New Bacterium Doubles Hydrogen Gas Production

Hydrogen gas is today used primarily for manufacturing chemicals, but a bright future is predicted for it as a vehicle fuel in combination with fuel cells. In order to produce hydrogen gas in a way that is climate neutral, bacteria are added to forestry or household waste, using a method similar to biogas production. One problem with this production method is that hydrogen exchange is low, i.e. the raw materials generate little hydrogen gas.

Now, for the first time, researchers have studied a newly discovered bacterium that produces twice as much hydrogen gas as the bacteria currently used. The results show how, when and why the bacterium can perform its excellent work and increase the possibilities of competitive biological production of hydrogen gas.

“There are three important explanations for why this bacterium, which is called Caldicellulosiruptor saccharolyticus, produces more hydrogen gas than others. One is that it has adapted to a low-energy environment, which has caused it to develop effective transport systems for carbohydrates and the ability to break down inaccessible parts of plants with the help of enzymes. This in turn means it produces more hydrogen gas. The second explanation is that it can cope with higher growth temperatures than many other bacteria. The higher the temperature, the more hydrogen gas can be formed,” summarises Karin Willquist, doctoral student in Applied Microbiology at Lund University. She will soon be presenting a thesis on the subject.

The third explanation is that the CS bacterium can still produce hydrogen gas even in difficult conditions, for example high partial hydrogen pressure, which is necessary if biological hydrogen gas production is to be financially viable.

On the other hand, the bacterium does not like high concentrations of salt or hydrogen gas. These affect the signalling molecules in the bacterium and, in turn, the metabolism in such a way that it produces less hydrogen gas.

“But it is possible to direct the process so that salt and hydrogen gas concentrations do not become too high,” points out Karin Willquist.

When hydrogen is used as an energy carrier, for example in car engines, water is the only by-product. However, because the hydrogen gas production itself, if it is carried out by a conventional method, consumes large amounts of energy, hydrogen gas is still not a very environmentally friendly energy carrier.

Reforming of methane or electrolysis of water are currently the most common ways to produce hydrogen gas. However, methane gas is not renewable and its use leads to increased carbon dioxide emissions. Electrolysis requires energy, usually acquired from fossil fuels, but also sometimes from wind or solar power. Hydrogen gas can also be generated from wind power, which is an environmentally friendly alternative, even if wind power is controversial for other reasons.

“If hydrogen gas is produced from biomass, there is no addition of carbon dioxide because the carbon dioxide formed in the production is the same that is absorbed from the atmosphere by the plants being used. Bio-hydrogen gas will probably complement biogas in the future,” predicts Karin Willquist.

Today there are cars that run on hydrogen gas, e.g. the Honda FCX, even if they are few in number. The reason for this is that it is too expensive to produce hydrogen gas and there is no functioning hydrogen infrastructure.

“A first step towards a hydrogen gas society could be to mix hydrogen gas with methane gas and use the existing methane gas infrastructure. Buses in Malmö, for example, drive on a mixture of hydrogen gas and methane gas,” says Karin Willquist.

Caldicellulosiruptor saccharolyticus was isolated for the first time in 1987 in a hot spring in New Zealand. It is only recently that researchers have really begun to realise the potential of the bacterium.

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Water into Hydrogen Fuel to recycle waste energy.

Materials scientists at the University of Wisconsin-Madison have taken the help of piezoelectric effect to harness random energy available in the atmosphere to turn water into usable hydrogen fuel. It might prove a simple, efficient method to recycle waste energy. The research team is led by Huifang Xu, who is a UW-Madison geologist and crystal specialist. They took nanocrystals of zinc oxide and barium titanate. These two nanocrystals were put in water. When these crystals received ultrasonic vibrations, the nanofibers flexed and catalyzed a chemical reaction. This whole process resulted in splitting the water molecules into hydrogen and oxygen.

“This study provides a simple and cost-effective technology for direct water splitting that may generate hydrogen fuels by scavenging energy wastes such as noise or stray vibrations from the environment,” the authors write in a new paper, published in the Journal of Physical Chemistry Letters. “This new discovery may have potential implications in solving the challenging energy and environmental issues that we are facing today and in the future.”

The researchers, led by UW-Madison geologist and crystal specialist Huifang Xu, grew nanocrystals of two common crystals, zinc oxide and barium titanate, and placed them in water. When pulsed with ultrasonic vibrations, the nanofibers flexed and catalyzed a chemical reaction to split the water molecules into hydrogen and oxygen.

But scientists didn’t utilize this electrical energy straightaway. They use this energy in breaking the chemical bonds in water to split oxygen and hydrogen. Xu explains, “This is a new phenomenon, converting mechanical energy directly to chemical energy.” Xu calls it a piezoelectrochemical (PZEC) effect. Why it seems that scientists are beating around the bush? Because chemical energy of hydrogen fuel is more stable than the electric charge. Storage of hydrogen fuel is easy and would not lose potency over time.

With the right technology, Xu foresees this method to be utilized where small amount of power is needed. Now we can imagine charging a cell phone while taking our morning walk or we can enjoy cool breeze that can power street lights. Xu says, “We have limited areas to collect large energy differences, like a waterfall or a big dam. But we have lots of places with small energies. If we can harvest that energy, it would be tremendous.”

Researchers found how to improve hydrogen storage

An international team of researchers has identified a new theoretical approach that may one day make the synthesis of hydrogen fuel storage materials less complicated and improve the thermodynamics and reversibility of the system.

Many researchers have their sights set on hydrogen as an alternative energy source to fossil fuels such as oil, natural gas and coal that contain carbon, pollute the environment and contribute to global warming. Known to be the most abundant element in the universe, hydrogen is considered an ideal energy carrier — not to mention that it’s clean, environmentally friendly and non-toxic. However, it has been difficult to find materials that can efficiently and safely store and release it with fast kinetics under ambient temperature and pressure.

The team of researchers from Virginia Commonwealth University; Peking University in Beijing; and the Chinese Academy of Science in Shanghai; have developed a process using an electric field that can significantly improve how hydrogen fuel is stored and released.

“Although tremendous efforts have been devoted to experimental and theoretical research in the past years, the biggest challenge is that all the existing methods do not meet the Department of Energy targets for hydrogen storage materials. The breakthrough can only be achieved by exploring new mechanisms and new principles for materials design,” said Qiang Sun, Ph.D., research associate professor with the VCU team, who led the study.

“We have made such an attempt, and we have proposed a new principle for the design of hydrogen storage materials which involves materials with low-coordinated, non-metal anions that are highly polarizable in an applied electric field,” he said.

“Using an external electric field as another variable in our search for such a material will bring a hydrogen economy closer to reality. This is a paradigm shift in the approach to store hydrogen. Thus far, the efforts have been on how to modify the composition of the storage material. Here we show that an applied electric field can do the same thing as doped metal ions ,” said Puru Jena, Ph.D. , distinguished professor in the VCU Department of Physics.

“More importantly, it avoids many problems associated with doping metal ions such as clustering of metal atoms, poisoning of metal ions by other gases, and a complicated synthesis process. In addition, once the electric field is removed, hydrogen desorbs, making the process reversible with fast kinetics under ambient conditions,” he said.

The team found that an external electric field can be used to store hydrogen just as an internal field can store hydrogen due to charge polarization caused by a metal ion.

“This work will help researchers create an entirely new way to store hydrogen and find materials that are most suitable. The challenge now is to find materials that are easily polarizable under an applied electric field. This will reduce the strength of the electric field needed for efficient hydrogen storage,” said Jena.

The research is published online in the Early Edition of the Proceedings of the National Academy of Sciences and will be highlighted in the front section of the print edition, “In this Issue.”

The research is based on a 1992 published polarization theory by Jena, the late B.K. Rao, a former professor of physics at VCU, and their student, J.Niu.

This work is supported by grants from the National Natural Science Foundation of China, the Foundation of National Laboratory for Infrared Physics, the National Grand Fundamental Research 973 Program of China, the U.S. National Science Foundation and the U.S. Department of Energy.

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