Micropower
Encyclopedia
Micropower describes the work that researchers at several universities are doing to develop very small electric generators and prime movers or devices to convert heat or motion to electricity, for use close to the generator. These devices offer the promise of a power source for portable electronic devices
which is lighter weight and has a longer operating time than batteries.
engine: the gas compressor
, the combustion chamber
, and the turbine
rotor itself, are fabricated from etched silicon
, much like integrated circuits. The technology holds the promise of ten times the operating time of a battery
of the same weight as the micropower unit, and similar efficiency
to large utility gas turbines
. Researchers at Massachusetts Institute of Technology
have thus far succeeded in fabricating the parts for such a micro turbine out of six etched and stacked silicon wafers, and are working towards combining them into a functioning engine about the size of a U.S quarter
coin.
Researchers at Georgia Tech have built a micro generator 10 mm wide, which spins a magnet
above an array of coil
s fabricated on a silicon chip. The device spins at 100,000 revolutions per minute, and produces 1.1 watt
s of electrical power
, sufficient to operate a cell phone. Their goal is to produce 20 to 50 watts, sufficient to power a laptop
computer.
Scientists at Lehigh University
are developing a hydrogen
generator on a silicon chip, which can convert methanol
, diesel, or gasoline
into fuel
for a microengine or a miniature fuel cell.
Professor Sanjeev Mukerjee of Northeastern University's chemistry department is developing fuel cells for the military which will burn hydrogen to power portable electronic equipment such as night vision goggles, computers, and communication equipment. In his system, a cartridge of methanol
would be used to produce hydrogen to run a small fuel cell for up to 5,000 hours. It would be lighter than rechargeable batteries needed to provide the same power output, with a longer run time. Similar technology could be improved and expanded in future years to power automobiles.
The National Academies' National Research Council
recommended in a 2004 report that the U.S. Army should investigate such micropower sources for powering electronic equipment to be carried by soldiers in the future, since batteries sufficient to power the computers, sensors, and communications devices would add considerable weight to the burden of infantry
soldiers.
The Future Warrior Concept of the U.S. Army envisions a 2 to 20 watt micro turbine fueled by a liquid hydrocarbon being used to power communications and wearable heating/cooling equipment for up to six days on 10 ounces of fuel.
Other microgenerator/nanogenerator
Professor Orest Symko of the University of Utah
physics department and his students developed Thermal Acoustic Piezo Energy Conversion (TAPEC), devices of a cubic inch (16 cubic centimeters) or so which convert waste heat into acoustic resonance and then into electricity. It would be used to power microelectromechanical systems, or MEMS. The research was funded by the U.S. Army. Symko was to present a paper at the Acoustical Society of America
. June 8, 2007.
Professor Zhong Lin Wang of the Georgia Institute of Technology
said his team of investigators had developed a "nanometer-scale generator (which) is based on arrays of vertically aligned zinc oxide
nanowires that move inside a "zigzag" plate electrode
." Built into shoes, it could generate electricity from walking to power small electronic devices. It could also be powered by blood flow to power biomedical devices. Per an account of the device which appeared in the journal Science
, bending of the zinc oxide nanowire arrays produces an electric field by the piezoelectric properties of the material. The semiconductor
properties of the device create a Schottky barrier
with rectifying
capabilities. The generator is estimated to be 17% to 30% efficient in converting mechanical motion into electricity. This could be used to power biomedical devices which have wireless transmission capabilities for data and control. A later development was to grow hundreds of such nanowires on a substrate which functioned as an electrode. On top of this was placed a silicon
electrode covered with a series of platinum
ridges. Vibration of the top electrode caused the generation of direct current. A report by Wang was to appear in the August 8, 2007 issue of the journal "Nano letters," saying that such devices could power implantable biomedical devices. The device would be powered by flowing blood or a beating heart. It could function while immersed in body fluids,and would get its energy from ultrasonic vibrations. Wang expects that an array of the devices could produce 4 watts per cubic centimeter. Goals for further development are to increase the efficiency of the array of nanowires, and to increase the lifetime of the device, which as of April 2007 was only about one hour. By November 2010 Wang and his team were able to produce 3 volts of potential and as much as 300 nanoamperes of current, an output level 100 times greater than was possible a year earlier, from an array measuring about 2 cm by 1.5 cm.
The windbelt
is a micropower technology invented by Shawn Frayne. It is essentially an aeolian harp
except that it exploits the motion of the string produced by aeroelastic flutter to create a physical oscillation that can be converted to electricity. It avoids the losses inherent in rotating wind powered generators. Prototypes have produced 40 milliwatts in a 10 mile per hour wind. Magnets on the vibrating membrane generate currents in stationary coils.
Piezoelectric nanofiber
s in clothing could generate enough electricity from the wearer's body movements to power small electronic devices such as iPod
s or some of the electronic equipment used by soldiers on the battlefield, based on research by UC Berkeley Professor Liwei Lin and his team. One million such fibers could power an iPod, and would be altogether as large as a grain of sand. Researchers at Stanford University
are developing "eTextiles," which are batteries made of fabric, which might serve to store power generated by such technology.
Electronics
Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...
which is lighter weight and has a longer operating time than batteries.
Microturbine technology
The components of any turbineTurbine
A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work.The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and...
engine: the gas compressor
Gas compressor
A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume.Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas...
, the combustion chamber
Combustion chamber
A combustion chamber is the part of an engine in which fuel is burned.-Internal combustion engine:The hot gases produced by the combustion occupy a far greater volume than the original fuel, thus creating an increase in pressure within the limited volume of the chamber...
, and the turbine
Turbine
A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work.The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and...
rotor itself, are fabricated from etched silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
, much like integrated circuits. The technology holds the promise of ten times the operating time of a battery
Battery (electricity)
An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 1800 by Alessandro Volta and especially since the technically improved Daniell cell in 1836, batteries have become a common power...
of the same weight as the micropower unit, and similar efficiency
Efficient energy use
Efficient energy use, sometimes simply called energy efficiency, is the goal of efforts to reduce the amount of energy required to provide products and services. For example, insulating a home allows a building to use less heating and cooling energy to achieve and maintain a comfortable temperature...
to large utility gas turbines
Electricity generation
Electricity generation is the process of generating electric energy from other forms of energy.The fundamental principles of electricity generation were discovered during the 1820s and early 1830s by the British scientist Michael Faraday...
. Researchers at Massachusetts Institute of Technology
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
have thus far succeeded in fabricating the parts for such a micro turbine out of six etched and stacked silicon wafers, and are working towards combining them into a functioning engine about the size of a U.S quarter
Quarter (United States coin)
A quarter dollar, commonly shortened to quarter, is a coin worth ¼ of a United States dollar, or 25 cents. The quarter has been produced since 1796. The choice of 25¢ as a denomination, as opposed to 20¢ which is more common in other parts of the world, originated with the practice of dividing...
coin.
Researchers at Georgia Tech have built a micro generator 10 mm wide, which spins a magnet
Magnet
A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, and attracts or repels other magnets.A permanent magnet is an object...
above an array of coil
Coil
A coil is a series of loops. A coiled coil is a structure in which the coil itself is in turn also looping.-Electromagnetic coils:An electromagnetic coil is formed when a conductor is wound around a core or form to create an inductor or electromagnet...
s fabricated on a silicon chip. The device spins at 100,000 revolutions per minute, and produces 1.1 watt
Watt
The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...
s of electrical power
Electric power
Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt.-Circuits:Electric power, like mechanical power, is represented by the letter P in electrical equations...
, sufficient to operate a cell phone. Their goal is to produce 20 to 50 watts, sufficient to power a laptop
Laptop
A laptop, also called a notebook, is a personal computer for mobile use. A laptop integrates most of the typical components of a desktop computer, including a display, a keyboard, a pointing device and speakers into a single unit...
computer.
Scientists at Lehigh University
Lehigh University
Lehigh University is a private, co-educational university located in Bethlehem, Pennsylvania, in the Lehigh Valley region of the United States. It was established in 1865 by Asa Packer as a four-year technical school, but has grown to include studies in a wide variety of disciplines...
are developing a hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
generator on a silicon chip, which can convert methanol
Methanol
Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...
, diesel, or gasoline
Gasoline
Gasoline , or petrol , is a toxic, translucent, petroleum-derived liquid that is primarily used as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. Some gasolines also contain...
into fuel
Fuel
Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...
for a microengine or a miniature fuel cell.
Professor Sanjeev Mukerjee of Northeastern University's chemistry department is developing fuel cells for the military which will burn hydrogen to power portable electronic equipment such as night vision goggles, computers, and communication equipment. In his system, a cartridge of methanol
Methanol
Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...
would be used to produce hydrogen to run a small fuel cell for up to 5,000 hours. It would be lighter than rechargeable batteries needed to provide the same power output, with a longer run time. Similar technology could be improved and expanded in future years to power automobiles.
The National Academies' National Research Council
United States National Research Council
The National Research Council of the USA is the working arm of the United States National Academies, carrying out most of the studies done in their names.The National Academies include:* National Academy of Sciences...
recommended in a 2004 report that the U.S. Army should investigate such micropower sources for powering electronic equipment to be carried by soldiers in the future, since batteries sufficient to power the computers, sensors, and communications devices would add considerable weight to the burden of infantry
Infantry
Infantrymen are soldiers who are specifically trained for the role of fighting on foot to engage the enemy face to face and have historically borne the brunt of the casualties of combat in wars. As the oldest branch of combat arms, they are the backbone of armies...
soldiers.
The Future Warrior Concept of the U.S. Army envisions a 2 to 20 watt micro turbine fueled by a liquid hydrocarbon being used to power communications and wearable heating/cooling equipment for up to six days on 10 ounces of fuel.
Other microgenerator/nanogeneratorNanogeneratorNanogenerator is an energy harvesting device converting the external kinetic energy into an electrical energy based on the energy conversion by nano-structured piezoelectric material. Although its definition may include any types of energy harvesting devices with nano-structure converting the...
technology
Professor Orest Symko of the University of UtahUniversity of Utah
The University of Utah, also known as the U or the U of U, is a public, coeducational research university in Salt Lake City, Utah, United States. The university was established in 1850 as the University of Deseret by the General Assembly of the provisional State of Deseret, making it Utah's oldest...
physics department and his students developed Thermal Acoustic Piezo Energy Conversion (TAPEC), devices of a cubic inch (16 cubic centimeters) or so which convert waste heat into acoustic resonance and then into electricity. It would be used to power microelectromechanical systems, or MEMS. The research was funded by the U.S. Army. Symko was to present a paper at the Acoustical Society of America
Acoustical Society of America
The Acoustical Society of America is an international scientific society dedicated to increasing and diffusing the knowledge of acoustics and its practical applications.-History:...
. June 8, 2007.
Professor Zhong Lin Wang of the Georgia Institute of Technology
Georgia Institute of Technology
The Georgia Institute of Technology is a public research university in Atlanta, Georgia, in the United States...
said his team of investigators had developed a "nanometer-scale generator (which) is based on arrays of vertically aligned zinc oxide
Zinc oxide
Zinc oxide is an inorganic compound with the formula ZnO. It is a white powder that is insoluble in water. The powder is widely used as an additive into numerous materials and products including plastics, ceramics, glass, cement, rubber , lubricants, paints, ointments, adhesives, sealants,...
nanowires that move inside a "zigzag" plate electrode
Electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...
." Built into shoes, it could generate electricity from walking to power small electronic devices. It could also be powered by blood flow to power biomedical devices. Per an account of the device which appeared in the journal Science
Science (journal)
Science is the academic journal of the American Association for the Advancement of Science and is one of the world's top scientific journals....
, bending of the zinc oxide nanowire arrays produces an electric field by the piezoelectric properties of the material. The semiconductor
Semiconductor
A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...
properties of the device create a Schottky barrier
Schottky barrier
A Schottky barrier, named after Walter H. Schottky, is a potential barrier formed at a metal–semiconductor junction which has rectifying characteristics, suitable for use as a diode...
with rectifying
Rectifier
A rectifier is an electrical device that converts alternating current , which periodically reverses direction, to direct current , which flows in only one direction. The process is known as rectification...
capabilities. The generator is estimated to be 17% to 30% efficient in converting mechanical motion into electricity. This could be used to power biomedical devices which have wireless transmission capabilities for data and control. A later development was to grow hundreds of such nanowires on a substrate which functioned as an electrode. On top of this was placed a silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
electrode covered with a series of platinum
Platinum
Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78. Its name is derived from the Spanish term platina del Pinto, which is literally translated into "little silver of the Pinto River." It is a dense, malleable, ductile, precious, gray-white transition metal...
ridges. Vibration of the top electrode caused the generation of direct current. A report by Wang was to appear in the August 8, 2007 issue of the journal "Nano letters," saying that such devices could power implantable biomedical devices. The device would be powered by flowing blood or a beating heart. It could function while immersed in body fluids,and would get its energy from ultrasonic vibrations. Wang expects that an array of the devices could produce 4 watts per cubic centimeter. Goals for further development are to increase the efficiency of the array of nanowires, and to increase the lifetime of the device, which as of April 2007 was only about one hour. By November 2010 Wang and his team were able to produce 3 volts of potential and as much as 300 nanoamperes of current, an output level 100 times greater than was possible a year earlier, from an array measuring about 2 cm by 1.5 cm.
The windbelt
Windbelt
The Windbelt is a device for converting wind power to electricity. A windbelt is essentially an aeolian harp except that it exploits the motion of the string produced by the aeroelastic flutter effect to move a magnet closer and farther from one or more electromagnetic coil and thus induce current...
is a micropower technology invented by Shawn Frayne. It is essentially an aeolian harp
Aeolian harp
An aeolian harp is a musical instrument that is "played" by the wind. It is named for Aeolus, the ancient Greek god of the wind. The traditional aeolian harp is essentially a wooden box including a sounding board, with strings stretched lengthwise across two bridges...
except that it exploits the motion of the string produced by aeroelastic flutter to create a physical oscillation that can be converted to electricity. It avoids the losses inherent in rotating wind powered generators. Prototypes have produced 40 milliwatts in a 10 mile per hour wind. Magnets on the vibrating membrane generate currents in stationary coils.
Piezoelectric nanofiber
Nanofiber
Nanofibers are defined as fibers with diameters less than 1000 nm nanometers. They can be produced by interfacial polymerization and electrospinning...
s in clothing could generate enough electricity from the wearer's body movements to power small electronic devices such as iPod
IPod
iPod is a line of portable media players created and marketed by Apple Inc. The product line-up currently consists of the hard drive-based iPod Classic, the touchscreen iPod Touch, the compact iPod Nano, and the ultra-compact iPod Shuffle...
s or some of the electronic equipment used by soldiers on the battlefield, based on research by UC Berkeley Professor Liwei Lin and his team. One million such fibers could power an iPod, and would be altogether as large as a grain of sand. Researchers at Stanford University
Stanford University
The Leland Stanford Junior University, commonly referred to as Stanford University or Stanford, is a private research university on an campus located near Palo Alto, California. It is situated in the northwestern Santa Clara Valley on the San Francisco Peninsula, approximately northwest of San...
are developing "eTextiles," which are batteries made of fabric, which might serve to store power generated by such technology.
See also
- Battery (electricity)Battery (electricity)An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 1800 by Alessandro Volta and especially since the technically improved Daniell cell in 1836, batteries have become a common power...
- Cell phone
- Electrical generatorElectrical generatorIn electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge to flow through an external electrical circuit. It is analogous to a water pump, which causes water to flow...
- ElectronicsElectronicsElectronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...
- Gas turbineGas turbineA gas turbine, also called a combustion turbine, is a type of internal combustion engine. It has an upstream rotating compressor coupled to a downstream turbine, and a combustion chamber in-between....
- Hub dynamoHub dynamoA hub dynamo is a small electrical generator built into the hub of a bicycle wheel that is usually used to power lights. Most modern hub dynamos are regulated to 3 watts at 6 volts, although some will drive up to 6 watts at 12 volts.-Models:...
- Integrated circuits
- LaptopLaptopA laptop, also called a notebook, is a personal computer for mobile use. A laptop integrates most of the typical components of a desktop computer, including a display, a keyboard, a pointing device and speakers into a single unit...
- MicroelectronicsMicroelectronicsMicroelectronics is a subfield of electronics. As the name suggests, microelectronics relates to the study and manufacture of very small electronic components. Usually, but not always, this means micrometre-scale or smaller,. These devices are made from semiconductors...
- Microelectromechanical systemsMicroelectromechanical systemsMicroelectromechanical systems is the technology of very small mechanical devices driven by electricity; it merges at the nano-scale into nanoelectromechanical systems and nanotechnology...
- Portable fuel cell applicationsPortable fuel cell applicationsFuel cell applications are stationary fuel cell applications and portable fuel cell plications...
- WindbeltWindbeltThe Windbelt is a device for converting wind power to electricity. A windbelt is essentially an aeolian harp except that it exploits the motion of the string produced by the aeroelastic flutter effect to move a magnet closer and farther from one or more electromagnetic coil and thus induce current...
- NanogeneratorNanogeneratorNanogenerator is an energy harvesting device converting the external kinetic energy into an electrical energy based on the energy conversion by nano-structured piezoelectric material. Although its definition may include any types of energy harvesting devices with nano-structure converting the...