in the landfill. In the future, however, they might not even be used to make more paper - instead they may be the feedstock for a biofuel-producing strain of bacteria. Named "TU-103," the microorganism was recently discovered by a team of scientists at New Orleans' Tulane University. It converts cellulose - such as that found in newspapers - into butanol, which can be substituted for gasoline.
"Cellulose is found in all green plants, and is the most abundant organic material on earth, and converting it into butanol is the dream of many," said team member Harshad Velankar. "In the United States alone, at least 323 million tons [293 million tonnes] of cellulosic materials that could be used to produce butanol are thrown out each year."
The scientists first discovered TU-103 in animal feces, and have since cultivated it, and developed a patent-pending process that allows it to produce butanol from cellulose. In their lab, they have had success using newspapers as the cellulose source. While other bacteria have been found to produce butanol in the past, they have all required an oxygen-free environment, which increases production costs. TU-103, on the other hand, is able to survive and function in the presence of oxygen.
Although ethanol is also derived from cellulose, butanol is reportedly superior to that biofuel in several ways - it can be used as is in all unmodified automobile engines, it can be pumped through existing pipelines, it is less corrosive, and it contains more energy.
"This discovery could reduce the cost to produce bio-butanol," said David Mullin, whose lab in Tulane's Department of Cell and Molecular Biology was the location of the research. "In addition to possible  savings on the price per gallon, as a fuel, bio-butanol produced from cellulose would dramatically reduce carbon dioxide and smog emissions in comparison to gasoline, and have a positive impact on landfill waste."

In-shoe device harvests energy created by walking

A new in-shoe device is designed to harvest the energy that is created by walking, and store it for use in mobile electronic devices


Although you may not be using a Get Smart-style shoe phone anytime soon, it is possible that your mobile phone may end up receiving its power from your shoes. University of Wisconsin-Madison engineering researchers Tom Krupenkin and J. Ashley Taylor have developed an in-shoe system that harvests the energy generated by walking. Currently, this energy is lost as heat. With their technology, however, they claim that up to 20 watts of electricity could be generated, and stored in an incorporated rechargeable battery.


While the details of the energy-harvesting technology are proprietary, it is said to involve a process known as "reverse electrowetting," which was discovered by Krupenkin and Taylor. It converts mechanical energy to electricity via a microfluidic device, in which thousands of moving microdroplets (of an undisclosed non-toxic, inexpensive liquid) interact with "a groundbreaking nanostructured substrate." The process is said to have a power density of up to one kilowatt per square meter (10.76 sq. ft.), plus it works with a wide range of mechanical forces, and is able to output a wide range of currents and voltages.

The battery is hermetically sealed, for protection against water and dirt. In order to get the power from it to the phone or other mobile device, the two would have to be temporarily physically joined with a wire, although the researchers are also looking into the use of conductive textiles and wireless inductive coupling.

Besides directly powering the phone, the device could also serve as a mobile WiFi hotspot, linking the phone to a wireless network. Having its own hotspot constantly nearby could drastically increase the phone's battery life - this is because the phone would only need to transmit in a low-power standard such as Bluetooth in order to reach the device, which would then use its own battery (which would be continuously getting recharged, by walking) for the high-power long-range transmissions to the network. Krupenkin claims that this could allow phone batteries to last up to ten times longer than normal.
The U Wisconsin technology is currently in the process of being commercialized, through Krupenkin and Taylor's company, InStep NanoPower. If it does make it to the marketplace, it may have some competition - Dr. Ville Kaajakari is also developing a piezoelectric device for shoes, that generates power as its user walks.

Paper mill waste recycled into foam

 

A new technology is able to convert paper mill waste into bio-foam
In a world increasingly concerned with waste, the smart manufacturers are identifying ways of utilizing the by-products of manufacturing and creating two products from one process. One example - a graduate student in agriculture at the Hebrew University of Jerusalem has developed a way of creating foam from the waste from paper mills, radically reducing waste from paper production and creating two products that are highly valuable and in demand.
In paper production, wood is chipped and mashed (mechanical pulping) or stewed in chemicals (chemical pulping) to separate the fibers in a water-intensive process. The fiber slush is then sprayed onto a continuously-moving mesh, the dimensions of which dictate the retention of fibers. While larger fibers are squeezed into paper, almost 50 percent of the finer fibers and water fall away to form a waste by-product that up till now has been wasted in millions of tons annually.
Ph.D. student Shaul Lapidot and his laboratory colleagues at the Robert H. Smith Faculty of Agriculture, Food and Environment of the Hebrew University in Rehovot found that the waste finer fibers are a perfect feed-stock for nano-crystalline cellulose (NCC). This can be formed using relatively low energy and chemical input compared to paper-making itself. Furthermore, they developed a technique to process the NCC into composite foams.
These bio-foams in their virgin state are lightweight and highly porous, but with the addition of furan resin (a hemicellulose-based resin from raw crop waste from sugar cane, oat and rice hulls, and corn cobs), the foam is strengthened into something that rivals high-end synthetic foams currently on the market.
Foam is an under-appreciated product, valued for its high strength, weight reduction, energy dissipation and insulation. Commonly thought of as a packaging product, it in fact plays an inconspicuous role as a sandwich product in a host of everyday items such as furniture, cars, and insulation. It is conventionally manufactured using oil-based polymers such as polyurethane, polystyrene, polyvinyl chloride (PVC) and polyethylene terephthalate (PET). The discovery and development of a new industrial foam from renewable resources represents an exciting opportunity.
Lapidot's research led to his being awarded of one of the Barenholz Prizes at the Hebrew University Board of Governors meeting. The technology has already been licensed by Melodea Ltd from Yissum, the technology transfer company of the Hebrew University. The bio-foam joins mushroom styrofoam, biodegradable milk and clay foam, and environmentally-friendly surfboard TufFoam on the wave of new foam alternatives.