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The International Clearinghouse for Hydrogen Commerce www.hydrogencommerce.com |
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Latest Advances in |
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"A hundred years from now, people are going to look back to
the days before we discovered the secret of hydrogen storage in carbon and
say, 'Why didn't they think of that sooner? It seems so simple, now! It was so cheap! It was so easy! And it ended the reign of Fossil Fuel forever! ' " |
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HUGE CARBON STORAGE |
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“When we started doing experiments, we realized the metal interaction doesn’t just increase the temperature at which hydrogen can be stored, but it also increases the density above that in solid hydrogen. This is absolutely the first time this has been encountered without having to use pressure.” |
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Center for Neutron Research scientist Craig Brown, Team Leader |
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 Metal-Organic Framework (MOF) |
GREATEST LOW-PRESSURE
HYDROGEN STORAGE DENSITY |
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One of the key engineering challenges to
building a clean, efficient, hydrogen-powered car is how to design the
fuel tank. Storing enough raw hydrogen for a reasonable driving range
would require either impractically high pressures for gaseous hydrogen or
extremely low temperatures for liquid hydrogen. In a new paper researchers
at the National Institute of Standards and Technology’s Center for Neutron
Research (NCNR) have demonstrated that a novel class of materials could
enable a practical hydrogen fuel tank. A research team from NIST, the University of Maryland and the California Institute of Technology studied metal-organic frameworks (MOFs). One of several classes of materials that can bind and release hydrogen under the right conditions, they have some distinct advantages over competitors. In principle they could be engineered so that refueling is as easy as pumping gas at a service station is today, and MOFs don’t require the high temperatures (110 to 500 C) some other materials need to release hydrogen. In particular, the team examined MOF-74, a porous crystalline powder developed at the University of California at Los Angeles. MOF-74 resembles a series of tightly packed straws comprised of mostly carbon atoms with columns of zinc ions running down the inside walls. A gram of the stuff has about the same surface area as two basketball courts. The researchers used neutron scattering and gas adsorption techniques to determine that at 77 K (-196 C), MOF-74 can adsorb more hydrogen than any unpressurized framework structure studied to date—packing the molecules in more densely than they would be if frozen in a block. NCNR scientist Craig Brown says that, though his team doesn’t understand exactly what allows the hydrogen to bond in this fashion, they think the zinc center has some interesting properties. “When we started doing experiments, we realized the metal interaction doesn’t just increase the temperature at which hydrogen can be stored, but it also increases the density above that in solid hydrogen,” Brown says. “This is absolutely the first time this has been encountered without having to use pressure.” Although the liquid-nitrogen temperature of MOF-74 is not exactly temperate, it’s easier to reach than the temperature of solid hydrogen (-269 C), and one of the goals of this research is to achieve energy densities great enough to be as economical as gasoline at ambient, and thus less costly, temperatures. MOF-74 is a step forward in terms of understanding energy density, but there are other factors left to be dealt with that, once addressed, could further increase the temperature at which the fuel can be stored. Fully understanding the physics of the interaction might allow scientists to develop means for removing refrigeration or insulation, both of which are costly in terms of fuel economy, fuel production, or both. The work was funded in part through the Department of Energy's Hydrogen Sorption Center of Excellence. |
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IS PROKHOROV EYEING CARBON STORAGE? |
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Hydrogen Fuel is the Way Ahead, Says Oligarch |
| Mr. Prokhorov told The Independent on Sunday that the UK's commitment to a nuclear energy programme overlooked research that suggests hydrogen technology could be a more efficient option. ..."A compelling advantage of energy produced from hydrogen fuel cells is that it can, thanks to nanotechnology advances, be stored. It can therefore be produced to coincide with consumption peaks." |
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Energy density (ED) of lead acid
batteries(PABs) is 14 -- 23 WHr/lb. |
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BREAKTHROUGH! |
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Researchers at the Swiss-Norwegian experimental stations (beamlines) at the European Synchrotron Radiation Facility are currently studying several compounds of light elements with hydrogen and the different forms they take at different pressure and temperature. Lithium borohydride, LiBH4, is one of the compounds they study as it has a high weight content of hydrogen (18%). The new form of this compound, which scientists have just discovered, is promising because it appears to be unstable. Until today, all the known forms of this material are too stable, which means that they don’t let the hydrogen go. |
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"...a nonprecious metal route to the design of new biohybrid architectures and building blocks for hydrogen-related technologies." |
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BREAKTHROUGH! |
| Nanotubes normally absorb and re-emit light at characteristic wavelengths but, after hydrogenase is added, this photoluminescence disappears, suggesting that the enzyme is feeding electrons into the nanotubes as it catalyses the oxidation hydrogen. The team found that they could control the catalytic reaction by changing the pH balance of the solution or the amount of hydrogen in it. As expected, when they added oxygen, which inactivates hydrogenase, the nanotubes lit up again. In the absence of oxygen, the hydrogenase-nanotube connections continued to work for up to a week. more |
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Background: In May2007, a team from the U.S. National Renewable Energy Laboratory led by Michael Heben announced significant progress in reducing the amount of platinum required in electrolysis: |
"We are interested in developing the scientific principles to control
catalysis and electrocatalysis on the nanoscale. We seek to design
interfaces and electrodes using nanoscience to permit; (1) highly
efficient and robust catalyst utilization, (2) fundamental investigations
of the key reaction steps which are relevant to fuel- forming and
fuel-cell reactions, and (3) a route away from precious metal catalysts.
We approach this problem using carbon single-walled nanotubes (SWNTs)..."An increase in the Pt catalyst utilization efficiency (currently less than 30%) would dramatically decrease the amount of catalyst needed in current PEMFCs. To effectively utilize the Pt catalyst in a PEMFC, the catalyst must have simultaneous access to the gas, the electron conducting medium, and the proton conducting medium. Typically, the catalyst layer for a conventional Pt-catalyzed fuel cell is prepared by an ink-process. Here, Pt-supported carbon particles are blended with Nafion in order to allow for the simultaneous access of the Pt catalyst to the electron conducting and proton conducting media. A common issue with this conventional blending process has been that the proton transport material, Nafion, tends to isolate the carbon support particles in the catalyst layer, leading to poor electron transport throughout the cell. The use of SWNT-supported electrocatalysts in PEMFCs has the potential to eliminate this problem and improve the utilization efficiency of the electrocatalyst. Preliminary results show that the current associated with oxygen reduction on the Pt/SWNT electrodes with [6 micrograms of platinum per square centimeter] is only 20% lower than g/cm the current for the Pt/SWNT electrode with [18 micrograms of platinum per square centimeter.] This result suggests that the Pt/ SWNT interaction has a pronounced affect on the kinetics of the oxygen reduction reaction. " Carbon Nanotube Materials for Substrate Enhanced Control of Catalytic Activity Michael J. Heben , Anne C. Dillon, Chaiwat Engtrakul, Se-Hee Lee NREL Now another team from NREL, again led by Michael Heben, has discovered a "new nanotube physics" that combines nanotubes with peculiar metalloenzymes called hydrogenases. Although discovered in the 1930s as the critical engine of anaerobic metabolism (life in the absence of oxygen), these enzymes were brought to public attention in 2000 by Dr. Tasios Melis of UC Berkeley who discovered a method of stimulating anaerobic hydrogen production from algae. Then on September 10, 2007, Heben and his team announced that they had developed a "biohybrid" technique using single-walled carbon nanotubes to entirely replace the precious metals previously required for catalyzing oxygen/hydrogen reactions, and creating, somewhat surprisingly, robust, biologically-driven nanoscale electron pumps that may possibly be harnessed to produce useable power. -- RDM
Wiring-Up Hydrogenase with Single-Walled Carbon Nanotubes |
| Abstract: Many envision a future where hydrogen is the centerpiece of a sustainable, carbon-free energy supply. For example, the energy in sunlight may be stored by splitting water into H2 and O2 using inorganic semiconductors and photoelectrochemical approaches or with artificial photosynthetic systems that seek to mimic the light absorption, energy transfer, electron transfer, and redox catalysis that occurs in green plants. Unfortunately, large scale deployment of artificial water-splitting technologies may be impeded by the need for the large amounts of precious metals required to catalyze the multielectron water-splitting reactions. Nature provides a variety of microbes that can activate the dihydrogen bond through the catalytic activity of [NiFe] and [FeFe] hydrogenases, and photobiological approaches to water splitting have been advanced. One may also consider a biohybrid approach; however, it is difficult to interface these sensitive metalloenzymes to other materials and systems. Here we show that surfactant-suspended carbon single-walled nanotubes (SWNTs) spontaneously self-assemble with [FeFe] hydrogenases in solution to form catalytically active biohybrids. Photoluminescence excitation and Raman spectroscopy studies show that SWNTs act as molecular wires to make electrical contact to the biocatalytic region of hydrogenase. Hydrogenase mediates electron injection into nanotubes having appropriately positioned lowest occupied molecular orbital levels when the H2 partial pressure is varied. The hydrogenase is strongly attached to the SWNTs, so mass transport effects are eliminated and the absolute potential of the electronic levels of the nanotubes can be unambiguously measured. Our findings reveal new nanotube physics and represent the first example of "wiring-up" an hydrogenase with another nanoscale material. This latter advance offers a nonprecious metal route to the design of new biohybrid architectures and building blocks for hydrogen-related technologies. more |
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H2 STORAGE
BREAKTHROUGH! |
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University of Virginia Scientists Discover Record-Breaking Hydrogen
Storage Materials |
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Scientists at the University of Virginia
have discovered a new class of hydrogen storage materials that could make
the storage and transportation of energy much more efficient — and
affordable — through higher-performing hydrogen fuel cells. Bellave S. Shivaram and Adam B. Phillips, the U.Va. physicists who invented the new materials, will present their finding at 8 p.m., Monday, Nov. 12, at the International Symposium on Materials Issues in a Hydrogen Economy at the Omni Hotel in Richmond, Va. “In terms of hydrogen absorption, these materials could prove a world record,” Phillips said. “Most materials today absorb only 7 to 8 percent of hydrogen by weight, and only at cryogenic [extremely low] temperatures. Our materials absorb hydrogen up to 14 percent by weight at room temperature. By absorbing twice as much hydrogen, the new materials could help make the dream of a hydrogen economy come true.” In the quest for alternative fuels, U.Va.’s new materials potentially could provide a highly affordable solution to energy storage and transportation problems with a wide variety of applications. They absorb a much higher percentage of hydrogen than predecessor materials while exhibiting faster kinetics at room temperature and much lower pressures, and are inexpensive and simple to produce. “These materials are the next generation in hydrogen fuel storage materials, unlike any others we have seen before,” Shivaram said. “They have passed every litmus test that we have performed, and we believe they have the potential to have a large impact.” The inventors believe the novel materials will translate to the marketplace and are working with the U.Va. Patent Foundation to patent their discovery. “The U.Va. Patent Foundation is very excited to be working with a material that one day may be used by millions in everyday life,” said Chris Harris, senior licensing manager for the U.Va. Patent Foundation. “Dr. Phillips and Dr. Shivaram have made an incredible breakthrough in the area of hydrogen absorption.” Phillips’s and Shivaram’s research was supported by the National Science Foundation and the U.S. Department of Energy. About the University of Virginia Patent Foundation The University of Virginia Patent Foundation is a not-for-profit corporation that serves to promote the translation of U.Va. technologies to the global marketplace by evaluating, protecting and licensing intellectual property generated in the course of research at U.Va. The Patent Foundation reviews and evaluates over 150 inventions per year and has generated more than $75 million in licensing revenue since its formation in 1978. For more information about the Patent Foundation, its services or technology transfer, visit www.uvapf.org. |
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HYDROGEN STORAGE
BREAKTHROUGH |
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Nanoporous polyanilines can be prepared using hypercrosslinking of commercially available polyaniline with diiodoalkanes or formaldehyde. Some of these polymers exhibit specific surface areas exceeding 630 m2 g -1 that are unprecedented for this class of polymers. ...Our preliminary experiments indicate that these materials have a certain potential for hydrogen storage. Although their overall hydrogen storage capacity at 77 K is currently lower than that of our hypercrosslinked polystyrene, they offer the highest enthalpy of adsorption of any air-stable sorbenttype hydrogen storage material. Further optimization of reaction conditions is expected to lead to materials with much higher surface areas and therefore enhanced hydrogen storage capacities.
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The Department of Energy's Chemical Hydrogen Storage
Center of Excellence is investigating a hydrogen storage medium that holds
promise in meeting long-term targets for transportation use. As part of
the center, PNNL scientists are using solid ammonia borane, or AB,
compressed into small pellets to serve as a hydrogen storage material.
Each milliliter of AB weighs about three-quarters of a gram and harbors up
to 1.8 liters of hydrogen. Researchers expect that a fuel system using
small AB pellets will occupy less space and be lighter in weight than
systems using pressurized hydrogen gas, thus enabling fuel cell vehicles
to have room, range and performance comparable to today's automobiles. ..."Once hydrogen from the storage material is depleted, the AB pellets must be safely and efficiently regenerated by way of chemical processing," said PNNL scientist Don Camaioni. "This 'refueling' method requires chemically digesting or breaking down the solid spent fuel into chemicals that can be recycled back to AB with hydrogen." more |
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A New Alloy May Revive Hope for the Hydrogen Economy |
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BREAKTHROUGH |
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"The results show that hydrogen interacts far more strongly with such carbonous nanostructures than it does to carbon nanotubes, suggesting that nanohorns and related nanostructures may offer significantly better prospects as light-weight media for hydrogen storage applications," the researchers said.
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Nanotechnology Breakthrough in Hydrogen Storage |
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Researchers from Bilkent University in Turkey and the US National Institute of Standards and Technology believe that they can use nanotechnology to create plastics that will 'package' hydrogen in an unusual way. The researchers believe that by attaching titanium atoms to opposite ends of an ethylene molecule they can form a complex structure that will absorb 10 hydrogen molecules. This would double the minimum target set by the US Department of Energy for economically practical storage of hydrogen in a solid state material. |
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"This could be a major
step towards the breakthrough that the fuel cell industry and the transport
sector have waited for."
Professor Peter Edwards, University of Oxford
Project Coordinator, UK Sustainable
Hydrogen Energy Consortium
LITHIUM:
UK Announces Breakthrough in Hydrogen Storage
Scenta (UK)
May 23, 2007
Prototype magnetic refrigerator at the
University of Victoria
50% Efficiency in sight for cryogenic hydrogen!
Efficient Liquid Hydrogen Storage
Gasworld
March 15, 2007
Studies using magnetic refrigeration to
efficiently obtain
liquid hydrogen are producing promising results
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HSM Announces Breakthrough Material |
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HSM through its Research and License
Agreement with the University of New Brunswick (UNB) is collaborating with
Dr. Craig Jensen, a leader with over 25 years experience in the field of
novel hydride materials and his team at the University of Hawaii. “Aluminum is the preferred material because it has many of the properties that are a pre requisite to be considered viable for hydrogen storage applications” said Dr. Jensen. Most notably these materials contain 10.1 wt % hydrogen and undergo dehydrogenation at appreciable rates at temperatures below 100 C. However, the very low enthalpy of dehydrogenation of alane prohibits subsequent re-hydrogenation through standard gas-solid techniques except at very high pressures or very low temperatures. Dr. Sean McGrady, lead researcher on the project who has over two decades in the handling of reactive inorganic materials, adds that the extremely low solubility of gaseous hydrogen in conventional organic solvents also vitiates a solution-based approach. “Re-hydrogenation of aluminum using a supercritical fluid potentially offers a workable approach since the fluid can act as a solvent, at the same time remaining completely miscible with permanent gases like hydrogen.” |
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STORAGE
BREAKTHROUGH! |
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From Farm Waste to Fuel Tanks Researchers have developed a
corncob-derived carbon "sponge" that can store natural gas.
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BREAKTHROUGH! |
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Results of modeling studies indicate that attaching
titanium atoms (blue) to the ends of an ethylene molecule (yellow-green)
will result in a capsule-shaped complex that absorbs 10 hydrogen molecules
(red). The results open a new avenue in the pursuit of materials that will
enable efficient solid-state storage of hydrogen.
Credit:
Taner Yildirim, NIST.
Ethylene Suggested for Hydrogen Storage |
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BREAKTHROUGH! Although reversible covalent activation of molecular hydrogen (H2) is a common reaction at transition metal centers, it has proven elusive in compounds of the lighter elements. We report that the compound (C6H2Me3)2PH(C6F4)BH(C6F5)2 (Me, methyl), which we derived through an unusual reaction involving dimesitylphosphine substitution at a para carbon of tris(pentafluorophenyl) borane, cleanly loses H2 at temperatures above 100°C. Preliminary kinetic studies reveal this process to be first order. Remarkably, the dehydrogenated product (C6H2Me3)2P(C6F4)B(C6F5)2 is stable and reacts with 1 atmosphere of H2 at 25°C to reform the starting complex. Deuteration studies were also carried out to probe the mechanism. |
A New Record for Absorbing Hydrogen
New Scientist
November 7, 2006
Nanoporous polymers should also be far cheaper to
produce than other materials currently being considered, such as carbon
nanotubes, as they can be made simply using existing manufacturing techniques.
13 European Research Institutions Unite to Develop
Solid State Hydrogen Storage Technology
EU Marie Curie Research Training Network
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Washington, D.C. – Water, the only indispensable ingredient of life, is
just about the most versatile stuff on Earth. Depending on its temperature
we can heat our homes with it, bathe in it, and even strap on skates and
glide across it, to name only the most common of its many forms. When
subjected to high pressures, however, water can take any of more than 15
different forms. Researchers have now used x-rays to dissociate water at high pressure to form a solid mixture—an alloy—of molecular oxygen and molecular hydrogen. The work, by a multi-institutional team* that includes Russell Hemley and Ho-kwang Mao of Carnegie’s Geophysical Laboratory, appears in the October 27 issue of Science. The researchers subjected a sample of water to extremely high pressures—about 170,000 times the pressure at sea level (17 Gigapascals)—using a diamond anvil, and zapped it with high-energy x-rays. Under these conditions, nearly all the water molecules split apart and re-formed into a solid alloy of O2 and H2. X-radiation proved to be the key to cleaving the O-H bonds in water; without it, the water remained in a high-pressure form of ice known as ice VII—one of at least 15 such variants of ice that exist under high pressure and variable temperature conditions. “We managed to hit on just the right level of x-ray energy input,” explained Hemley. “Any higher, and the radiation tends to pass right through the sample. Any lower, and the radiation is largely absorbed by the diamonds in our pressure apparatus.” This rather narrow range of energy requirement explains why, in hundreds of previous high-pressure x-ray experiments, the breakdown reaction had gone undiscovered: most such experiments tend to use more energetic x-rays. The experiments also required long, multiple-hour irradiation with x-rays; such long exposures had not been attempted before. The researchers put the alloy through its paces, subjecting it to a range of pressure, temperature, and bombardment with x-ray and laser radiation. As long as the sample remained under pressure equivalent to about 10,000 times atmospheric pressure at sea level (1 Gigapascal), it stood up to this punishment. Although the substance is clearly a crystalline solid, more experiments are needed to determine its precise crystal structure. “The new radiation chemistry at high pressure was surprising,” said lead author Wendy Mao of Los Alamos National Laboratory. “The new alloy containing the incompatible oxygen and hydrogen molecules will be a highly energetic material.” |
NANOSPRINGS:
Researchers Work on Hydrogen Energy
Andy Jones The Daily Evergreen (WA)
September 24, 2006
In the past decade, 17
countries have announced national programs to develop hydrogen energy,
according to the September issue of Scientific American. In North America,
more than 30 states and several Canadian provinces are developing similar
plans, although the U.S. has not implemented a national program.
Another issue with hydrogen protection has been the use of gas emissions
required to produce the fuels, McCluskey said. To reduce emissions, other
alternative sources, such as solar cells and wind turbines, need to be
mass-produced to provide the energy.
British Scientists Develop New Hydrogen Storage Material
Fuel Cell Today (UK)
September
8, 2006
Getting Hydrogen Storage Just Right
Chemical Science
August 10, 2006
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HYDROGEN STORAGE |
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South Korean Scientists Discover Matter for Hydrogen Storage |
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Professor Ihm discovered that the hydrogen can be stored in solid matter in normal temperatures and pressures by attaching a titanium atom to a polymer. Hydrogen, the gaseous matter, can be stably stored in the material, allowing for its immediate application in hydrogen vehicles. With the storage efficiency for commercialization of Professor Lim’s new material at 7.6 percent, surpassing that targeted by the U.S. Department of Energy 6.5 percent, his discovery is expected to draw interest from automobile makers worldwide.
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"The idea we explored was based on ball milling graphite processes found
in the hydrogen storage literature," said Angela D. Lueking, assistant
professor of energy and geoenvironmental engineering. "We substituted
anthracite coal for graphite because it is abundant and inexpensive. Now,
with 20/20 hindsight, we are struck by the fact that coal gasification is
currently the most economical way to produce hydrogen." ..."Ball milling imparts a lot of energy to the slurry," said Lueking. "There is high pressure and temperature in every impact of the balls on the slurry, but we do not really understand the structural changes in the carbon that occur in the process." Lueking is puzzled because, unlike the graphite experiments, her anthracite experiment has hydrogen gas evolving from the mixture at room temperature. The hydrogen is either trapped in the material in a tight pore structure or a new carbon structure is being formed. The hydrogen outgassing continued for about a year and increased with addition of moderate heat. "At first we thought the mass spectrograph was broken because hydrogen was just coming off," said Lueking. "We tried another mass spec and the same thing happened." Wanting to know the structure of the ball milled product, and looking for carbon nanotubes, the researchers used transmission electron microscopy to investigate the small particles. "When Gutierrez asked, 'do you know you have diamonds here?' our answer was no – we were not expecting to make diamonds,” Lueking said. What the researchers had were Bucky diamonds, a nanocrystalline diamond surrounded by onion–like layers of graphite. Diamonds are a natural form of pure carbon, but with a differing molecular structure than graphite or the graphite-like coal. "Bucky diamonds are relatively unexplored in terms of applications," said Lueking. "Nanocrystalline diamonds, however, have major industrial uses as abrasives and in electronics. These nanodiamonds are usually created by exploding TNT in a carbon source." more |
GAME CHANGER?
STUNNING DEVELOPMENT IN
HYDROGEN STORAGE
"This storage technology allows
hydrogen, normally a gas, to be stored and transported at normal temperatures in
a liquid form like conventional fuels."
Guido Pez, Chief Scientist
Corporate Science and Technology Center at
Air Products
Air Products Researchers Receive
Department of Energy Hydrogen Program Award
Air Products
June 13, 2006
Reversible Liquid Carriers for an Integrated Production, Storage and Delivery of
Hydrogen DOE Hydrogen Program 2005
Guido P. Pez, Bernard Toseland
Air Products & Chemicals
Hydrogen Storage
by the Reversible Hydrogenation of Liquid and Solid Substrates
Alan C. Cooper and Guido P. Pez Air Products
May 25, 2004
Design and Development of New Carbon-Based Sorbent Systems
for an Effective Containment of Hydrogen
Alan Cooper, Guido Pez, Hansong Cheng, Aaron Scott, Don Fowler, Atteye
Abdourazak Air Products and Chemicals
DOE Hydrogen Program Annual Progress Report 2004
NANOMIX:
Carbon Storage Breakthrough?
Nanomix
June 12, 2006
NEW
DOE
SOLICITATION
Due Date: May 10, 2006
Research and Development for On-Board Vehicular Hydrogen Storage
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UCLA, University of
Michigan Chemists Report Progress in Quest to Use Hydrogen as Fuel for
Cars & Electronic Devices Chemists at UCLA and the University
of Michigan report an advance toward the goal of cars that run on hydrogen
rather than gasoline. While the U.S. Department of Energy estimates that
practical hydrogen fuel will require concentrations of at least 6.5
percent, the chemists have achieved concentrations of 7.5 percent — nearly
three times as much as has been reported previously — but at a very low
temperature (77 degrees Kelvin). Contact: Stuart Wolpert ( swolpert@support.ucla.edu ) Phone: 310-206-0511 |
Brookhaven Scientists Working Toward
Practical Hydrogen-Storage Materials
Laura Mgrdichian
Brookhaven National Lab
March 15, 2006
Increased Solar Cell Efficiency and Hydrogen Production
With Titania Nanotubes
Azonano
January 31, 2006
Chemist Seeks Way to Make
Hydrogen Stick
Doug Main Washington University
in St. Louis (MO) November
2, 2005
 Pacific Northwest National Laboratory Unlocks a Secret of Ammonia HYDROGEN STORAGE: Filling Up with Hydrogen David Schneider American Scientist Sept/Oct 2005 |
| The surprising report, which appeared last June in the journal Angewandte Chemie, describes a way of storing hydrogen in the form of the compound ammonia borane, NH3BH3. Tom Autrey of the Pacific Northwest National Laboratory led the group of 12 authors who published the work. It builds on the decades-old idea of storing hydrogen in the form of ammonia, NH3. Unlike hydrogen gas, which requires cryogenic temperatures to liquefy, ammonia becomes a liquid at -34 degrees Celsius. |
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DENMARK Hydrogen Pill Raises Fuel Hopes
Copenhagen Post September
7, 2005
The Role of Titanium in Hydrogen
Storage
Brookahven National Laboratory
September 1, 2005
How Hydride-Based Hydrogen Compressors Work
Hera Hydrogen Storage Systems
New Look for Hydrogen Storage
Physics Web July 19, 2005
$2 Billion Market in Nanopore
Physorg.com July 15, 2005
Nano-Graphite
May Store H2 Gas
Physorg.com July 14, 2005
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| New quantum calculations and computer models show
that carbon nanotubes "decorated" with titanium or other transition metals can
latch on to hydrogen molecules in numbers more than adequate for efficient hydrogen
storage, a capability key to long-term efforts to develop fuel cells, an affordable
non-polluting alternative to gasoline. National Institute of Standards and Technology theorist Taner Yildirim and physicist Salim Ciraci of Turkey's Bilkent University report their "unanticipated" findings in the online issue of Physical Review Letters.*  Using established quantum
physics theory, they predict that hydrogen can amass in amounts equivalent to 8 percent of
the weight of "titanium-decorated" singled walled carbon nanotubes. That's
one-third better than the 6 percent minimum storage-capacity requirement set by the
FreedomCar Research Partnership involving the Department of Energy and the nation's
"Big 3" automakers. As important, the four hydrogen molecules (two atoms each) that link to a titanium atom are relinquished readily when heated. Such reversible desorption is another requirement for practical hydrogen storage. Resembling exceedingly small cylinders of chicken wire, so-called single-walled carbon nanotubes are among several candidate materials eyed for hydrogen storage. Reaching the 6 percent target, however, has proved difficult—a potential "showstopper," according to many in the field. Positioning a titanium atom above the center of hexagonally arranged carbon atoms (the repeating geometric pattern characteristic of carbon nanotubes) appears to resolve the impasse according to this new study. The new results, obtained with a method for calculating the electronic structure of materials, surprised the researchers. Interactions among carbon, titanium and hydrogen seem to give rise to unusual attractive forces. The upshot is that four hydrogen molecules can dock on a titanium atom, apparently by means of a unique chemical bond of modest strength. Several forces at work within the geometric arrangement appear to play a role in the reversible tethering of hydrogen, Yildirim says. Yildirim and Ciraci report that their findings "suggest a possible method of engineering new nanostructures for high-capacity storage and catalyst materials." The work was funded, in part, by the Department of Energy and National Science Foundation. *T. Yildirim and S. Ciraci, "Titanium-Decorated Carbon Nanotubes as a Potential High-Capacity Hydrogen Storage Medium", Phys. Rev. Lett. 94, p. 175501 (2005). More informat |