to Hydrogen Production

Science (June 1, 2010) — Scientists have been hard at work harnessing the power of microbes as an attractive source of clean energy. Now, Biodesign Institute at Arizona State University researcher Dr. Prathap Parameswaran and his colleagues have investigated a means for enhancing the efficiency of clean energy production by using specialized bacteria.

Microbial electrochemical cells or MXCs are able to use bacterial respiration as a means of liberating electrons, which can be used to generate current and make clean electricity. With minor reconfiguring such devices can also carry out electrolysis, providing a green path to hydrogen production, reducing reliance on natural gas and other fossil fuels, now used for most hydrogen manufacture.

MXCs resemble a battery, with a Mason jar-sized chamber setup for each terminal. The bacteria are grown in the “positive” chamber (called the anode). The research team, led by Bruce Rittmann, director of Biodesign’s Center for Environmental Biotechnology, had previously shown that the bacteria are able to live and thrive on the anode electrode, and can use waste materials as food, (the bacteria’s dietary staples include pig manure or other farm waste) to grow while transferring electrons onto the electrode to make electricity.

In a microbial electrolysis cell (MEC), like that used in the current study, the electrons produced at the anode join positiviely charged protons in the negative (cathode) chamber to form hydrogen gas. “The reactions that happen at the MEC anode are the same as for a microbial fuel cell which is used to generate electricity, ” Parameswaran says. “The final output is different depending on how we operate it.”

When the bacteria are grown in an oxygen-free, or anaerobic environment, they attach to the MXC’s anode, forming a sticky matrix of sugar and protein. In such environments, when fed with organic compounds, an efficient partnership of bacteria gets established in the biofilm anode, consisting of fermenters, hydrogen scavengers, and anode respiring bacteria (ARB). This living matrix, known as the biofilm anode, is a strong conductor, able to efficiently transfer electrons to the anode where they follow a current gradient across to the cathode side.

The present study demonstrates that the level of electron flow from the anode to the cathode can be improved by selecting for additional bacteria known as homo-acetogens, in the anode chamber. Homo-acetogens capture the electrons from hydrogen in waste material, producing acetate, which is a very favorable electron donor for the anode bacteria.

The study shows that under favorable conditions, the anode bacteria could convert hydrogen to current more efficiently after forming a mutual relationship or syntrophy with homo-acetogens. The team was also able to reduce the negative impact of other hydogen consuming microbes, such as methane-producing methanogens, which otherwise steal some of the available electrons in the system, thereby reducing current. The selective inhibition of methanogens was accomplished by the adding a chemical called 2-bromoethane sulfonic acid to the adode’s microbial stew.

The group used both chemical and genomic methods to confirm the identify of homo-acetogens. In addition to detection of acetate, formate, an intermediary product, was also discovered. With the aid of quantitative PCR analysis, the team was also able to pick up the genomic signature of acetogens in the form of FTHFS, a gene specifically associated with acetogenesis.

“We were able to establish that these homo-acetogens can prevail and form relationships,” Parameswaran says. Future research will explore ways to sustain syntrophic relations between homo-acetogens and anode bacteria, in the absence of the chemical inhibitors.

Further progress could pave the way for eventual large-scale commercialization of systems to simultaneously treat wastewater and generate clean energy. “One of the biggest limitations right now is our lack of knowledge,” says Cesar Torres, one of the current study’s co-authors, who stresses that there remains much to understand about the interactions of bacterial communities within MXCs.

The field is still very young, Torres points out, noting that work on MXCs only began about 8 years ago. “I think over the next 5-10 years the community will bring a lot of information that will be really helpful and that will lead us to good applications.”

The team’s results appear in the advanced online issue of the journal Bioresource Technology.

Sourced an dpublished by Henry Sapiecha 5th June 2010

Renewable Energy:

Inexpensive Metal Catalyst

Can Effectively Generate

Hydrogen from Water

Science (May 1, 2010) — Hydrogen would command a key role in future renewable energy technologies, experts agree, if a relatively cheap, efficient and carbon-neutral means of producing it can be developed. An important step towards this elusive goal has been taken by a team of researchers with the U.S. Department of Energy’s (DOE) Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California, Berkeley. The team has discovered an inexpensive metal catalyst that can effectively generate hydrogen gas from water.

“Our new proton reduction catalyst is based on a molybdenum-oxo metal complex that is about 70 times cheaper than platinum, today’s most widely used metal catalyst for splitting the water molecule,” said Hemamala Karunadasa, one of the co-discoverers of this complex. “In addition, our catalyst does not require organic additives, and can operate in neutral water, even if it is dirty, and can operate in sea water, the most abundant source of hydrogen on earth and a natural electrolyte. These qualities make our catalyst ideal for renewable energy and sustainable chemistry.”

Karunadasa holds joint appointments with Berkeley Lab’s Chemical Sciences Division and UC Berkeley’s Chemistry Department. She is the lead author of a paper describing this work that appears in the April 29, 2010 issue of the journal Nature, titled “A molecular molybdenum-oxo catalyst for generating hydrogen from water.” Co-authors of this paper were Christopher Chang and Jeffrey Long, who also hold joint appointments with Berkeley Lab and UC Berkeley. Chang, in addition, is also an investigator with the Howard Hughes Medical Institute (HHMI).

Hydrogen gas, whether combusted or used in fuel cells to generate electricity, emits only water vapor as an exhaust product, which is why this nation would already be rolling towards a hydrogen economy if only there were hydrogen wells to tap. However, hydrogen gas does not occur naturally and has to be produced. Most of the hydrogen gas in the United States today comes from natural gas, a fossil fuel. While inexpensive, this technique adds huge volumes of carbon emissions to the atmosphere. Hydrogen can also be produced through the electrolysis of water — using electricity to split molecules of water into molecules of hydrogen and oxygen. This is an environmentally clean and sustainable method of production — especially if the electricity is generated via a renewable technology such as solar or wind — but requires a water-splitting catalyst.

Nature has developed extremely efficient water-splitting enzymes — called hydrogenases — for use by plants during photosynthesis, however, these enzymes are highly unstable and easily deactivated when removed from their native environment. Human activities demand a stable metal catalyst that can operate under non-biological settings.

Metal catalysts are commercially available, but they are low valence precious metals whose high costs make their widespread use prohibitive. For example, platinum, the best of them, costs some $2,000 an ounce.

“The basic scientific challenge has been to create earth-abundant molecular systems that produce hydrogen from water with high catalytic activity and stability,” Chang says. “We believe our discovery of a molecular molybdenum-oxo catalyst for generating hydrogen from water without the use of additional acids or organic co-solvents establishes a new chemical paradigm for creating reduction catalysts that are highly active and robust in aqueous media.”

The molybdenum-oxo complex that Karunadasa, Chang and Long discovered is a high valence metal with the chemical name of (PY5Me2)Mo-oxo. In their studies, the research team found that this complex catalyzes the generation of hydrogen from neutral buffered water or even sea water with a turnover frequency of 2.4 moles of hydrogen per mole of catalyst per second.

Long says, “This metal-oxo complex represents a distinct molecular motif for reduction catalysis that has high activity and stability in water. We are now focused on modifying the PY5Me ligand portion of the complex and investigating other metal complexes based on similar ligand platforms to further facilitate electrical charge-driven as well as light-driven catalytic processes. Our particular emphasis is on chemistry relevant to sustainable energy cycles.”

This research was supported in part by the DOE Office of Science through Berkeley Lab’s Helios Solar Energy Research Center, and in part by a grant from the National science Foundation.

Sourced and published by Henry Sapiecha 3rd May 2010

Hydrogen Gas Production

India to Focus on Electric Vehicles

A number of lectures on the policies and current states of electric vehicle (EV) development in China and India were delivered at the 24th International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium & Exhibition (EVS24), which took place in Norway from May 13 to 16, 2009.

China is planning to allot half the total transportation energy consumption to EVs and fuel cell vehicles (FCVs) that primarily use energy other than petroleum by 2020. In India, on the other hand, the diffusion of EVs has become an important issue due to its environmental problems and transportation conditions.

Gasoline cars, EVs to co-exist for some time in China

Automotive sales are growing extremely fast in China. They reached about 9.3 million units in 2008 and are likely to surpass 10 million units, the largest sales volume in the world, in 2010. The number of vehicles owned in China is currently 40 million and is forecast to reach 150 million in 2020.

C. C. Chan, president of the Electric Vehicle Association of Asia Pacific China, and Duan Ruichun, executive president of Chinese Electro-technical Society China, reported data on automotive development including EVs in China.

China is planning to reduce gasoline cars and hybrids, which are powered primarily by oil, and allot half the total energy consumption in the transportation segment to EVs and FCVs, which are powered by energies other than oil, Chan said.

As half of the existing cars will remain, China will (1) maintain the infrastructure for gasoline and other liquid fuels, (2) make its mileage regulation for gasoline cars etc, meet international standards and (3) give priority to high-efficiency direct-injection engine cars and hybrids until 2020.

Ruichun said China is conducting 863 projects concerning EV and FCV development to meet this goal. As a result of those projects, EVs and hybrids are currently running in 13 cities in China. And the Chinese government is planning to increase the number of those vehicles to more than 1,000 units within three years.

At first, EVs and FCVs will be diffused as means of public transportation. To accomplish this goal, the government will increase the subsidies for purchasers of electric buses, etc. For example, for the purchase of a hybrid, electric or fuel-cell bus with a total length of 10m or more, a subsidy of up to Rmb420,000 (about ¥5.88 million or US$61,600), 500,000 (¥7 million) or 600,000 (¥8.4 million) will be paid, respectively.

As for the purchase of a general EV, a subsidy of up to Rmb50,000 (¥700,000), 60,000 (840,000) and 250,000 (3.5 million) will be granted to the purchaser of a hybrid, EV and FCV, respectively.

Aided by those stimulative policies, China is already at a state where it can start producing core technologies for EVs and automotive platforms, Ruichun said.

“We have already achieved 2,000W/kg output density of a Li-ion secondary battery with a current capacity of 6 to 100Ah and mounted a 1,300W/kg output motor with more than 93% efficiency on a car,” he said, emphasizing the fact that EV development is making smooth progress in China.

EVs are suited for India

Meanwhile, Indian population will outnumber the world’s largest Chinese population, exceeding 1.4 billion in about 2030. The Indian automotive market has been growing at an annual rate of more than 15% as well. The market will maintain the same scale as in the preceding year even during the global recession of 2008 to 2009.

The diffusion of EVs seems to have become a pressing challenge in India.

“Considering environmental issues, we will face a serious trouble if we do not start spreading more EVs in priority to gasoline cars,” said Chetan Maini, deputy chairman and CTO of Reva Electric Company of India.

“In large cities, the degree of atmospheric pollution due to auto emission is by far worse than our safety standards,” said Shanta Chatterji, chairman and managing director of Chattelec Vehicles India Ltd of India. “And the number of deaths caused by diseases from air pollution has already outpaced that of deaths in traffic accidents.”

EVs are suited not only for environmental reasons but also for transportation conditions in India. Behind this is the fact that “long-distance driving is difficult in India because of heavy traffic congestion in urban areas,” Maini said. He revealed that 95% or more of automobiles in India are estimated to travel 80km or less per trip, with 80% traveling 25km or less.

“An EV equipped with a Li-ion secondary battery can travel about 120km per charge,” Maini said. “In other words, more than 95% of cars in India can be covered. Even when traveling 240km, the EV can travel the distance with a quick charge for about 1.5 hours. So, there will be no problem if more than 99% of cars in India are EVs.”

Moreover, there is little chance that traffic congestions will improve in India, where urban population is expected to increase about 50% in 20 years.

Nevertheless, the current hottest car in India is the low-priced gasoline car, “Nano,” which Tata Motors Ltd of India is planning to release. Reportedly, nearly 200,000 units of the Nano have already been ordered.

“The diffusion of the Nano is likely to worsen the current transportation conditions and environmental issues,” Maini said, commenting on the Nano.

The Nano can be used as the second car in urban areas or a convenient car for people in rural areas. In India, the number of cars purchased as the second car has reportedly surpassed that of first car purchases since 2005.

EVs recently started to penetrate India. The total sales of electric motorcycles and EVs were about 10,000 units in 2007 to 2008, but the sales are expected to sharply soar to about 110,000 units in 2008 to 2009. However, electric motorcycles are making up the majority of the sales.

Although there are more than 15 manufacturers of electric motorcycles in India, only few Indian manufacturers deal with EVs or hybrids. At this moment, Reva is the only EV manufacturer and Mahindra & Mahindra Ltd is the only hybrid manufacturer in India. Tata, on the other hand, is planning to market EVs in Europe as a starter.

The Indian government is currently devising policies with three pillars, “ecology,” “economy” and “social equity,” to diffuse EVs. Of these three pillars, EVs hold the key to both ecology and economy, Chatterji said.

Sourced and published by Henry Sapiecha 1st July 2009

Hydrogen Fuel Cell

NGK Insulators Ltd developed a solid oxide fuel cell (SOFC) that uses hydrogen gas as fuel and achieved a lower heating value (LHV) of 63%, one of the highest in the world.

The SOFC features a power output of 700W and an operating temperature of 800°C.

The company lowered the resistance value by completely coating the cell’s supporting anode with a thin film (5?m thick) of electrolyte (zirconia) and secured a sufficient power generation area by forming cathodes on both sides of the cell to achieve the large output, it said.

To evenly spread fuel gas to the entire cell, flow channels for fuel gas were formed inside the prototype cell. The thickness of the cell is 1.5mm. Also, the new fuel cell is superior in terms of size and cost because it can generate power on both the top and bottom sides and its flow channels eliminate the need for components (separators) to separate fuel gas from air, NGK Insulators said.

The company provided a stack in which tens of the cells are layered to a leading oil company in Japan, asking it to evaluate the fuel cell’s power generation performance. And it will aim to commercialize the cell for use in homes and commercial facilities such as convenience stores and shopping malls by further improving its performance. The company is planning to advance the development through technical alliances and joint developments with other companies.

Sourced and published by Henry Sapiecha 1st July 2009