FuelCellsWorks

Hydrogen is a promising alternative energy carrier that can be efficiently converted into electrical energy in fuel cells. One hurdle to the introduction of sustainable hydrogen technology is the fact that the large-scale industrial production of hydrogen through reforming processes is still largely based on fossil fuels, and thus is not carbon neutral. “One of the most important goals for chemists is to use solar energy for the generation of energy carriers like hydrogen,” says Matthias Beller of the Leibniz Institute for Catalysis in Rostock (Germany). “The biggest attraction is the use of water as a source of hydrogen.” Beller’s Rostock team, in collaboration with scientists in Rennes (France), has now developed a new catalytic system that can make this dream come true. As the researchers report in the journal Angewandte Chemie, their efficient system is based on simple, inexpensive iron carbonyl complexes (“Light-Driven Hydrogen Generation: Efficient Iron-Based Water Reduction Catalysts”).

By means of photosynthesis, plants are particularly good at converting light into chemical energy. Their success relies on complicated reaction cascades that are activated by light energy. Electrons are passed on through multiple reaction steps that involve a number of “helper agents”. Based on this principle, light-driven reaction cascades for the reduction of water to hydrogen are currently being developed around the world. The significant components for Beller’s novel cascade are a photosensitizer, a source of electrons (electron donor), and the actual water-reduction catalyst. The photosensitizer absorbs the incoming light, capturing its energy. Subsequently, the electron donor transfers an electron to the excited photosensitizer. Now negatively charged, the photosensitizer transfers its extra electron to the water reduction catalyst. The catalyst uses the electron to reduce protons (H+ ions) from the water to hydrogen (H2). In order for the whole process to proceed, the individual components must be well tuned to each other. The team selected a known photosensitizer that contains the metal iridium; their electron donor is triethylamine. Whereas most researchers have concentrated on expensive precious metals as water reduction catalysts, the Rostock research team settled on an affordable alternative: simple, readily available iron carbonyls (coordination complexes made of iron atoms and CO molecules). “Our new catalytic system demonstrates that simple and affordable iron complexes can be used for the production of hydrogen from water,” says Beller. “In order to carry out this reaction on a larger scale in the future, we are currently working on improvements to the photosensitizer and the use of water as the electron donor.”

French scientists have demonstrated the potential of a new fuel cell catalyst inspired by hydrogenase enzymes. Although its activity doesn’t yet match that of platinum, the researchers say it is the first useful biomimetic catalyst capable of operating under fuel cell conditions.

In a hydrogen economy, power would be generated by oxidising stored hydrogen in fuel cells. This reversible reaction – the opposite of which produces hydrogen through the electrolysis of water – can be driven by platinum-based catalysts. Nature, however, in hydrogenase enzymes, has evolved a way of doing this without the need for such rare metals and thus borrowing from nature’s design may be a way to create fuel cell catalysts on the cheap.

Vincent Artero at Joseph Fourier University and colleagues have achieved a significant step towards this goal with a nickel bisdiphosphine-based design. Artero explains that it is the first time this has been shown for such a sophisticated bio-inspired compound. ‘Most people think these compounds are nice achievements of academic research, but that they will never be stable under technological conditions – under pressure, under heat and in very acidic solutions,’ he says. ‘We have demonstrated that we can use these compounds under the conditions that are used in the fuel cells, or electrolysers, that are developed at the moment.’

A close look at the catalyst reveals a striking similarity to the metalloproteins on which it is modelled. At the centre is a nickel atom, as in nickel-iron hydrogenases, combined with a diphosphine ligand bearing a basic N-H that mimics a co-factor in iron-iron hydrogenases and helps to control proton movement as hydrogen is either produced or oxidised. Artero’s team grafted their complexes onto electrically conducting carbon nanotubes that drive electrons to or from the active site and embedded them in a polymer to protect them from acidic electrolytes – mimicking the protection afforded by polypeptide chains in enzymes. The result is a catalyst that shows impressive efficiency and stability under operating conditions.

Dan DuBois, at the Institute for Interfacial Catalysis in Richland, Washington State, developed the original design on which Artero’s catalyst is built. ‘They’ve really shown that you can take these catalysts and put them in an operating cell,’ he says. ‘They’re actually functioning quite nicely, and I think that if we can get another one or two orders of magnitude in rate, which is doable, then they will be useful.’

Artero explains that the rate difference may be due to bulky functional groups used to anchor the catalysts to the nanotubes. ‘We think that may have slowed the catalytic activity,’ he says. ‘So we can now try to imagine another way to graft the catalyst and to keep the catalytic activity high.’ But he also points out that, crucially, the overvoltage – the amount of energy ‘wasted’ to drive the reaction at a sufficiently high rate – does approach that of platinum, unlike most other non-Nobel metal designs.

Hayley Birch

Company’s XX25 Fuel Cell Systems to Power Electronics, Recharge Batteries During Army Field Trials

LIVERMORE, Calif.–UltraCell Corporation, a leading producer of fuel cells for mobile power applications, today announced that it has been selected to provide portable power for electronic devices and recharge military batteries during the Army Expeditionary Warrior Experiment (AEWE), taking place at the Maneuver Battle Lab (MBL) in Fort Benning, Ga., beginning in early 2010.

The AEWE, in coordination with the United States Army Training and Doctrine Command (TRADOC) and the Army Capabilities Integration Center (ARCIC), will conduct experiments over a seven-week period through live force-on-force and constructive, virtual-land simulations to provide a credible and repeatable venue for network-enabled experimentation. The program, which began in 2004, focuses on emerging technologies and supports the Army’s effort to shorten material development and examine future force requirements and constructs through a linked campaign of experimentation.

UltraCell’s XX25 fuel cell systems will power military equipment including PRC-119F ASIP radios, rugged notebook computers and Long Range Thermal Video (LRTV) systems. Additionally, the XX25s will be used to recharge BB-2590 and Li-80/145 military batteries. The XX25 is capable of delivering 72 hours of continuous runtime using a single fuel tank, making it an extremely mobile and lightweight source of power.

“We continue to demonstrate that our fuel cell systems deliver the most efficient, lightweight and portable power solutions for military applications and off-grid environments,” said UltraCell CEO Keith Scott. “UltraCell’s participation at AEWE further underscores that commitment and is another example of the XX25’s field readiness and validation.”

Berlin-based provider of innovative energy storage solutions acquires two more orders for autonomous fuel cell-based power supply solutions

Berlin –Heliocentris Fuel Cells AG, a specialist in clean energy storage solutions, is pleased to report two more orders for the supply of autonomous power supply solutions. The clients are the oil company Bahrain Petroleum from Bahrain and a university from Germany.

The solutions are hybrid energy storage systems consisting of batteries, fuel cells, electrolysers and adapted power electronics that store the locally generated solar or wind power. For the oil company project, Heliocentris will also deliver the photovoltaic and wind solution.

The projects have a total volume of approx. EUR300,000.

Dr Henrik Colell, CEO, commented: ‘After just recently receiving an order for a complete energy storage system, we are pleased about the two additional projects for similar energy solutions. The associated significant increase in sales confirms our growth strategy towards hybrid storage solutions.’

About Heliocentris Fuel Cells AG

Heliocentris Fuel Cells AG is a specialist for clean energy storage solutions based on a smart combination of batteries, fuel cells and energy management. Areas of application are mobile and stationary applications that require longer ranges than current batteries can provide. Examples are electric vehicles, onboard and emergency power supplies as well as electricity supply for off-grid applications such as monitoring stations or energy self-sufficient houses.  Heliocentris has been developing and marketing fuel cell-based energy solutions for more than 10 years now. Heliocentris initially targeted the training and lab markets as typical pioneer markets, where it has successfully positioned itself as one of the worldwide market leaders. Since 2006, Heliocentris has been entering selected industrial markets with considerable growth potential. With customers in over 60 ountries and a broad distribution and partner network, Heliocentris is globally well positioned. Heliocentris Fuel Cells AG is listed at the Frankfurter Wertpapierbörse (Entry Standard) and employs in total 50 staff with its head office in Berlin and a subsidiary in Vancouver, Canada. Further information is available at: www.heliocentris.com.