The main campus of the laboratory is in Richland, Washington.
PNNL scientists conduct basic and applied research and development to strengthen U.S. scientific foundations for fundamental research and innovation; prevent and counter acts of terrorism through applied research in information analysis, cyber security, and the nonproliferation of weapons of mass destruction; increase the U.S. energy capacity and reduce dependence on imported oil; and reduce the effects of human activity on the environment. PNNL has been operated by Battelle Memorial Institute since 1965.
Pacific Northwest National Laboratory research articles from Innovation Toronto
- Power grid forecasting tool could save millions in wasted electricity – August 8, 2015
- Tiny grains of rice hold big promise for greenhouse gas reductions, bioenergy – July 30, 2015
- Packing heat: New fluid makes untapped geothermal energy cleaner – April 20, 2015
- Dendrite eraser: New electrolyte rids batteries of short-circuiting fibers enabling next-generation rechargeable batteries – March 3, 2015
- New flow battery to keep big cities lit, green & safe – February 26, 2015
- Better Fuel Cells: Angling chromium to let oxygen through – September 15, 2014
- “Wetting” a battery’s appetite for renewable energy storage – August 3, 2014
- New boron nanomaterial may be possible
- Battery development may extend range of electric cars | lithium-sulfur battery
- Algae to crude oil: Million-year natural process takes minutes in the lab
- Preparing for hell and high water
- DOE rooftop challenge winners offer energy, cost savings
- Fuel-efficient cars, planes cheaper with magnesium drawn from ocean
- Refrigerated trucks to keep their cool thanks to fuel cell technology
- Making sense of patterns in the Twitterverse
- Power grid getting smarter with big battery in Salem
- Compressing air for renewable energy storage
- A Sweet Solution to Sour Gas
- A solar booster shot for natural gas power plants
- UEA researchers make breakthrough in race to create ‘bio-batteries’
- Are Algae Biofuels a Realistic Alternative to Petroleum?
- Fast and efficient biologically inspired catalyst could someday make fuel cells cheaper
- In The Future, Your Clothes Will Be A Power Plant
- Uranium supply extracted from Seawater could last for Centuries
- Record setting small-scale solid oxide fuel cell could power neighborhoods
- Air compression energy storage
- Rising Air Pollution Worsens Drought, Flooding
- New Tech Can Reduce Battery Charging Time to Mere Seconds
- World’s Largest Wind Power Storage System Charges Ahead
- Human Influence On the 21st Century Climate
- New Method to Make Sodium Ion-Based Battery Cells Could Lead to Better, Cheaper Batteries for the Electrical Grid
- Digital Ants To Tackle Virus Menace!
- Algae Could Replace 17 Percent of US Oil Imports
- Electric Grid Reliability: Increasing Energy Storage in Vanadium Redox Batteries by 70 Percent
- Molten Metal Batteries Return for Renewable Energy Storage
- Scrubbing CO2 and sulfur from power plant emissions
- Digital Tools Help Users Save Energy, Study Finds
- Flat batteries could improve performance and lower cost of energy storage
- Wax and soap could help build a better rechargeable battery
- Study Paves Way for New Biofuels Models, Technologies
- Glimpsing a Greener Future: Computer Model Foresees Effects of Alternative Transportation Fuels
- New Geothermal Heat Extraction Process To Deliver Clean Power Generation
- Nanostructure coatings remove heat four times faster
Electron anions impart unconventional properties in a unique cement semiconductor for potentials uses in industrial catalysts and flat panel displays
Simple cements are everywhere in construction, but researchers want to create novel construction materials to build smarter infrastructure. The cement known as mayenite is one smart material — it can be turned from an insulator to a transparent conductor and back. Other unique properties of this material make it suitable for industrial production of chemicals such as ammonia and for use as semiconductors in flat panel displays.
The secret behind mayenite’s magic is a tiny change in its chemical composition, but researchers hadn’t been sure why the change had such a big effect on the material, also known as C12A7. In new work, researchers show how C12A7 components called electron anions help to transform crystalline C12A7 into semiconducting glass.
The study, published Aug. 24 in Proceedings of the National Academy of Sciences, uses computer modeling that zooms in at the electron level along with lab experiments. They showed how the small change in composition results in dramatic changes of the glass properties and, potentially, allows for greater control of the glass formation process.
“We want to get rid of the indium and gallium currently used in most flat panel displays,” said materials scientist Peter Sushko of the Department of Energy’s Pacific Northwest National Laboratory. “This research is leading us toward replacing them with abundant non-toxic elements such as calcium and aluminum.”
Breaking the glass ceiling
More than a decade ago, materials scientist Hideo Hosono at the Tokyo Institute of Technology and colleagues plucked an oxygen atom from a crystal of C12A7 oxide, which turned the transparent insulating material into a transparent conductor. This switch is rare because the conducting material is transparent: Most conductors are not transparent (think metals) and most transparent materials are not conductive (think window glass).
Back in the crystal, C12A7 oxide’s departing oxygen leaves behind a couple electrons and creates a material known as an electride. This electride is remarkably stable in air, water, and ambient temperatures. Most electrides fall apart in these conditions. Because of this stability, materials scientists want to harness the structure and properties of C12A7 electride. Unfortunately, its crystalline nature is not suitable for large-scale industrial processes, so they needed to make a glass equivalent of C12A7 electride.
And several years ago, they did. Hosono and colleagues converted crystalline C12A7 electride into glass. The glass shares many properties of the crystalline electride, including the remarkable stability.
Crystals are neat and tidy, like apples and oranges arranged orderly in a box, but glasses are unordered and messy, like that same fruit in a plastic grocery bag. Researchers make glass by melting a crystal and cooling the liquid in such a way that the ordered crystal doesn’t reform. With C12A7, the electride forms a glass at a temperature about 200 degrees lower than the oxide does.
This temperature — when the atoms stop flowing as a liquid and freeze in place — is known as the glass transition temperature. Controlling the glass transition temperature allows researchers to control certain properties of the material. For example, how car tires wear down and perform in bad weather depends on the glass transition temperature of the rubber they’re made from.
Sushko, his PNNL colleague Lewis Johnson, Hosono and others at Tokyo Tech wanted to determine why the electride’s glass transition temperature was so much lower than the oxide’s. They suspected components of the electride known as electron anions were responsible. Electron anions are essentially freely moving electrons in place of the much-larger negatively charged oxygen atoms that urge the oxide to form a tidy crystal.
The team simulated Hosono’s lab experiments using molecular dynamics software that could capture the movement of both the atoms and the electron anions in both the melted material and glass. The team found that that the negatively-charged electron anions paired up between positively charged aluminum or calcium atoms, replacing the negatively charged oxygen atoms that would typically be found between the metals.
The bonds that the electron anions formed between the metal atoms were weaker than bonds between metal and oxygen atoms. These weak links could also move rapidly through the material. This movement allowed a small number of electron anions to have a greater effect on the glass transition temperature than much larger quantities of minerals typically used as additives in glasses.
To rule out other factors as the impetus for the lower transition temperature — such as the electrical charge or change in oxygen atoms — the researchers simulated a material with the same composition as the C12A7 electride but with the electrons spread evenly through the material instead of packed in as electron anions. In this simulation, the glass transition temperature was no different than C12A7 oxide’s. This result confirmed that the network of weak links formed by the electron anions was responsible for changes to the glass transition temperature.
According to the scientists, electron anions form a new type of weak link that can affect the conditions under which a material can form a glass. They join the ranks of typical additives that disrupt the ability of the material to form long chains of atoms, such as fluoride, or form weak, randomly oriented bonds between atoms of opposite charge, such as sodium. The work suggests researchers might be able to control the transition temperature by changing the amount of electron anions they use.
“This work shows us not just how a glass forms,” said PNNL’s Johnson, “but also gives us a new tool for how to control it.”
Nature-inspired synthetic membranes could aid water purification, energy, and healthcare needs
Materials scientists have created a new material that performs like a cell membrane found in nature. Such a material has long been sought for applications as varied as water purification and drug delivery.
Referred to as a lipid-like peptoid (we’ll unpack that in a second), the material can assemble itself into a sheet thinner, but more stable, than a soap bubble, the researchers report this week in Nature Communications. The assembled sheet can withstand being submerged in a variety of liquids and can even repair itself after damage.
“Nature is very smart. Researchers are trying to make biomimetic membranes that are stable and have certain desired properties of cell membranes,” said chemist Chun-Long Chen at the Department of Energy’s Pacific Northwest National Laboratory. “We believe these materials have potential in water filters, sensors, drug delivery and especially fuel cells or other energy applications.”
Nanorods’ behavior first theorized 20 years ago, but not seen until now
After their nanorods were accidentally created when an experiment didn’t go as planned, the researchers gave the microscopic, unplanned spawns of science a closer look.
Chemist Satish Nune was inspecting the solid, carbon-rich nanorods with a vapor analysis instrument when he noticed the nanorods mysteriously lost weight as humidity increased. Thinking the instrument had malfunctioned, Nune and his colleagues moved on to another tool, a high-powered microscope.
They jumped as they saw an unknown fluid unexpectedly appear between bunches of the tiny sticks and ooze out. Video recorded under the microscope is shaky at the beginning, as they quickly moved the view finder to capture the surprising event again.
The team at the Department of Energy’s Pacific Northwest National Laboratory would go on to view the same phenomenon more than a dozen times. Immediately after expelling the fluid, the nanorods’ weight decreased by about half, causing the researchers to scratch their heads even harder.
A paper published today in Nature Nanotechnology describes the physical processes behind this spectacle, which turned out to be the first experimental viewing of a phenomenon theorized 20-some years ago. The discovery could lead to a large range of real-world applications, including low-energy water harvesting and purification for the developing world, and fabric that automatically pulls sweat away from the body and releases it as a vapor.
In surprise twist, story of how microbes produce methane ends with uncommon “radical”
Like the poet, microbes that make methane are taking chemists on a road less traveled: Of two competing ideas for how microbes make the main component of natural gas, the winning chemical reaction involves a molecule less favored by previous research, something called a methyl radical.
Reported today in the journal Science, the work is important for understanding not only how methane is made, but also how to make things from it.
“Methane is an interesting substance because it’s both a fossil fuel and a potentially renewable fuel that can come from microbes,” said study lead Stephen Ragsdale of the University of Michigan, Ann Arbor. “In addition, detailed knowledge of the chemical steps involved in making methane could lead to major breakthroughs in designing energy efficient catalysts for converting methane into liquid fuels and other chemicals.”
This study demonstrates one of a very few known instances of nature using a highly reactive methyl radical in its biological machinations.
“We were totally surprised,” said computational chemist Simone Raugei, a coauthor at the Department of Energy’s Pacific Northwest National Laboratory. “We thought we’d find evidence for other mechanisms.”
Hybrid batteries that charge faster than conventional ones could have significantly better electrical capacity and long-term stability when prepared with a gentle-sounding way of making electrodes.
Called ion soft-landing, the high-precision technique resulted in electrodes that could store a third more energy and had twice the lifespan compared to those prepared by a conventional method, the researchers report today in Nature Communications. Straightforward to set up, the method could eventually lead to cheaper, more powerful, longer-lasting rechargeable batteries.
“This is the first time anyone has been able to put together a functioning battery using ion soft-landing,” said chemist and Laboratory Fellow Julia Laskin of the Department of Energy’s Pacific Northwest National Laboratory.
The advantages come from soft-landing’s ability to build an electrode surface very specifically with only the most desirable molecules out of a complex mixture of raw components.
“It will help us unravel important scientific questions about this energy storage technology, a hybrid between common lithium rechargeable batteries and supercapacitors that have very high energy density,” said lead author, PNNL chemist Venkateshkumar Prabhakaran.
A different kind of hybrid
Although lithium ion rechargeable batteries are the go-to technology for small electronic devices, they release their energy slowly, which is why hybrid electric vehicles use gasoline for accelerating, and take a long time to recharge, which makes electric vehicles slower to “fill” than their gas-powered cousins.
One possible solution is a hybrid battery that crosses a lithium battery’s ability to hold a lot of charge for its size with a fast-charging supercapacitor. PNNL chemists wanted to know if they could make superior hybrid battery materials with a technology — called ion soft-landing — that intricately controls the raw components during preparation.
To find out, Laskin and colleagues created hybrid electrodes by spraying a chemical known as POM, or polyoxometalate, onto supercapacitor electrodes made of microscopically small carbon tubes. Off-the-shelf POM has both positively and negatively charged parts called ions, but only the negative ions are needed in hybrid electrodes.
Limited by its design, the conventional preparation technique sprays both the positive and negative ions onto the carbon nanotubes. Ion soft-landing, however, separates the charged parts and only sets down the negative ions on the electrode surface. The question that Laskin and team had was, do positive ions interfere with the performance of hybrid electrodes?
To find out, the team made centimeter-sized square hybrid batteries out of POM-carbon nanotube electrodes that sandwiched a specially developed ionic liquid membrane between them.
“We had to design a membrane that separated the electrodes and also served as the battery’s electrolyte, which allows conduction of ions,” said Prabhakaran. “Most people know electrolytes as the liquid sloshing around within a car battery. Ours was a solid gel.”
They tested this mini-hybrid battery for how much energy it could hold and how many cycles of charging and discharging it could handle before petering out.
They compared soft-landing with conventionally made hybrid batteries, which were made with a technique called electrospray deposition. They used an off-the-shelf POM containing positively charged sodium ions.
Cheers for the POMs
The team found that the POM hybrid electrodes made with soft-landing had superior energy storage capacity. They could hold a third more energy than the carbon nanotube supercapacitors by themselves, which were included as a minimum performance benchmark. And soft-landing hybrids held about 27 percent more energy than conventionally made electrospray deposited electrodes.
To make sure the team was using the optimal amount of POM, they made hybrid electrodes using different amounts and tested which one resulted in the highest capacity. Soft-landing produced the highest capacity overall using the lowest amount of POM. This indicated the electrodes used the active material extremely efficiently. In comparison, conventional, sodium-based POM electrodes required twice as much POM material to reach their highest capacity.
The conventionally-made devices used more POM, but the team couldn’t count them out yet. They might in fact have a longer lifespan than the soft-landing produced electrodes. To test that, the team charged and discharged the hybrids 1,000 times and measured how long they lasted.
As they did in the previous tests, the soft-landing-based devices performed the best, losing only a few percent capacity after 1000 cycles. The naked supercapacitors came in second, and the sodium-based, conventionally made devices lost about double the capacity of the soft-landed devices. This suggests that the soft-landing method has the potential to double the lifespan of these types of hybrid batteries.
The team was surprised that it took so little of the POM material to make such a big difference to the carbon nanotube supercapacitors. By weight, the amount of POM was just one-fifth of a percent of the amount of carbon nanotube material.
“The fact that the capacitance reaches a maximum with so little POM, and then drops off with more, is remarkable,” said Laskin. “We didn’t expect such a small amount of POM to be making such a large contribution to the capacitance.”
They decided to examine the structure of the electrodes using powerful microscopes in EMSL, the Environmental Molecular Sciences Laboratory, a DOE Office of Science User Facility at PNNL. They compared soft-landing with the conventionally made, sodium-POM electrodes.
Soft-landing created small discrete clusters of POM dotting the carbon nanotubes, but the conventional method resulted in larger clumps of POM clusters swamping out the nanotubes, aggregates up to ten times the size of those made by soft-landing.
This result suggested to the researchers that removing the positive ions from the POM starting material allowed the negative ions to disperse evenly over the surface. As long as the positive ions such as sodium remained, the POM and sodium appear to reform the crystalline material and aggregate on the surface. This prevented much of the POM from doing its job in the battery, thereby reducing capacity.
When the team zoomed out a little and viewed the nanotubes from above, the conventionally made electrodes were covered in large aggregates of POM. The soft-landed electrodes, however, were remarkably indistinguishable from the naked carbon nanotube supercapacitors.
In future research, the team wants to explore how to get the carbon materials to accept more POM, which might increase capacity and lifespan even further.
The oceans hold more than four billion tons of uranium—enough to meet global energy needs for the next 10,000 years if only we could capture the element from seawater to fuel nuclear power plants. Major advances in this area have been published by the American Chemical Society’s (ACS) journal Industrial & Engineering Chemistry Research.
For half a century, researchers worldwide have tried to mine uranium from the oceans with limited success.
In the 1990s, Japan Atomic Energy Agency (JAEA) scientists pioneered materials that hold uranium as it is stuck or adsorbed onto surfaces of the material submerged in seawater. In 2011, the U.S. Department of Energy (DOE) initiated a program involving a multidisciplinary team from U.S. national laboratories, universities and research institutes to address the fundamental challenges of economically extracting uranium from seawater.
Within five years this team has developed new adsorbents that reduce the cost of extracting uranium from seawater by three to four times.
To chronicle this and other successes, the special issue focused on “Uranium in Seawater” amasses research presented by international scientists at ACS’s spring 2015 meeting in Denver. Major contributions came from researchers supported by the Fuel Resources Program of DOE’s Office of Nuclear Energy who coordinate an international effort involving researchers in China and Japan under agreements with the Chinese Academy of Sciences and JAEA. The DOE program is laying the technological foundation to determine the economic feasibility of uranium recovery from seawater. It supports researchers at national laboratories, universities and research institutes focused on developing and testing the next generation of adsorbents that will exhibit higher adsorbent capacity, faster binding and lower degradation over multiple use cycles in seawater.
“For nuclear power to remain a sustainable energy source, an economically viable and secure source of nuclear fuel must be available,” said Phillip Britt, who provides technical and outreach leadership for the DOE program. “This special journal issue captures the dramatic successes that have been made by researchers across the world to make the oceans live up to their vast promise for a secure energy future.”
Scientists from two DOE labs, Oak Ridge National Laboratory in Tennessee and Pacific Northwest National Laboratory in Washington, led more than half of the 30 papers in the special issue. ORNL contributions concentrated on synthesizing and characterizing uranium adsorbents, whereas PNNL papers focused on marine testing of adsorbents synthesized at national labs and universities.
“Synthesizing a material that’s superior at adsorbing uranium from seawater required a multi-disciplinary, multi-institutional team including chemists, computational scientists, chemical engineers, marine scientists and economists,” said Sheng Dai, who has technical oversight of the ORNL uranium from seawater program. “Computational studies provided insight into chemical groups that selectively bind uranium. Thermodynamic studies provided insight into the chemistry of uranium and relevant chemical species in seawater. Kinetic studies uncovered factors that control how fast uranium in seawater binds to the adsorbent. Understanding adsorbent properties in the laboratory is key for us to develop more economical adsorbents and prepare them to grab as much uranium as possible.”
That teamwork culminated in the creation of braids of polyethylene fibers containing a chemical species called amidoxime that attracts uranium. So far, testing has been conducted in the laboratory with real seawater; but the braids are deployable in oceans, where nature would do the mixing, avoiding the expense of pumping large quantities of seawater through the fibers. After several weeks, uranium oxide–laden fibers are collected and subjected to an acidic treatment that releases, or desorbs, uranyl ions, regenerating the adsorbent for reuse. Further processing and enriching of the uranium produces a material to fuel nuclear power plants.
PNNL researchers tested the adsorbents developed at ORNL and other laboratories, including universities participating in the Nuclear Energy University Program, using natural filtered and unfiltered seawater from Sequim Bay in Washington under controlled temperature and flow-rate conditions. Gary Gill, deputy director of PNNL’s Coastal Sciences Division, coordinated three marine testing sites—at PNNL’s Marine Sciences Laboratory in Sequim, Wash., Woods Hole Oceanographic Institution in Massachusetts and the University of Miami in Florida.
“Understanding how the adsorbents perform under natural seawater conditions is critical to reliably assessing how well the uranium adsorbent materials work,” Gill said. “In addition to marine testing, we assessed how well the adsorbent attracted uranium versus other elements, adsorbent durability, whether buildup of marine organisms might impact adsorbent capacity, and we demonstrated that most of the adsorbent materials are not toxic. PNNL also performed experiments to optimize release of uranium from the adsorbents and adsorbent re-use using acid and bicarbonate solutions.”
Marine testing at PNNL showed an ORNL adsorbent material had the capacity to hold 5.2 grams of uranium per kilogram of adsorbent in 49 days of natural seawater exposure—the crowning result presented in the special issue. The Uranium from Seawater program continues to make significant advancements, producing adsorbents with even higher capacities for grabbing uranium. Recent testing exceeded 6 grams of uranium per kilogram of adsorbent after 56 days in natural seawater – an adsorbent capacity that is 15 percent higher than the results highlighted in the special edition.
The special issue captures a wide range of enterprises, including
- Uranium coordination and computer-aided ligand design (ORNL)
- Thermodynamic, kinetic and structural characterization of the adsorbent (Lawrence Berkeley National Laboratory, ORNL, PNNL)
- Adsorbent synthesis using radiation to graft more polymer onto the polyethylene (ORNL, Brookhaven National Laboratory, University of Maryland)
- Adsorbent synthesis using a chemical method (ORNL, University of Tennessee)
- Adsorbent nanosynthesis (ORNL, PNNL, Hunter College, University of Chicago, University of South Florida, SLAC National Accelerator Laboratory, University of California–Berkeley)
- Laboratory testing and modeling of adsorbent performance (ORNL, Georgia Tech)
- Marine testing and performance assessment of the adsorbent (PNNL, Woods Hole Oceanographic Institution, University of Miami)
- Adsorbent durability and reusability (PNNL, University of Idaho)
- Adsorbent characterization, toxicity and biofouling studies (ORNL, PNNL, UI)
- Technology cost analyses and modeling (University of Texas–Austin)
- Green chemistry: Adsorbents prepared using marine shellfish waste (University of Alabama)
- Adsorbent deployment (PNNL, ORNL, MIT)
Uranium from terrestrial sources can last for approximately 100 years, according to Erich Schneider of the University of Texas–Austin. As terrestrial uranium becomes depleted, prices are likely to rise. “If we have technology to capture uranium from seawater, we can ensure that an essentially unlimited supply of the element becomes available if uranium prices go up in the future,” Schneider said.
In July, experts in uranium extraction from seawater will convene at University of Maryland–College Park for the International Conference on Seawater Uranium Recovery. They will further explore the potential of uranium from seawater to keep the world’s lights on.
Better renewable energy storage possible thanks to chemical conversions
An unexpected discovery has led to a rechargeable battery that’s as inexpensive as conventional car batteries, but has a much higher energy density. The new battery could become a cost-effective, environmentally friendly alternative for storing renewable energy and supporting the power grid.
A team based at the Department of Energy’s Pacific Northwest National Laboratory identified this energy storage gem after realizing the new battery works in a different way than they had assumed. The journal Nature Energy published a paper today that describes the battery.
“The idea of a rechargeable zinc-manganese battery isn’t new; researchers have been studying them as an inexpensive, safe alternative to lithium-ion batteries since the late 1990s,” said PNNL Laboratory Fellow Jun Liu, the paper’s corresponding author. “But these batteries usually stop working after just a few charges. Our research suggests these failures could have occurred because we failed to control chemical equilibrium in rechargeable zinc-manganese energy storage systems.”
After years of focusing on rechargeable lithium-ion batteries, researchers are used to thinking about the back-and-forth shuttle of lithium ions. Lithium-ion batteries store and release energy through a process called intercalation, which involves lithium ions entering and exiting microscopic spaces in between the atoms of a battery’s two electrodes.
This concept is so engrained in energy storage research that when PNNL scientists, collaborating with the University of Washington, started considering a low-cost, safe alternative to lithium-ion batteries ? a rechargeable zinc-manganese oxide battery ? they assumed zinc would similarly move in and out of that battery’s electrodes.
After a battery of tests, the team was surprised to realize their device was undergoing an entirely different process. Instead of simply moving the zinc ions around, their zinc-manganese oxide battery was undergoing a reversible chemical reaction that converted its active materials into entirely new ones.
Liu and his colleagues started investigating rechargeable zinc-manganese batteries because they are attractive on paper. They can be as inexpensive as the lead-acid batteries because they use abundant, inexpensive materials (zinc and manganese). And the battery’s energy density can exceed lead-acid batteries. The PNNL scientists hoped they could produce a better-performing battery by digging deeper into the inner workings of the zinc-manganese oxide battery.
So they built their own battery with a negative zinc electrode, a positive manganese dioxide electrode and a water-based electrolyte in between the two. They put small, button-sized test batteries through the wringer, repeatedly charging and discharging them. As others had found before them, their test battery quickly lost its ability to store energy after just a few charging cycles. But why?
To find out, they first performed a detailed chemical and structural analysis of the electrolyte and electrode materials. They were surprised to not find evidence of zinc interacting with manganese oxide during the battery’s charge and discharge processes, as they had initially expected would happen. The unexpected finding led them to wonder if the battery didn’t undergo a simple intercalation process as they had previously thought. Perhaps the zinc-manganese battery is less like a lithium-ion battery and more like the traditional lead-acid battery, which also relies on chemical conversion reactions.
To dig deeper, they examined the electrodes with several advanced instruments with a variety of scientific techniques, includingTransmission Electron Microscopy, Nuclear Magnetic Resonance and X-Ray Diffraction. The instruments used were located at both PNNL and the Environmental Molecular Sciences Laboratory (EMSL), a DOE Office of Science user facility located at PNNL. Combining these techniques revealed manganese oxide was reversibly reacting with protons from the water-based electrolyte, which created a new material, zinc hydroxyl sulfate.
Typically, zinc-manganese oxide batteries significantly lose storage capacity after just a few cycles. This happens because manganese from the battery’s positive electrode begins to sluff off, making the battery’s active material inaccessible for energy storage. But after some manganese dissolves into the electrolyte, the battery gradually stabilizes and the storage capacity levels out, though at a much lower level.
A simple fix
The team used the new knowledge to prevent this manganese sluff-off. Knowing the battery underwent chemical conversions, they determined the rate of manganese dissolution could be slowed down by increasing the electrolyte’s initial manganese concentration.
So they added manganese ions to the electrolyte in a new test battery and put the revised battery through another round of tests. This time around, the test battery was able to reach a storage capacity of 285 milliAmpere-hours per gram of manganese oxide over 5,000 cycles, while retaining 92 percent of its initial storage capacity.
“This research shows equilibrium needs to be controlled during a chemical conversion reaction to improve zinc-manganese oxide battery performance,” Liu said. “As a result, zinc-manganese oxide batteries could be a more viable solution for large-scale energy storage than the lithium-ion and lead-acid batteries used to support the grid today.”
The team will continue their studies of the zinc-manganese oxide battery’s fundamental operations. Now that they’ve learned the products of the battery’s chemical conversion reactions, they will move on to identify the various in-between steps to create those products. They will also tinker with the battery’s electrolyte to see how additional changes affect its operation.
Learn more: Unexpected discovery leads to a better battery
With inexpensive chemical base, variety of materials could be as limitless as proteins are
Researchers hoping to design new materials for energy uses have developed a system to make synthetic polymers — some would say plastics — with the versatility of nature’s own polymers, the ubiquitous proteins. Based on an inexpensive industrial chemical, these synthetic polymers might one day be used to create materials with functions as limitless as proteins, which are involved in every facet of life.
Reporting in Angewandte Chemie International Edition March 14, researchers reveal a method to produce polymers that mimic proteins in the versatility of their raw ingredients and how those ingredients link together to form a larger structure.
“Proteins are sequence-defined polymers and have a whole variety of exquisite functions,” said materials scientist Jay Grate of the Department of Energy’s Pacific Northwest National Laboratory. “But natural materials are unstable. That’s good for nature, but if we want stable, long-lasting materials, we need to make our own sequence-defined polymers.”
Stuff of life
Proteins are at the core of life: In living things, they are architect and engineer. They are the wrenches and machines that build an organism’s varied parts, building those parts out of other proteins of many sizes and shapes. They form the power plants in cells, run the plants, make energy and store energy. They make things grow, and are the bricks of growth as well.
Because of their versatility, proteins are some of researchers’ favorite tools. Many drugs are re-engineered proteins such as converted antibodies (for example, drugs whose names end in -mab). The problem, however, is that proteins are also short-lived. Nature designed them to be temporary and recyclable. Any environment proteins find themselves in is full of things — often other proteins — that break them down.
One way to get around these butchers is to design a material that behaves like proteins but is not actually protein. To that end, researchers are pursuing materials that mimic the building blocks of proteins — amino acids. Amino acids bestow on proteins their tremendous variety and versatility.
Those qualities are what plastic protein researchers are trying to emulate. Amino acids come in 20 or so variations. Each has the same backbone, from which juts a group of atoms called a side chain that gives the amino acid its particular chemical characteristic. The amino acid backbones snap together like beads on a string, the side chains arranged in a particular order for each protein.
But proteins aren’t floppy pearl necklaces. The beads fold in upon themselves to form structured objects. Some proteins end up looking like balls, some like capital Ys, others like olive wreaths.
These shapes come about because the side chains and the protein backbone stick to other side chains and backbone regions like Post-Its stick to one another. The folding and sticking are very specific, like origami, resulting in a particular structure rather than a tangled mess.
Grate needed three things to mimic proteins: raw components with a backbone that can support a large variety of side chains; the ability to put the side chains in a particular order; the stickiness, which chemists refer to as non-covalent bonds.
He had been working with an industrial chemical called cyanuric chloride for unrelated purposes, but his understanding of its chemical properties made him think it might be a good starting point. Cyanuric chloride is a molecule that has three convenient places it could be extended. Two of them can link together, like two people holding hands, to form the backbone. The third can house a side chain. All together, Grate called the resulting molecule a triazine-based polymer, or TZP for short.
Although such a polymer would be immune to protein-destroying entities, Grate expects other things in the environment such as bacteria will break it down, based on TZP’s chemical nature. So the material would last, but not forever.
Idea in hand, Grate and PNNL chemist Kai-For Mo had to develop a way to synthesize TZP. They made a variety of monomers by adding different side chains to cyanuric chloride, with each monomer a single building block analogous to an amino acid. For this study, they created five different side chains. Then they found they could add one monomer at a time relatively simply by changing the temperature at which they performed the chemical reactions, among other synthesis tricks.
After synthesizing polymers six monomers long, called a 6-mer in polymer parlance, the researchers verified their creations. They used analytical instruments to show that the polymers were the right size, had the right side chains, and the side chains were in the right order. They also synthesized a 12-mer to show this method works with longer polymers.
To see whether TZPs would fold in a manner analogous to proteins, PNNL computer scientist Michael Daily simulated small TZPs, singly and interacting with each other. A 6-mer folded neatly in half, forming a straight rod three monomers long and two monomers wide, like a hairpin. Similarly, two 3-mers lined up along each other, partially intertwined like a zipper.
The stickiness holding these “nanorods” together were non-covalent bonds between backbone atoms, the same types of bonds nature uses so that proteins take their proper shapes. And like protein structures, the TZP side chains were arranged in specific positions around the exterior of the rods formed by the backbone-backbone interactions.
The next step is to create a larger library of side chains, the count of which is ten so far. Then they must make longer polymers and show that they really do take useful shapes. Once researchers understand the rules for how to get specific shapes with TZPs that also assemble into larger structures, they can design materials with desired functions — for example, a membrane for a battery, a catalyst for a fuel cell, or even a therapeutic drug.
Nature’s figured it out already, how to best break down food into fuel. Now scientists have caught up, showing that fungi found in the guts of goats, horses and sheep could help fill up your gas tank too.
The researchers report in the journal Science on February 18 that these anaerobic gut fungi perform as well as the best fungi engineered by industry in their ability to convert plant material into sugars that are easily transformed into fuel and other products.
“Nature has engineered these fungi to have what seems to be the world’s largest repertoire of enzymes that break down biomass,” said Michelle O’Malley, lead author and professor of chemical engineering at the University of California, Santa Barbara.
These enzymes — tools made of protein — work together to break down stubborn plant material. The researchers found that the fungi adapt their enzymes to wood, grass, agricultural waste, or whatever scientists feed it. The findings suggest that industry could modify the gut fungi so that they produce improved enzymes that will outperform the best available ones, potentially leading to cheaper biofuels and bio-based products.
To make the finding, O’Malley drew upon two U.S. Department of Energy Office of Science (SC) User Facilities: the Environmental Molecular Science Laboratory at Pacific Northwest National Laboratory and the DOE Joint Genome Institute. O’Malley’s study is the first to result from a partnership between the two facilities called Facilities Integrating Collaborations for User Science or FICUS. The partnership allows scientists around the world to draw on capabilities at both SC user facilities to get a more complete understanding of fundamental scientific questions. O’Malley’s team also included scientists from PNNL, DOE JGI, the Broad Institute of MIT and Harvard, and Harper Adams University.
“By tapping the RNA sequencing and protein characterization capabilities at the respective facilities, we have advanced biofuel research in ways not otherwise possible,” said Susannah Tringe, DOE JGI deputy for User Programs. “This collaborative program was established to encourage and enable researchers to more easily integrate the expertise and capabilities of multiple user facilities into their research. FICUS offers a one-stop shopping approach for access to technology infrastructure that is rapidly becoming a model for collaboration.”
The latest omics technologies and transcontinental teams aside, these finding would not be possible without the most humble of substances.
The poop scoop
Companies want to turn biomass like wood, algae and grasses into fuel or chemicals. The problem: The matrix of complex molecules found in plant cell walls—lignin, cellulose and hemicellulose—combine to create the biological equivalent of reinforced concrete. When industry can’t break down this biomass, they pretreat it with heat or chemicals. Or throw it away. Both options add to the cost of the finished product.
Many farm animals have no trouble breaking down these same molecules, which inspired the research team to investigate. Their search started at the Santa Barbara Zoo and a stable in Massachusetts, where they collected manure from goats, horses and sheep. The fresher the sample, the better, for this barnyard bounty held live specimens of biomass-eating fungi.
As some of the world’s first nucleus-containing single-celled organisms, anaerobic gut fungi have been around since before the dinosaurs. Scientists have long known they play a significant role in helping herbivores digest plants. One reason has to do with the swarming behavior of some fungi. When the fungi reproduce, they release dozens of spores with tail-like appendages called flagella. These baby fungi swim around like tadpoles and find new food in the gut. They then trade tails for root-like structures called hyphae, which dig into plant material. Then foliage becomes food.
O’Malley and her colleagues knew the fungi’s hyphae excrete proteins, called enzymes, that break down plant material. Like tools in a toolbox, the more diverse the enzymes, the better the fungi can take apart plants and turn them into food. If industry can harness fungi with such a toolbox, it can more effectively break down raw biomass.
“Despite their fascinating biology, anaerobic gut fungi can be difficult to isolate and study,” said Scott Baker, EMSL’s science theme lead for Biosystem Dynamics and Design. “By utilizing the cutting-edge scientific capabilities at EMSL and JGI, O’Malley showed how the huge catalog of anaerobic gut fungi enzymes could advance biofuel production.”
To find that prize, the research team needed a map. Well, two maps. So armed with a scoop of poop, they took a deeper look into the gut fungi.
Fungi that are the cream of the crop
In the hands of scientists, a list of enzymes produced by gut fungi is the first step to unlocking their biofuel-producing potential. Like monks in a monastery copying religious texts, messenger RNA molecules transcribe the genetic information needed to make proteins, including enzymes. So the DOE JGI sequenced the mRNA of several gut fungi to come up with their transcriptome, which represents all the possible proteins they could make.
O’Malley compared this effort to re-assembling a map from its pieces, only without seeing the complete picture. Since not all proteins are enzymes, the researchers needed to cross check their map with another one. Enter the EMSL, where researchers created that second map that identified enzymes the fungi actually produced. This so-called proteome acted like landmarks that matched up to JGI’s map, highlighting the biomass-degrading enzymes in the transcriptome.
Together, the maps from JGI and EMSL pointed to the treasure trove of enzymes gut fungi can produce. Compared to the industrial varieties, which top out around 100 enzymes, gut fungi can produce hundreds more. Of note, the fungi produce enzymes better at breaking down a hemicellulose found in wood, called xylan. And when the scientists changed the fungi’s diet from canary grass to sugar, the fungi responded by changing the enzymes it produced. In other words, the fungi can update their enzyme arsenal on the fly.
“Because gut fungi have more tools to convert biomass to fuel, they could work faster and on a larger variety of plant material. That would open up many opportunities for the biofuel industry,” said O’Malley, whose study was funded by the U.S. Department of Energy Office of Science, the U.S. Department of Agriculture and the Institute for Collaborative Biotechnologies. Additionally, O’Malley was the recipient of a DOE Office of Science Early Career Award within the Biological and Environmental Research Program.
Learn more: Biofuel Tech Straight from the Farm
Energy storage system owners could see significant savings from a new flow battery technology that is projected to cost 60 percent less than today’s standard flow batteries.
The organic aqueous flow battery, described in a paper published in the journal Advanced Energy Materials, is expected to cost $180 per kilowatt-hour once the technology is fully developed. The lower cost is due to the battery’s active materials being inexpensive organic molecules, compared to the commodity metals used in today’s flow batteries.
“Moving from transition metal elements to synthesized molecules is a significant advancement because it links battery costs to manufacturing rather than commodity metals pricing” said Imre Gyuk, energy storage program manager for the Department of Energy’s Office of Electricity Delivery and Energy Reliability (OE), which funded this research.
“The battery’s water-based liquid electrolytes are also designed to be a drop-in replacement for current flow battery systems,” said PNNL materials scientist Wei Wang, one of the paper’s corresponding authors. “Current flow battery owners can keep their existing infrastructure, drain their more expensive electrolytes and replace them with PNNL’s electrolytes.”
Flow batteries generate power by pumping liquids from external tanks into a central stack. The tanks contain liquid electrolytes that store energy. When energy is needed, pumps move the electrolytes from both tanks into the stack where electricity is produced by an electrochemical reaction.
Both flow and solid batteries, such as the lithium-ion batteries that power most electric vehicles and smartphones today, were invented in the 1970s. Lithium-ion batteries can carry much more energy in a smaller space, making them ideal for mobile uses. The technology gained market acceptance quickly, for both mobile uses like cell phones and larger, stationary uses like supporting the power grid.
Lithium-ion batteries now make up about 70 percent of the world’s working, grid-connected batteries, according to data from DOE-OE’s Global Energy Storage Database. However issues with performance, safety and lifespan can limit the technology’s use for stationary energy storage.
Flow batteries, on the other hand, store their active chemicals separately until power is needed, greatly reducing safety concerns. Vanadium-based flow batteries have become more popular in recent years, especially after PNNL developed a new vanadium battery design in 2011 that increased storage capacity by 70 percent. Three different companies have licensed the technology behind PNNL’s vanadium design.
Nearly 79 percent of the world’s working flow batteries are vanadium-based, according to data from the Global Energy Storage Database. While vanadium chemistries are expected to be the standard for some time, future flow battery cost reductions will require less expensive alternatives such as organics.
Tried & tested
PNNL’s new flow battery features two main electrolytes: a methyl viologen anolyte (negative electrolyte) and a 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl, or 4-HO-TEMPO catholyte (positive electrolyte). A third, supporting electrolyte carries sodium chloride, whose chloride ions enable the battery to discharge electricity by shuffling electrons in the central stack.
“Using readily available materials makes our all-organic aqueous flow battery more sustainable and environmentally friendly. As a result, it can also make the renewable energy it stores and the power grid it supports greener,” Wei said.
To test the new battery design, Wang and his colleagues created a small, 600-milliwatt battery on a lab countertop. They repeatedly charged and then discharged the battery at various electric current densities, ranging from 20 to 100 milliAmperes per square centimeter. The test battery’s optimal performance was between 40 and 50 milliAmperes per square centimeter, where about 70 percent of the battery’s original voltage was retained. They also found the battery continued to operate well beyond 100 cycles.
Next, the team plans to make a larger version of their test battery that is able to store up to 5 kilowatts of electricity, which could support the peak load of a typical U.S. home. Other ongoing efforts include improving the battery’s cycling so it can retain more of its storage capacity longer.
Accurately forecasting future electricity needs is tricky, with sudden weather changes and other variables impacting projections minute by minute. Errors can have grave repercussions, from blackouts to high market costs.
Now, a new forecasting tool that delivers up to a 50 percent increase in accuracy and the potential to save millions in wasted energy costs has been developed by researchers at the Department of Energy’s Pacific Northwest National Laboratory.
Performance of the tool, called the Power Model Integrator, was tested against five commonly used forecasting models processing a year’s worth of historical power system data.
“For forecasts one-to-four hours out, we saw a 30-55 percent reduction in errors,” said Luke Gosink, a staff scientist and project lead at PNNL. “It was with longer-term forecasts — the most difficult to accurately make — where we found the tool actually performed best.”
The advancement is featured this week as a best conference paper in the power system modeling and simulation session at the IEEE Power & Energy Society general meeting in Denver.
A delicate balancing act
Fluctuations in energy demand throughout the day, season and year along with weather events and increased use of intermittent renewable energy from the sun and wind all contribute to forecasting errors. Miscalculations can be costly, put stress on power generators and lead to instabilities in the power system.
Grid coordinators have the daily challenge of forecasting the need for and scheduling exchanges of power to and from a number of neighboring entities. The sum of these future transactions, called the net interchange schedule, is submitted and committed to in advance. Accurate forecasting of the schedule is critical not only to grid stability, but a power purchaser’s bottom line.
“Imagine the complexity for coordinators at regional transmission organizations who must accurately predict electricity needs for multiple entities across several states,” Gosink noted. “Our aim was to put better tools in their hands.”
Five heads better than one
Currently, forecasters rely on a combination of personal experience, historical data and often a preferred forecasting model. Each model tends to excel at capturing certain grid behavior characteristics, but not necessarily the whole picture. To address this gap, PNNL researchers theorized that they could develop a method to guide the selection of an ensemble of models with the ideal, collective set of attributes in response to what was occurring on the grid at any given moment.
First, the team developed a statistical framework capable of guiding an iterative process to assemble, design, evaluate and optimize a collection of forecasting models. Researchers then used this patent-pending framework to evaluate and fine tune a set of five forecasting methods that together delivered optimal results.
The resulting Power Model Integrator tool has the ability to adaptively combine the strengths of different forecasting models continuously and in real time to address a variety scenarios that impact electricity use, from peak periods during the day to seasonal swings. To do this, the tool accesses short- and long-term trends on the grid as well as the historical forecasting performance of the individual and combined models. Minute by minute, the system adapts to and accounts for this information to form the best aggregated forecast possible at any given time.