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Researchers at Nanotek Instruments (USA), working in collaboration with scientists at Angstron Materials (USA) and Dalian University of Technology (China), have developed novel graphene electrodes for supercapacitors that could lead to capacitors with more than five times the energy density of currently available devices.

 

By using specially prepared crumpled sheets of graphene (carbon sheets only one atom thick), Nanotek increased the surface area of the electrodes so they could hold more charge. According to Nanotek's Bor Jang, lead author of a paper published in the online version of the journal Nano Letters, their aim is to bridge the energy density gap between capacitors and rechargeable batteries.

 

Tests with a coin-sized supercapacitor cell showed that the graphene electrodes could store 85.6 watt-hours of energy per kilogram. A practical device would therefore have an energy density of around 28 watt-hours per kilogram, since the electrodes typically account for one-third the weight of a capacitor. By comparison, current supercapacitors have energy densities of 5 to 10 watt-hours per kilogram, versus 40 to 100 watt-hours per kilogram for nickel metal hydride batteries and over 120 watt-hours per kilogram for lithium-ion batteries.

 

However, batteries are typically operated in the middle range of their full charge cycle, often using only about 20 to 50% of their total charge capacity. This means that supercapacitors with about 20% of the energy density of a rechargeable battery, but with short recharge time and almost unlimited lifetime, could be competitive in some applications. Furthermore, the chemical reactions that charge a battery take hours and degrade the electrodes after a few thousand cycles, while supercapacitors charge in minutes and can last millions of recharge cycles because they store charge electrostatically.

 

Image: Nano Letters

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Nanotek Instruments websiteNano Letters publication



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Microchip Technology and Cymbet have joined hands to offer the XLP 16-bit Energy Harvesting Development Kit, a customizable energy-harvesting application development kit with a modular development board.

Microchip’s contribution to the kit is the PIC24F16KA102 microcontroller, featuring eXtreme low power technology, along with support for PICtail daughter boards for rapid evaluation of a wide variety of system functions, including ZigBee, proprietary wireless connectivity and SD memory cards.
Cymbet contributes its EnerChip EH Eval-08 energy harvesting board, which harvests indoor or outdoor light energy and stores it in solid-state, thin-film EnerChip rechargeable energy storage devices. The EnerChips supply power to the XLP development board when light is not available.

The development board portion of the kit features the PIC24F16KA102 XLP MCU, on-board temperature sensors, data EEPROM, a potentiometer, watch crystal, LEDs, and an expansion connector for PICtail modules. Supported PICtails include RF, SD/MMC cards, speech playback and more.

Power condition and capacity are monitored by the PIC24F using Energy Aware software algorithms developed by Microchip and Cymbet. The monitored information can be reported to the PC user interface over a USB connection. This allows users to experiment with balancing energy collection versus energy use and maximise the benefits of energy harvesting.

Image: Microchip

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Introducing the potential turbine of the future: the ultra efficient Wind Lens designed by Kyushu University  professor Yuji Ohya. According to Yuji Ohya and his team the Wind Lens’ honeycomb-like structure could triple the amount of wind energy that can be produced by offshore turbines.

The futuristic design was unveiled at Yokohama Renewable Energy International Exhibition 2010. The lens shape structure intensifies wind flow and allows the turbine blades to turn faster. Ohya’s design doesn’t have too many moving parts

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By: May Smith
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May Smith is a webmaster who manages a website about record keeping
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Glucose is a compound that is naturally found in the body. It supplies energy for the body and now, it is found to be capable of generating significant amount of energy that could possibly, if further improved, supply energy for implanted devices. This discovery is very significant to medical device suppliers (like pacemaker and artificial organs).

They call the technology as the "glucose biofuel cell". The device can convert the available glucose and oxygen into usable electricity. The device was tested by using two rats. It was implanted in the abdomen of the rats, and was able to attain the power of 6.5 microwatts. Wasn't bad, knowing that the standard pacemaker requires 10 microwatts to keep the heart beating properly. The device could nearly reach the standard power and if refined and improved could reach beyond that level. There is no reason why the device could not work in human. Researchers are very optimistic about improvement of its efficiency.

The question now is: how does this technology work inside a living body? Glucose, a source of energy for cells, is utilized by this device in generating energy. Enzymes are used to facilitate the oxidation process that causes the production of energy. Enzymes are contained in a graphite disc and protected by a dialysis bag. In this way the glucose and oxygen can enter while enzymes inside are prevented of going out. This technique also aims to protect the enzymes from an acidic environment because high acidity alters the process of oxidation. The process then produces a certain amount of energy. This energy is then transported to the machine.

Researchers are planning to test the "glucose biofuel cell" in larger animals. They are also looking forward for other improvements in their discovery, like making the device more biocompatible and prolonging its generating capacity. There will be a series of experiments that are expected to be done before the device can be practically used in humans. Maybe years from now, the device could be found in the market. Support from some companies could be a great help for its progress. The device may be very practical in the medical field. Glucose is an unlimited source of energy and it may be a substitute for batteries. This power-generating device does not need to be surgically removed and replaced.According to the researchers, the following experiments will aim to prove its effectiveness to larger animals and prolong its functioning. Improvement for the device would also include the incorporation of biocompatible materials. There will be a lot of experiments and enhancements that need to be done before its practical use. Possibly in a few years from now or, a shorter time, there may be some companies that will support the studies. It may be very useful in the field of medicine. It aims to replace batteries, which require regular operations.

In addition, besides the targeted pacemaker, the biofuel cell could find application in devices such as insulin pumps, artificial urinary sphincters, bone growth simulators and drug delivery devices as well as implanted medical sensors running for years. There's really an endless flowing of ideas and possibilities at the moment. The experiment may also lead for the development of failed experiments and as well as a motivation for those that are yet to be tried. It has reminded again those people concerned about the artificial organs. The technology is still considered to by young and its practical or commercial use is still far from reach.


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