Revolution in solar hydrogen A research group led by Prof. Craig Grimes at the Materials Research Institute, Penn State University, the United States, is “only a couple of problems away” from developing an inexpensive and easily scaleable technique for water photoelectrolysis – the splitting of water into oxygen and hydrogen using light energy – that could help power the proposed hydrogen economy. The team is fabricating thin films made of self-aligned, vertically oriented titanium iron oxide (Ti-Fe-O) nanotube arrays that demonstrate the ability to split water under natural sunlight. Previous research had reported the development of titanium dioxide or titania nanotube arrays with a photoconversion efficiency of 16.5 per cent under ultraviolet light. Titania, which is commonly used in white paints and sunscreens, has excellent charge-transfer properties and corrosion stability, making it a likely candidate for cheap and long-lasting solar cells. However, as ultraviolet light contains only about 5 per cent of the solar spectrum energy, the researchers needed to find a means to move the materials band gap into the visible spectrum. The team has reported a photocurrent of 2 mA/cm2 and a photoconversion rate of 1.5 per cent, the second highest rate achieved with an iron oxide related material. The team is now looking to optimize the nanotube architecture to overcome the low electron-hole mobility of iron. By reducing the wall thickness of the Ti-Fe-O nanotubes so as to correspond to the hole diffusion length of iron, which is around 4 nm, the researchers hope to reach an efficiency closer to the 12.9 per cent theoretical maximum for materials with the band gap of hematite. Source: www.mri.psu.edu High-efficiency hydrogen gas system Fuelcell Energy Inc. in the United States recently announced the scale up of a separation system that extracts hydrogen from a gas mixture while generating electricity. The electrochemical hydrogen separation or the DFC-H2-EHS system was developed for the United States Army’s Engineer Research & Development Centre – Construction Engineering Research Laboratory. The system enables the pure, extracted gas to be sold as fuel for hydrogen vehicles or other industrial uses. The prototype of DFC-H2-EHS system successfully operated for over 6,000 hours. It offers up to 50 per cent savings in operating costs, as compared with conventional hydrogen separation processes. Besides, the high efficiency of the fuel cell plant allows for significantly reduced carbon dioxide emissions. The EHS system, when combined with Fuelcell Energy’s Direct Fuelcell power plants, provides a solution for distributed generation of hydrogen and electricity. The overall co-production system is designed to operate using renewable fuel sources such as anaerobic digester gas from industrial or municipal wastewater processing, as well as readily available fuels such as natural gas and propane. Source: www.renewableenergyaccess.com Hydrogen pellets for vehicles Scientists at the Pacific Northwest National Laboratory (PNNL) in the United States are developing a new and attractive storage medium that may provide the “power of pellets” to fuel future transportation needs. The Department of Energy’s Chemical Hydrogen Storage Centre of Excellence is investigating a hydrogen storage medium that holds promise in meeting long-term targets for transportation use. As part of the Centre, PNNL scientists are using solid ammonia borane (AB), compressed into small pellets to serve as a hydrogen storage material. Each millilitre of AB weighs about 0.75 gram but harbours up to 1.8 l of hydrogen. Researchers expect that a fuel system using small AB pellets will occupy less space and be lighter in weight than systems using pressurized hydrogen gas, thus enabling fuel cell vehicles to have room, range and performance comparable to today’s automobiles. A small pellet (240 mg) of solid AB is capable of storing relatively large quantities of hydrogen (0.5 l) in a very small volume. The PNNL scientists are learning to manipulate the release of hydrogen from AB at predictable rates. By varying temperature and manipulating AB feed rates to a reactor, the researchers envision controlling the production of hydrogen and, thus, fuel cell power. Once hydrogen from the storage material gets depleted, the AB pellets must be safely and efficiently regenerated by way of chemical processing. This refuelling method requires chemically digesting or breaking down the solid spent fuel into chemicals that can then be recycled back to AB with hydrogen. Source: www.sciencedaily.com New catalysts may create more and cheaper hydrogen In the United States, a new class of catalysts created at the Department of Energy’s Argonne National Laboratory may help scientists and engineers overcome a few of the hurdles that have inhibited the production of hydrogen for use in fuel cells. The team, led by Dr. Michael Krumpelt, used “single-site” catalysts based on ceria or lanthanum chromite doped with either platinum or ruthenium to increase hydrogen production at lower temperatures during reforming. Most hydrogen is industrially produced through steam reforming. In this process, a nickel-based catalyst is used to react natural gas with steam to produce pure hydrogen and carbon dioxide. The nickel catalysts typically consist of metal grains tens of thousands of atoms in diameter that speckle the surface of metal oxide substrates. However, the new catalysts consist of single atomic sites embedded in an oxide matrix. As some reforming processes tend to clog much of the larger catalysts with by-products of carbon or sulphur, smaller catalysts process the fuel much more efficiently and can produce more hydrogen at lower temperatures. Contact: Ms. Sylvia Carson, Media Relations, Communications & Public Affairs, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439, United States of America. Tel: +1 (630) 252 5510 E-mail: scarson@anl.gov Source: www.anl.gov Hydrogen from industry by-product Research led by Dr. Abdul-Majeed Azad, a chemical engineer at the University of Toledo in the United States, has developed a method for using nanoscale iron oxide and solar rays to split water and produce hydrogen. Many tonnes of iron oxide are produced every year as a byproduct of the steel industry. To produce hydrogen, water is piped to a clear quartz cylinder above the solar collector. The heat of the collector turns the water to steam. The steam rushes across the iron nanoparticles in the same airtight quartz cylinder. The iron captures the oxygen from the water. The remaining hydrogen is streamed towards a 12-volt fuel cell – powerful enough to light a driveway lamp. The iron that is oxidized during this process can also be reprocessed and reused. The iron nanoparticles can also be used to remove arsenic from water and are currently being tested in a water purification project in Pakistan. Source: www.merid.org Hydrogen fuel bike In China, Shanghai Pearl Hydrogen Power Source Technology Co. has introduced a concept bike driven by an environmentally clean hydrogen fuel cell. A battery tank and a pair of hydrogen gas bottles make up the energy system for the bike, making it different in appearance from other electric bikes in current use. The hydrogen bike also has some other advantages. It only takes 30 minutes to refill the gas bottles, as against the 3 hours to recharge the lead battery in conventional electric bikes. The energy system, including the battery tank and gas bottles, is also about half the weight of the power system on conventional electric bikes. The hydrogen bike costs about US$2,632 but that could be reduced to about US$527 on mass production, making the price more comparable to electric bikes. With two full gas bottles, the bike could be expected to complete a trip of 100 km at a speed of 25 km/h. Source: www.shanghaidaily.com