Splitting Water for Renewable Energy Simpler Than First Thought?

Their findings, developed with the assistance of researchers at UC Davis in the USA and using the facilities at the Australian Synchrotron, was published in the journalNature Chemistryon May 15, 2011.

Professor Leone Spiccia from the School of Chemistry at Monash University said the ultimate goal of researchers in this area is to create a cheap, efficient way to split water, powered by sunlight, which would open up production of hydrogen as a clean fuel, and leading to long-term solutions for our renewable energy crisis.

To achieve this, they have been studying complex catalysts designed to mimic the catalysts plants use to split water with sunlight. But the new study shows that there might be much simpler alternatives to hand.

"The hardest part about turning water into fuel is splitting water into hydrogen and oxygen, but the team at Monash seems to have uncovered the process, developing a water-splitting cell based on a manganese-based catalyst," Professor Spiccia said.

"Birnessite, it turns out, is what does the work. Like other elements in the middle of the Periodic Table, manganese can exist in a number of what chemists call oxidation states. These correspond to the number of oxygen atoms with which a metal atom could be combined," Professor Spiccia said.

"When an electrical voltage is applied to the cell, it splits water into hydrogen and oxygen and when the researchers carefully examined the catalyst as it was working, using advanced spectroscopic methods they found that it had decomposed into a much simpler material called birnessite, well-known to geologists as a black stain on many rocks."

The manganese in the catalyst cycles between two oxidation states. First, the voltage is applied to oxidize from the manganese-II state to manganese-IV state in birnessite. Then in sunlight, birnessite goes back to the manganese-II State.

This cycling process is responsible for the oxidation of water to produce oxygen gas, protons and electrons.

Co-author on the research paper was Dr Rosalie Hocking, Research Fellow in the Australian Centre for Electromaterials Science who explained that what was interesting was the operation of the catalyst, which follows closely natures biogeochemical cycling of manganese in the oceans.

"This may provide important insights into the evolution of Nature's water splitting catalyst found in all plants which uses manganese centres," Dr Hocking said.

"Scientists have put huge efforts into making very complicated manganese molecules to copy plants, but it turns out that they convert to a very common material found in the Earth, a material sufficiently robust to survive tough use."

The reaction has two steps. First, two molecules of water are oxidized to form one molecule of oxygen gas (O₂), four positively-charged hydrogen nuclei (protons) and four electrons. Second, the protons and electrons combine to form two molecules of hydrogen gas (H₂).

The experimental work was conducted using state-of-the art equipment at three major facilities including the Australian Synchrotron, the Australian National Beam-line Facility in Japan and the Monash Centre for Electron Microscopy, and involved collaboration with Professor Bill Casey, a geochemist at UC Davis.

"The research highlights the insight obtainable from the synchrotron based spectroscopic techniques -- without them the important discovery linking common earth materials to water oxidation catalysts would not have been made," Dr Hocking said.

It is hoped the research will ultimately lead to the development of cheaper devices, which produce hydrogen.

The work was primarily funded by the U.S. National Science Foundation and the U.S. Department of Energy Monash University, the Australian Research Council through the Australian Centre of Excellence for Electromaterials Science, and the Australian Synchrotron.

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New Green Technology for Hydrogen Production

Hydrogen is a valuable feedstock for the petrochemical industry and it may play a big role in the energy supply of the future, as a green, non-polluting, and efficient energy carrier. If it is burnt, only water is formed. However, the conventional technology for hydrogen production from natural gas ('steam reforming') is a highly energy intensive process, operated at high pressures (up to 25 bar) and high temperature (850^oC), with multistage subsequent separation and purification units. Moreover, huge amounts of CO₂have to be handled in post-processing steps.

TU Eindhoven has now developed a new and improved technology called"sorption enhanced catalytic reforming of methane," using novel catalyst/sorbent materials. Halabi, working in collaboration with the Energy Research Centre of the Netherlands (ECN), has demonstrated the feasibility of producing hydrogen through such a process at much lower temperatures (400 to 500 degrees Celsius).

The process is performed in a packed bed reactor using a Rhodium-based catalyst and a Hydrotalcite-based sorbent as a new system of materials. Hydrogen is produced on the active catalyst and the cogenerated CO₂is effectively adsorbed on the sorbent, hence preventing any CO₂emissions to the atmosphere.

Halabi:"Direct production of high purity hydrogen and fuel conversion greater than 99.5% is experimentally achieved at low temperature range of (400 -- 500^oC) and at a pressure of 4.5 bar with a low level of carbon oxides impurities: less than 100 ppm." The enormous reduction of the reactor size, material loading, catalyst/sorbent ratio, and energy requirements are beneficial key factors for the success of the concept over the conventional technologies. Small size hydrogen generation plants for residential or industrial application operated at a relatively low pressure, of less than 4.5 bar, seem to be feasible.

Dr. Mohamed Halabi received his PhD on May 9, 2011, at TU Eindhoven based on his dissertation"Sorption Enhanced Catalytic Reforming of Methane for Pure Hydrogen Production -- Experimental and Modeling." He conducted his research at the laboratory of Chemical Reactor Engineering, under the supervision of Prof. Jaap Schouten.

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Improving Photosynthesis? Solar Cells Beat Plants at Harvesting Sun's Energy, for Now

Plants are less efficient at capturing the energy in sunlight than solar cells mostly because they have too much evolutionary baggage. Plants have to power a living thing, whereas solar cells only have to send electricity down a wire. This is a big difference because if photosynthesis makes a mistake, it makes toxic byproducts that kill the organism. Photosynthesis has to be conservative to avoid killing the organisms it powers.

"This is critical since it's the process that powers all of life in our ecosystem," said Kramer, a Hannah Distinguished Professor of Photosynthesis and Bioenergetics."The efficiency of photosynthesis, and our ability to improve it, is critical to whether the entire biofuels industry is viable."

The annually averaged efficiency of photovoltaic electrolysis based on silicon semiconductors to produce fuel in the form of hydrogen is about 10 percent, while a plant's annually averaged efficiency using photosynthesis to form biomass for fuel is about 1 or 2 percent.

Plants, following the path of evolution, are primarily interested in reproducing and repairing themselves. The efficiency at which they produce stored solar energy in biomass is secondary.

Still, things can change.

Just as early Native Americans manipulated skinny, non-nutritious Teosinte into fat, juicy kernel corn, today's plants can be manipulated to become much better sources of energy.

Researcher Arthur J.Nozik, a NREL senior research fellow, and Senior Scientist Mark Hanna working at DOE's National Renewable Energy Laboratory (NREL), recently demonstrated how a multi-junction, tandem solar cell for water splitting to produce hydrogen can provide higher efficiency -- more than 40 percent -- by using multiple semiconductors and/or special photoactive organic molecules with different band gaps arranged in a tandem structure.

The coupling of different materials with different gaps means photons can be absorbed and converted to energy over a wider range of the solar spectrum.

"In photovoltaics, we know that to increase power conversion efficiency you have to have different band gaps (i.e., colors) in a tandem arrangement so they can more efficiently use different regions of the solar spectrum," Nozik said."If you had the same gap, they would compete with each other and both would absorb the same photon energies and not enhance the solar conversion efficiency."

Photosynthesis does use two gaps based on chlorophyll molecules to provide enough energy to drive the photosynthesis reaction. But the two gaps have the same energy value, which means they don't help each other to produce energy over a wider stretch of the spectrum of solar light and enhance conversion efficiency.

Furthermore, most plants do use the full intensity of sunlight but divert some of it to protect the plant from damage. Whereas photovoltaics use the second material to gain that photoconversion edge, plants do not, Nozik noted.

One of NREL's roles at the DOE workshop was to help make it clear how the efficiency of photosynthesis could be improved by re-engineering the structure of plants through modern synthetic biology and genetic manipulation based on the principles of high efficiency photovoltaic cells, Nozik said. In synthetic biology plants can be built from scratch, starting with amino acid building blocks, allowing the formation of optimum biological band gaps.

The newly engineered plants would be darker, incorporating some biological pigments in certain of nature's flora that would be able to absorb photons in the red and infrared regions of the solar spectrum.

As plants store more solar energy efficiently, they potentially could play a greater role as alternative renewable fuel sources. The food that plants provide also would get a boost. And that would mean less land would be required to grow an equivalent amount of food.

The new information in theSciencemanuscript will help direct the development of new plants that have a better propensity for reducing carbon dioxide to biomass. This could spur exploration of blue algae, which not only comprise about one quarter of all plant life, but are ideal candidates for being genetically engineered into feedstock, because they absorb light from an entirely different part of the spectrum compared to most other plants.

"It would be the biological equivalent of a tandem photovoltaic cell," said Robert Blankenship, one of the lead authors in theSciencepaper who studies photosynthesis at Washington University in St. Louis."And those can have very high efficiencies."

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Forklift Trucks That Run on a Green Charge

Risavika harbour just outside Stavanger is among the candidates for trials of ten of the 30 forklift trucks, says SINTEF's Steffen Møller-Holst.

SINTEF is a participant in the project's development phase, which will bring the green European truck to its final goal. Under its bodywork, the truck houses a miniature power station in the shape of a fuel cell that runs on hydrogen, and which delivers power to its electric motor. All that the truck emits in operation is water vapour!

The best of both worlds

"A hydrogen-driven forklift truck running on fuel cells combines the advantages of diesel and battery-driven vehicles. The hydrogen-based technology means rapid refuelling, just like diesel, while it is also energy-efficient and every bit as environmentally friendly as a battery truck," says Møller-Holst.

The SINTEF scientist points out that a forklift truck fitted with fuel cells and operating two eight-hour shifts a day reduces CO₂emissions by the equivalent of eight private cars.

Developed under the European Union's auspices

The truck's power system has been developed in the course of a joint European effort run by the European Union.

SINTEF is to perform laboratory tests that will explore how much fuel cell performance falls by over time. At the same time, SINTEF will systematise and analyse feedback from the trials of the 30 demonstration trucks. The knowledge gained in this process will be used to improve the control system and optimise operation, which will ensure that the fuel cell will have a life-cycle that meets the commercial requirements of the market.

Danish projects

The Danish company H2 Logic AS has been responsible for developing the trucks' fuel-cell technology. The solution is a development of a fuel cell that the company had previous developed with Scandinavian backing; its partners included SINTEF and Statoil.

These large forklift trucks in the joint European project have been designed to carry heavy loads. They are manufactured by the Danish company Dantruck, which is showing them off this week at the enormous CeMAT trade fair in Hanover.

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A Renewable Twist on Fossil Fuels

Such a feat could help reduce the rising CO₂levels implicated in global warming and also offer a new method of renewable energy production.

Oak Ridge Associated Universities (ORAU), a consortium of 98 Ph.D.-granting universities, of which UD is a member, has selected Rosenthal to receive the Ralph E. Powe Junior Faculty Enhancement Award to pursue the novel research. Rosenthal is one of 30 award winners nationwide.

The competitive award, which provides$5,000 in seed funding from ORAU and$5,000 in matching funding from the faculty member's university, is intended to enrich the research and educational growth of young faculty and serve as a springboard to new funding opportunities.

Rosenthal and his team are designing electrocatalysts from metals such as nickel and palladium that will freely give away electrons when they react with carbon dioxide, thus chemically reducing this greenhouse gas into energy-rich carbon monoxide or methanol.

Besides its use in making plastics, solvents, carpet and other products, methanol fuels race cars in the United States and currently is being researched as a hydrogen carrier for fuel cell vehicles.

Carbon monoxide is an important precursor to liquid hydrocarbons in the energy arena, in addition to its applications as an industrial chemical for producing plastics to detergents to the acetic acid used in food preservation, drug manufacturing and other fields.

"The catalytic reduction of carbon dioxide to carbon monoxide is an important transformation that would allow for the mitigation of atmospheric CO₂levels, while producing an energy-rich substrate that forms a basis for fuels production," Rosenthal says.

"The chemistry we're doing is energetically uphill -- it's an energy-storing process rather than a downhill, energy-liberating process," he notes."And our goal is to make liquid fuel renewably from wind and solar sources, not from typical fossil fuel bases."

As early as junior high, Rosenthal said, he realized that basic life processes are linked to molecular energy conversion. Then his undergraduate and graduate research took off on renewables.

He earned his undergraduate degree in organic chemistry from New York University and his doctorate in inorganic chemistry at MIT while studying how metals catalyze various energy conversion processes. His doctoral adviser at MIT was Dan Nocera, a leading scientist in renewable energy research.

The strong reputation of the chemistry and biochemistry department lured Rosenthal, a New York City native, to UD. He joined the UD faculty this past fall and already has a research group of eight focusing on the project -- one postdoctoral researcher, four graduate students and three undergraduates.

"The CO₂problem is very important, and people have to tackle it," Rosenthal says."It's my hope to be able to map out the molecular design principles for efficient CO₂conversion into fuels. Then you can think about doing this on a commercially relevant scale."

Conservative estimates predict that by 2050, the rate of global energy consumption will roughly double the rate recorded at the end of the 20th century. Most scientists believe that rising carbon dioxide levels are leading to global climate change.

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Portable Tech Might Provide Drinking Water, Power to Villages

Such a technology might be used to provide power and drinking water to villages and also for military operations, said Jerry Woodall, a Purdue University distinguished professor of electrical and computer engineering.

The alloy contains aluminum, gallium, indium and tin. Immersing the alloy in freshwater or saltwater causes a spontaneous reaction, splitting the water into hydrogen and oxygen molecules. The hydrogen could then be fed to a fuel cell to generate electricity, producing water in the form of steam as a byproduct, he said.

"The steam would kill any bacteria contained in the water, and then it would condense to purified water," Woodall said."So, you are converting undrinkable water to drinking water."

Because the technology works with saltwater, it might have marine applications, such as powering boats and robotic underwater vehicles. The technology also might be used to desalinate water, said Woodall, who is working with doctoral student Go Choi.

A patent on the design is pending.

Woodall envisions a new portable technology for regions that aren't connected to a power grid, such as villages in Africa and other remote areas.

"There is a big need for this sort of technology in places lacking connectivity to a power grid and where potable water is in short supply," he said."Because aluminum is a low-cost, non-hazardous metal that is the third-most abundant metal on Earth, this technology promises to enable a global-scale potable water and power technology, especially for off-grid and remote locations."

The potable water could be produced for about$1 per gallon, and electricity could be generated for about 35 cents per kilowatt hour of energy.

"There is no other technology to compare it against, economically, but it's obvious that 34 cents per kilowatt hour is cheap compared to building a power plant and installing power lines, especially in remote areas," Woodall said.

The unit, including the alloy, the reactor and fuel cell might weigh less than 100 pounds.

"You could drop the alloy, a small reaction vessel and a fuel cell into a remote area via parachute," Woodall said."Then the reactor could be assembled along with the fuel cell. The polluted water or the seawater would be added to the reactor and the reaction converts the aluminum and water into aluminum hydroxide, heat and hydrogen gas on demand."

The aluminum hydroxide waste is non-toxic and could be disposed of in a landfill.

The researchers have a design but haven't built a prototype.

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Hydrogen Fuel Tech Gets Boost from Low-Cost, Efficient Catalyst

The discovery is an important development in the worldwide effort to mimic the way plants make fuel from sunlight, a key step in creating a green energy economy. It was reported inNature Materialsby theorist Jens Nørskov of the Department of Energy's SLAC National Accelerator Laboratory and Stanford University and a team of colleagues led by Ib Chorkendorff and Søren Dahl at the Technical University of Denmark (DTU).

Hydrogen is an energy dense and clean fuel, which upon combustion releases only water. Today, most hydrogen is produced from natural gas which results in large CO₂-emissions. An alternative, clean method is to make hydrogen fuel from sunlight and water. The process is called photo-electrochemical, or PEC, water splitting. When sun hits the PEC cell, the solar energy is absorbed and used for splitting water molecules into its components, hydrogen and oxygen.

Progress has so far been limited in part by a lack of cheap catalysts that can speed up the generation of hydrogen and oxygen. A vital part of the American-Danish effort was combining theory and advanced computation with synthesis and testing to accelerate the process of identifying new catalysts. This is a new development in a field that has historically relied on trial and error."If we can find new ways of rationally designing catalysts, we can speed up the development of new catalytic materials enormously," Nørskov said.

The team first tackled the hydrogen half of the problem. The DTU researchers created a device to harvest the energy from part of the solar spectrum and used it to power the conversion of single hydrogen ions into hydrogen gas. However, the process requires a catalyst to facilitate the reaction. Platinum is already known as an efficient catalyst, but platinum is too rare and too expensive for widespread use. So the collaborators turned to nature for inspiration.

They investigated hydrogen producing enzymes -- natural catalysts -- from certain organisms, using a theoretical approach Nørskov's group has been developing to describe catalyst behavior."We did the calculations," Nørskov explained,"and found out why these enzymes work as well as they do." These studies led them to related compounds, which eventually took them to molybdenum sulfide."Molybdenum is an inexpensive solution" for catalyzing hydrogen production, Chorkendorff said.

The team also optimized parts of the device, introducing a"chemical solar cell" designed to capture as much solar energy as possible. The experimental researchers at DTU designed light absorbers that consist of silicon arranged in closely packed pillars, and dotted the pillars with tiny clusters of the molybdenum sulfide. When they exposed the pillars to light, hydrogen gas bubbled up -- as quickly as if they'd used costly platinum.

The hydrogen gas-generating device is only half of a full photo-electrochemical cell. The other half of the PEC would generate oxygen gas from the water; though hydrogen gas is the goal, without the simultaneous generation of oxygen, the whole PEC cell shuts down. Many groups -- including Chorkendorff, Dahl and Nørskov and their colleagues -- are working on finding catalysts and sunlight absorbers to do this well."This is the most difficult half of the problem, and we are attacking this in the same way as we attacked the hydrogen side," Dahl said.

Nørskov looks forward to solving that problem as well."A sustainable energy choice that no one can afford is not sustainable at all," he said."I hope this approach will enable us to choose a truly sustainable fuel."

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Cheaper Hydrogen Fuel Cells: Utility of Non-Precious-Metal Catalysts Documented

In a paper published April 21 inScience, Los Alamos researchers Gang Wu, Christina Johnston, and Piotr Zelenay, joined by researcher Karren More of Oak Ridge National Laboratory, describe the use of a platinum-free catalyst in the cathode of a hydrogen fuel cell. Eliminating platinum -- a precious metal more expensive than gold -- would solve a significant economic challenge that has thwarted widespread use of large-scale hydrogen fuel cell systems.

Polymer-electrolyte hydrogen fuel cells convert hydrogen and oxygen into electricity. The cells can be enlarged and combined in series for high-power applications, including automobiles. Under optimal conditions, the hydrogen fuel cell produces water as a"waste" product and does not emit greenhouse gasses. However, because the use of platinum in catalysts is necessary to facilitate the reactions that produce electricity within a fuel cell, widespread use of fuel cells in common applications has been cost prohibitive. An increase in the demand for platinum-based catalysts could drive up the cost of platinum even higher than its current value of nearly$1,800 an ounce.

The Los Alamos researchers developed non-precious-metal catalysts for the part of the fuel cell that reacts with oxygen. The catalysts -- which use carbon (partially derived from polyaniline in a high-temperature process), and inexpensive iron and cobalt instead of platinum -- yielded high power output, good efficiency, and promising longevity. The researchers found that fuel cells containing the carbon-iron-cobalt catalyst synthesized by Wu not only generated currents comparable to the output of precious-metal-catalyst fuel cells, but held up favorably when cycled on and off -- a condition that can damage inferior catalysts relatively quickly.

Moreover, the carbon-iron-cobalt catalyst fuel cells effectively completed the conversion of hydrogen and oxygen into water, rather than producing large amounts of undesirable hydrogen peroxide. Inefficient conversion of the fuels, which generates hydrogen peroxide, can reduce power output by up to 50 percent, and also has the potential to destroy fuel cell membranes. Fortunately, the carbon- iron-cobalt catalysts synthesized at Los Alamos create extremely small amounts of hydrogen peroxide, even when compared with state-of-the-art platinum-based oxygen-reduction catalysts.

Because of the successful performance of the new catalyst, the Los Alamos researchers have filed a patent for it.

"The encouraging point is that we have found a catalyst with a good durability and life cycle relative to platinum-based catalysts," said Zelenay, corresponding author for the paper."For all intents and purposes, this is a zero-cost catalyst in comparison to platinum, so it directly addresses one of the main barriers to hydrogen fuel cells."

The next step in the team's research will be to better understand the mechanism underlying the carbon-iron-cobalt catalyst. Micrographic images of portions of the catalyst by researcher More have provided some insight into how it functions, but further work must be done to confirm theories by the research team. Such an understanding could lead to improvements in non-precious-metal catalysts, further increasing their efficiency and lifespan.

Project funding for the Los Alamos research came from the U.S. Department of Energy's Energy Efficiency and Renewable Energy (EERE) Office as well as from Los Alamos National Laboratory's Laboratory-Directed Research and Development program. Microscopy research was done at Oak Ridge National Laboratory's SHaRE user facility with support from the DOE's Office of Basic Energy Sciences.

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Laser Sparks Revolution in Internal Combustion Engines

In the past, lasers strong enough to ignite an engine's air-fuel mixtures were too large to fit under an automobile's hood. At this year's Conference on Lasers and Electro Optics (CLEO: 2011), to be held in Baltimore May 1-6, researchers from Japan will describe the first multibeam laser system small enough to screw into an engine's cylinder head.

Equally significant, the new laser system is made from ceramics, and could be produced inexpensively in large volumes, according to one of the presentation's authors, Takunori Taira of Japan's National Institutes of Natural Sciences.

According to Taira, conventional spark plugs pose a barrier to improving fuel economy and reducing emissions of nitrogen oxides (NO_x), a key component of smog.

Spark plugs work by sending small, high-voltage electrical sparks across a gap between two metal electrodes. The spark ignites the air-fuel mixture in the engine's cylinder -- producing a controlled explosion that forces the piston down to the bottom of the cylinder, generating the horsepower needed to move the vehicle.

Engines make NO_xas a byproduct of combustion. If engines ran leaner -- burnt more air and less fuel -- they would produce significantly smaller NO_xemissions.

Spark plugs can ignite leaner fuel mixtures, but only by increasing spark energy. Unfortunately, these high voltages erode spark plug electrodes so fast, the solution is not economical. By contrast, lasers, which ignite the air-fuel mixture with concentrated optical energy, have no electrodes and are not affected.

Lasers also improve efficiency. Conventional spark plugs sit on top of the cylinder and only ignite the air-fuel mixture close to them. The relatively cold metal of nearby electrodes and cylinder walls absorbs heat from the explosion, quenching the flame front just as it starts to expand.

Lasers, Taira explains, can focus their beams directly into the center of the mixture. Without quenching, the flame front expands more symmetrically and up to three times faster than those produced by spark plugs.

Equally important, he says, lasers inject their energy within nanoseconds, compared with milliseconds for spark plugs."Timing -- quick combustion -- is very important. The more precise the timing, the more efficient the combustion and the better the fuel economy," he says.

Lasers promise less pollution and greater fuel efficiency, but making small, powerful lasers has, until now, proven hard. To ignite combustion, a laser must focus light to approximately 100 gigawatts per square centimeter with short pulses of more than 10 millijoules each.

"In the past, lasers that could meet those requirements were limited to basic research because they were big, inefficient, and unstable," Taira says. Nor could they be located away from the engine, because their powerful beams would destroy any optical fibers that delivered light to the cylinders.

Taira's research team overcame this problem by making composite lasers from ceramic powders. The team heats the powders to fuse them into optically transparent solids and embeds metal ions in them to tune their properties.

Ceramics are easier to tune optically than conventional crystals. They are also much stronger, more durable, and thermally conductive, so they can dissipate the heat from an engine without breaking down.

Taira's team built its laser from two yttrium-aluminum-gallium (YAG) segments, one doped with neodymium, the other with chromium. They bonded the two sections together to form a powerful laser only 9 millimeters in diameter and 11 millimeters long (a bit less than half an inch).

The composite generates two laser beams that can ignite fuel in two separate locations at the same time. This would produce a flame wall that grows faster and more uniformly than one lit by a single laser.

The laser is not strong enough to light the leanest fuel mixtures with a single pulse. By using several 800-picosecond-long pulses, however, they can inject enough energy to ignite the mixture completely.

A commercial automotive engine will require 60 Hz (or pulse trains per second), Taira says. He has already tested the new dual-beam laser at 100 Hz. The team is also at work on a three-beam laser that will enable even faster and more uniform combustion.

The laser-ignition system, although highly promising, is not yet being installed into actual automobiles made in a factory. Taira's team is, however, working with a large spark-plug company and with DENSO Corporation, a member of the Toyota Group.

This work is supported by the Japan Science and Technical Agency (JST).

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Chance Discovery May Revolutionize Hydrogen Production

The results of the research are published online inChemical Science. An international patent based on this discovery has just been filled.

Existing in large quantities on Earth, water is composed of hydrogen and oxygen. It can be broken down by applying an electrical current; this is the process known as electrolysis. To improve this particularly slow reaction, platinum is generally used as a catalyst. However, platinum is a particularly expensive material that has tripled in price over the last decade. Now EPFL scientists have shown that amorphous molybdenum sulphides, found abundantly, are efficient catalysts and hydrogen production cost can be significantly lowered.

Industrial prospects

The new catalysts exhibit many advantageous technical characteristics. They are stable and compatible with acidic, neutral or basic conditions in water. Also, the rate of the hydrogen production is faster than other catalysts of the same price. The discovery opens up some interesting possibilities for industrial applications such as in the area of solar energy storage.

It's only by chance that Daniel Merki, Stéphane Fierro, Heron Vrubel and Xile Hu made this discovery during an electrochemical experience."It's a perfect illustration of the famous serendipity principle in fundamental research," as Xile Hu emphasizes:"Thanks to this unexpected result, we've revealed a unique phenomenon," he explains."But we don't yet know exactly why the catalysts are so efficient."

The next stage is to create a prototype that can help to improve sunlight-driven hydrogen production. But a better understanding of the observed phenomenon is also required in order to optimize the catalysts.

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First Macro-Scale Thin-Film Solid-Oxide Fuel Cell: Strong, Nanostructured Membrane Enables Scaling for Clean-Energy Applications

While SOFCs have previously worked at the micro-scale, this is the first time any research group has overcome the structural challenges of scaling the technology up to a practical size with a proportionally higher power output.

Reported online April 3 inNature Nanotechnology, the demonstration of this fully functional SOFC indicates the potential of electrochemical fuel cells to be a viable source of clean energy.

"The breakthrough in this work is that we have demonstrated power density comparable to what you can get with tiny membranes, but with membranes that are a factor of a hundred or so larger, demonstrating that the technology is scalable," says principal investigator Shriram Ramanathan, Associate Professor of Materials Science at SEAS.

SOFCs create electrical energy via an electrochemical reaction that takes place across an ultra-thin membrane. This 100-nanometer membrane, comprising the electrolyte and electrodes, has to be thin enough to allow ions to pass through it at a relatively low temperature (which, for ceramic fuel cells, lies in the range of 300 to 500 degrees Celsius). These low temperatures allow for a quick start-up, a more compact design, and less use of rare-earth materials.

So far, however, thin films have been successfully implemented only in micro-SOFCs, where each chip in the fuel cell wafer is about 100 microns wide. For practical applications, such as use in compact power sources, SOFCs need to be about 50 times wider.

The electrochemical membranes are so thin that creating one on that scale is roughly equivalent to making a 16-foot-wide sheet of paper. Naturally, the structural issues are significant.

"If you make a conventional thin membrane on that scale without a support structure, you can't do anything -- it will just break," says co-author Bo-Kuai Lai, a postdoctoral fellow at SEAS."You make the membrane in the lab, but you can't even take it out. It will just shatter."

With lead author Masaru Tsuchiya (Ph.D. '09), a former member of Ramanathan's lab who is now at SiEnergy, Ramanathan and Lai fortified the thin film membrane using a metallic grid that looks like nanoscale chicken wire.

The tiny metal honeycomb provides the critical structural element for the large membrane while also serving as a current collector. Ramanathan's team was able to manufacture membrane chips that were 5 mm wide, combining hundreds of these chips into palm-sized SOFC wafers.

While other researchers' earlier attempts at implementing the metallic grid showed structural success, Ramanathan's team is the first to demonstrate a fully functional SOFC on this scale. Their fuel cell's power density of 155 milliwatts per square centimeter (at 510 degrees Celsius) is comparable to the power density of micro-SOFCs.

When multiplied by the much larger active area of this new fuel cell, that power density translates into an output high enough for relevance to portable power.

Previous work in Ramanathan's lab has developed micro-SOFCs that are all-ceramic or that use methane as the fuel source instead of hydrogen. The researchers hope that future work on SOFCs will incorporate these technologies into the large-scale fuel cells, improving their affordability.

In the coming months, they will explore the design of novel nanostructured anodes for hydrogen-alternative fuels that are operable at these low temperatures and work to enhance the microstructural stability of the electrodes.

The research was supported in part by the National Science Foundation (NSF) and performed in part at the Harvard University Center for Nanoscale Systems, a member of the NSF-funded National Nanotechnology Infrastructure Network.

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Novel Nanowires Boost Fuel Cell Efficiency

But one reason fuel cells aren't already more widespread is their lack of endurance. Over time, the catalysts used even in today's state-of-the-art fuels cells break down, inhibiting the chemical reaction that converts fuel into electricity. In addition, current technology relies on small particles coated with the catalyst; however, the particles' limited surface area means only a fraction of the catalyst is available at any given time.

Now a team of engineers at the Yale School of Engineering& Applied Science has created a new fuel cell catalyst system using nanowires made of a novel material that boosts long-term performance by 2.4 times compared to today's technology. Their findings appear on the cover of the April issue ofACS Nano.

Yale engineers Jan Schroers and André Taylor have developed miniscule nanowires made of an innovative metal alloy known as a bulk metallic glass (BMG) that have high surface areas, thereby exposing more of the catalyst. They also maintain their activity longer than traditional fuel cell catalyst systems.

Current fuel cell technology uses carbon black, an inexpensive and electrically conductive carbon material, as a support for platinum particles. The carbon transports electricity, while the platinum is the catalyst that drives the production of electricity. The more platinum particles the fuel is exposed to, the more electricity is produced. Yet carbon black is porous, so the platinum inside the inner pores may not be exposed. Carbon black also tends to corrode over time.

"In order to produce more efficient fuel cells, you want to increase the active surface area of the catalyst, and you want your catalyst to last," Taylor said.

At 13 nanometers in scale (about 1/10,000 the width of a human hair), the BMG nanowires that Schroers and Taylor developed are about three times smaller than carbon black particles. The nanowires' long, thin shape gives them much more active surface area per mass compared to carbon black. In addition, rather than sticking platinum particles onto a support material, the Yale team incorporated the platinum into the nanowire alloy itself, ensuring that it continues to react with the fuel over time.

It's the nanowires' unique chemical composition that makes it possible to shape them into such small rods using a hot-press method, said Schroers, who has developed other BMG alloys that can also be blow molded into complicated shapes. The BMG nanowires also conduct electricity better than carbon black and carbon nanotubes, and are less expensive to process.

So far Taylor has tested their catalyst system for alcohol-based fuel cells (including those that use ethanol and methanol as fuel sources), but they say the system could be used in other types of fuel cells and could one day be used in portable electronic devices such as laptop computers and cell phones as well as in remote sensors.

"This is the introduction of a new class of materials that can be used as electrocatalysts," Taylor said."It's a real step toward making fuel cells commercially viable and, ultimately, supplementing or replacing batteries in electronic devices."

Other authors of the paper include Marcelo Carmo, Ryan C. Sekol, Shiyan Ding and Golden Kumar (all of Yale University).

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Researchers Close in on Technology for Making Renewable Petroleum

Graduate student Janice Frias, who earned her doctorate in January, made the critical step by figuring out how to use a protein to transform fatty acids produced by the bacteria into ketones, which can be cracked to make hydrocarbon fuels. The university is filing patents on the process.

The research is published in the April 1 issue of theJournal of Biological Chemistry. Frias, whose advisor was Larry Wackett, Distinguished McKnight Professor of Biochemistry, is lead author. Other team members include organic chemist Jack Richman, a researcher in the College of Biological Sciences' Department of Biochemistry, Molecular Biology and Biophysics, and undergraduate Jasmine Erickson, a junior in the College of Biological Sciences. Wackett, who is senior author, is a faculty member in the College of Biological Sciences and the university's BioTechnology Institute.

Aditya Bhan and Lanny Schmidt, chemical engineering professors in the College of Science and Engineering, are turning the ketones into diesel fuel using catalytic technology they have developed. The ability to produce ketones opens the door to making petroleum-like hydrocarbon fuels using only bacteria, sunlight and carbon dioxide.

"There is enormous interest in using carbon dioxide to make hydrocarbon fuels," Wackett says."CO₂is the major greenhouse gas mediating global climate change, so removing it from the atmosphere is good for the environment. It's also free. And we can use the same infrastructure to process and transport this new hydrocarbon fuel that we use for fossil fuels."

The research is funded by a$2.2 million grant from the U.S. Department of Energy's Advanced Research Projects Agency-energy (ARPA-e) program, created to stimulate American leadership in renewable energy technology.

Wackett is principal investigator for the ARPA-e grant. His team of co-investigators includes Jeffrey Gralnick, assistant professor of microbiology and Marc von Keitz, chief technical officer of BioCee, as well as Bhan and Schmidt. They are the only group using a photosynthetic bacterium and a hydrocarbon-producing bacterium together to make hydrocarbons from carbon dioxide.

The U of M team is usingSynechococcus, a bacterium that fixes carbon dioxide in sunlight and converts CO₂to sugars. Next, they feed the sugars toShewanella, a bacterium that produces hydrocarbons. This turns CO₂, a greenhouse gas produced by combustion of fossil fuel petroleum, into hydrocarbons.

Hydrocarbons (made from carbon and hydrogen) are the main component of fossil fuels. It took hundreds of millions of years of heat and compression to produce fossil fuels, which experts expect to be largely depleted within 50 years.

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The Drive Toward Hydrogen Vehicles Just Got Shorter

In an article appearing recently in the journalScience, Los Alamos National Laboratory (LANL) and University of Alabama researchers working within the U.S. Department of Energy's Chemical Hydrogen Storage Center of Excellence describe a significant advance in hydrogen storage science.

Hydrogen is in many ways an ideal fuel. It possesses a high energy content per unit mass when compared to petroleum, and it can be used to run a fuel cell, which in turn can be used to power a very clean engine. On the down side, H2 has a low energy content per unit volume versus petroleum (it is very light and bulky). The crux of the hydrogen issue has been how to get enough of the element on board a vehicle to power it a reasonable distance.

Work at LANL and elsewhere has focused on chemical hydrides for storing hydrogen, with one material in particular, ammonia borane, taking center stage. Ammonia borane is attractive because its hydrogen storage capacity approaches a whopping 20 percent by weight -- enough that it should, with appropriate engineering, permit hydrogen-fueled vehicles to go farther than 300 miles on a single"tank," a benchmark set by the U.S. Department of Energy.

Hydrogen release from ammonia borane has been well demonstrated, and its chief drawback to use has been the lack of energy-efficient methods to reintroduce hydrogen into the spent fuel once burned. In other words, until now, after hydrogen release, the ammonia borane couldn't be recycled efficiently enough.

The Science paper describes a simple scheme that regenerates ammonia borane from a hydrogen depleted"spent fuel" form (called polyborazylene) back into usable fuel via reactions taking place in a single container. This"one pot" method represents a significant step toward the practical use of hydrogen in vehicles by potentially reducing the expense and complexity of the recycle stage. Regeneration takes place in a sealed pressure vessel using hydrazine and liquid ammonia at 40 degrees Celsius and necessarily takes place off-board a vehicle. The researchers envision vehicles with interchangeable hydrogen storage"tanks" containing ammonia borane that are used, and sent back to a factory for recharge.

The Chemical Hydrogen Storage Center of Excellence was one of three Center efforts funded by DOE. The other two focused on hydrogen sorption technologies and storage in metal hydrides. The Center of Excellence was a collaboration between Los Alamos, Pacific Northwest National Laboratory, and academic and industrial partners.

LANL researcher Dr. John Gordon, a corresponding author for the paper, credits collaboration encouraged by the Center model with the breakthrough.

"Crucial predictive calculations carried out by University of Alabama Professor Dave Dixon's group guided the experimental work of the Los Alamos team, which included researchers from both the Chemistry Division and the Materials Physics and Applications Division at LANL," Gordon said.

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Breakthrough in Nanocomposite for High-Capacity Hydrogen Storage

In recent years, researchers have attempted to tackle both issues by locking hydrogen into solids, packing larger quantities into smaller volumes with low reactivity -- a necessity in keeping this volatile gas stable. However, most of these solids can only absorb a small amount of hydrogen and require extreme heating or cooling to boost their overall energy efficiency.

Now, scientists with the U.S. Department of Energy (DOE) Lawrence Berkeley National Laboratory (Berkeley Lab) have designed a new composite material for hydrogen storage consisting of nanoparticles of magnesium metal sprinkled through a matrix of polymethyl methacrylate, a polymer related to Plexiglas. This pliable nanocomposite rapidly absorbs and releases hydrogen at modest temperatures without oxidizing the metal after cycling -- a major breakthrough in materials design for hydrogen storage, batteries and fuel cells.

"This work showcases our ability to design composite nanoscale materials that overcome fundamental thermodynamic and kinetic barriers to realize a materials combination that has been very elusive historically," says Jeff Urban, Deputy Director of the Inorganic Nanostructures Facility at the Molecular Foundry, a DOE Office of Science nanoscience center and national user facility located at Berkeley Lab."Moreover, we are able to productively leverage the unique properties of both the polymer and nanoparticle in this new composite material, which may have broad applicability to related problems in other areas of energy research."

Urban, along with coauthors Ki-Joon Jeon and Christian Kisielowski used the TEAM 0.5 microscope at the National Center for Electron Microscopy (NCEM), another DOE Office of Science national user facility housed at Berkeley Lab, to observe individual magnesium nanocrystals dispersed throughout the polymer. With the high-resolution imaging capabilities of TEAM 0.5, the world's most powerful electron microscope, the researchers were also able to track defects -- atomic vacancies in an otherwise-ordered crystalline framework -- providing unprecedented insight into the behavior of hydrogen within this new class of storage materials.

"Discovering new materials that could help us find a more sustainable energy solution is at the core of the Department of Energy's mission. Our lab provides outstanding experiments to support this mission with great success," says Kisielowski."We confirmed the presence of hydrogen in this material through time-dependent spectroscopic investigations with the TEAM 0.5 microscope. This investigation suggests that even direct imaging of hydrogen columns in such materials can be attempted using the TEAM microscope."

"The unique nature of Berkeley Lab encourages cross-division collaborations without any limitations," said Jeon, now at the Ulsan National Institute of Science and Technology, whose postdoctoral work with Urban led to this publication.

To investigate the uptake and release of hydrogen in their nanocomposite material, the team turned to Berkeley Lab's Energy and Environmental Technologies Division (EETD), whose research is aimed at developing more environmentally friendly technologies for generating and storing energy, including hydrogen storage.

"Here at EETD, we have been working closely with industry to maintain a hydrogen storage facility as well as develop hydrogen storage property testing protocols," says Samuel Mao, director of the Clean Energy Laboratory at Berkeley Lab and an adjunct engineering faculty member at the University of California (UC), Berkeley."We very much enjoy this collaboration with Jeff and his team in the Materials Sciences Division, where they developed and synthesized this new material, and were then able to use our facility for their hydrogen storage research."

Adds Urban,"This ambitious science is uniquely well-positioned to be pursued within the strong collaborative ethos here at Berkeley Lab. The successes we achieve depend critically upon close ties between cutting-edge microscopy at NCEM, tools and expertise from EETD, and the characterization and materials know-how from MSD."

This research is reported in a paper titled,"Air-stable magnesium nanocomposites provide rapid and high-capacity hydrogen storage without heavy metal catalysts," appearing in the journalNature Materials. Co-authoring the paper with Urban, Kisielowski and Jeon were Hoi Ri Moon, Anne M. Ruminski, Bin Jiang and Rizia Bardhan.

This work was supported by DOE's Office of Science.

The Molecular Foundry is one of the five DOE Nanoscale Science Research Centers (NSRCs), premier national user facilities for interdisciplinary research at the nanoscale. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE's Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge and Sandia and Los Alamos National Laboratories. For more information about the DOE NSRCs, please visithttp://nano.energy.gov.

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Algae Converted to Butanol; Fuel Can Be Used in Automobiles

"We can make cars go," said Jamie Hestekin, assistant professor and leader of the project."Our conversion process is efficient and inexpensive. Butanol has many advantages compared to ethanol, but the coolest thing about this process is that we're actually making rivers and lakes healthier by growing and harvesting the raw material."

Hestekin and his research team -- undergraduates from the Honors College and several graduate students, including a doctoral student who has discovered a more efficient and technologically superior fermentation method -- grow algae on"raceways," which are long troughs -- usually 2 feet wide and ranging from 5-feet to 80-feet long, depending on the scale of the operation. The troughs are made of screens or carpet, although Hestekin said algae will grow on almost any surface.

Algae survive on nitrogen, phosphorus, carbon dioxide and natural sunlight, so the researchers grow algae by running nitrogen- and phosphorus-rich creek water over the surface of the troughs. They enhance this growth by delivering high concentrations of carbon dioxide through hollow fiber membranes that look like long strands of spaghetti. Municipal and state governments, primarily on the East Coast, have implemented large-scale processes similar to this to address so-called"dead zones," where excess nitrogen and phosphorus have killed fish and plants.

The researchers harvest the algae every five to eight days by vacuuming or scraping it off the screens. After waiting for it to dry, they crush and grind the algae into a fine powder as the means to extract carbohydrates from the plant cells. Carbohydrates are made of sugars and starches. For this project, Hestekin's team works with starches. They treat the carbohydrates with acid and then heat them to break apart the starches and convert them into simple, natural sugars. They then begin a unique, two-step fermentation process in which organisms turn the sugars into organic acids -- butyric, lactic and acetic.

The second stage of the fermentation process focuses on butyric acid and its conversion into butanol. The researchers use a unique process called electrodeionization, a technique developed by one of Hestekin's doctoral students. This technique involves the use of a special membrane that rapidly and efficiently separates the acids during the application of electrical charges. By quickly isolating butyric acid, the process increases productivity, which makes the conversion process easier and less expensive.

As Hestekin mentioned, butanol has several significant advantages over ethanol, the current primary additive in gasoline. Butanol releases more energy per unit mass and can be mixed in higher concentrations than ethanol. It is less corrosive than ethanol and can be shipped through existing pipelines. These attributes are in addition to the advantages gleaned from butanol's source. Unlike corn, algae are not in demand by the food industry. Furthermore, it can be grown virtually anywhere and thus does not require large tracts of valuable farmland.

Hestekin's team is currently working with the New York City Department of Environmental Protection to create biofuel from algae grown at the Rockaway Wastewater Treatment Plant in Queens.

Research articles detailing findings from algae-to-fuel project have been submitted toBiotechnology and BioengineeringandSeparation Science and Technology.

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Turning Forests Into Fuel: Promise and Limits of Biomass Energy in Northeastern U.S.

But the report also has sharp caveats: The potential for forest biomass varies widely within the region, and forest resources must be carefully managed to protect the other important services and goods they provide. Under the right circumstances, however, the report found that forest biomass can provide a domestic energy resource, create local jobs, and provide incentives to forest owners.

"In targeted applications, the heat generated by locally-grown biomass can reduce dependence on fossil fuels and support local economies," said Dr. Charles D. Canham, a forest ecologist at the Cary Institute and co-author of the report."But each forested landscape is different, and regional variation in forest conditions and energy infrastructure means there is no one-size-fits-all solution."

The report analyzed U.S.D.A. Forest Service Forest data from Connecticut, Maine, Massachusetts, New Hampshire, New York, Pennsylvania, Rhode Island, and Vermont.

It found that using forest biomass for heat in the region was far more effective in replacing liquid fossil fuels than converting it to cellulosic ethanol for road transport. Biomass burned in combined heat and power plants reduced fossil fuel use more than five times more effectively than substituting gasoline with cellulosic ethanol.

Under best-case scenarios, however, the energy generated sustainably from forest biomass in the Northeast could replace only 1.4% of the region's total fossil fuel energy. But for some states, biomass energy could be much more compelling when replacing fossil fuel use in certain sectors.

"Maine and New Hampshire show the greatest potential for forest biomass energy," said Dr. Thomas Buchholz, a researcher at the University of Vermont's Carbon Dynamics Lab and co-author on the report."Our study found that New Hampshire could replace as much as 84 percent of its liquid fossil fuel dependence in the industrial and commercial heating sector, and Maine could replace 49 percent of its liquid fossil fuel dependence in the home-heating sector."

But the report cautioned that utmost care must be observed in all parts of the region.

"There is a misconception that Northeastern forestland is a vast, untapped resource," Canham commented."This is simply not true. Unrealistic growth in biomass energy facilities could lead to serious degradation of forest resources. While forest biomass is part of the renewable energy toolkit, it is by no means a panacea."

"Forest biomass can be an important element of a low-carbon energy future," added contributing author Dr. Steven Hamburg of Environmental Defense Fund."But we'll need ongoing scientific oversight to ensure it is done sustainably."

Full report: Forest Biomass and Bioenergy: Opportunities and Constraints in the Northeastern United States

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Paperweight for Platinum: Bracing Catalyst in Material Makes Fuel Cell Component Work Better and Last Longer

"Fuel cells are an important area of energy technology, but cost and durability are big challenges," said chemist Jun Liu."The unique structure of this material provides much needed stability, good electrical conductivity and other desired properties."

Liu and his colleagues at the Department of Energy's Pacific Northwest National Laboratory, Princeton University in Princeton, N.J., and Washington State University in Pullman, Wash., combined graphene, a one-atom-thick honeycomb of carbon with handy electrical and structural properties, with metal oxide nanoparticles to stabilize a fuel cell catalyst and make it better available to do its job.

"This material has great potential to make fuel cells cheaper and last longer," said catalytic chemist Yong Wang, who has a joint appointment with PNNL and WSU."The work may also provide lessons for improving the performance of other carbon-based catalysts for a broad range of industrial applications."

Muscle Metal Oxide

Fuel cells work by chemically breaking down oxygen and hydrogen gases to create an electrical current, producing water and heat in the process. The centerpiece of the fuel cell is the chemical catalyst -- usually a metal such as platinum -- sitting on a support that is often made of carbon. A good supporting material spreads the platinum evenly over its surface to maximize the surface area with which it can attack gas molecules. It is also electrically conductive.

Fuel cell developers most commonly use black carbon -- think pencil lead -- but platinum atoms tend to clump on such carbon. In addition, water can degrade the carbon away. Another support option is metal oxides -- think rust -- but what metal oxides make up for in stability and catalyst dispersion, they lose in conductivity and ease of synthesis. Other researchers have begun to explore metal oxides in conjunction with carbon materials to get the best of both worlds.

As a carbon support, Liu and his colleagues thought graphene intriguing. The honeycomb lattice of graphene is porous, electrically conductive and affords a lot of room for platinum atoms to work. First, the team crystallized nanoparticles of the metal oxide known as indium tin oxide -- or ITO -- directly onto specially treated graphene. Then they added platinum nanoparticles to the graphene-ITO and tested the materials.

Platinumweight

The team viewed the materials under high-resolution microscopes at EMSL, DOE's Environmental Molecular Sciences Laboratory on the PNNL campus. The images showed that without ITO, platinum atoms clumped up on the graphene surface. But with ITO, the platinum spread out nicely. Those images also showed catalytic platinum wedged between the nanoparticles and the graphene surface, with the nanoparticles partially sitting on the platinum like a paperweight.

To see how stable this arrangement was, the team performed theoretical calculations of molecular interactions between the graphene, platinum and ITO. This number-crunching on EMSL's Chinook supercomputer showed that the threesome was more stable than the metal oxide alone on graphene or the catalyst alone on graphene.

But stability makes no difference if the catalyst doesn't work. In tests for how well the materials break down oxygen as they would in a fuel cell, the triple-threat packed about 40% more of a wallop than the catalyst alone on graphene or the catalyst alone on other carbon-based supports such as activated carbon.

Last, the team tested how well the new material stands up to repeated usage by artificially aging it. After aging, the tripartite material proved to be three times as durable as the lone catalyst on graphene and twice as durable as on commonly used activated carbon. Corrosion tests revealed that the triple threat was more resistant than the other materials tested as well.

The team is now incorporating the platinum-ITO-graphene material into experimental fuel cells to determine how well it works under real world conditions and how long it lasts.

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Microbiologists Aim to Optimize Bio-Ethanol Production

The age of diesel and gasoline is approaching its inevitable end. However, one of the alternatives, bio-ethanol made from plant material by way of microorganism fermentation, is under attack. Until now, bio-ethanol has been produced from crops such as wheat, sugar cane or corn, or more accurately, from the sugar these crops contain in the form of starch. However, when field crops are used for the production of bio-ethanol, they are no longer available as food. Researchers at the TUM Department of Microbiology are working on a solution to this dilemma. The idea: Make the sugar stored in the stems and leaves of plants in the form of cellulose available for bio-ethanol production."It is our goal to take the cellulose, which has so far hardly been used, and turn it into sugar on an industrial scale, which can then be processed to bio-ethanol," says microbiologist Dr. Wolfgang Schwarz.

But it is not that simple. As the main constituent of plant cell walls, cellulose is responsible for the stability of the plant during growth -- and it is therefore extremely sturdy. Sugar molecules form cellulose molecules, which are connected in robust chains to form extremely resilient fibers. Breaking down the stable cellulose into sugar is difficult. Luckily, nature provides enzymes that can do just that. They are found in bacteria, for instance, that live in the stomachs of cows. In these natural"bio-reactors" they help digest grass and release the sugar. However, the bacteria take a very long time to break down the cellulose. Before cellulose can be transformed into bio-fuel in an efficient and cost-effective way on an industrial scale, the process must improve significantly.

The TUM Department of Microbiology has taken on this task. On the one hand its scientists search through nature's immense microbial diversity for as yet unknown cellulose-degrading enzymes. On the other hand they are isolating new"cellulose-eating" germs from nature in order to examine them more closely. Dr. Schwarz's work group is now taking a closer look at the most promising of these bacteria,Clostridium thermocellum. This soil bacterium has altogether over 70 enzymes that it uses to degrade different parts of plant cell walls. Thanks to this"toolbox" the bacterium can adapt perfectly to its environment. Depending on whether it lives in straw, leaves or waste wood,C. thermocellumproduces a different, effective enzyme complex on its surface to degrade the cellulose.

The TUM researchers are now testing this principle in the lab. They want to use the bacterium's toolbox to find ideal enzyme combinations for the industrial degradation of cellulose. To do this they firstly identified the most powerful enzymes and generated them in a test tube. These components were then combined to produce multiple variations, the best of which were selected by the microbiologists. Doctoral candidate Jan Krauss spent three years working on this:"We are now optimizing the most effective combinations for industrial use. Our ultimate goal is to develop a specialized degradation tool for every individual plant waste material containing cellulose. With a bit of luck we will find the perfect enzyme mixtures, which can then become established in bio-ethanol production facilities."

With this research program the TUM scientists are in sync with current industrial trends. Süd-Chemie AG is building a pilot plant in Straubing to convert the biogenic residual product straw into ethanol.

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'Tall Order' Sunlight-to-Hydrogen System Works, Neutron Analysis Confirms

Photosynthesis, the natural process carried out by plants, algae and some bacterial species, converts sunlight energy into chemical energy and sustains much of the life on earth. Researchers have long sought inspiration from photosynthesis to develop new materials to harness the sun's energy for electricity and fuel production.

In a step toward synthetic solar conversion systems, the ORNL researchers have demonstrated and confirmed with small-angle neutron scattering analysis that light harvesting complex II (LHC-II) proteins can self-assemble with polymers into a synthetic membrane structure and produce hydrogen.

The researchers envision energy-producing photoconversion systems similar to photovoltaic cells that generate hydrogen fuel, comparable to the way plants and other photosynthetic organisms convert light to energy.

"Making a, self-repairing synthetic photoconversion system is a pretty tall order. The ability to control structure and order in these materials for self-repair is of interest because, as the system degrades, it loses its effectiveness," ORNL researcher Hugh O'Neill, of the lab's Center for Structural Molecular Biology, said.

"This is the first example of a protein altering the phase behavior of a synthetic polymer that we have found in the literature. This finding could be exploited for the introduction of self-repair mechanisms in future solar conversion systems," he said.

Small angle neutron scattering analysis performed at ORNL's High Flux Isotope Reactor (HFIR) showed that the LHC-II, when introduced into a liquid environment that contained polymers, interacted with polymers to form lamellar sheets similar to those found in natural photosynthetic membranes.

The ability of LHC-II to force the assembly of structural polymers into an ordered, layered state -- instead of languishing in an ineffectual mush -- could make possible the development of biohybrid photoconversion systems. These systems would consist of high surface area, light-collecting panes that use the proteins combined with a catalyst such as platinum to convert the sunlight into hydrogen, which could be used for fuel.

The research builds on previous ORNL investigations into the energy-conversion capabilities of platinized photosystem I complexes -- and how synthetic systems based on plant biochemistry can become part of the solution to the global energy challenge.

"We're building on the photosynthesis research to explore the development of self-assembly in biohybrid systems. The neutron studies give us direct evidence that this is occurring," O'Neill said.

The researchers confirmed the proteins' structural behavior through analysis with HFIR's Bio-SANS, a small-angle neutron scattering instrument specifically designed for analysis of biomolecular materials.

"Cold source" neutrons, in which energy is removed by passing them through cryogenically chilled hydrogen, are ideal for studying the molecular structures of biological tissue and polymers.

The LHC-II protein for the experiment was derived from a simple source: spinach procured from a local produce section, then processed to separate the LHC-II proteins from other cellular components. Eventually, the protein could be synthetically produced and optimized to respond to light.

O'Neill said the primary role of the LHC-II protein is as a solar collector, absorbing sunlight and transferring it to the photosynthetic reaction centers, maximizing their output."However, this study shows that LHC-II can also carry out electron transfer reactions, a role not known to occur in vivo," he said.

The research team, which came from various laboratory organizations including its Chemical Sciences Division, Neutron Scattering Sciences Division, the Center for Structural Molecular Biology and the Center for Nanophase Materials Sciences, consisted of O'Neill, William T. Heller, and Kunlun Hong, all of ORNL; Dimitry Smolensky of the University of Tennessee; and Mateus Cardoso, a former postdoctoral researcher at ORNL now of the Laboratio Nacional de Luz Sincrotron in Brazil.

"That's one of the nice things about working at a national laboratory. Expertise is available from a variety of organizations," O'Neill said.

The work, published in the journalEnergy& Environmental Science, was supported with Laboratory-Directed Research and Development funding. HFIR is supported by the DOE Office of Science.

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Cheap, Clean Ways to Produce Hydrogen for Use in Fuel Cells? A Dash of Disorder Yields a Very Efficient Photocatalyst

Their photocatalyst, which accelerates light-driven chemical reactions, is the first to combine durability and record-breaking efficiency, making it a contender for use in several clean-energy technologies.

It could offer a pollution-free way to produce hydrogen for use as an energy carrier in fuel cells. Fuel cells have been eyed as an alternative to combustion engines in vehicles. Molecular hydrogen, however, exists naturally on Earth only in very low concentrations. It must be extracted from feedstocks such as natural gas or water, an energy-intensive process that is one of the barriers to the widespread implementation of the technology.

"We are trying to find better ways to generate hydrogen from water using sunshine," says Samuel Mao, a scientist in Berkeley Lab's Environmental Energy Technologies Division who led the research."In this work, we introduced disorder in titanium dioxide nanocrystals, which greatly improves its light absorption ability and efficiency in producing hydrogen from water."

Mao is the corresponding author of a paper on this research that was published online Jan. 20, 2011 inScience Expresswith the title"Increasing Solar Absorption for Photocatalysis with Black, Hydrogenated Titanium Dioxide Nanocrystals." Co-authoring the paper with Mao are fellow Berkeley Lab researchers Xiaobo Chen, Lei Liu, and Peter Yu.

Mao and his research group started with nanocrystals of titanium dioxide, which is a semiconductor material that is used as a photocatalyst to accelerate chemical reactions, such as harnessing energy from the sun to supply electrons that split water into oxygen and hydrogen. Although durable, titanium dioxide isn't a very efficient photocatlayst. Scientists have worked to increase its efficiency by adding impurities and making other modifications.

The Berkeley Lab scientists tried a new approach. In addition to adding impurities, they engineered disorder into the ordinarily perfect atom-by-atom lattice structure of the surface layer of titanium dioxide nanocrystals. This disorder was introduced via hydrogenation.

The result is the first disorder-engineered nanocrystal. One transformation was obvious: the usually white titanium dioxide nanocrystals turned black, a sign that engineered disorder yielded infrared absorption.

The scientists also surmised disorder boosted the photocatalyst's performance. To find out if their hunch was correct, they immersed disorder-engineered nanocrystals in water and exposed them to simulated sunlight. They found that 24 percent of the sunlight absorbed by the photocatalyst was converted into hydrogen, a production rate that is about 100 times greater than the yields of most semiconductor photocatalysts.

In addition, their photocatalyst did not show any signs of degradation during a 22-day testing period, meaning it is potentially durable enough for real-world use.

Its landmark efficiency stems largely from the photocatalyst's ability to absorb infrared light, making it the first titanium dioxide photocatalyst to absorb light in this wavelength. It also absorbs visible and ultraviolet light. In contrast, most titanium dioxide photocatalysts only absorbs ultraviolet light, and those containing defects may absorb visible light. Ultraviolet light accounts for less than ten percent of solar energy.

"The more energy from the sun that can be absorbed by a photocatalyst, the more electrons can be supplied to a chemical reaction, which makes black titanium dioxide a very attractive material," says Mao, who is also an adjunct engineering professor in the University of California at Berkeley.

The team's intriguing experimental findings were further elucidated by theoretical physicists Peter Yu and Lei Liu, who explored how jumbling the latticework of atoms on the nanocrystal's surface via hydrogenation changes its electronic properties. Their calculations revealed that disorder, in the form of lattice defects and hydrogen, makes it possible for incoming photons to excite electrons, which then jump across a gap where no electron states can exist. Once across this gap, the electrons are free to energize the chemical reaction that splits water into hydrogen and oxygen.

"By introducing a specific kind of disorder, mid-gap electronic states are created accompanied by a reduced band gap," says Yu, who is also a professor in the University of California at Berkeley's Physics Department."This makes it possible for the infrared part of the solar spectrum to be absorbed and contribute to the photocatalysis."

This research was supported by the Department of Energy's Office of Energy Efficiency and Renewable Energy. Transmission electron microscopy imaging used to study the nanocrystals at the atomic scale was performed at the National Center for Electron Microscopy, a national user facility located at Berkeley Lab.

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New Reactor Paves the Way for Efficiently Producing Fuel from Sunlight

Solar energy has long been touted as the solution to our energy woes, but while it is plentiful and free, it can't be bottled up and transported from sunny locations to the drearier -- but more energy-hungry -- parts of the world. The process developed by Haile -- a professor of materials science and chemical engineering at the California Institute of Technology (Caltech) -- and her colleagues could make that possible.

The researchers designed and built a two-foot-tall prototype reactor that has a quartz window and a cavity that absorbs concentrated sunlight. The concentrator works"like the magnifying glass you used as a kid" to focus the sun's rays, says Haile.

At the heart of the reactor is a cylindrical lining of ceria. Ceria -- a metal oxide that is commonly embedded in the walls of self-cleaning ovens, where it catalyzes reactions that decompose food and other stuck-on gunk -- propels the solar-driven reactions. The reactor takes advantage of ceria's ability to"exhale" oxygen from its crystalline framework at very high temperatures and then"inhale" oxygen back in at lower temperatures.

"What is special about the material is that it doesn't release all of the oxygen. That helps to leave the framework of the material intact as oxygen leaves," Haile explains."When we cool it back down, the material's thermodynamically preferred state is to pull oxygen back into the structure."

Specifically, the inhaled oxygen is stripped off of carbon dioxide (CO₂) and/or water (H₂O) gas molecules that are pumped into the reactor, producing carbon monoxide (CO) and/or hydrogen gas (H₂). H₂can be used to fuel hydrogen fuel cells; CO, combined with H₂, can be used to create synthetic gas, or"syngas," which is the precursor to liquid hydrocarbon fuels. Adding other catalysts to the gas mixture, meanwhile, produces methane. And once the ceria is oxygenated to full capacity, it can be heated back up again, and the cycle can begin anew.

For all of this to work, the temperatures in the reactor have to be very high -- nearly 3,000 degrees Fahrenheit. At Caltech, Haile and her students achieved such temperatures using electrical furnaces. But for a real-world test, she says,"we needed to use photons, so we went to Switzerland." At the Paul Scherrer Institute's High-Flux Solar Simulator, the researchers and their collaborators -- led by Aldo Steinfeld of the institute's Solar Technology Laboratory -- installed the reactor on a large solar simulator capable of delivering the heat of 1,500 suns.

In experiments conducted last spring, Haile and her colleagues achieved the best rates for CO₂dissociation ever achieved,"by orders of magnitude," she says. The efficiency of the reactor was uncommonly high for CO₂splitting, in part, she says,"because we're using the whole solar spectrum, and not just particular wavelengths." And unlike in electrolysis, the rate is not limited by the low solubility of CO₂in water. Furthermore, Haile says, the high operating temperatures of the reactor mean that fast catalysis is possible, without the need for expensive and rare metal catalysts (cerium, in fact, is the most common of the rare earth metals -- about as abundant as copper).

In the short term, Haile and her colleagues plan to tinker with the ceria formulation so that the reaction temperature can be lowered, and to re-engineer the reactor, to improve its efficiency. Currently, the system harnesses less than 1% of the solar energy it receives, with most of the energy lost as heat through the reactor's walls or by re-radiation through the quartz window."When we designed the reactor, we didn't do much to control these losses," says Haile. Thermodynamic modeling by lead author and former Caltech graduate student William Chueh suggests that efficiencies of 15% or higher are possible.

Ultimately, Haile says, the process could be adopted in large-scale energy plants, allowing solar-derived power to be reliably available during the day and night. The CO₂emitted by vehicles could be collected and converted to fuel,"but that is difficult," she says. A more realistic scenario might be to take the CO₂emissions from coal-powered electric plants and convert them to transportation fuels."You'd effectively be using the carbon twice," Haile explains. Alternatively, she says, the reactor could be used in a"zero CO₂emissions" cycle: H₂O and CO₂would be converted to methane, would fuel electricity-producing power plants that generate more CO₂and H₂O, to keep the process going.

The work was funded by the National Science Foundation, the State of Minnesota Initiative for Renewable Energy and the Environment, and the Swiss National Science Foundation.

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Study Estimates Land Available for Biofuel Crops

Published in the journalEnvironmental Science and Technology, the study led by civil and environmental engineering professor Ximing Cai identified land around the globe available to produce grass crops for biofuels, with minimal impact on agriculture or the environment.

Many studies on biofuel crop viability focus on biomass yield, or how productive a crop can be regionally. There has been relatively little research on land availability, one of the key constraints of biofuel development. Of special concern is whether the world could even produce enough biofuel to meet demand without compromising food production.

"The questions we're trying to address are, what kind of land could be used for biofuel crops? If we have land, where is it, and what is the current land cover?" Cai said.

Cai's team assessed land availability from a physical perspective -- focusing on soil properties, soil quality, land slope, and regional climate. The researchers collected data on soil, topography, climate and current land use from some of the best data sources available, including remote sensing maps.

The critical concept of the Illinois study was that only marginal land would be considered for biofuel crops. Marginal land refers to land with low inherent productivity, that has been abandoned or degraded, or is of low quality for agricultural uses. In focusing on marginal land, the researchers rule out current crop land, pasture land, and forests. They also assume that any biofuel crops would be watered by rainfall and not irrigation, so no water would have to be diverted from agricultural land.

Using fuzzy logic modeling, a technique to address uncertainty and ambiguity in analysis, the researchers considered multiple scenarios for land availability. First, they considered only idle land and vegetation land with marginal productivity; for the second scenario, they added degraded or low-quality cropland. For the second scenario, they estimated 702 million hectares of land available for second-generation biofuel crops, such as switchgrass or miscanthus.

The researchers then expanded their sights to marginal grassland. A class of biofuel crops called low-impact high-diversity (LIHD) perennial grasses could produce bioenergy while maintaining grassland. While they have a lower ethanol yield than grasses such as miscanthus or switchgrass, LIHD grasses have minimal environmental impact and are similar to grassland's natural land cover.

Adding LIHD crops grown on marginal grassland to the marginal cropland estimate from earlier scenarios nearly doubled the estimated land area to 1,107 million hectares globally, even after subtracting possible pasture land -- an area that would produce 26 to 56 percent of the world's current liquid fuel consumption.

Next, the team plans to study the possible effect of climate change on land use and availability."Based on the historical data, we now have an estimation for current land use, but climate may change in the near future as a result of the increase in greenhouse gas emissions, which will have effect on the land availability," said graduate student Xiao Zhang, a co-author of the paper. Former postdoctoral fellow Dingbao Wang, now at the University of Central Florida, also co-wrote the paper."We hope this will provide a physical basis for future research," Cai said."For example, agricultural economists could use the dataset to do some research with the impact of institutions, community acceptance and so on, or some impact on the market. We want to provide a start so others can use our research data."

The Energy Biosciences Institute at U. of I. and the National Science Foundation supported the study.

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Biofuel Grasslands Better for Birds Than Ethanol Staple Corn, Researchers Find

Federal mandates and market forces both are expected to promote rising biofuel production, MSU biologist Bruce Robertson says, but the environmental consequences of turning more acreage over to row crops for fuel are a serious concern.

Ethanol in America is chiefly made from corn, but research is focusing on how to cost-effectively process cellulosic sources such as wood, corn stalks and grasses. Perennial grasses promise low cost and energy inputs -- planting, fertilizing, watering -- and the new study quantifies substantial environmental benefits.

"Native perennial grasses might provide an opportunity to produce biomass in ways that are compatible with the conservation of biodiversity and important ecosystem services such as pest control," Robertson said."This work demonstrates that next-generation biofuel crops have potential to provide a new source of habitat for a threatened group of birds."

With its rich variety of ecosystems, including historic prairie, southern Michigan provided a convenient place to compare bird populations in 20 sites of varying size for each of the three fuel feedstocks. Grassland birds are of special concern, Robertson said, having suffered more dramatic population losses than any other group of North American birds.

In the first such empirical comparison and the first to simultaneously study grassland bird communities across habitat scales, Robertson and colleagues found that bugs and the birds that feed on them thrive more in mixed prairie grasses than in corn. Almost twice as many species made their homes in grasses, while plots of switchgrass, a federally designated model fuel crop, fell between the two in their ability to sustain biodiversity.

The larger the plot of any type, researchers found, the greater the concentration of birds supported. But if grasslands offer conservation and biofuel opportunities, Robertson said, the biodiversity benefits could decrease as biofuel grass feedstocks are bred and cultivated for commercial uniformity.

Robertson was a research associate at MSU's W.K. Kellogg Biological Station in Kalamazoo County during the two-year research project. Today he is an MSU adjunct entomology professor and a postdoctoral fellow at the Smithsonian Conservation Biology Institute Migratory Bird Center in Washington, D.C. His research colleagues included John A. Hannah Distinguished Professor of plant biology Douglas Schemske and research associate Liz Loomis, both at the Kellogg Biological Station; Patrick Doran of The Nature Conservancy in Lansing; and statistician J. Roy Robertson of Battle Creek.

The research was funded by the U.S. Department of Energy Great Lakes Bioenergy Research Center with support from The Nature Conservancy's Great Lakes Fund for Partnership in Conservation Science and Economics. Results were recently published in the scientific journalGCB (Global Change Biology) Bioenergy.

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US Does Not Have Infrastructure to Consume More Ethanol, Study Finds

Wally Tyner, the James and Lois Ackerman Professor of Agricultural Economics, and co-authors Frank Dooley, a Purdue professor of agricultural economics, and Daniela Viteri, a former Purdue graduate student, used U.S. Department of Energy and Environmental Protection Agency data to determine that the United States is at the"blending wall," the saturation point for ethanol use. Without new technology or a significant increase in infrastructure, Tyner predicts that the country will not be able to consume more ethanol than is being currently produced.

The federal Renewable Fuel Standard requires an increase of renewable fuel production to 36 billion gallons per year by 2022. About 13 billion gallons of renewable fuel was required for 2010, the same amount Tyner predicts is the threshold for U.S. infrastructure and consumption ability.

"You can't get there with ethanol," said Tyner, whose findings were published in the December issue of theAmerican Journal of Agricultural Economics.

Tyner said there simply aren't enough flex-fuel vehicles, which use an 85 percent ethanol blend, or E85 stations to distribute more biofuels. According to EPA estimates, flex-fuel vehicles make up 7.3 million of the 240 million vehicles on the nation's roads. Of those, about 3 million of flex-fuel vehicle owners aren't even aware they can use E85 fuel.

There are only about 2,000 E85 fuel pumps in the United States, and it took more than 20 years to install them.

"Even if you could produce a whole bunch of E85, there is no way to distribute it," Tyner said."We would need to install about 2,000 pumps per year through 2022 to do it. You're not going to go from 100 per year to 2,000 per year overnight. It's just not going to happen."

And even if the fuel could be distributed, E85 would have to be substantially cheaper than gasoline to entice consumers to use it because E85 gets lower mileage, Tyner said. If gasoline were$3 per gallon, E85 would have to be$2.34 per gallon to break even on mileage.

There is talk of increasing the maximum amount of ethanol that can be blended with gasoline for regular vehicles from 10 percent to 15 percent. But Tyner said that even if the EPA does allow it, the blending wall would be reached again in about four years.

Tyner said advances in the production of thermo-chemical biofuels, which are created by using heat to chemically alter biomass and create fuels, would be necessary to meet the Renewable Fuel Standard. He said those fuels would be similar enough to gasoline to allow unlimited blending and would increase the amount of biofuel that could be used.

"Producing the hydrocarbons directly doesn't have the infrastructure problems of ethanol, and there is no blend wall because you're producing gasoline," Tyner said."If that comes on and works, then we get there. There is significant potential to produce drop-in hydrocarbons from cellulosic feedstocks."

The U.S. Department of Agriculture funded Tyner's research.

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