A University of Utah team of chemical engineers have developed a new kind of jet mixer for creating biomass from algae that extracts the lipids from the watery plants with much less energy than the older extraction method. This key discovery now puts this form of energy closer to becoming a viable, cost-effective alternative fuel.

Biofuel experts have long sought a more economically-viable way to turn algae into biocrude oil to power vehicles, ships and even jets. University of Utah researchers believe they have found an answer. They have developed an unusually rapid method to deliver cost-effective algal biocrude in large quantities using a specially-designed jet mixer.

A new kind of jet mixer for turning algae into biomass that extracts the lipids with much less energy than the older extraction methods. Image Credit: University of Utah College of Engineering. Click image for the largest view.

Packed inside the algal microorganisms growing in ponds, lakes and rivers are lipids, which are fatty acid molecules containing oil that can be extracted to power diesel engines. When extracted the lipids are called biocrude. That makes organisms such as microalgae an attractive form of biomass, organic matter that can be used as a sustainable fuel source. These lipids are also found in a variety of other single-cell organisms such as yeasts used in cheese processing. But the problem with using algae for biomass has always been the amount of energy it takes to pull the lipids or biocrude from the watery plants. Under current methods, it takes more energy to turn algae into biocrude than the amount of energy you get back out of it.

The team of University of Utah chemical engineers have developed a new kind of jet mixer that extracts the lipids with much less energy than the older extraction method, a key discovery that now puts this form of energy closer to becoming a viable, cost-effective alternative fuel. The new mixer is fast, too, extracting lipids in seconds.

The team’s results were published in a new peer-reviewed journal, Chemical Engineering Science X. The article, “Algal Lipid Extraction Using Confined Impinging Jet Mixers,” can be downloaded here.

Dr. Leonard Pease, a co-author of the paper said, “The key piece here is trying to get energy parity. We’re not there yet, but this is a really important step toward accomplishing it. We have removed a significant development barrier to make algal biofuel production more efficient and smarter. Our method puts us much closer to creating biofuels energy parity than we were before.”

Right now, in order to extract the oil-rich lipids from the algae, scientists have to pull the water from the algae first, leaving either a slurry or dry powder of the biomass. T hat is the most energy-intensive part of the process. That residue is then mixed with a solvent where the lipids are separated from the biomass. What’s left is a precursor, the biocrude, used to produce algae-based biofuel. That fuel is then mixed with diesel fuel to power long-haul trucks, tractors and other large diesel-powered machinery. But because it requires so much energy to extract the water from the plants at the beginning of the process, turning algae into biofuel has thus far not been a practical, efficient or economical process.

University of Utah chemical engineering assistant professor Swomitra “Bobby” Mohanty, a co-author on the paper said, “There have been many laudable research efforts to advance algal biofuel, but nothing has yet produced a price point capable of attracting commercial development. Our designs may change that equation and put algal biofuel back in play.”

Mohanty also noted the team has created a new mixing extractor, a reactor that shoots jets of the solvent at jets of algae, creating a localized turbulence in which the lipids “jump” a short distance into the stream of solvent. The solvent then is taken out and can be recycled to be used again in the process. “Our designs ensure you don’t have to expend all that energy in drying the algae and are much more rapid than competing technologies,” noted Mohanty. This technology could also be applied beyond algae and include a variety of microorganisms such as bacteria, fungi, or any microbial-derived oil, he added.

In 2017, about 5 percent of total primary energy use in the United States came from biomass, according to the U.S. Department of Energy. Other forms of biomass include burning wood for electricity, ethanol that is made from crops such as corn and sugar cane, and food and yard waste in garbage that is converted to biogas. The benefit of algae is that it can be grown in ponds, raceways or custom-designed bioreactors and then harvested to produce an abundance of fuel. Growing algae in such mass quantities also could positively affect the atmosphere by reducing the amount of carbon dioxide in the air.

“This is game-changing,” Pease says of their work on algae research. “The breakthrough technologies we are creating could drive a revolution in algae and other cell-derived biofuels development. The dream may soon be within reach.”

Other co-authors are former U chemical engineering doctoral student Yen-Hsun “Robert” Tseng and U chemical engineering associate professor John McLennan.

The big problem now has a solution. Presumably it will scale up to industrial levels. For now algae is way closer than last fall for getting to market with economical potential. There is a way to go, especially with crude oil so cheap. But these conditions are what make certain that when algae breaks out it will be for the very long haul.

Cornell University scientists’ new research advances the design of solid-state batteries, a technology that is inherently safer and more energy-dense than today’s lithium-ion batteries, which rely on flammable liquid electrolytes for fast transfer of chemical energy stored in molecular bonds to electricity.

By starting with liquid electrolytes and then transforming them into solid polymers inside the electrochemical cell, the researchers take advantage of both liquid and solid properties to overcome key limitations in current battery designs.

Users ask batteries to deliver energy when it’s needed and for as long as it is wanted, recharge quickly and don’t burst into flames.

A rash of cell phone fires in 2016 jolted consumer confidence in lithium-ion batteries, a technology that helped usher in modern portable electronics but has been plagued by safety concerns since it was introduced in the 1980s. As interest in electric vehicles revs up, researchers and industry insiders are searching for improved rechargeable battery technology that can safely and reliably power cars, autonomous vehicles, robotics and other next-generation devices.

The new method for designing solid-state batteries starts with liquid electrolytes inside the electrochemical cell. Special molecules then initiate polymerization, improving contact between the electrolyte and electrodes. Image Credit: Qing Zhao, Cornell University. Click image for the largest view.

The new Cornell research advances the design of solid-state batteries, a technology that is inherently safer and more energy-dense than today’s lithium-ion batteries, which rely on flammable liquid electrolytes for fast transfer of chemical energy stored in molecular bonds to electricity. By starting with liquid electrolytes and then transforming them into solid polymers inside the electrochemical cell, the researchers take advantage of both liquid and solid properties to overcome key limitations in current battery designs.

Qing Zhao, a postdoctoral researcher and lead author on the study explained, “Imagine a glass full of ice cubes: Some of the ice will contact the glass, but there are gaps.” The study paper “Solid-State Polymer Electrolytes With In-Built Fast Interfacial Transport for Secondary Lithium Batteries,” has been published in Nature Energy.

Qing continued, “But if you fill the glass with water and freeze it, the interfaces will be fully coated, and you establish a strong connection between the solid surface of the glass and its liquid contents. This same general concept in a battery facilitates high rates of ion transfer across the solid surfaces of a battery electrode to an electrolyte without needing a combustible liquid to operate.”

The key insight is the introduction of special molecules capable of initiating polymerization inside the electrochemical cell, without compromising other functions of the cell. If the electrolyte is a cyclic ether, the initiator can be designed to rip open the ring, producing reactive monomer strands that bond together to create long chain-like molecules with essentially the same chemistry as the ether. This now-solid polymer retains the tight connections at the metal interfaces, much like the ice inside a glass.

Beyond their relevance for improving battery safety, solid-state electrolytes are also beneficial for enabling next-generation batteries that utilize metals, including lithium and aluminum, as anodes for achieving far more energy storage than is possible in today’s state-of-the-art battery technology. In this context, the solid-state electrolyte prevents the metal from forming dendrites, a phenomenon that can short circuit a battery and lead to overheating and failure.

A solid-state system also circumvents the need for battery cooling by providing stability to thermal changes.

Despite the perceived advantages of solid-state batteries, industry attempts to produce them at a large scale have encountered setbacks. Manufacturing costs are high, and the poor interfacial properties of previous designs present significant technical hurdles.

Senior author Lynden Archer, the James A. Friend Family Distinguished Professor of Engineering in the Smith School of Chemical and Biomolecular Engineering said, “Our findings open an entirely new pathway to create practical solid-state batteries that can be used in a range of applications.”

According to Archer, the new in-situ strategy for creating solid polymer electrolytes is particularly exciting because it shows promise for extending cycle life and recharging capabilities of high-energy-density rechargeable metal batteries.

“Our approach works for today’s lithium ion technology by making it safer, but offers opportunity for future battery technology,” Archer said.

Other authors are doctoral students Xiaotun Liu and Sanjuna Stalin, and Kasim Khan ’20. The research was supported by the Department of Energy’s Basic Energy Sciences program and through facilities funding from the National Science Foundation.

We’ll see over the next few years if this is the technology that supercharges the conversion of and more development of a wider range of electrical devices and much higher market acceptance and growth.

Washington University in St. Louis engineers have developed a high-powered fuel cell that operates at double the voltage of today’s commercial fuel cells. It could power underwater vehicles, drones and eventually electric aircraft at a significantly lower cost.

The transportation industry is one of the largest consumers of energy in the U.S. economy with increasing demand to make it cleaner and more efficient. While more people are using electric cars, designing electric-powered planes, ships and submarines is much harder due to power and energy requirements.

This is an artistic representation of the pH-gradient enabled microscale bipolar interface (PMBI) created by Vijay Ramani and his lab. The two layers that make up the interface are covering the third bottom layer, which is the electrode with palladium particles on it. The submarine and drones are envisioned applications of the direct borohydride fuel cell which incorporates the PMBI.  Image Credit: McKelvey School of Engineering, Washington University. Click image for the largest view.

A team of engineers in the McKelvey School of Engineering at Washington University in St. Louis has developed a high-power fuel cell that advances technology in this area. Led by Vijay Ramani, the Roma B. and Raymond H. Wittcoff Distinguished University Professor, the team has developed a direct borohydride fuel cell that operates at double the voltage of today’s commercial fuel cells.

The paper detailing the advancement using a unique pH-gradient-enabled microscale bipolar interface (PMBI), has been published in Nature Energy. The improvement could power a variety of transportation modes – including unmanned underwater vehicles, drones and eventually electric aircraft – at significantly lower cost.

Ramani, also professor of energy, environmental & chemical engineering said, “The pH-gradient-enabled microscale bipolar interface is at the heart of this technology. It allows us to run this fuel cell with liquid reactants and products in submersibles, in which neutral buoyancy is critical, while also letting us apply it in higher-power applications such as drone flight.”

The fuel cell uses an acidic electrolyte at one electrode and an alkaline electrolyte at the other electrode. Typically, the acid and alkali will quickly react when brought in contact with each other. Ramani said the key breakthrough is the PMBI, which is thinner than a strand of human hair. Using membrane technology developed at the McKelvey Engineering School, the PMBI can keep the acid and alkali from mixing, forming a sharp pH gradient and enabling the successful operation of this system.

Shrihari Sankarasubramanian, a research scientist on Ramani’s team said, “Previous attempts to achieve this kind of acid-alkali separation were not able to synthesize and fully characterize the pH gradient across the PMBI. Using a novel electrode design in conjunction with electroanalytical techniques, we were able to unequivocally show that the acid and alkali remain separated.”

Lead author Zhongyang Wang, a doctoral candidate in Ramani’s lab, added, “Once the PBMI synthesized using our novel membranes was proven to work effectively, we optimized the fuel cell device and identified the best operating conditions to achieve a high-performance fuel cell. It has been a tremendously challenging and rewarding pathway to developing the new ion-exchange membranes that has enabled the PMBI.”

“This is a very promising technology, and we are now ready to move on to scaling it up for applications in both submersibles and drones,” Ramani said.

Other participants in this work include Cheng He, a doctoral candidate, and Javier Parrondo, a former research scientist in Ramani’s lab. The team is working with the university’s Office of Technology Management to explore commercialization opportunities.

Double the voltage is always a good thing at the levels where fuel cells and batteries work. Cars, trucks, ships and trains are good prospects, but flying might prove more of a challenge. But never say never, the past decade here has been both a surprise and disappointment on what comes to market.

Purdue University researchers produce a fuel cell with a new method increasing the fuel cell electrode activity at least tenfold and using 90 percent less platinum.

Electric vehicles running on fuel cells tout zero emissions and higher efficiency, but expensive platinum is holding them back from entering a larger market.

The 2019 Toyota Mirai electric vehicle touts zero emissions, thanks to a fuel cell that runs on hydrogen instead of gasoline. But the Mirai has barely left California, partly because today’s fuel cell electrodes are made of super expensive platinum.

Cutting down on the platinum would also cut costs, allowing more electric cars to go to market.

A platinum-like metal only five atomic layers thick is “just right” for optimizing the performance of a fuel cell electrode. Image Credit: Johns Hopkins University. Image by Lei Wang. Click image for the largest view.

The new method borrows some thinking from “Goldilocks” – just the right amount – for evaluating how much metal would be required for fuel cell electrodes. The technique uses the forces on a metal’s surface to identify the ideal electrode thickness.

Jeffrey Greeley, professor of chemical engineering at Purdue said, “There is exactly the right amount of metal that will give fuel cell electrodes the best properties. If they are too thick or too thin, the main reaction for deploying a fuel cell doesn’t work as well, so there’s sort of a Goldilocks principle here.”

The study published in the journal Science, was a collaborative effort between Johns Hopkins University, Purdue University and the University of California at Irvine.

The researchers tested their theory on palladium, a metal very similar to platinum.

“We’re essentially using force to tune the properties of thin metal sheets that make up electrocatalysts, which are part of the electrodes of fuel cells,” Greeley said. “The ultimate goal is to test this method on a variety of metals.”

Fuel cells convert hydrogen, combining with oxygen, into electricity through a so-called oxygen-reduction reaction that an electrocatalyst starts. Finding exactly the right thickness stresses the surface of the electrocatalyst and enhances how well it performs this reaction.

Researchers in the past have tried using outside forces to expand or compress an electrocatalyst’s surface, but doing so risked making the electrocatalyst less stable.

Instead, Greeley’s group predicted through computer simulations that the inherent force on the surface of a palladium electrocatalyst could be manipulated for the best possible properties.

According to the simulations, an electrocatalyst five layers thick, each layer as thin as an atom, would be enough to optimize performance.

Zhenhua Zheng, a Purdue postdoctoral researcher in chemical engineering, and co-first and co-corresponding author on this paper said, “Don’t fight forces, use them. This is kind of like how some structures in architecture don’t need external beams or columns because tensional and compressive forces are distributed and balanced.”

Experiments in Chao Wang’s lab at Johns Hopkins confirmed the simulation predictions, finding that the method can increase catalyst activity by 10 to 50 times, using 90 percent less of the metal than what is currently used in fuel cell electrodes.

This is because the surface force on the atomically thin electrodes tunes the strain, or distance between atoms, of the metal sheets, altering their catalytic properties.

“By tuning the material’s thickness, we were able to create more strain. This means you have more freedom to accelerate the reaction you want on the material’s surface,” Wang said.

The study was supported by multiple entities, including the U.S. Department of Energy, National Energy Research Scientific Computing Center and the National Science Foundation.

The work aligns with Purdue’s Giant Leaps celebration, acknowledging the university’s global advancements made toward a sustainable economy and planet as part of Purdue’s 150th anniversary. This is one of the four themes of the yearlong celebration’s Ideas Festival, designed to showcase Purdue as an intellectual center solving real-world issues.

The hydrogen economy folks might well be breaking out the Champaign. It sounds like the team is going to try other catalysts as well. The fuel cell might be getting its marketable legs at last. Now, to find the safe cheap way to store hydrogen without it getting away.

A Technical University of Denmark team of researchers has solved one of the biggest challenges in making effective nanoelectronics based on graphene.

The biggest challenges of making effective nano electronics based on graphene is to carve out graphene to nanoscale dimensions without ruining the electrical properties.

For 15 years, scientists have tried to exploit the “miracle material” graphene to produce nanoscale electronics. On paper, graphene should be great for just that: it is ultra-thin – only one atom thick in fact and therefore two-dimensional, it is excellent for conducting electrical current and should be ideal for future forms of electronics that are faster and more energy efficient. Additionally graphene consists of carbon atoms – of which we have an unlimited supply.

In theory, graphene can be altered to perform many different tasks within e.g. electronics, photonics or sensors simply by drawing tiny patterns in it, as this fundamentally alters its quantum properties. Thos one “simple” task, which has turned out to be surprisingly difficult, is to induce a bandgap – which is crucial for making transistors and optoelectronic devices. However, since graphene is only an atom thick all of the atoms are important and even tiny irregularities in the pattern can destroy its properties.

New Process achieves electrical currents orders of magnitude higher than previously achieved for such structures. The work shows that the quantum transport properties needed for future electronics can survive scaling down to 10 nanometer dimensions.  Image Credit: Otto Moesgaard, Technical University of Denmark.  Click image for the largest view.

Peter Bøggild, a professor at DTU Physics pointed out, “Graphene is a fantastic material, which I think will play a crucial role in making new nanoscale electronics. The problem is that it is extremely difficult to engineer the electrical properties.”

The Center for Nanostructured Graphene at DTU and Aalborg University was established in 2012 specifically to study how the properties of graphene can be engineered, for instance by making a very fine pattern of holes. This should subtly change the quantum nature of the electrons in the material, and allow the properties of graphene to be tailored. However, the team of researchers from DTU and Aalborg experienced the same as many other researchers worldwide: it didn’t work.

Professor Bøggild explained, “When you make patterns in a material like graphene, you do so in order to change its properties in a controlled way – to match your design. However, what we have seen throughout the years is that we can make the holes, but not without introducing so much disorder and contamination that it no longer behaves like graphene. It is a bit similar to making a water pipe, with a poor flow rate because of coarse manufacturing. On the outside, it might look fine. For electronics, that is obviously disastrous.”

Now, the team of scientists have solved the problem. Two postdocs from DTU Physics, Bjarke Jessen and Lene Gammelgaard, first encapsulated graphene inside another two-dimensional material – hexagonal boron nitride, a non-conductive material that is often used for protecting graphene’s properties.

Next, they used a technique called electron beam lithography to carefully pattern the protective layer of boron nitride and graphene below with a dense array of ultra small holes. The holes have a diameter of approximately 20 nanometers, with just 12 nanometers between them – however, the roughness at the edge of the holes is less than 1 nanometer or a billionth of a meter. This allows 1000 times more electrical current to flow than had been reported in such small graphene structures.

Bøggild said, “We have shown that we can control graphene’s band structure and design how it should behave. When we control the band structure, we have access to all of graphene’s properties – and we found to our surprise that some of the most subtle quantum electronic effects survive the dense patterning – that is extremely encouraging. Our work suggests that we can sit in front of the computer and design components and devices – or dream up something entirely new – and then go to the laboratory and realize them in practice.”

“Many scientists had long since abandoned attempting nanolithography in graphene on this scale, and it is quite a pity since nanostructuring is a crucial tool for exploiting the most exciting features of graphene electronics and photonics. Now we have figured out how it can be done; one could say that the curse is lifted. There are other challenges, but the fact that we can tailor electronic properties of graphene is a big step towards creating new electronics with extremely small dimensions,” said Bøggild.

The research paper “Lithographic band structure engineering of graphene” has been published in Nature Nanotechnology.

Looks like the first and hardest step is covered for industrialization. More needed. More to come, for sure.


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