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
Researchers have successfully turned carbon dioxide into solid rock by injecting it into ancient lava flows
For the first time, scientists have injected carbon dioxide into ancient lava flows and watched it solidify, demonstrating that capturing carbon dioxide from the atmosphere or a power plant smokestack and safely storing it underground may be a realistic way to help reduce greenhouse gas emissions to tackle climate change, according to research published Friday.
Scientists working at the Wallula Basalt Pilot Project in Washington State turned liquefied carbon dioxide into solid rock by injecting the gas into basalt formations. Over a span of about two years, the carbon dioxide solidified into a mineral called ankerite, according to the study conducted by Pacific Northwest National Laboratory researchers. The research was published in the journal Environmental Science and Technology.
“This study further supports the idea that one of the major rock types on the planet—basalts—can be used to store carbon dioxide permanently and safely,” said study lead author Pete McGrail, a carbon dioxide and climate change researcher at PNNL.
Carbon capture and storage may be critical to helping prevent global warming from exceeding 2°C (3.6°F), either by capturing emissions from their source or by directly removing carbon dioxide from the atmosphere, according to the Intergovernmental Panel on Climate Change.
But scientists worry that storing captured carbon underground as a liquid or a gas may not be safe because stored carbon dioxide could explosively leak into the atmosphere through fissures in the earth or be exposed to terrorism risk, creating a climate catastrophe.
To solve that problem, researchers have been studying ways to store carbon dioxide underground as a solid, especially in basalt formations.
Basalt is a volcanic rock that makes up roughly 70 percent of the earth’s surface. When it is exposed to carbon dioxide and water, a chemical reaction occurs, converting the gas to a chalk-like solid material. Scientists previously thought the chemical reaction would take thousands of years to occur, but new research shows it can happen within a few years.
“Basalt storage is unique in the geologic sequestration of carbon dioxide because the principal trapping mechanism is a chemical reaction that locks the carbon dioxide away as a carbonate mineral that can never leak or return to the atmosphere,” McGrail said.
Earlier this year, researchers at the CarbFix project in Iceland were able to pump a geothermal power plant’s carbon dioxide-rich volcanic gases into deep underground but recently formed basalt formations and chemically solidify them in about two years.
Rutgers professor Ashutosh Goel invents way to contain radioactive iodine
How do you handle nuclear waste that will be radioactive for millions of years, keeping it from harming people and the environment?
It isn’t easy, but Rutgers researcher Ashutosh Goel has discovered ways to immobilize such waste – the offshoot of decades of nuclear weapons production – in glass and ceramics.
Goel, an assistant professor in the Department of Materials Science and Engineering, is the primary inventor of a new method to immobilize radioactive iodine in ceramics at room temperature. He’s also the principal investigator (PI) or co-PI for six glass-related research projects totaling $6.34 million in federal and private funding, with $3.335 million going to Rutgers.
“Glass is a perfect material for immobilizing the radioactive wastes with excellent chemical durability,” said Goel, who works in the School of Engineering. Developing ways to immobilize iodine-129, which is especially troublesome, is crucial for its safe storage and disposal in underground geological formations.
The half-life of iodine-129 is 15.7 million years, and it can disperse rapidly in air and water, according to the U.S. Environmental Protection Agency. If it’s released into the environment, iodine will linger for millions of years. Iodine targets the thyroid gland and can increase the chances of getting cancer.
Among Goel’s major funders is the U.S. Department of Energy (DOE), which oversees one of the world’s largest nuclear cleanups following 45 years of producing nuclear weapons. The national weapons complex once had 16 major facilities that covered vast swaths of Idaho, Nevada, South Carolina, Tennessee and Washington state, according to the DOE.
The agency says the Hanford site in southeastern Washington, which manufactured more than 20 million pieces of uranium metal fuel for nine nuclear reactors near the Columbia River, is its biggest cleanup challenge.
Hanford plants processed 110,000 tons of fuel from the reactors. Some 56 million gallons of radioactive waste – enough to fill more than 1 million bathtubs – went to 177 large underground tanks. As many as 67 tanks – more than one third – are thought to have leaked, the DOE says. The liquids have been pumped out of the 67 tanks, leaving mostly dried solids.
The Hanford cleanup mission commenced in 1989, and construction of a waste treatment plant for the liquid radioactive waste in tanks was launched a decade later and is more than three-fifths finished.
“What we’re talking about here is highly complex, multicomponent radioactive waste which contains almost everything in the periodic table,” Goel said. “What we’re focusing on is underground and has to be immobilized.”
Goel, a native of Punjab state in northern India, earned a doctorate in glasses and glass-ceramics from the University of Aveiro in Portugal in 2009 and was a postdoctoral researcher there. He worked as a “glass scientist” at the Pacific Northwest National Laboratory in 2011 and 2012, and then as a senior scientist at Sterlite Technologies Ltd. in India before joining the Rutgers faculty in January 2014.
The six projects he’s leading or co-leading are funded by the DOE Office of River Protection, National Science Foundation and Corning Inc., with collaborators from Washington State University, University of North Texas and Pacific Northwest National Laboratory.
One of his inventions involves mass producing chemically durable apatite minerals, or glasses, to immobilize iodine without using high temperatures. A second innovation deploys synthesizing apatite minerals from silver iodide particles. He’s also studying how to immobilize sodium and alumina in high-level radioactive waste in borosilicate glasses that resist crystallization.
At the Hanford site, creating glass with radioactive waste is expected to start in around 2022 or 2023, Goel said, and “the implications of our research will be much more visible by that time.”
“It depends on its composition, how complex it is and what it contains,” Goel said. “If we know the chemical composition of the nuclear waste coming out from those plants, we can definitely work on it.”
Technology converts human waste into bio-based fuel
It may sound like science fiction, but wastewater treatment plants across the United States may one day turn ordinary sewage into biocrude oil, thanks to new research at the Department of Energy’s Pacific Northwest National Laboratory.
The technology, hydrothermal liquefaction, mimics the geological conditions the Earth uses to create crude oil, using high pressure and temperature to achieve in minutes something that takes Mother Nature millions of years. The resulting material is similar to petroleum pumped out of the ground, with a small amount of water and oxygen mixed in. This biocrude can then be refined using conventional petroleum refining operations.
Wastewater treatment plants across the U.S. treat approximately 34 billion gallons of sewage every day. That amount could produce the equivalent of up to approximately 30 million barrels of oil per year. PNNL estimates that a single person could generate two to three gallons of biocrude per year.
Sewage, or more specifically sewage sludge, has long been viewed as a poor ingredient for producing biofuel because it’s too wet. The approach being studied by PNNL eliminates the need for drying required in a majority of current thermal technologies which historically has made wastewater to fuel conversion too energy intensive and expensive. HTL may also be used to make fuel from other types of wet organic feedstock, such as agricultural waste.
What we flush can be converted into a biocrude oil with properties very similar to fossil fuels. PNNL researchers have worked out a process that does not require that sewage be dried before transforming it under heat and pressure to biocrude. Metro Vancouver in Canada hopes to build a demonstration plant.
Using hydrothermal liquefaction, organic matter such as human waste can be broken down to simpler chemical compounds. The material is pressurized to 3,000 pounds per square inch — nearly one hundred times that of a car tire. Pressurized sludge then goes into a reactor system operating at about 660 degrees Fahrenheit. The heat and pressure cause the cells of the waste material to break down into different fractions — biocrude and an aqueous liquid phase.
“There is plenty of carbon in municipal waste water sludge and interestingly, there are also fats,” said Corinne Drennan, who is responsible for bioenergy technologies research at PNNL. “The fats or lipids appear to facilitate the conversion of other materials in the wastewater such as toilet paper, keep the sludge moving through the reactor, and produce a very high quality biocrude that, when refined, yields fuels such as gasoline, diesel and jet fuels.”
In addition to producing useful fuel, HTL could give local governments significant cost savings by virtually eliminating the need for sewage residuals processing, transport and disposal.
Simple and efficient
“The best thing about this process is how simple it is,” said Drennan. “The reactor is literally a hot, pressurized tube. We’ve really accelerated hydrothermal conversion technology over the last six years to create a continuous, and scalable process which allows the use of wet wastes like sewage sludge.”
An independent assessment for the Water Environment & Reuse Foundation calls HTL a highly disruptive technology that has potential for treating wastewater solids. WE&RF investigators noted the process has high carbon conversion efficiency with nearly 60 percent of available carbon in primary sludge becoming bio-crude. The report calls for further demonstration, which may soon be in the works.
Demonstration Facility in the Works
PNNL has licensed its HTL technology to Utah-based Genifuel Corporation, which is now working with Metro Vancouver, a partnership of 23 local authorities in British Columbia, Canada, to build a demonstration plant.
“Metro Vancouver hopes to be the first wastewater treatment utility in North America to host hydrothermal liquefaction at one of its treatment plants,” said Darrell Mussatto, chair of Metro Vancouver’s Utilities Committee. “The pilot project will cost between $8 to $9 million (Canadian) with Metro Vancouver providing nearly one-half of the cost directly and the remaining balance subject to external funding.”
Once funding is in place, Metro Vancouver plans to move to the design phase in 2017, followed by equipment fabrication, with start-up occurring in 2018.
“If this emerging technology is a success, a future production facility could lead the way for Metro Vancouver’s wastewater operation to meet its sustainability objectives of zero net energy, zero odours and zero residuals,” Mussatto added.
Nothing left behind
In addition to the biocrude, the liquid phase can be treated with a catalyst to create other fuels and chemical products. A small amount of solid material is also generated, which contains important nutrients. For example, early efforts have demonstrated the ability to recover phosphorus, which can replace phosphorus ore used in fertilizer production.
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.