Solar Power: Ninety Percent Of Captured Light Converted Into Heat

A multidisciplinary engineering team at the University of California, San Diego developed a new nanoparticle-based material for concentrating solar power plants designed to absorb and convert to heat more than 90 percent of the sunlight it captures. The new material can also withstand temperatures greater than 700 degrees Celsius and survive many years outdoors in spite of exposure to air and humidity. Their work, funded by the U.S. Department of Energy’s SunShot program, was published recently in two separate articles in the journal Nano Energy. By contrast, current solar absorber material functions at lower temperatures and needs to be overhauled almost every year for high temperature operations.

solarPanel

We wanted to create a material that absorbs sunlight that doesn’t let any of it escape. We want the black hole of sunlight,” said Sungho Jin, a professor in the department of Mechanical and Aerospace Engineering at UC San Diego Jacobs School of Engineering. Jin, along with professor Zhaowei Liu of the department of Electrical and Computer Engineering, and Mechanical Engineering professor Renkun Chen, developed the Silicon boride-coated nanoshell material. They are all experts in functional materials engineering.

Source:  http://www.jacobsschool.ucsd.edu/

Cheap Hydrogen Fuel

The race is on to optimize solar energy’s performance. More efficient silicon photovoltaic panels, dye-sensitized solar cells, concentrated cells and thermodynamic solar plants all pursue the same goal: to produce a maximum amount of electrons from sunlight. Those electrons can then be converted into electricity to turn on lights and power your refrigerator.
hydrogen-electric car At the Laboratory of Photonics and Interfaces from Ecole Polytechnique Fédérale de Lausanne (EPFL) – Switzerland -, led by Michael Grätzel, where scientists invented dye solar cells that mimic photosynthesis in plants, they have also developed methods for generating fuels such as hydrogen through solar water splitting. To do this, they either use photoelectrochemical cells that directly split water into hydrogen and oxygen when exposed to sunlight, or they combine electricity-generating cells with an electrolyzer that separates the water molecules.

By using the latter technique, Grätzel’s post-doctoral student Jingshan Luo and his colleagues were able to obtain a performance spectacular: their device converts into hydrogen 12.3 percent of the energy diffused by the sun on perovskite absorbers – a compound that can be obtained in the laboratory from common materials, such as those used in conventional car batteries, eliminating the need for rare-earth metals in the production of usable hydrogen fuel. This high efficiency provides stiff competition for other techniques used to convert solar energy. But this method has several advantages over others:
Both the perovskite used in the cells and the nickel and iron catalysts making up the electrodes require resources that are abundant on Earth and that are also cheap,” explained Jingshan Luo. “However, our electrodes work just as well as the expensive platinum-based models customarily used.”
The research is being published today in the journal Science.
Source: http://actu.epfl.ch/

Defect-Free Graphene For Electric Car Batteries

Researchers at from Korea’s KAIST institute developed a new method to fabricate defect-free graphene. Using this graphene, they developed a promising high-performance anode for Li-Ion batteries. Graphene has already been demonstrated to be useful in Li-ion batteries, despite the fact that the graphene used often contains defects. Large-scale fabrication of graphene that is chemically pure, structurally uniform, and size-tunable for battery applications has so far remained elusive. Now in a new study, scientists have developed a method to fabricate defect-free graphene (df-G) without any trace of structural damage. Wrapping a large sheet of negatively charged df-G around a positively charged Co3O4 creates a very promising anode for high-performance Li-ion batteries.
electric car

The research groups of Professor Junk-Ki Park and Professor Hee-Tak Kim from Korea Advanced Institute of Science and Technology (KAIST) and Professor Yong-Min Lee’s research group from Hanbat National University, all in Daejeon, South Korea, have published their paper on the new fabrication method in a recent issue of Nano Letters.

Source: http://phys.org/

Electric Car: How To Produce Cheap Hydrogen

Rutgers University researchers have developed a technology that could overcome a major cost barrier to make clean-burning hydrogen fuel – a fuel that could replace expensive and environmentally harmful fossil fuels.

The new technology is a novel catalyst that performs almost as well as cost-prohibitive platinum for so-called electrolysis reactions, which use electric currents to split water molecules into hydrogen and oxygen. The Rutgers technology is also far more efficient than less-expensive catalysts investigated to-date.
Hydrogen has long been expected to play a vital role in our future energy landscapes by mitigating, if not completely eliminating, our reliance on fossil fuels,” said Tewodros (Teddy) Asefa, associate professor of chemistry and chemical biology in the School of Arts and Sciences. “We have developed a sustainable chemical catalyst that, we hope with the right industry partner, can bring this vision to life”. He and his colleagues based their new catalyst on carbon nanotubesone-atom-thick sheets of carbon rolled into tubes 10,000 times thinner than a human hair.
carbon nanotubes to produce hydrogen

A new technology based on carbon nanotubes promises commercially viable hydrogen production from water

Finding ways to make electrolysis reactions commercially viable is important because processes that make hydrogen today start with methane – itself a fossil fuel. The need to consume fossil fuel therefore negates current claims that hydrogen is a “green” fuel.
Source: http://news.rutgers.edu

Car Waste Heat Transformed Into Electricity

Thermoelectric materials can turn a temperature difference into an electric voltage. Among their uses in a variety of specialized applications: generating power on space probes and cooling seats in fancy cars.

University of Miami physicist Joshua Cohn and his collaborators report new surprising properties of a metal named lithium purple-bronze (LiPB) that may impact the search for materials useful in power generation, refrigeration, or energy detection.

If current efficiencies of thermoelectric materials were doubled, thermoelectric coolers might replace the conventional gas refrigerators in your home,” said Cohn, professor and chairman of the UM Department of Physics in the College of Arts and Sciences and lead author of the study. “Converting waste heat into electric power, for example, using vehicle exhaust, is a near-termgreen’ application of such materials.”
The findings are published in the journal Physical Review Letters.

Source: http://www.miami.edu/

World’s Smallest, Fastest Nanomotor

Researchers at the Cockrell School of Engineering at The University of Texas at Austin have built the smallest, fastest and longest-running tiny synthetic motor to date. The team’s nanomotor is an important step toward developing miniature machines that could one day move through the body to administer insulin for diabetics when needed, or target and treat cancer cells without harming good cells.

With the goal of powering these yet-to-be invented devices, UT Austin engineers focused on building a reliable, ultra-high-speed nanomotor that can convert electrical energy into mechanical motion on a scale 500 times smaller than a grain of salt.

Mechanical engineering assistant professor Donglei “Emma” Fan led a team of researchers in the successful design, assembly and testing of a high-performing nanomotor in a nonbiological setting. The team’s three-part nanomotor can rapidly mix and pump biochemicals and move through liquids, which is important for future applications. One amazing arena of application for this nanomotor is the field of nanoelectromechanical systems (NEMS), where such a machine will be able to push forward the frontiers of cheaper and more energy efficient systems.
The team’s study was published in the April issue of Nature Communications.

Source: http://www.engr.utexas.edu/

How To Heat Your House At Night With Sun’s Energy

It’s an obvious truism, but one that may soon be outdated: The problem with solar power is that sometimes the sun doesn’t shine. Now a team at the Massachusetts Institute of Technology ( MIT) and Harvard University has come up with an ingenious workaround — a material that can absorb the sun’s heat and store that energy in chemical form, ready to be released again on demand. This solution is no solar-energy panacea: While it could produce electricity, it would be inefficient at doing so. But for applications where heat is the desired output — whether for heating buildings, cooking, or powering heat-based industrial processes — this could provide an opportunity for the expansion of solar power into new realms.

It could change the game, since it makes the sun’s energy, in the form of heat, storable and distributable,” says Jeffrey Grossman, the Carl Richard Soderberg Associate Professor of Power Engineering at MIT, who is a co-author of a paper describing the new process in the journal Nature Chemistry. Timothy Kucharski, a postdoc at MIT and Harvard, is the paper’s lead author.
Source: http://mitei.mit.edu/

Very Cheap, Powerful Solar Cells

Working on dye-sensitized solar cells – researchers from University Malaya (UM) – Indonesia – and National Tsing Hua University (NTHU) – Taiwan – have achieved an efficiency of 1.12 %, at a fraction of the cost compared to those used by platinum devices.
The study carried out in Taiwan took on the challenge of making the technology behind dye-sensitized solar cells more affordable by replacing the costly platinum counter-electrodes with bismuth telluride (Bi2Te3) nanosheet arrays.
Using a novel electrolysis process, the group managed to closely manipulate the spacing between individual nanosheets and hence control the thermal and electrical conductivity parameters to achieve the high efficiency of 1.12%, which is comparable to platinum devices, but at only at a fraction of the cost.
The research was led by Prof. Yu-Lun Chueh of the Nanoscience & Nanodevices Laboratory, NTHU, and Alireza Yaghoubi, UM HIR Young Scientist.


In light of the recent report by the United Nations about the irreversible effects of fossil fuels on climate change and as we gradually run out of economically recoverable oil reserves, we think it is necessary to look for a sustainable, yet practical source of energy” Yaghoubi stated.
Meanwhile at University Malaya, Dr. Wee Siong Chiu and colleagues were working on controlling the secondary nucleation and self-assembly in zinc oxide (ZnO), a material which is currently being scrutinized for its potential applications in dye-sensitized solar cells as well as photocatalytic reactions to generate clean electricity by splitting water under sunlight.
This work has been accepted for publication in the journal, Nanoscale published by the Royal Society of Chemistry and has been selected for the front cover of the issue.
Source: http://phys.org/

Cheap Batteries Last 3 Times Longer, Recharge in 10 minutes

Researchers at the University of Southernn California (USC) have developed a new lithium-ion battery design that uses porous silicon nanoparticles in place of the traditional graphite anodes to provide superior performance.

The new batteries — which could be used in anything from cellphones to hybrid cars — hold three times as much energy as comparable graphite-based designs and recharge within 10 minutes. The design, currently under a provisional patent, could be commercially available within two to three years.
On the left, a vial of the silicon nanoparticles; on the right, silicon nanoparticles viewed under magnification
It’s an exciting research. It opens the door for the design of the next generation lithium-ion batteries,” said Chongwu Zhou, professor at the USC Viterbi School of Engineering, who led the team that developed the battery.

Zhou worked with USC graduate students Mingyuan Ge, Jiepeng Rong, Xin Fang and Anyi Zhang, as well as Yunhao Lu of Zhejiang University in China. Their research was published in Nano Research in January.

Source: http://news.usc.edu/

Solar Cells: Huge Efficiency Boost

In a new study, a team of physicists and chemists at Umeå University – Sweden – have joined forces to produce nano-engineered carbon nanotubes networks with novel properties.
For the first time, the researchers show that carbon nanotubes can be engineered into complex network architectures, and with controlled nano-scale dimensions inside a polymer matrix.
Carbon nanotubes are becoming increasingly attractive for photovoltaic solar cells as a replacement to silicon. Researchers at Umeå University have discovered that controlled placement of the carbon nanotubes into nano-structures produces a huge boost in electronic performance.


Carbon nanotubes, CNTs, are one dimensional nanoscale cylinders made of carbon atoms that possess very unique properties. For example, they have very high tensile strength and exceptional electron mobility, which make them very attractive for the next generation of organic and carbon-based electronic devices
We have found that the resulting nano networks possess exceptional ability to transport charges, up to 100 million times higher than previously measured carbon nanotube random networks produced by conventional methods,” says Dr David Barbero, leader of the project and assistant professor at the Department of Physics at Umeå University.

Their groundbreaking results are published in the prestigious journal Advanced Materials.

Source: http://www.umu.se/