New metal hydride clusters provide insights into hydrogen storage

ScienceDaily (Sep. 23, 2011) — A study published by researchers at the RIKEN Advanced Science Institute (ASI) has shed first-ever light on a class of heterometallic molecular structures whose unique features point the way to breakthroughs in the development of lightweight fuel cell technology. The structures contain a previously-unexplored combination of rare-earth and d-transition metals ideally suited to the compact storage of hydrogen.

The most abundant element in the universe, hydrogen holds great promise as a source of clean, renewable energy, producing nothing but water as a byproduct and thus avoiding the environmental dangers associated with existing mainstream energy sources. Broad adoption of hydrogen, however, has stalled because in its natural gaseous state, the element simply takes up too much space to store and transport efficiently.

One way to solve this problem is to use metal hydrides, metallic compounds that incorporate hydrogen atoms, as a storage medium for hydrogen. In this technique, the metal hydrides bind to hydrogen to produce a solid one thousand times or more smaller than the original hydrogen gas. The hydrogen can then later be released from the solid by heating it to a given temperature.

The new heterometallic hydride clusters synthesized by the RIKEN researchers use rare-earth and d-transition metals as building blocks and exploit the advantages of both. Rare earth metal hydrides remove one major obstacle by enabling analysis using X-ray diffraction, a technique which is infeasible for most other metal hydrides -- offering unique insights into underlying reaction processes involved. Rare earth metal hydrides on their own, however, do not undergo reversible hydrogen addition and release, the cornerstone of hydrogen storage. This becomes possible through the addition of a d-transition metal, in this case tungsten (W) or molybdenum (Mo).

While rare-earth / d-transition metal-type metallic hydride complexes have been studied in the past, the current research is the first to explore complexes with multiple rare earth atoms of the form Ln4MHn and with well-defined structures (Ln = a rare-earth metal such as yttrium, M = a d-transition metal, either tungsten or molybdenum, and H = hydrogen). In a paper in Nature Chemistry, the researchers show that these complexes exhibit unique reactivity properties, pointing the way to new hydrogen storage techniques and promising environmentally-friendly solutions to today's pressing energy needs.

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Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by RIKEN.

Journal Reference:

Takanori Shima, Yi Luo, Timothy Stewart, Robert Bau, Garry J. McIntyre, Sax A. Mason, Zhaomin Hou. Molecular heterometallic hydride clusters composed of rare-earth and d-transition metals. Nature Chemistry, 2011; DOI: 10.1038/NCHEM.1147

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Hydrogen released to fuel cell more quickly when stored in metal nanoparticles

ScienceDaily (Oct. 1, 2011) — Researchers from TU Delft and VU University Amsterdam in the Netherlands have demonstrated that the size of a metal alloy nanoparticle influences the speed with which hydrogen gas is released when stored in a metal hydride. The smaller the size of the nanoparticle, the greater the speed at which the hydrogen gas makes its way to the fuel cell.

The researchers publish their findings in the October issue of the scientific journal Advanced Energy Materials.

Hydrogen heaven

On 27 September Dutch Minister of Infrastructure and the Environment, Ms Schultz van Haegen, announced she will earmark 5 million Euros to stimulate hydrogen transport in the Netherlands. According to the Minister the Netherlands and neighbouring countries have all it takes to become a 'hydrogen heaven'. In July 2011, the German car manufacturer Daimler announced its intention to build twenty new hydrogen fuelling stations along Germany's motorways. Hydrogen is back on the agenda. Hydrogen gas is currently stored in a vehicle fuel tank at 700 bar pressure. Fuelling stations thus require high-pressure pumps to fill these tanks and these systems consume a lot of energy.

Hydrogen storage

There are thus good reasons for finding alternative hydrogen storage techniques. Hydrogen can be absorbed in high densities in metals such as magnesium, without the need for high pressure. However, the disadvantage is that releasing the hydrogen again is a very difficult and very slow process. One way of speeding up the release of the hydrogen is to use magnesium nanoparticles that are fixed in a matrix to prevent them from aggregating.

Nanoparticles in a matrix

Professor of Materials for Energy Conversion and Storage, Bernard Dam, and his colleagues at TU Delft and VU University Amsterdam have demonstrated experimentally that the interaction between the nanoparticles and the matrix can cause the hydrogen gas to be released faster. Using models consisting of thin layers of magnesium and titanium, they show how the pressure of the hydrogen being released from the magnesium increases as the layers become thinner. This means that it indeed makes sense to store hydrogen in nanoparticles in a matrix. The choice of matrix determines to what extent the hydrogen desorption pressure increases. The researchers published their findings in the October 2011 edition of the scientific journal Advanced Energy Materials.

Efficient and affordable hydrogen storage techniques can play an important role in the large-scale adoption of hydrogen fuel cells. Bernard Dam foresees the development of hybrid vehicles that use batteries for short distances but switch to hydrogen for long distances: 'Your electric motor will be powered by batteries inside the city, and by hydrogen when you go further afield.'

The research was funded by the ACTS Sustainable Hydrogen Program of the Netherlands Organisation for Scientific Research.

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Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Delft University of Technology.

Journal Reference:

Lennard P.A. Mooij, Andrea Baldi, Christiaan Boelsma, Kun Shen, Marnix Wagemaker, Yevheniy Pivak, Herman Schreuders, Ronald Griessen, Bernard Dam. Interface Energy Controlled Thermodynamics of Nanoscale Metal Hydrides. Advanced Energy Materials, Volume 1, issue 5, pages 754-758, October 2011.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

New metal hydride clusters provide insights into hydrogen storage

ScienceDaily (Sep. 23, 2011) — A study published by researchers at the RIKEN Advanced Science Institute (ASI) has shed first-ever light on a class of heterometallic molecular structures whose unique features point the way to breakthroughs in the development of lightweight fuel cell technology. The structures contain a previously-unexplored combination of rare-earth and d-transition metals ideally suited to the compact storage of hydrogen.

The most abundant element in the universe, hydrogen holds great promise as a source of clean, renewable energy, producing nothing but water as a byproduct and thus avoiding the environmental dangers associated with existing mainstream energy sources. Broad adoption of hydrogen, however, has stalled because in its natural gaseous state, the element simply takes up too much space to store and transport efficiently.

One way to solve this problem is to use metal hydrides, metallic compounds that incorporate hydrogen atoms, as a storage medium for hydrogen. In this technique, the metal hydrides bind to hydrogen to produce a solid one thousand times or more smaller than the original hydrogen gas. The hydrogen can then later be released from the solid by heating it to a given temperature.

The new heterometallic hydride clusters synthesized by the RIKEN researchers use rare-earth and d-transition metals as building blocks and exploit the advantages of both. Rare earth metal hydrides remove one major obstacle by enabling analysis using X-ray diffraction, a technique which is infeasible for most other metal hydrides -- offering unique insights into underlying reaction processes involved. Rare earth metal hydrides on their own, however, do not undergo reversible hydrogen addition and release, the cornerstone of hydrogen storage. This becomes possible through the addition of a d-transition metal, in this case tungsten (W) or molybdenum (Mo).

While rare-earth / d-transition metal-type metallic hydride complexes have been studied in the past, the current research is the first to explore complexes with multiple rare earth atoms of the form Ln4MHn and with well-defined structures (Ln = a rare-earth metal such as yttrium, M = a d-transition metal, either tungsten or molybdenum, and H = hydrogen). In a paper in Nature Chemistry, the researchers show that these complexes exhibit unique reactivity properties, pointing the way to new hydrogen storage techniques and promising environmentally-friendly solutions to today's pressing energy needs.

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by RIKEN.

Journal Reference:

Takanori Shima, Yi Luo, Timothy Stewart, Robert Bau, Garry J. McIntyre, Sax A. Mason, Zhaomin Hou. Molecular heterometallic hydride clusters composed of rare-earth and d-transition metals. Nature Chemistry, 2011; DOI: 10.1038/NCHEM.1147

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Hydrogen released to fuel cell more quickly when stored in metal nanoparticles

ScienceDaily (Oct. 1, 2011) — Researchers from TU Delft and VU University Amsterdam in the Netherlands have demonstrated that the size of a metal alloy nanoparticle influences the speed with which hydrogen gas is released when stored in a metal hydride. The smaller the size of the nanoparticle, the greater the speed at which the hydrogen gas makes its way to the fuel cell.

The researchers publish their findings in the October issue of the scientific journal Advanced Energy Materials.

Hydrogen heaven

On 27 September Dutch Minister of Infrastructure and the Environment, Ms Schultz van Haegen, announced she will earmark 5 million Euros to stimulate hydrogen transport in the Netherlands. According to the Minister the Netherlands and neighbouring countries have all it takes to become a 'hydrogen heaven'. In July 2011, the German car manufacturer Daimler announced its intention to build twenty new hydrogen fuelling stations along Germany's motorways. Hydrogen is back on the agenda. Hydrogen gas is currently stored in a vehicle fuel tank at 700 bar pressure. Fuelling stations thus require high-pressure pumps to fill these tanks and these systems consume a lot of energy.

Hydrogen storage

There are thus good reasons for finding alternative hydrogen storage techniques. Hydrogen can be absorbed in high densities in metals such as magnesium, without the need for high pressure. However, the disadvantage is that releasing the hydrogen again is a very difficult and very slow process. One way of speeding up the release of the hydrogen is to use magnesium nanoparticles that are fixed in a matrix to prevent them from aggregating.

Nanoparticles in a matrix

Professor of Materials for Energy Conversion and Storage, Bernard Dam, and his colleagues at TU Delft and VU University Amsterdam have demonstrated experimentally that the interaction between the nanoparticles and the matrix can cause the hydrogen gas to be released faster. Using models consisting of thin layers of magnesium and titanium, they show how the pressure of the hydrogen being released from the magnesium increases as the layers become thinner. This means that it indeed makes sense to store hydrogen in nanoparticles in a matrix. The choice of matrix determines to what extent the hydrogen desorption pressure increases. The researchers published their findings in the October 2011 edition of the scientific journal Advanced Energy Materials.

Efficient and affordable hydrogen storage techniques can play an important role in the large-scale adoption of hydrogen fuel cells. Bernard Dam foresees the development of hybrid vehicles that use batteries for short distances but switch to hydrogen for long distances: 'Your electric motor will be powered by batteries inside the city, and by hydrogen when you go further afield.'

The research was funded by the ACTS Sustainable Hydrogen Program of the Netherlands Organisation for Scientific Research.

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Delft University of Technology.

Journal Reference:

Lennard P.A. Mooij, Andrea Baldi, Christiaan Boelsma, Kun Shen, Marnix Wagemaker, Yevheniy Pivak, Herman Schreuders, Ronald Griessen, Bernard Dam. Interface Energy Controlled Thermodynamics of Nanoscale Metal Hydrides. Advanced Energy Materials, Volume 1, issue 5, pages 754-758, October 2011.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Under pressure, sodium, hydrogen could undergo a metamorphosis, emerging as superconductor

ScienceDaily (June 13, 2011) — In the search for superconductors, finding ways to compress hydrogen into a metal has been a point of focus ever since scientists predicted many years ago that electricity would flow, uninhibited, through such a material.

Liquid metallic hydrogen is thought to exist in the high-gravity interiors of Jupiter and Saturn. But so far, on Earth, researchers have been unable to use static compression techniques to squeeze hydrogen under high enough pressures to convert it into a metal. Shock-wave methods have been successful, but as experiments with diamond anvil cells have shown, hydrogen remains an insulator even under pressures equivalent to those found in Earth's core.

To circumvent the problem, a pair of University at Buffalo chemists has proposed an alternative solution for metallizing hydrogen: Add sodium to hydrogen, they say, and it just might be possible to convert the compound into a superconducting metal under significantly lower pressures.

The research, published June 10 in Physical Review Letters, details the findings of UB Assistant Professor Eva Zurek and UB postdoctoral associate Pio Baettig.

Using an open-source computer program that UB PhD student David Lonie designed, Zurek and Baettig looked for sodium polyhydrides that, under pressure, would be viable superconductor candidates. The program, XtalOpt , is an evolutionary algorithm that incorporates quantum mechanical calculations to determine the most stable geometries or crystal structures of solids.

In analyzing the results, Baettig and Zurek found that NaH9, which contains one sodium atom for every nine hydrogen atoms, is predicted to become metallic at an experimentally achievable pressure of about 250 gigapascals -- about 2.5 million times Earth's standard atmospheric pressure, but less than the pressure at Earth's core (about 3.5 million atmospheres).

"It is very basic research," says Zurek, a theoretical chemist. "But if one could potentially metallize hydrogen using the addition of sodium, it could ultimately help us better understand superconductors and lead to new approaches to designing a room-temperature superconductor."

By permitting electricity to travel freely, without resistance, such a superconductor could dramatically improve the efficiency of power transmission technologies.

Zurek, who joined UB in 2009, conducted research at Cornell University as a postdoctoral associate under Roald Hoffmann, a Nobel Prize-winning theoretical chemist whose research interests include the behavior of matter under high pressure.

In October 2009, Zurek co-authored a paper with Hoffman and other colleagues in the Proceedings of the National Academy of Sciences predicting that LiH6 -- a compound containing one lithium atom for every six hydrogen atoms -- could form as a stable metal at a pressure of around 1 million atmospheres.

Neither LiH6 and NaH9 exists naturally as stable compounds on Earth, but under high pressures, their structure is predicted to be stable.

"One of the things that I always like to emphasize is that chemistry is very different under high pressures," Zurek says. "Our chemical intuition is based upon our experience at one atmosphere. Under pressure, elements that do not usually combine on the Earth's surface may mix, or mix in different proportions. The insulator iodine becomes a metal, and sodium becomes insulating. Our aim is to use the results of computational experiments in order to help develop a chemical intuition under pressure, and to predict new materials with unusual properties."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University at Buffalo.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Under pressure, sodium, hydrogen could undergo a metamorphosis, emerging as superconductor

ScienceDaily (June 13, 2011) — In the search for superconductors, finding ways to compress hydrogen into a metal has been a point of focus ever since scientists predicted many years ago that electricity would flow, uninhibited, through such a material.

Liquid metallic hydrogen is thought to exist in the high-gravity interiors of Jupiter and Saturn. But so far, on Earth, researchers have been unable to use static compression techniques to squeeze hydrogen under high enough pressures to convert it into a metal. Shock-wave methods have been successful, but as experiments with diamond anvil cells have shown, hydrogen remains an insulator even under pressures equivalent to those found in Earth's core.

To circumvent the problem, a pair of University at Buffalo chemists has proposed an alternative solution for metallizing hydrogen: Add sodium to hydrogen, they say, and it just might be possible to convert the compound into a superconducting metal under significantly lower pressures.

The research, published June 10 in Physical Review Letters, details the findings of UB Assistant Professor Eva Zurek and UB postdoctoral associate Pio Baettig.

Using an open-source computer program that UB PhD student David Lonie designed, Zurek and Baettig looked for sodium polyhydrides that, under pressure, would be viable superconductor candidates. The program, XtalOpt , is an evolutionary algorithm that incorporates quantum mechanical calculations to determine the most stable geometries or crystal structures of solids.

In analyzing the results, Baettig and Zurek found that NaH9, which contains one sodium atom for every nine hydrogen atoms, is predicted to become metallic at an experimentally achievable pressure of about 250 gigapascals -- about 2.5 million times Earth's standard atmospheric pressure, but less than the pressure at Earth's core (about 3.5 million atmospheres).

"It is very basic research," says Zurek, a theoretical chemist. "But if one could potentially metallize hydrogen using the addition of sodium, it could ultimately help us better understand superconductors and lead to new approaches to designing a room-temperature superconductor."

By permitting electricity to travel freely, without resistance, such a superconductor could dramatically improve the efficiency of power transmission technologies.

Zurek, who joined UB in 2009, conducted research at Cornell University as a postdoctoral associate under Roald Hoffmann, a Nobel Prize-winning theoretical chemist whose research interests include the behavior of matter under high pressure.

In October 2009, Zurek co-authored a paper with Hoffman and other colleagues in the Proceedings of the National Academy of Sciences predicting that LiH6 -- a compound containing one lithium atom for every six hydrogen atoms -- could form as a stable metal at a pressure of around 1 million atmospheres.

Neither LiH6 and NaH9 exists naturally as stable compounds on Earth, but under high pressures, their structure is predicted to be stable.

"One of the things that I always like to emphasize is that chemistry is very different under high pressures," Zurek says. "Our chemical intuition is based upon our experience at one atmosphere. Under pressure, elements that do not usually combine on the Earth's surface may mix, or mix in different proportions. The insulator iodine becomes a metal, and sodium becomes insulating. Our aim is to use the results of computational experiments in order to help develop a chemical intuition under pressure, and to predict new materials with unusual properties."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University at Buffalo.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Teaching algae to make fuel: New process could lead to production of hydrogen using bioengineered microorganisms

ScienceDaily (May 24, 2011) — Many kinds of algae and cyanobacteria, common water-dwelling microorganisms, are capable of using energy from sunlight to split water molecules and release hydrogen, which holds promise as a clean and carbon-free fuel for the future. One reason this approach hasn't yet been harnessed for fuel production is that under ordinary circumstances, hydrogen production takes a back seat to the production of compounds that the organisms use to support their own growth.

But Shuguang Zhang, associate director of MIT's Center for Biomedical Engineering, and postdocs Iftach Yacoby and Sergii Pochekailov, together with colleagues at Tel Aviv University in Israel and the National Renewable Energy Laboratory in Colorado, have found a way to use bioengineered proteins to flip this preference, allowing more hydrogen to be produced.

"The algae are really not interested in producing hydrogen, they want to produce sugar," Yacoby says -- the sugar is what they need for their own survival, and the hydrogen is just a byproduct. But a multitasking enzyme, introduced into the liquid where the algae are at work, both suppresses the sugar production and redirects the organisms' energies into hydrogen production. The work is described in a paper being published online this week in the Proceedings of the National Academy of Sciences, and was supported in part by a European Molecular Biology Organization postdoctoral fellowship, the Yang Trust Fund and the U.S. Department of Energy's National Renewable Energy Laboratory.

Adding the bioengineered enzyme increases the rate of algal hydrogen production by about 400 percent, Yacoby says. The sugar production is suppressed but not eliminated, he explains, because "if it went to zero, it would kill the organism."

The research demonstrates for the first time how the two processes carried out by algae compete with each other; it also shows how that competition could be modified to favor hydrogen production in a laboratory environment. Zhang and Yacoby plan to continue developing the system to increase its efficiency of hydrogen production.

"It's one step closer to an industrial process," Zhang says. "First, you have to understand the science" -- which has been achieved through this experimental work. Now, developing it further -- through refinements to produce a viable commercial system for hydrogen-fuel manufacturing -- is "a matter of time and money," Zhang says.

Ultimately, such a system could be used to produce hydrogen on a large scale using water and sunlight. The hydrogen could be used directly to generate electricity in a fuel cell or to power a vehicle, or could be combined with carbon dioxide to make methane or other fuels in a renewable, carbon-neutral way, the researchers say.

In the long run, "the only viable way to produce renewable energy is to use the sun, [either] to make electricity or in a biochemical reaction to produce hydrogen," Yacoby says. "I believe there is no one solution," he adds, but rather many different approaches depending on the location and the end uses.

This particular approach, he says, is simple enough that it has promise "not just in industrialized countries, but in developing countries as well" as a source of inexpensive fuel. The algae needed for the process exist everywhere on Earth, and there are no toxic materials involved in any part of the process, he says.

"The beauty is in its simplicity," he says.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Massachusetts Institute of Technology. The original article was written by David L. Chandler.

Journal Reference:

I. Yacoby, S. Pochekailov, H. Toporik, M. L. Ghirardi, P. W. King, S. Zhang. Photosynthetic electron partitioning between [FeFe]-hydrogenase and ferredoxin:NADP -oxidoreductase (FNR) enzymes in vitro. Proceedings of the National Academy of Sciences, 2011; DOI: 10.1073/pnas.1103659108

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Portable hydrogen reactor for fuel cells

ScienceDaily (May 23, 2011) — Chemical engineering students at Stevens Institute of Technology are transforming the way that American soldiers power their battery-operated devices by making a small change: a really small change. Capitalizing on the unique properties of microscale systems, the students have invented a microreactor that converts everyday fossil fuels like propane and butane into pure hydrogen for fuel cell batteries. These batteries are not only highly efficient, but also can be replenished with hydrogen again and again for years of resilient performance in the field.

With soldiers carrying up to 80% of gear weight in batteries, the Army has a high interest in replacing the current paradigm of single-use batteries with a reliable, reusable power source. The Stevens-made microreactors thus have the potential to not only reduce waste from disposable batteries, but also provide American soldiers with a dependable way to recharge the batteries for the critical devices that keep them safe.

Current methods for generating fuel cell hydrogen are both sophisticated and risky, requiring high temperatures and a vacuum to produce the necessary chemical-reaction-causing plasmas. Once in a container, hydrogen is a highly volatile substance that is dangerous and expensive to transport.

The Stevens microreactor overcomes both of these barriers by using low temperatures and atmospheric pressure, and by producing hydrogen only as needed to avoid creating explosive targets in combat areas. These advanced reactors are created using cutting-edge microfabrication techniques, similar to those used to create plasma television screens, which use microscale physics to produce plasma under normal atmospheres.

The team has already had success producing hydrogen from methanol. After gasifying methanol by suspending it in hot nitrogen gas, the mixture is drawn into a 25µm channel in the microreactor. There, it reacts with plasma to cause thermal decomposition, breaking down the methanol into its elemental components. Now the team is conducting tests to see what kind of yields are realizable from various starter fuels. Eventually, soldiers will be able to convert everyday liquid fuels like propane or butane, commonly found on military bases, into high-potency juice for portable fuel cell batteries.

The team, made up of seniors Ali Acosta, Kyle Lazzaro, Randy Parrilla, and Andrew Robertson, are supporting Ph.D. candidate Peter Lindner in a research project sponsored by the U.S. Army. The project is overseen by Dr. Ronald Besser. The team will be presenting their device prototype at Senior Projects Expo on April 27.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Stevens Institute of Technology.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Teaching algae to make fuel: New process could lead to production of hydrogen using bioengineered microorganisms

ScienceDaily (May 24, 2011) — Many kinds of algae and cyanobacteria, common water-dwelling microorganisms, are capable of using energy from sunlight to split water molecules and release hydrogen, which holds promise as a clean and carbon-free fuel for the future. One reason this approach hasn't yet been harnessed for fuel production is that under ordinary circumstances, hydrogen production takes a back seat to the production of compounds that the organisms use to support their own growth.

But Shuguang Zhang, associate director of MIT's Center for Biomedical Engineering, and postdocs Iftach Yacoby and Sergii Pochekailov, together with colleagues at Tel Aviv University in Israel and the National Renewable Energy Laboratory in Colorado, have found a way to use bioengineered proteins to flip this preference, allowing more hydrogen to be produced.

"The algae are really not interested in producing hydrogen, they want to produce sugar," Yacoby says -- the sugar is what they need for their own survival, and the hydrogen is just a byproduct. But a multitasking enzyme, introduced into the liquid where the algae are at work, both suppresses the sugar production and redirects the organisms' energies into hydrogen production. The work is described in a paper being published online this week in the Proceedings of the National Academy of Sciences, and was supported in part by a European Molecular Biology Organization postdoctoral fellowship, the Yang Trust Fund and the U.S. Department of Energy's National Renewable Energy Laboratory.

Adding the bioengineered enzyme increases the rate of algal hydrogen production by about 400 percent, Yacoby says. The sugar production is suppressed but not eliminated, he explains, because "if it went to zero, it would kill the organism."

The research demonstrates for the first time how the two processes carried out by algae compete with each other; it also shows how that competition could be modified to favor hydrogen production in a laboratory environment. Zhang and Yacoby plan to continue developing the system to increase its efficiency of hydrogen production.

"It's one step closer to an industrial process," Zhang says. "First, you have to understand the science" -- which has been achieved through this experimental work. Now, developing it further -- through refinements to produce a viable commercial system for hydrogen-fuel manufacturing -- is "a matter of time and money," Zhang says.

Ultimately, such a system could be used to produce hydrogen on a large scale using water and sunlight. The hydrogen could be used directly to generate electricity in a fuel cell or to power a vehicle, or could be combined with carbon dioxide to make methane or other fuels in a renewable, carbon-neutral way, the researchers say.

In the long run, "the only viable way to produce renewable energy is to use the sun, [either] to make electricity or in a biochemical reaction to produce hydrogen," Yacoby says. "I believe there is no one solution," he adds, but rather many different approaches depending on the location and the end uses.

This particular approach, he says, is simple enough that it has promise "not just in industrialized countries, but in developing countries as well" as a source of inexpensive fuel. The algae needed for the process exist everywhere on Earth, and there are no toxic materials involved in any part of the process, he says.

"The beauty is in its simplicity," he says.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Massachusetts Institute of Technology. The original article was written by David L. Chandler.

Journal Reference:

I. Yacoby, S. Pochekailov, H. Toporik, M. L. Ghirardi, P. W. King, S. Zhang. Photosynthetic electron partitioning between [FeFe]-hydrogenase and ferredoxin:NADP -oxidoreductase (FNR) enzymes in vitro. Proceedings of the National Academy of Sciences, 2011; DOI: 10.1073/pnas.1103659108

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Portable hydrogen reactor for fuel cells

ScienceDaily (May 23, 2011) — Chemical engineering students at Stevens Institute of Technology are transforming the way that American soldiers power their battery-operated devices by making a small change: a really small change. Capitalizing on the unique properties of microscale systems, the students have invented a microreactor that converts everyday fossil fuels like propane and butane into pure hydrogen for fuel cell batteries. These batteries are not only highly efficient, but also can be replenished with hydrogen again and again for years of resilient performance in the field.

With soldiers carrying up to 80% of gear weight in batteries, the Army has a high interest in replacing the current paradigm of single-use batteries with a reliable, reusable power source. The Stevens-made microreactors thus have the potential to not only reduce waste from disposable batteries, but also provide American soldiers with a dependable way to recharge the batteries for the critical devices that keep them safe.

Current methods for generating fuel cell hydrogen are both sophisticated and risky, requiring high temperatures and a vacuum to produce the necessary chemical-reaction-causing plasmas. Once in a container, hydrogen is a highly volatile substance that is dangerous and expensive to transport.

The Stevens microreactor overcomes both of these barriers by using low temperatures and atmospheric pressure, and by producing hydrogen only as needed to avoid creating explosive targets in combat areas. These advanced reactors are created using cutting-edge microfabrication techniques, similar to those used to create plasma television screens, which use microscale physics to produce plasma under normal atmospheres.

The team has already had success producing hydrogen from methanol. After gasifying methanol by suspending it in hot nitrogen gas, the mixture is drawn into a 25µm channel in the microreactor. There, it reacts with plasma to cause thermal decomposition, breaking down the methanol into its elemental components. Now the team is conducting tests to see what kind of yields are realizable from various starter fuels. Eventually, soldiers will be able to convert everyday liquid fuels like propane or butane, commonly found on military bases, into high-potency juice for portable fuel cell batteries.

The team, made up of seniors Ali Acosta, Kyle Lazzaro, Randy Parrilla, and Andrew Robertson, are supporting Ph.D. candidate Peter Lindner in a research project sponsored by the U.S. Army. The project is overseen by Dr. Ronald Besser. The team will be presenting their device prototype at Senior Projects Expo on April 27.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Stevens Institute of Technology.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Hydrogen opens the road to graphene ... and graphane

ScienceDaily (May 10, 2011) — An international research team has discovered a new method to produce belts of graphene called nanoribbons. By using hydrogen, they have managed to unzip single-walled carbon nanotubes. The method also opens the road for producing nanoribbons of graphane, a modified and promising version of graphene.

A thin flake plain carbon, just one atom thick, became world famous last year. The discovery of the super material graphene gave Andre Geim and Konstantin Novoselov the Nobel Prize in Physics 2010. Graphene has a wide range of unusual and highly interesting properties. As a conductor of electricity it performs as well as copper. As a conductor of heat it outperforms all other known materials.

There are possibilities to achieve strong variations of the graphene properties for instance by making graphene in a form of belts with various width, so called nanoribbons. Nanoribbons were prepared for the first time two years ago. A method to produce them is to start from carbon nanotubes and to use oxygen treatment to unzip into nanoribbons. However, this method leaves oxygen atoms on the edges of nanoribbons, which is not always desirable.

In the new study the research team shows that it is also possible to unzip single-walled carbon nanotubes by using a reaction with molecular hydrogen. Nanoribbons produced by the new method will have hydrogen on the edges and this can be an advantage for some applications. Alexandr Talyzin, physicist at Umeå University in Sweden, has over the past decade been studying how hydrogen reacts with fullerenes, which are football-shaped carbon molecules.

"Treating the carbon nanotubes with hydrogen was a logical extension of our research. Our previous experience has been of great help in this work," says Alexandr Talyzin.

Nanotubes are typically closed by semi-spherical cups, essentially halves of fullerene molecules. The researchers have previously proved that fullerene molecules can be completely destroyed by very strong hydrogenation. Therefore, they expected similar results for nanotube end cups and tried to open the nanotubes by using hydrogenation. The effect was indeed confirmed and they also managed to reveal some other exciting effects.

The most interesting discovery was that some carbon nanotubes were unzipped into graphene nanoribbons as a result of prolonged hydrogen treatment. What is even more exciting -- unzipping of nanotube with hydrogen attached to the side walls could possibly lead to synthesis of hydrogenated graphene: graphane. So far, graphane was attempted to be synthesized mostly by reaction of hydrogen with graphene. This appeared to be very difficult, especially if the graphene is supported on some substrate and only one side is available for the reaction. However, hydrogen reacts much easier with the curved surface of carbon nanotubes.

"Our new idea is to use hydrogenated nanotubes and unzip them into graphane nanoribbons. So far, only the first step towards graphane nanoribbon synthesis is done and a lot more work is required to make our approach effective," explains Alexandr Talyzin. "Combined experience and expertise from several groups at different universities, was a key to success."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Umeå University, via AlphaGalileo.

Journal Reference:

Alexandr V. Talyzin, Serhiy Luzan, Ilya V. Anoshkin, Albert G. Nasibulin, Jiang Hua, Esko I Kauppinen, Valery M. Mikoushkin, Vladimir V Shnitov, Dmitry E. Marchenko, Dag Noreus. Hydrogenation, Purification and Unzipping of Carbon Nanotubes by Reaction with Molecular Hydrogen: Road to Graphane Nanoribbons. ACS Nano, 2011; 110419124402048 DOI: 10.1021/nn201224k

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New green technology for hydrogen production

ScienceDaily (May 12, 2011) — Researcher Mohamed Halabi of Eindhoven University of Technology demonstrates a proof-of-concept for a new and clean technology to produce high purity hydrogen from natural gas. This allows hydrogen to be produced in an elegant technique at much lower temperatures, and without releasing CO2 into the atmosphere.

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 CO2 have 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 CO2 is effectively adsorbed on the sorbent, hence preventing any CO2 emissions 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.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Eindhoven University of Technology.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

New green technology for hydrogen production

ScienceDaily (May 12, 2011) — Researcher Mohamed Halabi of Eindhoven University of Technology demonstrates a proof-of-concept for a new and clean technology to produce high purity hydrogen from natural gas. This allows hydrogen to be produced in an elegant technique at much lower temperatures, and without releasing CO2 into the atmosphere.

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 CO2 have 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 CO2 is effectively adsorbed on the sorbent, hence preventing any CO2 emissions 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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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Eindhoven University of Technology.

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Cheaper hydrogen fuel cells: Utility of non-precious-metal catalysts documented

ScienceDaily (Apr. 25, 2011) — Los Alamos National Laboratory scientists have developed a way to avoid the use of expensive platinum in hydrogen fuel cells, the environmentally friendly devices that might replace current power sources in everything from personal data devices to automobiles.

In a paper published April 21 in Science, 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.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by DOE/Los Alamos National Laboratory.

Journal Reference:

G. Wu, K. L. More, C. M. Johnston, P. Zelenay. High-Performance Electrocatalysts for Oxygen Reduction Derived from Polyaniline, Iron, and Cobalt. Science, 2011; 332 (6028): 443 DOI: 10.1126/science.1200832

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