Colleen IversenColleen Iversen's outdoor childhood sparked underground research

As the daughter of hydrogeologists, Colleen Iversen was raised to explore mountains and caves. Disguised as family vacations, trips to study rocks and groundwater movement fueled her love of nature and the need to study and preserve it.

Years later, following studies at Hope College and the University of Notre Dame that culminated in a doctorate in Ecology and Evolutionary Biology at the University of Tennessee in Knoxville, Iversen is a staff scientist at Oak Ridge National Laboratory. But instead of studying hydrogeology like her parents, Iversen is an ecosystem ecologist focusing her research on how climate change affects carbon and nutrient cycling in roots and soil systems.

“Fine plant roots are an important component of ecosystem carbon and nutrient cycling,” Iversen says. “The production of fine roots can contribute one-third of annual plant production, and roots are responsible for plant uptake of nutrients and water. Therefore, they directly mediate the survival and growth of plants that take up atmospheric CO2 via photosynthesis. The death and decomposition of fine roots also contribute to the accumulation of carbon and nutrients in the soil.”

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At JBEI, Seema Singh and Blake Simmons lead reasearch on blending biofuel feedstocks.Vintage biofuel: a Joint Bioenergy Institute blend

Making a fine wine often means combining juices from just the right assortment of different grapes. Scientists at DOE’s Joint Bioenergy Institute (JBEI), led by DOE's Lawrence Berkeley National Laboratory (Berkeley Lab) and working with colleagues from Idaho National Laboratory (INL), have taken the first steps toward blending biofuels in the same way. Someday soon, biofuel blends could be tailored for specific uses, whether in cars, trucks, ships, trains, or jet planes.

Like wines, biofuels result from sugar fermentation by microbes. Unlike sugar from grapes, however, the sugars in fibrous lignocellulosic biomass are complex polysaccharides, deeply embedded within recalcitrant plant material called lignin. Pretreatment with ionic liquids – environmentally benign organic salts that can be substituted for volatile organic solvents in many chemical processes – helps break apart the complex lignocellulose, then hydrolyzes the polysaccharides into more easily fermented sugars that microbes can handle.

Another challenge in dealing with lignocellulosic feedstocks is their low density – both in terms of weight versus volume and the amount of energy they store in that volume. Bulky straw and wood, for example, store far less energy and are far more awkward to transport than coal or crude oil. Researchers at INL have been leaders in finding ways to increase the energy density of biomass feedstocks and make delivery to refineries more economical.

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See also…

DOE Pulse
  • Number 385  |
  • April 1, 2013
  • Quarks' spins dictate their location in the proton

    In a proton, quarks with spin pointed in the up direction (red and blue) tend to gather in the left half of the proton as seen by the incoming electron, whereas down-spinning quarks (green) tended to gather in the right half of the proton. A successful measurement of the distribution of quarks that make up protons conducted at DOE's Jefferson Lab has found that a quark's spin can predict its general location inside the proton. Quarks with spin pointed in the up direction will congregate in the left half of the proton, while down-spinning quarks hang out on the right. The research also confirms that scientists are on track to the first-ever three-dimensional inside view of the proton.

    The proton lies at the heart of every atom that builds our visible universe, yet scientists are still struggling to obtain a detailed picture of how it is composed of its primary building blocks: quarks and gluons. Too small to see with ordinary microscopes, protons and their quarks and gluons are instead illuminated by particle accelerators. At Jefferson Lab, the CEBAF accelerator directs a stream of electrons into protons, and huge detectors then collect information about how the particles interact.

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  • Adding natural elements to synthetic catalysts speeds hydrogen production

    Scientists at Pacific Northwest National Laboratory showed that adding a carbon-nitrogen bond in just the right spot on the catalyst's outer edge can cause the catalyst to work far faster. By grafting features analogous to those in Mother Nature's catalysts onto a synthetic catalyst, scientists at DOE's Pacific Northwest National Laboratory created a hydrogen production catalyst that is 40% faster than the unmodified catalyst. The team discovered that adding small molecules made from amino acids in the outer coordination sphere increased the speed without requiring additional energy to drive the catalyst. The outer coordination sphere is part of the catalyst's scaffolding. It creates channels used by electrons and protons to reach the heart of the catalyst, where the reaction occurs. This study graces the cover of Chemistry: A European Journal.

    To build energy storage for wind farms, long-lasting electric car batteries, and new affordable fuels, scientists must create never-before-seen catalysts that are both fast and durable. These catalysts must be based on earth-abundant metals, like nickel and iron. This study provides foundational information that could, one day, help design and synthesize these catalysts. 

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  • Computational study of ionic liquids illuminates detailed CO2 interactions

    The η2 and η1-CT structures of the acetate-CO2 complex.

    Ionic liquids (ILs), which can be thought of as salts that are molten at room temperature, are being studied for use as part of CO2 adsorption and/or separation technologies. These applications depend on having strong interactions between the CO2 and the ions of the IL. In order for significant advances to occur in this area of research, the interaction between the CO2 and each IL must be understood and described with accuracy. Computational methods are used to describe these interactions on a molecular level.

    National Energy Technology Laboratory scientist Jan Steckel has used a variety of methods to elucidate the complex nature of the interactions between CO2 and acetate ion. The results of this study were published recently in the Journal of Physical Chemistry A. The acetate ion was chosen because it is representative of the anions used in many ILs currently under investigation as CO2 sorbents or as part of a separation technology.

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  • Reinventing the power line cable

    An interior glimpse of centrifugal atomization apparatus constructed at the Ames Laboratory, showing the spinning disc. The disc will intercept a stream of molten calcium and fling off a spray of fine droplets. The droplets, less than one hundred microns in diameter, solidify as they cool and are captured in a quenching bath of hydrocarbon oil, which prevents the calcium from reacting.

    Materials scientists at the U.S. Department of Energy’s Ames Laboratory are researching ways to perfect a next generation power cable made of an aluminum and calcium composite. Cables of this composite will be lighter and stronger, and its conductivity at least 10 percent better than existing materials for DC power, a growing segment of global power transmission. The steel-cored aluminum cables used today have been the industry standard for nearly half a century, but are a classic example of engineering “trade-offs.”

    “Pure aluminum power cable would be the perfect answer. Aluminum is light, highly conductive, easy to work with, and inexpensive. Its big failing is that it’s too weak. If you put pure aluminum cables up, they would sag right to the ground,” says Ames Laboratory materials scientist Alan Russell.

    The steel core is necessary to hold them aloft, but adds weight and a host of difficulties in manufacturing, spooling, erecting, and maintaining traditional cable. 

    “The amount that aluminum and steel deform under elastic loading is different so you start to have problems with the fact you’ve got two very dissimilar metals clamped together. Then you add ice, plus wind, plus the occasional hurricane or tornado,” said Russell, “and a cable of one uniform material begins to look immensely appealing.”

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