Nissan doubles power density with new Fuel Cell Stack

Nissan yesterday revealed a new Fuel Cell Stack for Fuel Cell Electric Vehicles (FCEV) that packs 85 kilowatts into a 34-liter package

One area of energy storage that appears to be moving towards viability quicker than battery technology at present is the hydrogen fuel cell. Nissan Motor yesterday revealed its next generation Fuel Cell Stack (2011 Model) for Fuel Cell Electric Vehicles (FCEV).
Through improvements to the Membrane Electrode Assembly and the separator flow path, Nissan has improved the power density of the Fuel Cell Stack to 2.5 times greater than its 2005 model, and in so doing has created a world's best 2.5 kW-h per liter power density.
The cost of the 2011 model Fuel Cell Stack has been reduced to one sixth of the 2005 model.
Furthermore, molding the supporting frame of the Membrane Electrode Assembly (MEA) integrally with the MEA's single-row lamination has reduced its size by more than half compared to conventional models.
Compared with the 2005 model, both the usage of platinum and parts variation has been reduced to one quarter, thereby reducing cost of the Next Generation Fuel Cell Stack to one-sixth of the 2005 model.
In so doing, Nissan engineers have achieved an important breakthrough with the development of a compact and durable hydrogen fuel-cell stack - capable of delivering ample power - that can be manufactured in volume at competitive cost.
Most importantly, it's not one of those Japanese research lab breakthroughs that's still effectively ten years away. Nissan's fuel-cell team says it can be ready for market as soon as sufficient supplies of hydrogen are available.
According to Nissan, taxis, delivery vans and other city-specific fleets could quickly be converted to zero-emission fuel cells.
"We never got discouraged and we never gave up," says Masanari Yanagisawa, a 10-year veteran in the company's fuel-cell R&D efforts. "So we just kept working, patiently and persistently. As a result, we have achieved what we believe is a major breakthrough.
"We have made great strides in two critical areas: power density and cost. Our 2011-model fuel-cell stack delivers power density at 2.5 kilowatt-hrs per liter, 2.5 times better than our 2005 model.
"As a result, the new stack is also a lot smaller. We can now pack 85 kilowatts of power in a 34-liter package. Better yet, we have brought the production cost down by 85 percent, close to meeting the U.S. Department of Energy cost target for 2010 - a widely referenced benchmark.
"We slashed the price by reducing the need for platinum by 75 percent," Yanagisawa says. "The Membrane Electrode Assembly [MEA] comprises 80 percent of the stack's cost, and platinum is half the cost of an MEA, so this was a huge step forward."
The other key challenge in developing fuel-cell stacks is to design a structure that delivers high power- density; that's durable and easy to manufacture without flaws. This is very tricky.
Each fuel cell is a carefully built sandwich with layers ultra-thin polymer electrolyte membrane. Each membrane has an anode layer and a cathode layer on both sides. On the outer side of each of each of these anode/cathode layers are separators, which form channels through which hydrogen, air and cooling water flow.
As each fuel cell generates a maximum of one volt, you need to stack lots of sandwiches together to get enough power to run a car.
The process is so fiddly that building a model ship in a bottle seems a snap by comparison. No wonder so many teams around the world have given up in frustration. But with their craft legacy of patient attention to minute detail, this is the kind of work that Japanese tend to excel at.
Since 2001, the Nissan team has built a succession of prototype fuel-cell vehicles, first with partners like Ballard Power Systems and UTC Fuel Cells, then in-house from 2005. Each stack was incrementally better than its predecessor.
The 2005 prototype achieved a range of 500 kilometers, matching a conventional car. A 2008 version achieved an important breakthrough in cold-weather tolerance. But putting enough cells together in a durable stack was a hurdle the team just couldn't get over. After managing to stack more than 400 cells, they would watch in frustration as the brittle contraption fell apart on the lab floor.
Finally, in 2009, the team had a conceptual breakthrough with a technique that involves molding plastic around the MEA to create insulating frames between each of 400+ layers in the stack - thereby ensuring the layers neither short out nor fall apart.
"This breakthrough puts us, no question, in the front rank of fuel-cell developers around the world," Yanagisawa says. "Best of all," he adds with a grin, "it puts us ahead of our competitors."
So can we expect to see a Nissan Fuel Cell Electric Vehicle (FCEV) coming round the corner soon? "We are now ready to go to market at any time," Yanagisawa says. "The only hurdle remaining is hydrogen distribution. Give us the hydrogen and we'll give you an FCEV. We're good to go!"

Waste glass could be used to clean water

Dr. Nichola Coleman and Cameron Abercrombie, a final year Chemistry student from the University of Greenwich

While you may feel quite virtuous when you leave all your glass containers out for recycling, you might be surprised to know that much of your colored glass won't be used. That's because even though there's a fairly constant demand for recycled clear glass, glass in colors such as green, brown and blue isn't all that sought-after, so many recycling centers don't bother processing it. As a result, waste colored glass is now being stock-piled in some locations, waiting for a use. Thanks to research conducted at the University of Greenwich, however, that glass may soon be used for filtering pollutants out of ground water.
Dr. Nichola Coleman, a senior lecturer in Materials Chemistry, has been leading the research.
Her team combined ground colored glass, lime and caustic soda, then heated the mixture to 100C (212F) in a sealed stainless steel container. This transformed the ingredients into tobermorite, a mineral that is effective at removing heavy metals from ground- or waste-water streams. She is hoping to incorporate the tobermorite into filtration devices, that could be used to prevent water-borne pollutants from spreading from contaminated areas.
"The novelty of the research is that the glass can be recycled into something useful," the U Greenwich researcher stated. "Nobody has previously thought to use waste glass in this way."
A paper on the research was recently published in the International Journal of Environment and Waste Management.

Graphene “Big Mac” brings next gen computer chips a step closer

Researchers have sandwiched layers of graphene between layers of boron nitrate to create a graphene 'Big Mac'
Since its discovery in 2004, the two-dimensional layer of carbon atoms known as graphene has promised to revolutionize materials science, enabling flexible, transparent touch displays, lighter aircraft, cheaper batteries and faster, smaller electronic devices. Now in what could be a key step towards replacing silicon chips in computers, researchers at the University of Manchester have sandwiched two sheets of graphene with another two-dimensional material, boron nitride, to create what they have dubbed a graphene "Big Mac".
The researchers used two layers of boron nitrate to not only separate two graphene layers, but also to see how graphene reacts when it is completely encapsulated by another material. The researchers say this has allowed them, for the first time, to observe how graphene behaves when unaffected by the environment and demonstrates how graphene inside electronic circuits will probably look in the future.
"Creating the multilayer structure has allowed us to isolate graphene from negative influence of the environment and control graphene's electronic properties in a way it was impossible before," said Dr Leonid Ponomarenko. "So far people have never seen graphene as an insulator unless it has been purposefully damaged, but here high-quality graphene becomes an insulator for the first time."
"Leaving the new physics we report aside, technologically important is our demonstration that graphene encapsulated within boron nitride offers the best and most advanced platform for future graphene electronics," added Professor Andre Geim who, along with Professor Kostya Novoselov, was awarded the Nobel Prize for Physics last year for the discovery of graphene at the University of Manchester in 2004.
"It solves several nasty issues about graphene's stability and quality that were hanging for a long time as dark clouds over the future road for graphene electronics. We did this on a small scale but the experience shows that everything with graphene can be scaled up," said Geim. "It could be only a matter of several months before we have encapsulated graphene transistors with characteristics better than previously demonstrated."
The research team's paper, Tunable metal-insulator transition in double-layer graphene heterostructures appears in the journal Nature Physics.

Collaboration aims to improve methods for detecting contaminants in water supplies

Dr. Shane Snyder is working with Agilent to develop ways to detect emerging contaminants in water

Agilent Technologies has announced it will begin collaborations with the University of Arizona's Department of Chemical and Environmental Engineering's BIO5 Institute to develop ways to detect and treat emerging contaminants in drinking water. While a considerable body of work has been done in the area of potable water quality and safety this research stands apart from the rest in the way it treats contaminants as mixtures rather than separate chemicals that are usually targeted individually.
Dr. Shane Snyder - an internationally recognized authority on water contamination from the University of Arizona's Department of Chemical and Environmental Engineering who will be heading-up the project explains: "Not only will we investigate known potential threats to water quality, we will also bridge the gap between detection and health by developing methodologies that can screen water for toxicity from multiple compounds."

Emerging Contaminants

While the issue of unsafe drinking water is commonplace in developing countries it is not often thought of in areas such as the United States or Europe. We take clean and safe drinking water for granted because organizations such as the EPA have got our backs on this one - delivering potable water to our homes each and every day. In recent years a new class of contaminant known as "emerging contaminants" has come to light. A study conducted in 2000 by the US Geological Survey's (USGS) Toxic Substances Hydrology Program revealed that of the 139 streams they examined 80 per cent contained emerging contaminants. The most common chemicals found were steroids, antibiotics, non-prescription drugs, caffeine and insect repellent.
Move forward to September 2009 when the EPA released the Contaminant Candidate List 3 (CCL3), a list of 116 drinking water contaminants. These include pharmaceuticals, pesticides, disinfection by-products, chemicals from manufacturing, waterborne pathogens, and biological toxins. An example of example one of these is the active pharmaceutical ingredients (APIs), a class that contains steroids such as cortisone.
These APIs can end up in waste water as a result of bathing, where a person has say been applying cortisone topically to their sore hamstring. These APIs can then make their way into the drinking water and into your body. The effect on humans of consuming such contaminants is still largely unknown however studies on fish that live in streams contaminated by steroids have shown significant hormone disruption. There is also concern that exposure to antibiotics in drinking water could increase the occurrence of drug-resistant strains of bacteria and diseases.

University of Arizona

So ... back to the new research. Agilent Technologies Inc. and University of Arizona's Department of Chemical and Environmental Engineering's collaboration hopes to increase the ability of scientists to accurately detect contamination in water supplies in order to protect the environment and public health.
"The partnership with Agilent allows the University of Arizona to more effectively influence water reuse and desalination strategies by ensuring that the required water quality has been achieved for its intended use," said Dr Snyder.
The deal will see Agilent provide the university and BIO5 with detection equipment. This includes technology that enables the development of chemical signatures unique to a particular water source.
The research will be centered at the BIO5 Institute on the University of Arizona campus, where the infrastructure for cross-cutting work combining biological and chemical research already exists.

UCLA researchers discover rhythmic secrets of the brain

UCLA neuro-physicists have discovered that changes in synaptic strength have an optimal 'rhythm,' or frequency

Neuroscientists have long pondered the mechanism behind learning and memory formation in the human brain. On the cellular level, it's generally agreed that we learn when stimuli are repeated frequently enough that our synapses - the gap-connections between neurons - respond and become stronger. Now, a team of UCLA neuro-physicists has discovered that this change in synaptic strength actually has an optimal "rhythm," or frequency, a finding that could one day lead to new strategies for treating learning disabilities.
"Many people have learning and memory disorders, and beyond that group, most of us are not Einstein or Mozart," said Mayank R. Mehta, one of the study's co-investigators. "Our work suggests that some problems with learning and memory are caused by synapses not being tuned to the right frequency."
The tendency for connections between neurons to grow stronger in response to repeated stimuli is known as synaptic plasticity. The series of signals one neuron gets from the others to which it's connected, dubbed "spike trains," arrive with variable frequencies and timing, and it's these trains that induce formation of stronger synapses- the very basis for "practice makes perfect."
In previous studies, it was shown that very high frequency neuronal stimulation (about 100 spikes per second) led to stronger connecting synapses, while stimulation at a much lower frequency (one spike per second) actually reduced synaptic strength. But real-life neurons, performing routine behavioral tasks, only fire 10 or so consecutive spikes, not hundreds, and they do this at a far lower frequency - around 50 spikes per second.
Achieving experimental spike rates that more closely approximate real life has proved rather elusive, however. Mehta explains one of the variables they encountered: "Spike frequency refers to how fast the spikes come. Ten spikes could be delivered at a frequency of 100 spikes a second or at a frequency of one spike per second."
But Mehta and his co-investigator, Arvind Kumar, didn't let that hurdle stop them. Instead, they worked out a complex mathematical model and validated it with actual data from their experiments. Now able to generate spike patterns closer to those that occur naturally, the team discovered that, contrary to their predictions, neuron stimulation at the highest frequencies wasn't the ideal way to bolster synaptic strength.
"The expectation, based on previous studies, was that if you drove the synapse at a higher frequency, the effect on synaptic strengthening, or learning, would be at least as good as, if not better than, the naturally occurring lower frequency," Mehta said. "To our surprise, we found that beyond the optimal frequency, synaptic strengthening actually declined as the frequencies got higher."
The realization that synapses have optimal frequencies for learning prompted Mehta and Kumar to determine whether synapse location on a neuron had any specific role. They discovered that the more distant the synapse was from the neuron's bulbous main body, the higher the frequency it required for optimal strengthening. "Incredibly, when it comes to learning, the neuron behaves like a giant antenna, with different branches of dendrites tuned to different frequencies for maximal learning," Mehta said.
The team also revealed that aside from having optimal frequencies at which maximal learning occurs, synapses also strengthen best when those frequencies are exactly-timed in perfect rhythms. Take away the beat, they found, and even with the ideal frequency, synaptic strengthening is appreciably compromised.

The image shows a neuron with a tree trunk-like dendrite. Each triangular shape touching the dendrite represents a synapse, where inputs from other neurons, called spikes, arrive (the squiggly shapes). Synapses that are further away on the dendritic tree from the cell body require a higher spike frequency (spikes that come closer together in time) and spikes that arrive with perfect timing to generate maximal learning (Image: UCLA Newsroom)
As if these remarkable revelations weren't enough, they also discovered that a synapse's optimal frequency changes once it learns. The researchers feel that understanding of this fundamental could yield insight into treatments for conditions related to memory dysfunction (or the need to forget), such as post-traumatic stress disorder.
With additional study, these findings could possibly lead to the development of new drugs capable of "re-calibrating" faulty brain rhythms in people with memory or learning disorders. "We already know there are drugs and electrical stimuli that can alter brain rhythms," Mehta said.
"Our findings suggest that we can use these tools to deliver the optimal brain rhythm to targeted connections to enhance learning."
The research paper entitled Frequency-dependent changes in NMDAR-dependent synaptic plasticity is available online at Frontiers in Computational Neuroscience.