A multidisciplinary engineering team at University of California San Diego Jacobs School of Engineering (UCSD) has developed a new nanoparticle-based material designed to absorb and convert to heat more than 90% of the sunlight it captures. The new material can also withstand temperatures greater than 700º C (1292º F) and survive many years outdoors in spite of exposure to air and humidity.
The remarkable new nanoparticle-based material is destined for use in concentrating solar power plants.
The UCSD team’s paper has been published recently in two separate articles in the journal Nano Energy. The effort was funded by the U.S. Department of Energy’s SunShot program.
Sungho Jin, a professor in the department of Mechanical and Aerospace Engineering at UC San Diego Jacobs School of Engineering said, “We wanted to create a material that absorbs sunlight that doesn’t let any of it escape. We want the black hole of sunlight.”
Jin worked with professor Zhaowei Liu of the department of Electrical and Computer Engineering, and Mechanical Engineering professor Renkun Chen, all experts in functional materials engineering.
The novel material is a Silicon boride-coated nanoshell material featuring a “multiscale” surface created by using particles of many sizes ranging from 10 nanometers to 10 micrometers. The multiscale structures can trap and absorb light which contributes to the material’s high efficiency when operated at higher temperatures.
Keep in mind current solar absorber materials function at lower temperatures and need to be overhauled almost every year for high temperature operations.
Concentrating solar power (CSP) is an emerging alternative clean energy market that produces approximately 3.5 gigawatts worth of power at power plants around the globe, enough to power more than 2 million homes, with additional construction in progress to provide as much as 20 gigawatts of power in coming years. One of the technology’s attractions is that it can be used to retrofit existing power plants that use coal or fossil fuels because it uses the same process to generate electricity from steam.
Traditional power plants burn coal or fossil fuels to create heat that evaporates water into steam. The steam turns a giant turbine that generates electricity from spinning magnets and conductor wire coils. CSP power plants create the steam needed to turn the turbine by using sunlight to heat molten salt. The molten salt can also be stored in thermal storage tanks overnight where it can continue to generate steam and electricity, 24 hours a day if desired, a significant advantage over photovoltaic systems that stop producing energy with the sunset.
One of the most common types of CSP systems uses more than 100,000 reflective mirrors to aim sunlight at a tower that has been spray painted with a light absorbing black paint material. The material is designed to maximize sun light absorption and minimize the loss of light that would naturally emit from the surface in the form of infrared radiation.
The UCSD team’s combined expertise developed, optimized and characterized the new material for this type of system over the past three years. Researchers included a group of UC San Diego graduate students in materials science and engineering, Justin Taekyoung Kim, Bryan VanSaders, and Jaeyun Moon, who recently joined the faculty of the University of Nevada, Las Vegas. The synthesized nanoshell material is spray-painted in Chen’s lab onto a metal substrate for thermal and mechanical testing. The material’s ability to absorb sunlight is measured in Liu’s optics laboratory using a unique set of instruments that takes spectral measurements from visible light to infrared.
Current CSP plants are shut down about once a year to chip off the degraded sunlight absorbing material and reapply a new coating, which means no power is generated while a replacement coating is applied and cured. That’s why DOE’s SunShot program challenged and supported the UCSD research team to come up with a material with a substantially longer life cycle, in addition to the higher operating temperature for enhanced energy conversion efficiency. The UCSD research team is aiming for many years of usage life, a feat they believe they are close to achieving.
The DOE’s SunShot program is modeled after President Kennedy’s moon landing program that inspired widespread interest in science and space exploration. Energy Secretary at the time Steven P. Chu launched the Sunshot Initiative in 2010 with the goal of making solar power cost competitive with other means of producing electricity by 2020.
For all the waste, weirdness and bizarre ideas the Fed’s fund, some gets through with remarkable results. Funding programs done right can payoff to economy in a powerful way. Lets hope the UCSD team’s material works out in the field trials. Concentrated solar has a useful place in power generation and the better and cheaper CSP gets the better for everyone.
Umeå University reports Swedish and Chinese researchers are showing how a unique nano-alloy composed of palladium nano-islands embedded in tungsten nanoparticles creates a new type of catalyst for fuel cells.
The new type of catalyst is highly efficient at oxygen reduction, the most important reaction in hydrogen fuel cells. The team’s paper has been published in the scientific journal Nature Communications.
Fuel cell systems represent a promising alternative for low carbon emission energy production. But traditional fuel cells are limited by the need of efficient catalysts to drive the chemical reactions involved in the fuel cell. Historically, the rare mineral platinum and its alloys have frequently been used as anodic and cathodic catalysts in fuel cells, but the high cost of platinum due to its rarity, motivates researchers to find efficient catalysts based on more earth-abundant elements.
Thomas Wågberg, senior lecturer at Department of Physics, Umeå University said, “In our study we report a unique novel alloy with a palladium (Pd) and tungsten (W) ratio of only one to eight, which still has similar efficiency as a pure platinum catalyst. Considering the cost, it would be 40 times lower.”
The reason for the very high efficiency is the unique molecular structure and features of the alloy. It is neither a fully mixed together homogeneous alloy, nor a fully segregated two-phase system, but rather its something in between.
Using advanced experimental and theoretical investigations, the researchers show that the alloy is composed of metallic Pd-islands embedded in the Pd-W alloy. The size of the islands are about one nanometer in diameter and are composed of 10-20 atoms that are segregated to the surface. The unique environment around the Pd-islands gives rise to special effects that all together turn the islands into highly efficient catalytic hot-spots for oxygen reduction.
To stabilize the nanoparticles in practical applications, they are anchored on ordered mesoporous carbon. The anchoring keep the nanoparticles stable over a long time by hindering them from fusing together in the fuel cell tests.
Now the concept gets very interesting:
Wågberg explains, “The unique formation of the material is based on a synthesis method, which can be performed in an ordinary kitchen micro-wave oven purchased at the local supermarket. If we were not using argon as protective inert gas, it would be fully possible to synthesize this advanced catalyst in my own kitchen!”
Looking good. Much lower cost palladium vs. platinum and a manufacturing process on the very low end of the potential.
Wågberg and his fellow researchers have recently received funding from the Kempe Foundation to buy a more advanced micro-wave oven so they will be able to run more advanced experiments to fine tune some of the catalyst properties.
The oxygen reduction reaction at the cathode side of proton exchange membrane inside of fuel cells is one of the major technical challenges to building mass market fuel cells. Today fuel cells are very expensive and admittedly, slow producers of energy output in electric current. For the transportation market the fuel cell just isn’t ready for prime time consumer demands.
Finding efficient yet cheap electrocatalysts to speed up this reaction is driving researchers the world over.
Maybe the Swedish and Chinese team have found the next solution to the fuel cell development track.
October 28, 2014 | Leave a Comment
Researchers from the Hong Kong University of Science and Technology, China (HKST) have devised an ultra-thin liquid crystal displays (LCDs) screen that operates without a power source. The compact, energy-efficient display technology of visual information may one day have applications in products such as e-book readers, flexible displays or as a security measure on credit cards.
A first impression of the static, grayscale display created by the HKST group of researchers might not catch the eye of a thoughtful consumer in a market saturated with flashy, colorful electronics.
A closer look at the specs could change that: the ultra-thin LCD screen has been described in a paper published in The Optical Society’s (OSA) journal Optics Letters. The optically rewritable liquid crystal display is a concept based on the optically addressed bi-stable display that does not need any power to hold the image after being uploaded.
Current technology LCDs are used in numerous technological applications, from television screens to digital clock faces. In a traditional LCD, liquid crystal molecules are sandwiched between polarized glass plates. Electrodes pass current through the apparatus, influencing the orientation of the liquid crystals inside and manipulating the way they interact with the polarized light. The light and dark sections of the readout display are controlled by the amount of current flowing into them.
The new displays from HKST ditches the electrodes, simultaneously making the screen thinner and decreasing its energy requirements. Once an image is uploaded to the screen via a flash of light, no power is required to keep it there. Because these so-called bi-stable displays draw power only when the image is changed, they are particularly advantageous in applications where a screen displays a static image for most of the time, such as e-book readers or battery status monitors for electronic devices.
Researcher Abhishek Srivastava, one of the authors of the paper said, “Because the proposed LCD does not have any driving electronics, the fabrication is extremely simple. The bi-stable feature provides a low power consumption display that can store an image for several years.”
The researchers went further than creating a simple LCD display, however – they engineered their screen to display images in 3D. Real-world objects appear three-dimensional because the separation between your left eye and your right creates perspective. 3D movies replicate this phenomenon on a flat screen by merging two films shot from slightly different angles, and the glasses that you wear during the film selectively filter the light, allowing one view to reach your left eye and another to fall on your right to create a three-dimensional image.
However, instead of displaying multiple images on separate panels and carefully aligning them – a tedious and time-consuming process – the researchers create the illusion of depth from a single image by altering the polarization of the light passing through the display. They divide the image into three zones: one in which the light is twisted 45 degrees to the left, another in which it is twisted 45 degrees to the right, and a third in which it is unmodified. When passed through a special filter, the light from the three zones is polarized in different directions. Glasses worn by the viewer then make the image appear three-dimensional by providing a different view to each eye.
This technology isn’t ready to hit the television market just yet: it only displays images in grayscale and can’t refresh them fast enough to show a film. However, Srivastava and his colleagues are in the process of optimizing their device for consumer use by adding color capabilities and improving the refresh rate. The thin profile and minimal energy requirements of devices could also make it useful in flexible displays or as a security measure on credit cards.
Sharp folk there with a great idea. The 3-D thing might be better left to a post color image design with a faster refresh rate.
No power to run and a simple quick flash to upload an image is quite a feat on creativity and engineering. Your humble writer expects this tech will be coming to us shortly.
Researchers at MIT and in Saudi Arabia say they have found an economical solution to cleaning out the biggest pollutant from hydraulic fracturing oil and gas wells. The pollutant is salt in the water used to fracture the rock, that’s much saltier than seawater, after leaching salts from deep below the surface.
The boom in oil and gas produced through hydraulic fracturing, or fracking, is also a boon for meeting U.S. energy needs. The team’s new analysis appears this week in the journal Applied Energy, in a paper co-authored by MIT professor John Lienhard, postdoc Ronan McGovern, and four others.
The method they propose for treating the “produced water” that flows from oil and gas wells throughout their operation is one that has been known for decades, but had not been considered a viable candidate for extremely high-salinity water, such as that produced from oil and gas wells. The technology, electrodialysis, “has been around for at least 50 years,” says Lienhard, the Abdul Latif Jameel Professor of Water and Food as well as director of the Center for Clean Water and Clean Energy at MIT and King Fahd University of Petroleum and Minerals (KFUPM).
Water recovered from fossil-fuel wells can have salinity three to six times greater than that of seawater; the new research indicates that this salt can be effectively removed through a succession of stages of electrodialysis.
“Electrodialysis is generally thought of as being advantageous for relatively low-salinity water,” Lienhard says — such as the brackish, shallow groundwater found in many locations, generally with salinity around one-tenth that of seawater. But electrodialysis also turns out to be economically viable at the other end of the salinity spectrum, the new analysis shows.
The idea would not be to purify the water sufficiently to make it potable, the researchers say. Rather, it could be cleaned up enough to enable its reuse as part of the hydraulic fracturing fluid injected in subsequent wells, significantly reducing the water needed from other sources.
Lienhard explains that if you’re trying to make pure water, electrodialysis becomes less and less efficient as the water gets less saline, because it requires that electric current flow through the water itself: Salty water conducts electricity well, but pure water does not.
McGovern, a postdoc in MIT’s Department of Mechanical Engineering and lead author of the paper, says another advantage of the proposed system is “flexibility in the amount of salt we remove. We can produce any level of output salinity.” The costs of installing an electrodialysis system, he says, appear to compare favorably to other widely used systems for dealing with produced water.
It’s not clear at this point, McGovern says, what the optimal salinity is for fracking fluids. “The big question at the moment is what salinity you should reuse the water at,” he says. “We offer a way to be able to control that concentration.”
Before reaching the desalination stage, the researchers envision that chemical impurities in the water would be removed using conventional filtration. One remaining uncertainty is how well the membranes used for electrodialysis would hold up following exposure to water that contains traces of oil or gas. “We need some lab-based characterization of the response,” McGovern says.
If the system works as well as this analysis suggests, it could not only provide significant savings in the amount of fresh water that needs to be diverted from agriculture, drinking water, or other uses, but it would also significantly reduce the volume of contaminated water that would need to be disposed of from these drilling sites.
“If you can close the cycle,” Lienhard says, “you can reduce or eliminate the burden of the need for fresh water.” This could be especially significant in major oil-producing areas such as Texas, which is already experiencing water scarcity, he says.
While electrodialysis technology is available now, Lienhard explains that this application would require the development of some new equipment.
Few people understand all the issues in keeping houses warm, people and supplies moving. For the coming decades hydraulic fracturing is going to be key for keeping the modern world working.
Khanh-Quang Tran, an associate professor at the Norwegian University of Science and Technology’s (NTNU) Department of Energy and Process Engineering turns 79% of kelp into bio-oil. Kelp, also known as seaweed, offers all of the advantages of a biofuel feedstock with the additional benefit of growing, not surprisingly, in the ocean.
Tran conducted preliminary studies using sugar kelp (Laminaria saccharina), which grows naturally along the Norwegian coast. The results have been published in the academic journal Algal Research.
Tran said, “What we are trying to do is to mimic natural processes to produce oil. However, while petroleum oil is produced naturally on a geologic time scale, we can do it in minutes.”
Tran heated the kelp in small quartz tube ‘reactors’ – which look like tiny sealed straws – containing a slurry made from the kelp biomass and water to 350º C (662º F) at a very high rate of 585º C (1085º F) per minute.
The technique, called fast hydrothermal liquefaction, gave Tran a bio-oil yield of 79% meaning 79% of the kelp biomass in the reactors was converted to bio-oil. A similar study in the UK using the same species of kelp yielded just 19%. The secret, Tran said, is the rapid heating.
Biofuel has long been seen as a promising way to help shift humankind towards a more sustainable and climate friendly lifestyle. The logic is simple: petroleum-like fuels made from crops or substances take up CO2 as they grow and release that same CO2 when they are burned, so they are essentially carbon-neutral.
Tran like others references the International Energy Agency (IEA) report “Tracking Clean Energy Progress 2014 that said biofuel production worldwide was 113 billion liters in 2013, and could reach 140 billion liters by 2018. But the IEA says biofuel production will need to grow 22-fold by 2025 to produce the amount of biofuel the world will need to keep global temperatures from rising more than the oft quoted mystical 2oC.
Like others Tran is trying to solve the biomass feedstock problem. It’s relatively easy to turn corn or sugar beets into ethanol that we can pump into our car’s fuel tanks. But using land that can produce human food biomass for fuel is more and more problematic as the world’s population climbs towards 8 billion and beyond.
To solve the arable land limits, biofuels are beginning to be produced from non-food biomass including agricultural residues, land-based energy crops such as fast-growing trees and grasses, and aquatic crops such as seaweed and microalgae.
However, all of these feedstocks have their challenges, especially those that are land based. At least part of the issue is the fact that crops for biofuel could potentially displace crops for food. But seaweed offers all of the advantages of a biofuel feedstock with the additional benefit of growing at sea.
Turning big pieces of slippery, salty kelp into biocrude is a challenge, too Many studies have used catalysts to help make the process go more quickly or easily But, catalysts are normally expensive and require catalyst recovery. The UK study noted above that resulted in a 19% yield used a catalyst in its process.
Tran said the advantage of his process is that it is relatively simple and does not need a catalyst. The high heating rate also results in a biocrude that has molecular properties that will make it easier to refine. But Tran’s experiments were what are called screening tests.
Tran worked with batch reactors that were small and not suitable for an industrial scale. “When you want to scale up the process you have to work with a flow reactor,” or a reactor with a continuous flow of reactants and products, he said. “I already have a very good idea for such a reactor.”
Even though the preliminary tests gave a yield of 79%, Tran believes he can improve the results even more. He’s now looking for industrial partners and additional funding to continue his research.
Hitting 79% in the first development step is a huge encouragement. It would be great if the funding for more research found its way to Tran. This is another example how important high temperature process heat is going to be in the future. Great ideas like this one are going to be extremely useful and will need other great ideas to mature as well.