Posts belonging to Category green power



How To Split Water At Low Cost To Produce Hydrogen

UNSW (Australia) scientists have developed a highly efficient oxygen-producing electrode for splitting water that has the potential to be scaled up for industrial production of clean energy fuel, hydrogen. This breaktrough is important for the future development of hydrogen electric cars (H mobil). The new technology is based on an inexpensive, specially coated foam material that lets the bubbles of oxygen escape quickly. Inefficient and costly oxygen-producing electrodes are one of the major barriers to the widespread commercial production of hydrogen by electrolysis, where the water is split into hydrogen and oxygen using an electrical current.

watersplitting Electrode

Our electrode is the most efficient oxygen-producing electrode in alkaline electrolytes reported to date, to the best of our knowledge,” says Associate Professor Chuan Zhao, of the UNSW School of Chemistry. “It is inexpensive, sturdy and simple to make, and can potentially be scaled up for industrial application of water splitting.”

The research, by Associate Professor Zhao and Dr Xunyu Lu, is published in the journal Nature Communications.

Source: http://www.newsroom.unsw.edu.au/

Electric Car Race: The Rise Of Formula E

Downtown Miami has been converted into a race track. Cement blocks, fencing and grandstands are all in place for the first electric car race ever held on U.S. soil. Miami is the fifth of ten cities around the world to host during the inaugural year of the Formula E Championship, a fully electric race car series. Teams of mechanics are preparing their electric cars for Saturday’s race. Mark Schneider from Team Audi ABT says Formula E is in many ways similar to Formula 1. The cars are fast, the suspense on race day is high, but instead of the roar of a gasoline powered engines, these electric cars let out a high pitched hum as they barrel down the track. Schneider says pits stop are a bit different as well.
mazda-kaan-electric-car2
We do a pit stops like other racing series but when formula 1 changes tires we change cars. So we have two cars for each driver and after roughly half an hour the driver gets into the pits, jumps out of the car, jumps into another car and goes out again“, says Mark Schneider. Each car is powered by a massive lithium ion battery that makes up a third of the cars overall weight. Formula E CEO Alejandro Agag says with time those batteries will become more efficient and smaller allowing them to power a single car for an entire race. He says the concept behind formula E is to drive research and development in the electric automotive space to new heights.

Formula 1, Indy Car, NASCAR are places where new technologies have been developed that then have been used on road cars and we want Formula E to be the place that happens for the electric car,” he noticed. Along with innovations on the track, Agag says he wants to attract young fans to Formula E by utilizing technology off the track as well. He says plans are in the works to develop an interactive virtual track that will allow people to compete on race day from their homes. He concludes: “So if you are a kid at home you can play with the virtual car, a shadow car, against the real racers in real time.
Source: http://www.reuters.com/

How To Print Solar Cells Massively

Flexible optoelectronic devices that can be produced roll-to-roll – much like newspapers are printed – are a highly promising path to cheaper devices such as solar cells and LED lighting panels. Scientists from “TREASORES” European project present prototype flexible solar cell modules as well as novel silver-based transparent electrodes that outperform currently used materials.

printes solar cells
A flexible organic solar cell from TREASORES project undergoing mechanical testing: the cell is repeatedly flexed to a 25 mm radius whilst monitoring its performance. Such cells have shown lifetimes in excess of 4000 hours

In order to make solar energy widely affordable scientists and engineers all over the world are looking for low-cost production technologies. Flexible organic solar cells have a huge potential in this regard because they require only a minimum amount of (rather cheap) materials and can be manufactured in large quantities by roll-to-roll (R2R) processing. This requires, however, that the transparent electrodes, the barrier layers and even the entire devices be flexible. With these «ultra-flat» electrodes record efficiencies of up to 7% were obtained for organic solar cells using commercially available materials for light harvesting.
Source: http://www.empa.ch/

Electric Car: How To Increase the Batteries Life-Span

Drexel University (Philadephia) researchers, along with colleagues at Aix-Marseille University in France, have discovered a high performance cathode material with great promise for use in next generation lithium-sulfur batteries that could one day be used to power mobile devices and electric cars.

Lithium-sulfur batteries have recently become one of the hottest topics in the field of energy storage devices due to their high energy density — which is about four times higher than that of lithium-ion batteries currently used in mobile devices. One of the major challenges for the practical application of lithium-sulfur batteries is to find cathode materials that demonstrate long-term stability.

An international research collaboration led by Drexel’s Yury Gogotsi, PhD, professor in the College of Engineering and director of its Nanomaterials Research Group, has created a two-dimensional carbon/sulfur nanolaminate that could be a viable candidate for use as a lithium-sulfur cathode.
Tesla-Model-S One of the major challenges for the practical application of lithium-sulfur batteries is to find cathode materials that demonstrate long-term stability.

The carbon/sulfur nanolaminates synthesized by Gogotsi’s group demonstrate the same uniformity as the infiltrated carbon nanomaterials, but the sulfur in the nanolaminates is uniformly deposited in the carbon matrix as atomically thin layers and a strong covalent bonding between carbon and sulfur is observed. This may have a significant impact on increasing the life-span of next generation batteries.

In a paper they recently published in the chemistry journal Angewandte Chemie, Gogotsi, along with his colleagues at Aix-Marseille University explain their process for extracting the nanolaminate from a three-dimensional material called a Ti2SC MAX phase.
Source: http://drexel.edu

Boosted Lithium Sulfur Batteries For Electric Car

Lithium-sulfur batteries have been a hot topic in battery research because of their ability to produce up to 10 times more energy than conventional batteries, which means they hold great promise for applications in energy-demanding electric vehicles.
However, there have been fundamental road blocks to commercializing these sulfur batteries. One of the main problems is the tendency for lithium and sulfur reaction products, called lithium polysulfides, to dissolve in the battery’s electrolyte and travel to the opposite electrode permanently. This causes the battery’s capacity to decrease over its lifetime.
Researchers in the Bourns College of Engineering at the University of California, Riverside have investigated a strategy to prevent this “polysulfide shuttling” phenomenon by creating nano-sized sulfur particles, and coating them in silica (SiO2), otherwise known as glass.
Bourns College
Ph.D. students in Cengiz Ozkan’s and Mihri Ozkan ‘s research groups have been working on designing a cathode material in which silica cages “trap” polysulfides having a very thin shell of silica, and the particles’ polysulfide products now face a trapping barrier – a glass cage. The team used an organic precursor to construct the trapping barrier.

Our biggest challenge was to optimize the process to deposit SiO2 – not too thick, not too thin, about the thickness of a virus”, Mihri Ozkan said.
The work is outlined in the journal Nanoscale.
Source: http://ucrtoday.ucr.edu/

Cloth That Produces Electricity

Fully flexible, foldable nanopatterned wearable triboelectric nanogenerator (WTNG) with high power-generating performance and mechanical robustness have been designed by researchers from the SKKU Advanced Institute of Nanotechnology (SAINT) (Korea). Triboelectric is an electrical charge produced by friction between two objects that are nonconductive. Very high voltage and current outputs with an average value of 170 V were obtained from a four-layer-stacked WTNG. The researchers created a novel tribo electric nano generator fabric out of a silvery textile coated with nanorods and a silicon-based organic material.
nanogenerator3
When they stacked four pieces of the cloth together and pushed down on the material, it captured the energy generated from the pressure. The material immediately pumped out that energy, which was used to power light-emitting diodes, a liquid crystal display and a vehicle’s keyless entry remote. The cloth worked for more than 12,000 cycles.

Source: http://pubs.acs.org/

Solar Film: How To Increase The Absorption Of Sunlight

A biological structure in mammalian eyes has inspired a team headed by Silke Christiansen to design an inorganic counterpart for use in solar cells. With the help of conventional semiconductor processes, they etched micron-sized vertical funnels shoulder-to-shoulder in a silicon substrate. Using mathematical models and experiments, they tested how these kind of funnel arrays collect incident light and conduct it to the active layer of a silicon solar cell. Their result: this arrangement of funnels increases photo absorption by about 65% in a thin-film solar cell fitted with such an array and is reflected in considerably increased solar cell efficiency, among other improved parameters. This closely packed arrangement of cones has now inspired the team headed by Prof. Silke Christiansen to replicate something similar in silicon as a surface for solar cells and investigate its suitability for collecting and conducting light. Christiansen heads the Institute for Nanoarchitectures for Energy Conversion at the Helmholtz-Zentrum Berlin (HZB) and a research team at the Max Planck Institute for the Science of Light (MPL) – Germany..

solar funnelThe simulation shows how the concentration of light (red = high concentration, yellow= low concentration) rises in the funnels with declining diameter of the lower end of the funnel
We’ve shown in this work that the light funnels absorbs considerably more light than other optical architectures tested over the last while”, says Sebastian Schmitt, one of the two first authors of the publication that has appeared in journal Nature Scientific Reports.

Source: http://www.helmholtz-berlin.de/

How To Boost Electric Vehicle Batteries

Researchers from the Professor Mihri Ozkan lab at the University of California, Riverside’s Bourns College of Engineering have developed a novel paper-like material for lithium-ion batteries. It has the potential to boost by several times the specific energy, or amount of energy that can be delivered per unit weight of the battery.
This paper-like material is composed of sponge-like silicon nanofibers more than 100 times thinner than human hair. It could be used in batteries for electric vehicles and personal electronics.

electric carThe problem with silicon is that is suffers from significant volume expansion, which can quickly degrade the battery. The silicon nanofiber structure created in the Ozkan’s labs circumvents this issue and allows the battery to be cycled hundreds of times without significant degradation. This technology also solves a problem that has plagued free-standing, or binderless, electrodes for years: scalability. Free-standing materials grown using chemical vapor deposition, such as carbon nanotubes or silicon nanowires, can only be produced in very small quantities (micrograms). However, the team was able to produce several grams of silicon nanofibers at a time even at the lab scale.

The nanofibers were produced using a technique known as electrospinning, whereby 20,000 to 40,000 volts are applied between a rotating drum and a nozzle, which emits a solution composed mainly of tetraethyl orthosilicate (TEOS), a chemical compound frequently used in the semiconductor industry. The nanofibers are then exposed to magnesium vapor to produce the sponge-like silicon fiber structure.

The findings were just published in the journal Nature Scientific Reports.
Source: http://www.mse.ucr.edu/

How To Grow High-Efficiency Perovskite Solar Cells

Los Alamos National Laboratory researchers reveal a new solution-based hot-casting technique that allows growth of highly efficient and reproducible solar cells from large-area perovskite crystals.
State-of-the-art photovoltaics using high-purity, large-area, wafer-scale single-crystalline semiconductors grown by sophisticated, high temperature crystal-growth processes are seen as the future of efficient solar technology. Solar cells composed of organic-inorganic perovskites offer efficiencies approaching that of silicon, but they have been plagued with some important deficiencies limiting their commercial viability. It is this failure that the Los Alamos technique successfully corrects.

The researchers fabricated planar solar cells from pervoskite materials with large crystalline grains that had efficiencies approaching 18%, among the highest reported in the field of perovskite-based light-to-energy conversion devices.
peroskite solar cell

These perovskite crystals offer promising routes for developing low-cost, solar-based, clean global energy solutions for the future,” said Aditya Mohite, the Los Alamos scientist leading the project.
Characterization and modeling attribute the improved performance to reduced bulk defects and improved charge-carrier mobility in large-grain pervoskite materials,” said Mohite, “and we’ve demonstrated that the crystalline quality is on par with that observed for high-quality semiconductors like silicon and gallium arsenides.

The resuls have been published in the journal Science,

Source: http://www.lanl.gov/

Doubling The Electrical Output Of Solar Cells

One challenge in improving the efficiency of solar cells is that some of the absorbed light energy is lost as heat. So scientists have been looking to design materials that can convert more of that energy into useful electricity. Now a team from the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory and Columbia University has paired up polymers that recover some of that lost energy by producing two electrical charge carriers per unit of light instead of the usual one.

solar cell
Critically, we show how this multiplication process can be made efficient on a single molecular polymer chain,” said physicist Matthew Sfeir, who led the research at Brookhaven Lab’s Center for Functional Nanomaterials (CFN), a DOE Office of Science User Facility. Having the two charges on the same molecule means the light-absorbing, energy-producing materials don’t have to be arrayed as perfect crystals to produce extra electrical charges. Instead, the self-contained materials work efficiently when dissolved in liquids, which opens the way for a wide range of industrial scale manufacturing processes, including “printingsolar-energy-producing material like ink.

The research is published as an Advance Online Publication in Nature Materials, January 12, 2015.

Source: http://www.bnl.gov/