Turning Forests Into Fuel: Promise and Limits of Biomass Energy in Northeastern U.S.

But the report also has sharp caveats: The potential for forest biomass varies widely within the region, and forest resources must be carefully managed to protect the other important services and goods they provide. Under the right circumstances, however, the report found that forest biomass can provide a domestic energy resource, create local jobs, and provide incentives to forest owners.

"In targeted applications, the heat generated by locally-grown biomass can reduce dependence on fossil fuels and support local economies," said Dr. Charles D. Canham, a forest ecologist at the Cary Institute and co-author of the report."But each forested landscape is different, and regional variation in forest conditions and energy infrastructure means there is no one-size-fits-all solution."

The report analyzed U.S.D.A. Forest Service Forest data from Connecticut, Maine, Massachusetts, New Hampshire, New York, Pennsylvania, Rhode Island, and Vermont.

It found that using forest biomass for heat in the region was far more effective in replacing liquid fossil fuels than converting it to cellulosic ethanol for road transport. Biomass burned in combined heat and power plants reduced fossil fuel use more than five times more effectively than substituting gasoline with cellulosic ethanol.

Under best-case scenarios, however, the energy generated sustainably from forest biomass in the Northeast could replace only 1.4% of the region's total fossil fuel energy. But for some states, biomass energy could be much more compelling when replacing fossil fuel use in certain sectors.

"Maine and New Hampshire show the greatest potential for forest biomass energy," said Dr. Thomas Buchholz, a researcher at the University of Vermont's Carbon Dynamics Lab and co-author on the report."Our study found that New Hampshire could replace as much as 84 percent of its liquid fossil fuel dependence in the industrial and commercial heating sector, and Maine could replace 49 percent of its liquid fossil fuel dependence in the home-heating sector."

But the report cautioned that utmost care must be observed in all parts of the region.

"There is a misconception that Northeastern forestland is a vast, untapped resource," Canham commented."This is simply not true. Unrealistic growth in biomass energy facilities could lead to serious degradation of forest resources. While forest biomass is part of the renewable energy toolkit, it is by no means a panacea."

"Forest biomass can be an important element of a low-carbon energy future," added contributing author Dr. Steven Hamburg of Environmental Defense Fund."But we'll need ongoing scientific oversight to ensure it is done sustainably."

Full report: Forest Biomass and Bioenergy: Opportunities and Constraints in the Northeastern United States

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Paperweight for Platinum: Bracing Catalyst in Material Makes Fuel Cell Component Work Better and Last Longer

"Fuel cells are an important area of energy technology, but cost and durability are big challenges," said chemist Jun Liu."The unique structure of this material provides much needed stability, good electrical conductivity and other desired properties."

Liu and his colleagues at the Department of Energy's Pacific Northwest National Laboratory, Princeton University in Princeton, N.J., and Washington State University in Pullman, Wash., combined graphene, a one-atom-thick honeycomb of carbon with handy electrical and structural properties, with metal oxide nanoparticles to stabilize a fuel cell catalyst and make it better available to do its job.

"This material has great potential to make fuel cells cheaper and last longer," said catalytic chemist Yong Wang, who has a joint appointment with PNNL and WSU."The work may also provide lessons for improving the performance of other carbon-based catalysts for a broad range of industrial applications."

Muscle Metal Oxide

Fuel cells work by chemically breaking down oxygen and hydrogen gases to create an electrical current, producing water and heat in the process. The centerpiece of the fuel cell is the chemical catalyst -- usually a metal such as platinum -- sitting on a support that is often made of carbon. A good supporting material spreads the platinum evenly over its surface to maximize the surface area with which it can attack gas molecules. It is also electrically conductive.

Fuel cell developers most commonly use black carbon -- think pencil lead -- but platinum atoms tend to clump on such carbon. In addition, water can degrade the carbon away. Another support option is metal oxides -- think rust -- but what metal oxides make up for in stability and catalyst dispersion, they lose in conductivity and ease of synthesis. Other researchers have begun to explore metal oxides in conjunction with carbon materials to get the best of both worlds.

As a carbon support, Liu and his colleagues thought graphene intriguing. The honeycomb lattice of graphene is porous, electrically conductive and affords a lot of room for platinum atoms to work. First, the team crystallized nanoparticles of the metal oxide known as indium tin oxide -- or ITO -- directly onto specially treated graphene. Then they added platinum nanoparticles to the graphene-ITO and tested the materials.

Platinumweight

The team viewed the materials under high-resolution microscopes at EMSL, DOE's Environmental Molecular Sciences Laboratory on the PNNL campus. The images showed that without ITO, platinum atoms clumped up on the graphene surface. But with ITO, the platinum spread out nicely. Those images also showed catalytic platinum wedged between the nanoparticles and the graphene surface, with the nanoparticles partially sitting on the platinum like a paperweight.

To see how stable this arrangement was, the team performed theoretical calculations of molecular interactions between the graphene, platinum and ITO. This number-crunching on EMSL's Chinook supercomputer showed that the threesome was more stable than the metal oxide alone on graphene or the catalyst alone on graphene.

But stability makes no difference if the catalyst doesn't work. In tests for how well the materials break down oxygen as they would in a fuel cell, the triple-threat packed about 40% more of a wallop than the catalyst alone on graphene or the catalyst alone on other carbon-based supports such as activated carbon.

Last, the team tested how well the new material stands up to repeated usage by artificially aging it. After aging, the tripartite material proved to be three times as durable as the lone catalyst on graphene and twice as durable as on commonly used activated carbon. Corrosion tests revealed that the triple threat was more resistant than the other materials tested as well.

The team is now incorporating the platinum-ITO-graphene material into experimental fuel cells to determine how well it works under real world conditions and how long it lasts.

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Microbiologists Aim to Optimize Bio-Ethanol Production

The age of diesel and gasoline is approaching its inevitable end. However, one of the alternatives, bio-ethanol made from plant material by way of microorganism fermentation, is under attack. Until now, bio-ethanol has been produced from crops such as wheat, sugar cane or corn, or more accurately, from the sugar these crops contain in the form of starch. However, when field crops are used for the production of bio-ethanol, they are no longer available as food. Researchers at the TUM Department of Microbiology are working on a solution to this dilemma. The idea: Make the sugar stored in the stems and leaves of plants in the form of cellulose available for bio-ethanol production."It is our goal to take the cellulose, which has so far hardly been used, and turn it into sugar on an industrial scale, which can then be processed to bio-ethanol," says microbiologist Dr. Wolfgang Schwarz.

But it is not that simple. As the main constituent of plant cell walls, cellulose is responsible for the stability of the plant during growth -- and it is therefore extremely sturdy. Sugar molecules form cellulose molecules, which are connected in robust chains to form extremely resilient fibers. Breaking down the stable cellulose into sugar is difficult. Luckily, nature provides enzymes that can do just that. They are found in bacteria, for instance, that live in the stomachs of cows. In these natural"bio-reactors" they help digest grass and release the sugar. However, the bacteria take a very long time to break down the cellulose. Before cellulose can be transformed into bio-fuel in an efficient and cost-effective way on an industrial scale, the process must improve significantly.

The TUM Department of Microbiology has taken on this task. On the one hand its scientists search through nature's immense microbial diversity for as yet unknown cellulose-degrading enzymes. On the other hand they are isolating new"cellulose-eating" germs from nature in order to examine them more closely. Dr. Schwarz's work group is now taking a closer look at the most promising of these bacteria,Clostridium thermocellum. This soil bacterium has altogether over 70 enzymes that it uses to degrade different parts of plant cell walls. Thanks to this"toolbox" the bacterium can adapt perfectly to its environment. Depending on whether it lives in straw, leaves or waste wood,C. thermocellumproduces a different, effective enzyme complex on its surface to degrade the cellulose.

The TUM researchers are now testing this principle in the lab. They want to use the bacterium's toolbox to find ideal enzyme combinations for the industrial degradation of cellulose. To do this they firstly identified the most powerful enzymes and generated them in a test tube. These components were then combined to produce multiple variations, the best of which were selected by the microbiologists. Doctoral candidate Jan Krauss spent three years working on this:"We are now optimizing the most effective combinations for industrial use. Our ultimate goal is to develop a specialized degradation tool for every individual plant waste material containing cellulose. With a bit of luck we will find the perfect enzyme mixtures, which can then become established in bio-ethanol production facilities."

With this research program the TUM scientists are in sync with current industrial trends. Süd-Chemie AG is building a pilot plant in Straubing to convert the biogenic residual product straw into ethanol.

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'Tall Order' Sunlight-to-Hydrogen System Works, Neutron Analysis Confirms

Photosynthesis, the natural process carried out by plants, algae and some bacterial species, converts sunlight energy into chemical energy and sustains much of the life on earth. Researchers have long sought inspiration from photosynthesis to develop new materials to harness the sun's energy for electricity and fuel production.

In a step toward synthetic solar conversion systems, the ORNL researchers have demonstrated and confirmed with small-angle neutron scattering analysis that light harvesting complex II (LHC-II) proteins can self-assemble with polymers into a synthetic membrane structure and produce hydrogen.

The researchers envision energy-producing photoconversion systems similar to photovoltaic cells that generate hydrogen fuel, comparable to the way plants and other photosynthetic organisms convert light to energy.

"Making a, self-repairing synthetic photoconversion system is a pretty tall order. The ability to control structure and order in these materials for self-repair is of interest because, as the system degrades, it loses its effectiveness," ORNL researcher Hugh O'Neill, of the lab's Center for Structural Molecular Biology, said.

"This is the first example of a protein altering the phase behavior of a synthetic polymer that we have found in the literature. This finding could be exploited for the introduction of self-repair mechanisms in future solar conversion systems," he said.

Small angle neutron scattering analysis performed at ORNL's High Flux Isotope Reactor (HFIR) showed that the LHC-II, when introduced into a liquid environment that contained polymers, interacted with polymers to form lamellar sheets similar to those found in natural photosynthetic membranes.

The ability of LHC-II to force the assembly of structural polymers into an ordered, layered state -- instead of languishing in an ineffectual mush -- could make possible the development of biohybrid photoconversion systems. These systems would consist of high surface area, light-collecting panes that use the proteins combined with a catalyst such as platinum to convert the sunlight into hydrogen, which could be used for fuel.

The research builds on previous ORNL investigations into the energy-conversion capabilities of platinized photosystem I complexes -- and how synthetic systems based on plant biochemistry can become part of the solution to the global energy challenge.

"We're building on the photosynthesis research to explore the development of self-assembly in biohybrid systems. The neutron studies give us direct evidence that this is occurring," O'Neill said.

The researchers confirmed the proteins' structural behavior through analysis with HFIR's Bio-SANS, a small-angle neutron scattering instrument specifically designed for analysis of biomolecular materials.

"Cold source" neutrons, in which energy is removed by passing them through cryogenically chilled hydrogen, are ideal for studying the molecular structures of biological tissue and polymers.

The LHC-II protein for the experiment was derived from a simple source: spinach procured from a local produce section, then processed to separate the LHC-II proteins from other cellular components. Eventually, the protein could be synthetically produced and optimized to respond to light.

O'Neill said the primary role of the LHC-II protein is as a solar collector, absorbing sunlight and transferring it to the photosynthetic reaction centers, maximizing their output."However, this study shows that LHC-II can also carry out electron transfer reactions, a role not known to occur in vivo," he said.

The research team, which came from various laboratory organizations including its Chemical Sciences Division, Neutron Scattering Sciences Division, the Center for Structural Molecular Biology and the Center for Nanophase Materials Sciences, consisted of O'Neill, William T. Heller, and Kunlun Hong, all of ORNL; Dimitry Smolensky of the University of Tennessee; and Mateus Cardoso, a former postdoctoral researcher at ORNL now of the Laboratio Nacional de Luz Sincrotron in Brazil.

"That's one of the nice things about working at a national laboratory. Expertise is available from a variety of organizations," O'Neill said.

The work, published in the journalEnergy& Environmental Science, was supported with Laboratory-Directed Research and Development funding. HFIR is supported by the DOE Office of Science.

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Cheap, Clean Ways to Produce Hydrogen for Use in Fuel Cells? A Dash of Disorder Yields a Very Efficient Photocatalyst

Their photocatalyst, which accelerates light-driven chemical reactions, is the first to combine durability and record-breaking efficiency, making it a contender for use in several clean-energy technologies.

It could offer a pollution-free way to produce hydrogen for use as an energy carrier in fuel cells. Fuel cells have been eyed as an alternative to combustion engines in vehicles. Molecular hydrogen, however, exists naturally on Earth only in very low concentrations. It must be extracted from feedstocks such as natural gas or water, an energy-intensive process that is one of the barriers to the widespread implementation of the technology.

"We are trying to find better ways to generate hydrogen from water using sunshine," says Samuel Mao, a scientist in Berkeley Lab's Environmental Energy Technologies Division who led the research."In this work, we introduced disorder in titanium dioxide nanocrystals, which greatly improves its light absorption ability and efficiency in producing hydrogen from water."

Mao is the corresponding author of a paper on this research that was published online Jan. 20, 2011 inScience Expresswith the title"Increasing Solar Absorption for Photocatalysis with Black, Hydrogenated Titanium Dioxide Nanocrystals." Co-authoring the paper with Mao are fellow Berkeley Lab researchers Xiaobo Chen, Lei Liu, and Peter Yu.

Mao and his research group started with nanocrystals of titanium dioxide, which is a semiconductor material that is used as a photocatalyst to accelerate chemical reactions, such as harnessing energy from the sun to supply electrons that split water into oxygen and hydrogen. Although durable, titanium dioxide isn't a very efficient photocatlayst. Scientists have worked to increase its efficiency by adding impurities and making other modifications.

The Berkeley Lab scientists tried a new approach. In addition to adding impurities, they engineered disorder into the ordinarily perfect atom-by-atom lattice structure of the surface layer of titanium dioxide nanocrystals. This disorder was introduced via hydrogenation.

The result is the first disorder-engineered nanocrystal. One transformation was obvious: the usually white titanium dioxide nanocrystals turned black, a sign that engineered disorder yielded infrared absorption.

The scientists also surmised disorder boosted the photocatalyst's performance. To find out if their hunch was correct, they immersed disorder-engineered nanocrystals in water and exposed them to simulated sunlight. They found that 24 percent of the sunlight absorbed by the photocatalyst was converted into hydrogen, a production rate that is about 100 times greater than the yields of most semiconductor photocatalysts.

In addition, their photocatalyst did not show any signs of degradation during a 22-day testing period, meaning it is potentially durable enough for real-world use.

Its landmark efficiency stems largely from the photocatalyst's ability to absorb infrared light, making it the first titanium dioxide photocatalyst to absorb light in this wavelength. It also absorbs visible and ultraviolet light. In contrast, most titanium dioxide photocatalysts only absorbs ultraviolet light, and those containing defects may absorb visible light. Ultraviolet light accounts for less than ten percent of solar energy.

"The more energy from the sun that can be absorbed by a photocatalyst, the more electrons can be supplied to a chemical reaction, which makes black titanium dioxide a very attractive material," says Mao, who is also an adjunct engineering professor in the University of California at Berkeley.

The team's intriguing experimental findings were further elucidated by theoretical physicists Peter Yu and Lei Liu, who explored how jumbling the latticework of atoms on the nanocrystal's surface via hydrogenation changes its electronic properties. Their calculations revealed that disorder, in the form of lattice defects and hydrogen, makes it possible for incoming photons to excite electrons, which then jump across a gap where no electron states can exist. Once across this gap, the electrons are free to energize the chemical reaction that splits water into hydrogen and oxygen.

"By introducing a specific kind of disorder, mid-gap electronic states are created accompanied by a reduced band gap," says Yu, who is also a professor in the University of California at Berkeley's Physics Department."This makes it possible for the infrared part of the solar spectrum to be absorbed and contribute to the photocatalysis."

This research was supported by the Department of Energy's Office of Energy Efficiency and Renewable Energy. Transmission electron microscopy imaging used to study the nanocrystals at the atomic scale was performed at the National Center for Electron Microscopy, a national user facility located at Berkeley Lab.

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