August 30, 2016 | Leave a Comment
Scientists from the University of Toronto (UT) believe they’ve found a catalytic way to convert CO2 emissions back into energy-rich fuel precursor. They have developed a process to convert these emissions in a carbon-neutral cycle that uses a very abundant natural resource: silicon. Readily available in sand, it’s the seventh most-abundant element in the universe and the second most-abundant element in the earth’s crust.
The idea of converting carbon dioxide emissions back into energy isn’t new: there’s been a global race to discover a material that can efficiently convert sunlight, carbon dioxide and water or hydrogen to fuel for decades. However, the chemical stability of carbon dioxide has made it difficult to find a practical solution.
Geoffrey Ozin, a chemistry professor in UT’s Faculty of Arts & Science, the Canada Research Chair in Materials Chemistry and lead of U of T’s Solar Fuels Research Cluster said, “A chemistry solution to climate change requires a material that is a highly active and selective catalyst to enable the conversion of carbon dioxide to fuel. It also needs to be made of elements that are low cost, non-toxic and readily available.”
The hydride-terminated silicon nanocrystals – nanostructured hydrides for short – have an average diameter of 3.5 nanometers and feature a surface area and optical absorption strength sufficient to efficiently harvest the near-infrared, visible and ultraviolet wavelengths of light from the sun together with a powerful chemical-reducing agent on the surface that efficiently and selectively converts gaseous carbon dioxide to gaseous carbon monoxide.
The potential result is a fuel precursor without harmful emissions.
Ozin said, “Making use of the reducing power of nanostructured hydrides is a conceptually distinct and commercially interesting strategy for making fuels directly from sunlight.”
The UT Solar Fuels Research Cluster is working to find ways and means to increase the activity, enhance the scale, and boost the rate of production. Their goal is a laboratory demonstration unit and, if successful, a pilot solar refinery.
While impressive, there are some big issues to work out. There is that oxygen atom product that seems to be oxidizing the catalyst. There is no method yet to drive the nanostructured hydrides production to a commercial scale volume. Those are just two matters that will be getting intense attention.
But the breakthrough value here is cost. The active agent here is silicon, an abundant and low cost material. This research crashes most all other venues to recycling CO2. This is the tech for research future until something better is discovered. That may not be needed, as this technology has just emerged with lots of room to improve.
Penn State Materials Research Institute scientists have developed a polymer dielectric material with high energy density, high power density and excellent charge-discharge efficiency for electric and hybrid vehicle use.
The key is a unique three-dimensional sandwich-like structure that protects the dense electric field in the polymer/ceramic composite from dielectric breakdown.
Qing Wang, professor of materials science and engineering and the team leader begins, “Polymers are ideal for energy storage for transportation due to their light weight, scalability and high dielectric strength. However, the existing commercial polymer used in hybrid and electric vehicles, called BOPP, cannot stand up to the high operating temperatures without considerable additional cooling equipment. This adds to the weight and expense of the vehicles.”
The researchers had to overcome two problems to achieve their goal. In normal two-dimensional polymer films such as BOPP, increasing the dielectric constant, the strength of the electric field, is in conflict with stability and charge-discharge efficiency. The higher the field, the more likely a material is to leak energy in the form of heat.
The Penn State researchers originally attacked this problem by mixing different materials while trying to balance competing properties in a two-dimensional form. While this increased the energy capacity, they found that the film broke down at high temperatures when electrons escaped the electrodes and were injected into the polymer, which caused an electric current to form.
“That’s why we developed this sandwich structure. We have the top and bottom layers that block charge injection from the electrodes. Then in the central layer we can put all of the high dielectric constant ceramic/polymer filler material that improves the energy and power density,” Wang explained.
The outer layers, composed of boron nitride nanosheets in a polymer matrix, are excellent insulators. While the central layer is a high dielectric constant material called barium titanate.
“We show that we can operate this material at high temperature for 24 hours straight over more than 30,000 cycles and it shows no degradation,” Wang said.
A comparison of BOPP and the sandwich structure nanocomposite, termed SSN-x, in which the x refers to the percentage of barium titanate nanocomposites in the central layer, shows that at 150º C (302º F), SSN-x has essentially the same charge-discharge energy as BOPP at its typical operating temperature of 70º C (158º F). However, SSN-x has several times the energy density of BOPP, which makes SSN-x highly preferable for electric vehicle and aerospace applications as an energy storage device due to the ability to reduce the size and weight of the electronics significantly while improving system performance and stability. The elimination of bulky and expensive cooling equipment required for BOPP is an additional bonus.
Looking ahead Wang said, “Our next step is to work with a company or with more resources to do processability studies to see if the material can be produced at a larger scale at a reasonable cost. We have demonstrated the materials performance in the lab. We are developing a number of state-of-the-art materials working with our theory colleague Long-Qing Chen in our department. Because we are dealing with a three-dimensional space, it is not just selecting the materials, but how we organize the multiple nanosized materials in specific locations. Theory helps us design materials in a rational fashion.”
This is very early high tech that seems to pull forward the barium titanate of EEStor fame. Still, the temp is pretty high at 300º F+, challenging the consumer personal vehicle market’s usefulness. We’ll watch for energy density and capacity numbers and patent trolls. The tech might need some lower temp innovation.
Meanwhile, its just a grand satisfying moment to see the barium titanate chemistry come to fruition out where the world can see it.
August 24, 2016 | Leave a Comment
A newly discovered polymer-based material could bridge the gap between the operating temperature ranges of two existing types of polymer fuel cells. The breakthrough offers the potential of a new class of fuel cells to accelerate the commercialization of low-cost fuel cells for automotive and stationary applications.
The Los Alamos National Laboratory team, in collaboration with Yoong-Kee Choe at the National Institute of Advanced Industrial Science and Technology in Japan and Cy Fujimoto of Sandia National Laboratories, has discovered that fuel cells made from phosphate-quaternary ammonium ion-pair can be operated between 80°C and 200°C with and without water, enhancing the fuel cells usability in a range of conditions.
Yu Seung Kim, the project leader at Los Alamos, explains the importance of the discovery, “Polymer-based fuel cells are regarded as the key technology of the future for both vehicle and stationary energy systems. There’s a huge benefit to running fuel cells at the widest possible operating temperature with water tolerance. But current fuel-cell vehicles need humidified inlet streams and large radiators to dissipate waste heat, which can increase the fuel-cell system cost substantially, so people have looked for materials that can conduct protons under flexible operating conditions. It is very exciting that we have now found such materials.”
Los Alamos has been a leader in fuel-cell research since the 1970s. Fuel cell technologies can significantly benefit the nation’s energy security, the environment and economy through reduced oil consumption, greenhouse gas emissions, and air pollution. The current research work supports the Laboratory’s missions related to energy security and materials for the future.
Currently, two main classes of polymer-based fuel cells exist. One is the class of low-temperature fuel cells that require water for proton conduction and cannot operate above 100°C. The other type is high-temperature fuel cells that can operate up to 180°C without water; however, the performance degrades under water-absorbing conditions below 140°C.
The research team found that a phosphate-quaternary ammonium ion-pair has much stronger interaction, which allows the transport of protons effectively even under water-condensing conditions.
Kim tells the story, “The discovery happened when we were investigating alkaline hydroxide conducting membranes, which have quaternary ammonium groups. While the alkaline membranes work only under high pH conditions, the idea came across that alkaline membranes can be used under low pH conditions by combining with phosphoric acid” said Kim. “This was a breathtaking moment, when Choe brought the calculation data that showed the interaction between quaternary ammonium and biphosphate is 8.7 times stronger than conventional acid-base interaction.”
The Los Alamos team collaborated with Fujimoto at Sandia to prepare quaternary ammonium functionalized polymers. The prototype fuel cells made from the ion-pair-coordinated membrane demonstrated excellent fuel-cell performance and durability at 80-200°C, which is unattainable with existing fuel cell technology.
Kim tells us what is coming up next, “The performance and durability of this new class of fuel cells could even be further improved by high-performing electrode materials,” he said, citing an advance expected within five to ten years that is another critical step to replace current low-temperature fuel cells used in vehicle and stationary applications.
Fuel cells have been used for decades with the limit to commercial market being their costs. The PEM cells offer hope that fuel cells can be economically practical. This team has just made a huge leap forward. More leaps are needed, but practical affordable fuel cells are coming more sooner than later.
Bubble wrap and a sponge?
The design the researchers call a ‘solar vapor generator’ requires no expensive mirrors or lenses to concentrate the sunlight, but instead relies on a combination of relatively low-tech materials to capture ambient sunlight and concentrate it as heat. The heat is then directed toward the pores of the sponge, which draw water up and release it as steam.
During their experiments – including one in which they simply placed the solar sponge on the roof of MIT’s Building 3 – the researchers found the structure heated water to its boiling temperature of 100º C, even on relatively cool, overcast days. The sponge also converted 20% of the incoming sunlight to steam.
The low-tech design may provide inexpensive alternatives for applications ranging from desalination and residential water heating, to wastewater treatment and medical tool sterilization.
The research was led by George Ni, an MIT graduate student; and Gang Chen, the Carl Richard Soderberg Professor in Power Engineering and the head of the Department of Mechanical Engineering; in collaboration with TieJun Zhang and his group members Hongxia Li and Weilin Yang from the Department of Mechanical and Materials Engineering at the Masdar Institute of Science and Technology, in the United Arab Emirates.
The researchers’ current design builds on a solar-absorbing structure they developed in 2014 – a similar floating, sponge-like material made of graphite and carbon foam, that was able to boil water to 100º C and convert 85 percent of the incoming sunlight to steam.
To generate steam at such efficient levels, the researchers had to expose the structure to simulated sunlight that was 10 times the intensity of sunlight in normal, ambient conditions.
Chen starts the story with, “It was relatively low optical concentration. But I kept asking myself, ‘Can we basically boil water on a rooftop, in normal conditions, without optically concentrating the sunlight?’ That was the basic premise.”
In ambient sunlight, the researchers found that, while the black graphite structure absorbed sunlight well, it also tended to radiate heat back out into the environment. To minimize the amount of heat lost, the team looked for materials that would better trap solar energy.
In their new design, the researchers settled on a spectrally-selective absorber – a thin, blue, metallic-like film that is commonly used in solar water heaters and possesses unique absorptive properties. The material absorbs radiation in the visible range of the electromagnetic spectrum, but it does not radiate in the infrared range, meaning that it both absorbs sunlight and traps heat, minimizing heat loss.
The researchers obtained a thin sheet of copper, chosen for its heat-conducting abilities and coated it with the spectrally-selective absorber. They then mounted the structure on a thermally-insulating piece of floating foam. However, they found that even though the structure did not radiate much heat back out to the environment, heat was still escaping through convection, in which moving air molecules such as wind would naturally cool the surface.
A solution to this problem came from an unlikely source: Chen’s 16-year-old daughter, who at the time was working on a science fair project in which she constructed a makeshift greenhouse from simple materials, including bubble wrap.
“She was able to heat it to 160º F, in winter!” Chen says. “It was very effective.”
Chen proposed the packing material to Ni, as a cost-effective way to prevent heat loss by convection. This approach would let sunlight in through the material’s transparent wrapping, while trapping air in its insulating bubbles.
“I was very skeptical of the idea at first,” Ni recalls. “I thought it was not a high-performance material. But we tried the clearer bubble wrap with bigger bubbles for more air trapping effect, and it turns out, it works. Now because of this bubble wrap, we don’t need mirrors to concentrate the sun.”
The bubble wrap, combined with the selective absorber, kept heat from escaping the surface of the sponge. Once the heat was trapped, the copper layer conducted the heat toward a single hole, or channel, that the researchers had drilled through the structure. When they placed the sponge in water, they found that water crept up the channel, where it was heated to 100 C, then turned to steam.
Chen and Ni say that solar absorbers based on this general design could be used as large sheets to desalinate small bodies of water, or to treat wastewater. Ni says other solar-based technologies that rely on optical-concentrating technologies typically are designed to last 10 to 20 years, though they require expensive parts and maintenance. This new, low-tech design, he says, could operate for one to two years before needing to be replaced.
“Even so, the cost is pretty competitive,” Ni says. “It’s kind of a different approach, where before, people were doing high-tech and long-term [solar absorbers]. We’re doing low-tech and short-term.”
“What fascinates us is the innovative idea behind this inexpensive device, where we have creatively designed this device based on basic understanding of capillarity and solar thermal radiation. Meanwhile, we are excited to continue probing the complicated physics of solar vapor generation and to discover new knowledge for the scientific community,” Zhang says.
This research was funded, in part, by a cooperative agreement between the Masdar Institute of Science and Technology; and by the Solid-State Solar Thermal Energy Conversion Center, an Energy Frontier Research Center funded by U.S. Department of Energy.
What fascinates your humble writer is only needing 110º F home potable hot water and 120º F radiant heating hot water, in an environment where the insurance for rooftop panels runs 20-25% of the install cost per year. (risking wind, hail, snow, freezing rain)
Keep that development coming!
University of Michigan researchers have flown aircraft over an oil and gas field and pinpointed with unprecedented precision the sources of the natural gas or methane leaks in real time. The technique led to the detection and immediate repair of two leaks in natural gas pipelines in the Four Corners region of the U.S. Southwest.
This is good news for consumers. Natural gas is first purchased at the well and any losses are priced in to the users bill. Less leak loss is good, and is should calm the global warming folks as methane is considered a greenhouse gas.
The new approach could help build strategies for meeting the new federal limits expected on methane emissions from the oil and gas industry. Methane emissions have risen in recent decades along with the boom in natural gas drilling.
Eric Kort, assistant professor of climate and space sciences and engineering at the University of Michigan and co-author of the team’s research paper said, “If there’s a desire to identify and address the largest methane emitters, our approach provides a way to do that. The method shows that you can easily fly over an area and actually see the plumes in real time.”
Kort collaborated on deploying the new approach, which was developed by Christian Frankenberg of NASA’s Jet Propulsion Laboratory and the California Institute of Technology. The overall project is led by the National Oceanic and Atmospheric Administration.
The team previously used satellite measurements to identify the Four Corners region as a hotbed for methane emissions. The new work builds on the previous finding by zooming in on the region with enough detail to pinpoint individual methane plumes instead of giving an averaged view for an area many miles wide.
One of the drivers for the research, if likely the primary driver, is the Obama administration has set targets of cutting methane emissions by up to 45 percent of 2012 levels by 2025. In May, the EPA released the first round of regulations. To meet the goals, however, the sources of so-called fugitive methane emissions must be found.
Methane is the primary component of natural gas, but the administration alleges when it’s released directly into the air, it’s a potent greenhouse agent that plays a role in warming the planet. Never mind massive amounts of methane are produced from decomposition and digestion, world wide, every second. Still, from a producer and consumer standpoint the effort has significant benefits.
For a long time, there’s been a discrepancy between methane levels measured from point sources on the ground, and levels measured higher in the atmosphere, says co-author Colm Sweeney, a scientist with NOAA’s Cooperative Institute for Research in Environmental Sciences.
The atmosphere holds stores of the gas whose sources on the ground are difficult to locate. This new detection technique can help locate them. The pipeline leaks it identified are a good example of how. Operators can’t always know where a pipeline may be leaking, and pipelines can be hard to access for testing from the ground.
All told, the team identified 250 methane plumes emanating from natural gas processing facilities, storage tanks, well pads, pipeline leaks, a coal mine venting shaft and natural sources. Not all of these plumes can be mitigated, the researchers say.
Although some represent leaks, others result from relatively unavoidable losses. Still others illuminate instances where an energy company has focused on capturing a different resource, such as oil, and loses some of the natural gas that was buried with it. And the coal mine venting shaft is necessary to protect miners from explosions.
To conduct the research, the team flew two specially instrumented Twin Otter aircraft over a 1,900-square-mile area where Arizona, New Mexico, Colorado and Utah meet.
Each aircraft carried a unique imaging spectrometer that operates a bit like an infrared camera. One imaged at near-infrared wavelengths and the other at thermal wavelengths. Two additional NOAA program aircraft flew low over and around the larger sources measuring the concentration of methane in the plumes as calibration points for the NASA remote measurements.
Statistical analysis showed that 10 percent of the methane sources the researchers identified were responsible for more than half of the observed point-source emissions in the region. This analysis confirmed the so-called “fat” or “heavy” tail statistical distribution they expected to see.
Kort explained, “A relatively small number of sources emit a disproportionate share of emissions. As far as we know, this is the first direct observation of this heavy tail distribution of sources over an entire basin.”
The pattern is common in both nature and human behavior, explained JPL’s Frankenberg. “Take earthquakes, for instance. A lot of smaller earthquakes are happening all the time and you don’t even feel them. What actually matters are the few big ones,” he said.
Kort said a satellite could possibly be designed to detect methane plumes in this way.
This is work well worth the effort and the proposed reductions in losses. Lets just hope the EPA rule and regulations makers don’t get too greedy and do more economic harm than worthwhile good.