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Ali Javey and Zhiyong Fan at Berkeley Lab have invented a method for growing highly regular, single-crystalline nanopillar arrays of optically active semiconductors to produce efficient, 3D solar cells. The 3D configuration allows for less stringent requirements in terms of the quality and purity of the input materials, providing for a reduction in cost compared to other solar cell configurations.
The Berkeley Lab invention uses a "vapor-liquid-solid" process that produces large-scale modules of dense, ordered arrays of nanopillars. Researchers tested their method by producing a solar cell composed of electron-rich CdS nanopillars embedded in a polycrystalline thin film of hole-rich CdTe. The efficiency of this prototype was 6%, which may be readily improved with concentrators, more transparent top contacts, and optimization of the nanopillar dimensions. The technology was also used to produce solar modules on flexible substrates that offer more efficient light absorption and carrier collection than rigid arrays. These flexible arrays could be bent repeatedly without damage or loss of cell performance.
The ability to deposit single-crystalline semiconductors on support substrates is crucial in the development of efficient photovoltaics. However, the process, usually performed with epitaxial crystal growth, has been expensive and inefficient. In addition, when amorphous substrates have been used to grow single-crystalline nanowires non-epitaxially, at less expense, the nanowires have varied in size, alignment, and density giving the resulting arrays a limited efficiency of approximately 0.5%. The Berkeley Lab technology offers a significant improvement in efficiency and manufacturability.
Researchers at Argonne National Laboratory have developed a low-cost process that accelerates biological methane production rates at least fivefold — the Enhanced Renewable Methane Production System. The system could enhance biological methane production at wastewater treatment plants, farms, and landfills. This system addresses one of the largest barriers to the expansion of renewable methane — the naturally slow rate of production. To overcome this challenge, Argonne researchers examined the natural biology of methane production, the natural processes for carbon dioxide sequestration, and the environmental quality of the water found in coal bed methane wells. Their research led to the novel, low-cost treatment to accelerate biological methane production while sequestering CO2. The treatment enhances the heating value of biogas, delivering a gas that is close to pipeline quality. In addition, the renewable methane process leaves coal's environmental pollutants, such as sulfur and mercury, in the ground, avoiding their emissions.
The Enhanced Renewable Methane Production System provides a method for biological methane production from a carbonaceous feedstock to generate methane, while simultaneously sequestering the CO2 produced during the process by reacting with magnesium and calcium silicate rocks. This process links the biological conversion (renewable carbon source being converted to methane and carbon dioxide) to a geochemical mechanism (producing solid carbonate-enriched minerals), thus sequestering the CO2.
In the long term, hydrogen is expected to be the fuel of choice for both the power and transportation industries. Just as conventional cars need gas stations, hydrogen-powered fuel cell cars will need an infrastructure. Hydrogen separation technology is integral to successful fossil-based hydrogen production technologies. Thin, dense composite membranes fabricated from ceramic and hydrogen-transport metal may provide a simple, efficient means for separating hydrogen from fossil-based gas streams. New ceramic-metal composite (cermet) membranes developed at Argonne, called hydrogen transport membranes, could eliminate the need for costly, conventional hydrogen-manufacturing facilities; the membranes could one day be small and efficient enough to be installed at every gas station.
Membranes currently used by industry to separate gases are not selective enough to isolate pure hydrogen—the simplest and smallest of all elements. Argonne has developed a composite cermet that transports only atomic hydrogen, allowing the membrane to separate pure hydrogen for use as a clean-burning fuel and in production of fertilizers and other products. The new membrane material works on a different principle than conventional porous membranes; hydrogen is the only species that passes through it because it dissolves in, and diffuses rapidly through, the metal phase in the composite. Unlike most membrane systems, Argonne's hydrogen membrane tolerates temperatures as high as 900 degrees Celsius. Such elevated temperatures push more hydrogen atoms into the membrane, accelerating the rate of gas separation.
The most likely raw feedstock material for hydrogen separation is syngas, a mixture of hydrogen and carbon monoxide made by reacting natural gas with oxygen. Because syngas can be expensive to produce, Argonne is exploring the use of another membrane to extract oxygen. The team has demonstrated that the oxygen membranes successfully separate oxygen and that this separated oxygen, when reacted with methane, forms syngas. Because Argonne's oxygen and hydrogen membranes both function at the same high temperatures, they can work in tandem: one membrane adding oxygen to methane to create syngas and the other extracting hydrogen from the syngas.
Fatty acids (oils) from the seeds of oilseed crops such as soybeans, sunflower and etc. are processed into vegetable oil for consumption and food preparation. Seeds of other plants naturally contain specialty fatty acids, called "modified fatty acids" ("mFAs"), that are useful as chemical feedstocks, replacing chemicals otherwise obtained from petroleum. Unfortunately seeds of these plants are not amenable to being grown and harvested in commercially relevant amounts. Thus, there has been considerable effort devoted to developing altered oilseed crops that efficiently produce modified fatty acids. The present technology provides means to produce fatty acids having a cyclopropane ring, which makes the oil extremely useful for chemical processing into such products as plastics, paints, dyes, coatings and the like. This technology exemplifies how normal oilseed crops can be modified to produce valuable chemicals. In addition to being renewable, production of such chemicals in plant seeds is environmentally safe and clean.
The present technology provides modified oilseed crops having increased amounts of a non-native, modified fatty acid compound of interest. The system involves transformation of a crop plant with a gene encoding a synthase or encoding a fatty acid modifying enzyme specific for the mFA of interest and an acyltransferase gene and expressing both genes in the transformed plant. Specific embodiments include synthase genes or fatty acid modifying genes isolated from source plants that normally accumulate elevated amounts of the particular mFA. Preferred embodiments of the technology include acyltransferases that transfer either the substrate for the synthase enzyme or transfer the modified fatty acid of interest to, for example, monoacyl- or diacylglycerol. Preferably, acyltransferase genes are obtained from source plants that normally accumulate elevated amounts of the mFA of interest. Manipulation of the accumulation of the proper substrate for the synthase or FA modifying enzyme was useful in preferred embodiments. Enzymes that compete for the synthase or modifying enzyme substrates are suppressed by genotypic and phenotypic mutation of genes encoding the competing enzymes. A particular embodiment of the invention focuses on generating transformed plants accumulating elevated amounts of cyclopropane fatty acids (CPFAs). CPFAs are of particular interest because the presence of the cyclopropane ring creates a reaction center for facile synthesis of branched chain fatty acids. The optimal CPFA synthase may depend on the targeted crop plant. In some embodiments, an Escherichia coli cyclopropane fatty acid synthase was a preferred choice. Acyltransferase genes were selected from the group consisting of lysophosphatidic acid acyltransferase (LPAT), Phospholipid Diacyl Glycerol Acyl Transferase acyltransferase (PDAT) and diacylglycerol acyltransferase (DGAT) genes. A Sterculia foetida LPAT gene provided a particularly preferred embodiment.
Computer engineers have developed a new design to support construction of large computer systems that perform closer to their theoretical peak. This approach emphasizes scalable throughput rather than attempting to tailor systems around the highest performing accelerators, and allows selection of individual components that maximize performance against energy draw or cost. The design makes use of commodity components that are modest in computing power and energy consumption.
Most supercomputer applications require some non-local communication. As a result, the relatively high-latency and low-bandwidth interconnection network becomes a limiting factor on the machine’s efficiency. In addition, designers are extending the peak performance of supercomputers by adding multi-core accelerators such as Cell processors or Graphics Processing Units (GPUs). This introduces another high-latency and low-bandwidth bottleneck, at the point where data moves into and out of the accelerator, as well as another dimension of complexity in software.
These factors limit the kinds of applications that can run effectively on supercomputers, and increase the cost of developing or porting those applications. Algorithms that require intercommunication result in underutilized components, wasting energy and the potential of the machine. Furthermore, there appear to be some problems which perform poorly on these architectures, regardless of optimization.
Los Alamos National Laboratory (LANL) researchers have developed a new design to support construction of large machines, allowing the machines to perform closer to their theoretical peak. This approach emphasizes scalable throughput rather than attempting to tailor machines around the highest performing accelerators, and allows selection of individual components that maximize performance against energy draw or cost. The design makes use of commodity components that are modest in computing power and energy consumption.
The LANL hardware is being co-designed along with a powerful and expressive high-level programming language, adapted from a well-studied body of research languages. It is expected that applications written in this language will require no other system-level or low-level programming in order to run efficiently, but diagnostic feedback could allow selection of more efficient idioms.
LANL’s design supports the data-intensive applications currently encountered in scientific computing, while opening the door to new levels of capability for communication-intensive and throughput-intensive applications such as molecular dynamics and signal correlation. In addition, researchers expect the LANL design can support transparent fail-over, allowing failed nodes to be replaced on-the-fly without stopping ongoing computations.
Research is active on the patent pending technology titled, "High Performance Hydrophobic Solvent for CO2 Capture." This technology is available for licensing and/or further collaborative research from the U.S. Department of Energy’s National Energy Technology Laboratory.
Integrated gasification combined cycle (IGCC) plants have demonstrated that coal can be combusted with greater efficiency, but CO2 extraction from the mixed gas stream has proved to be costly. One reason for the expense is that while currently employed ethylene-glycol-based materials (Selexol) are highly selective in removing CO2, they are also hydrophilic, so water must first be removed before the solvent can be used to dissolve the CO2. In order to remove the water, the fuel gas stream must be cooled to 40 ?C—a costly and energy-demanding process. Polydimethylsiloxanes (PDMS) have overcome the problem of miscibility in water, but suffer from low selectivity.
This invention describes a method to remove CO2 from a mixed gas stream using a solvent that is not only highly selective, but also has no affinity for water. A hydrophobic solvent allows absorption of CO2 at higher temperatures while eliminating the need for a water removal step at IGCC plants, which will simplify the gas removal process and reduce operating costs while increasing thermal efficiency.
The successful integration of this technology into industrial processes could replace ethylene-glycol-based solvent and PDMS to significantly reduce CO2 from fuel gas streams while simplifying IGCC processes in a cost-effective manner.
Research is active on the patent pending technology titled, "Method for the Separation of a Gaseous Component Using a Solvent-Membrane Capture Process.” This technology is available for licensing and/or further collaborative research from the U.S. Department of Energy’s National Energy Technology Laboratory.
The current invention describes a hybrid process for post-combustion CO2 capture using a solvent-based absorption/high pressure stripping gas step coupled with selective CO2 membrane separation. The method is unique in that the solvent-based absorption/stripping process uses thermal compression to efficiently increase the concentration and partial pressure of CO2 in the gas mixture, allowing for more efficient membrane separation. The hybrid process integrates the most efficient aspects of each method resulting in a reduction of the parasitic energy demand of the post-combustion CO2 capture process.
Although research is currently inactive on the patented technology "Low Temperature Sorbents for Removal of Sulfur Compounds from Fluid Feed Streams," the technology is available for licensing from the U.S. Department of Energy’s National Energy Technology Laboratory (NETL).
Disclosed in this patent is a process consisting of a material reactive with sulfur, a binder unreactive with sulfur, and an inert material that in combination can absorb sulfur from fluid feed gas streams at temperatures ranging between 30 and 200 degrees Centigrade. Research has shown that the sulfur absorption capacity has reached as high as 22 weight percent through the application of this process.
Although vapor-phase fuel streams provide valuable commodities, such as liquefied petroleum gases, these commodities cannot be commercially used until contaminants within them are removed. The most typical contaminants are sulfur-containing compounds, such as hydrogen sulfide and others. Removal of the sulfur is necessary to preserve the environment and protect components, such as catalysts, fuel cells, and turbines, contained in power generation systems. Some techniques currently exist for sulfur removal but are limited by only incorporating high temperature ranges. Low temperature processes for removing sulfur also exist but are limited by low sulfur capacities.
The NETL-developed technology provides a solid sorbent that removes sulfur compounds at low temperatures. The process operates at temperatures ranging between 30 degrees and 200 degrees Centigrade, while exhibiting the capacity to absorb high levels of sulfur. In addition, the sorbent itself is relatively inexpensive to manufacture and maintain. The process features a combination of readily available sulfur-reactive materials with diluents and support materials to produce a porous sulfur-absorbing substrate, resulting in the use of less materials and minimal costs.
NREL has developed the following laboratory analytical procedures (LAPs) for standard biomass analysis. The American Society for Testing and Materials (ASTM) and the Technical Association of the Pulp and Paper Industry (TAPPI) may have adopted similar procedures. ASTM and TAPPI versions may be ordered from those organizations.
Near-infrared (NIR) calibration models are created by applying multivariate calibration methods to the combination of wet chemistry data and NIR spectra of a given set of biomass samples. Wet chemical compositional data and NIR spectra exist for the following types of biomass samples: corn stover, switchgrass, mixed hardwoods, mixed softwoods, sorghum, and miscanthus. These samples may be feedstock samples, washed and dried solids from one or more pretreatment processes, liquors derived from one or more pretreatment processes, or whole pretreated slurries.
Xiaogan Liang of Berkeley Lab has invented an inexpensive, high-throughput process for depositing pure few-layer-graphene (FLG) in a desired pattern onto substrates, such as silicon wafers. This method uses electrostatic forces to print FLG in dimensions ranging from less than 20 nm to 100 μm and has the potential to be combined with step-and-repeat technology to cover large areas.
In the Berkeley Lab technology, the desired pattern is created on the pristine surface of a highly oriented pyrolytic graphite (HOPG) stamp. The stamp is brought into contact with the substrate, and one to three layers of graphene are deposited with great accuracy by the application of electrostatic forces. The stamp is removed and the graphene remains bonded to the substrate by van de Waals forces alone.
The invention was used to create 1.4 μm pillars and 18 nm-wide nanolines of FLG on SiO2/Si substrates. These structures were visualized with scanning electron microscopy and atomic force microscopy, and their graphene composition was confirmed with Raman spectroscopy. The nanolines were used to create transistors that had excellent transport properties with highly mobile holes and electrons. The rapid current in the FLG nanolines and nanoribbons and their high sensitivity to electric fields may also allow for applications in biosensors, antennae, and photovoltaics.
Graphene offers significant advantages over silicon as a potential semiconductor because of its exceptional electronic properties: high carrier mobility, stable 2D structure, and the potential to enable scatter-free electron movement at room temperature. However, several obstacles have prevented graphene from being used for commercial electronics. Primarily, it is difficult to deposit graphene in a precise and electronically useful pattern over the relatively large (6 in., 8 in., or 12 in.) surface of a standard silicon wafer or other substrate. Current methods such as epitaxial growth, adhesive application, and reactive deposition are either expensive or risk contamination of the deposited material. The Berkeley Lab technology overcomes these limitations to make graphene a viable semiconductor material.
Recent investigations by a number of groups have shown that a beta zeolite catalyst (and other solid Brønsted acids) will convert methanol and/or dimethyl ether (DME) to iso-alkanes such as triptane (2,2,3-trimethylbutane), with uniquely high selectivity to C4 and C7 (termed the DME to high octane gasoline process or DTHOG). In comparison, the Exxon-Mobil methanol to gasoline (MTG) process produces a broader mixture of hydrocarbons, which is heavy in benzene, toluene, and xylene (BTX). DTHOG is milder than MTG (350-450 °F vs. 650-950 °F and 130 psia vs. 315 psia), thus offering the benefit of reduced capital and operating costs for the reactor. However, similar to MTG, this new low-temperature, selective production of alkanes is still a hydrogen-deficient process. That is, to produce alkanes, a quantitative production of aromatics is required to maintain stoichiometry—a result of oxygen from methanol or DME being rejected as water.
Scientists at the National Renewable Energy Laboratory (NREL) have developed a catalyst formulation and structure that is capable of incorporating hydrogen from gaseous co-fed H2 into methylation and alkylation products without altering aliphatic hydrocarbon selectivity or lowering reaction rates. Volumetric and gravimetric activities are increased and the rate of formation of heavy aromatic residues is decreased. The catalysts are comprised of a beta zeolite modified with Cu, Ga, other non-noble metals, and combinations thereof. The metals provide sites for H2 dissociation, hydrogen addition, and hydrogen abstraction, all of which modulate critical reaction steps—providing H for alkane formation and H removal for alkene formation, bringing products back into the carbon chain growth pathway and minimizing side-reactions that produce unwanted byproducts. The metals work with the Brønsted acids of the zeolite, which act as the catalyst for alkene methylation and carbon chain growth. Physical mixtures of the metal catalyst and zeolite do not yield the same benefits. Metal loadings are low (< 5 wt%) and include metals in metallic clusters, oxide clusters, and cationic forms.
Platinum is the most efficient electrocatalyst for accelerating the oxygen reduction reaction in fuel cells. It is also expensive. Palladium-cobalt particles have been used to replace platinum to catalyze this reaction, leading to a much lower cost electrocatalyst.
Ternary alloys of palladium, cobalt, and a third transition metal are formed into nanoparticles, bound to a conducting medium, and applied as the anode in a fuel cell to reduce oxygen. Palladium-cobalt alloys may also incorporate two additional transition metals to make a four-component, or quaternary, alloy. These alloys are deployed on the anode of fuel cells as electrocatalysts for the oxygen reduction reaction. Nickel and iron are preferred transition metal components.