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Dynamic Impregnator Reactor System (Poster)

Description: IBRF poster developed for the IBRF showcase. Describes the multifarious system designed for complex feedstock impregnation and processing. IBRF feedstock system has several unit operations combined into one robust system that provides for flexible and staged process configurations, such as spraying, soaking, low-severity pretreatment, enzymatic hydrolysis, fermentation, concentration/evaporation, and distillation.
Date: September 1, 2012
Partner: UNT Libraries Government Documents Department

Glycosylation Helps Cellulase Enzymes Bind to Plant Cell Walls (Fact Sheet)

Description: Computer simulations suggest a new strategy to design enhanced enzymes for biofuels production. Large-scale computer simulations predict that the addition of glycosylation on carbohydrate-binding modules can dramatically improve the binding affinity of these protein domains over amino acid mutations alone. These simulations suggest that glycosylation can be used as a protein engineering tool to enhance the activity of cellulase enzymes, which are a key component in the conversion of cellulose to soluble sugars in the production of biofuels. Glycosylation is the covalent attachment of carbohydrate molecules to protein side chains, and is present in many proteins across all kingdoms of life. Moreover, glycosylation is known to serve a wide variety of functions in biological recognition, cell signaling, and metabolism. Cellulase enzymes, which are responsible for deconstructing cellulose found in plant cell walls to glucose, contain glycosylation that when modified can affect enzymatic activity-often in an unpredictable manner. To gain insight into the role of glycosylation on cellulase activity, scientists at the National Renewable Energy Laboratory (NREL) used computer simulation to predict that adding glycosylation on the carbohydrate-binding module of a cellulase enzyme dramatically boosts the binding affinity to cellulose-more than standard protein engineering approaches in which amino acids are mutated. Because it is known that higher binding affinity in cellulases leads to higher activity, this work suggests a new route to designing enhanced enzymes for biofuels production. More generally, this work suggests that tuning glycosylation in cellulase enzymes is a key factor to consider when engineering biochemical conversion processes, and that more work is needed to understand how glycosylation affects cellulase activity at the molecular level.
Date: June 1, 2012
Partner: UNT Libraries Government Documents Department

NREL Produces Ethylene via Photosynthesis; Breakthrough Offers Cleaner Alternative for Transportation Fuels (Fact Sheet)

Description: NREL scientists have demonstrated a way to produce ethylene through photosynthesis, a breakthrough that could lead to more environmentally friendly ways to produce a variety of materials, chemicals, and transportation fuels. The scientists introduced a gene into a cyanobacterium and demonstrated that the organism remains stable through at least four generations, producing ethylene gas that can be easily captured. In the laboratory, the organism, Synechocystis sp. PCC 6803, produced 720 milligrams of ethylene per liter each day.
Date: August 1, 2013
Partner: UNT Libraries Government Documents Department

Reducing Enzyme Costs Increases the Market Potential of Biofuels (Fact Sheet)

Description: Cellulosic ethanol prices depend heavily on the cost of the cellulase enzymes used to break down the biomass into fermentable sugars. To reduce these costs, NREL partnered with two leading enzyme companies, Novozymes and Genencor, to engineer new cellulase enzymes that are exceptionally good at breaking down cellulose. Genencor is now part of DuPont Industrial Biosciences.
Date: August 1, 2013
Partner: UNT Libraries Government Documents Department

Renewable Diesel from Algal Lipids: An Integrated Baseline for Cost, Emissions, and Resource Potential from a Harmonized Model

Description: The U.S. Department of Energy's Biomass Program has begun an initiative to obtain consistent quantitative metrics for algal biofuel production to establish an 'integrated baseline' by harmonizing and combining the Program's national resource assessment (RA), techno-economic analysis (TEA), and life-cycle analysis (LCA) models. The baseline attempts to represent a plausible near-term production scenario with freshwater microalgae growth, extraction of lipids, and conversion via hydroprocessing to produce a renewable diesel (RD) blendstock. Differences in the prior TEA and LCA models were reconciled (harmonized) and the RA model was used to prioritize and select the most favorable consortium of sites that supports production of 5 billion gallons per year of RD. Aligning the TEA and LCA models produced slightly higher costs and emissions compared to the pre-harmonized results. However, after then applying the productivities predicted by the RA model (13 g/m2/d on annual average vs. 25 g/m2/d in the original models), the integrated baseline resulted in markedly higher costs and emissions. The relationship between performance (cost and emissions) and either productivity or lipid fraction was found to be non-linear, and important implications on the TEA and LCA results were observed after introducing seasonal variability from the RA model. Increasing productivity and lipid fraction alone was insufficient to achieve cost and emission targets; however, combined with lower energy, less expensive alternative technology scenarios, emissions and costs were substantially reduced.
Date: June 1, 2012
Creator: Davis, R.; Fishman, D.; Frank, E. D.; Wigmosta, M. S.; Aden, A.; Coleman, A. M. et al.
Partner: UNT Libraries Government Documents Department

Land Use and Water Efficiency in Current and Potential Future U.S. Corn and Brazilian Sugarcane Ethanol Systems (Poster)

Description: The potential for unintended consequences of biofuels--competition for land and water--necessitates that sustainable biofuel expansion considers the complexities of resource requirements within specific context (e.g., technology, feedstock, supply chain, local resource availability).
Date: November 1, 2012
Creator: Warner, E.; Zhang, Y.; Chum, H. & Newmark, R.
Partner: UNT Libraries Government Documents Department

Magnetic Resonance Facility (Fact Sheet)

Description: This fact sheet provides information about Magnetic Resonance Facility capabilities and applications at NREL's National Bioenergy Center. Liquid and solid-state analysis capability for a variety of biomass, photovoltaic, and materials characterization applications across NREL. NREL scientists analyze solid and liquid samples on three nuclear magnetic resonance (NMR) spectrometers as well as an electron paramagnetic resonance (EPR) spectrometer.
Date: March 1, 2012
Partner: UNT Libraries Government Documents Department

Collaboratives for Wildlife-Wind Turbine Interaction Research: Fostering Multistakeholder Involvement (Poster)

Description: This poster highlights the various wildlife-wind collaboratives (specific to wildlife-wind turbine interaction research) that currently exist. Examples of collaboratives are included along with contact information, objectives, benefits, and ways to advance the knowledge base.
Date: April 1, 2013
Creator: Sinclair, K.
Partner: UNT Libraries Government Documents Department

Comparison of API & IEC Standards for Offshore Wind Turbine Applications in the U.S. Atlantic Ocean: Phase II; March 9, 2009 - September 9, 2009

Description: This report compares two design guidelines for offshore wind turbines: Recommended Practice for Planning, Designing, and Constructing Fixed Offshore Platform Structures and the International Electrotechnical Commission 61400-3 Design Requirements for Offshore Wind Turbines.
Date: January 1, 2013
Creator: Jha, A.; Dolan, D.; Gur, T.; Soyoz, S. & Alpdogan, C.
Partner: UNT Libraries Government Documents Department

Duration Test Report for the Viryd CS8 Wind Turbine

Description: This report summarizes the results of a duration noise test that the National Renewable Energy Laboratory (NREL) conducted on the Viryd CS8 wind turbine. This test was conducted in accordance with Clause 9.4 of the International Electrotechnical Commission's (IEC) standard, Wind turbines - Part 2: Design requirements for small wind turbines, IEC 61400-2 Ed. 2.0:2006-03. NREL researchers evaluated the turbine based on structural integrity and material degradation, quality of environmental protection, and dynamic behavior.
Date: June 1, 2013
Creator: Roadman, J.; Murphy, M. & van Dam, J.
Partner: UNT Libraries Government Documents Department

Gearbox Reliability Collaborative Phase 3 Gearbox 2 Test Plan

Description: Gearboxes in wind turbines have not been achieving their expected design life even though they commonly meet or exceed the design criteria specified in current design standards. One of the basic premises of the National Renewable Energy Laboratory (NREL) Gearbox Reliability Collaborative (GRC) is that the low gearbox reliability results from the absence of critical elements in the design process or insufficient design tools. Key goals of the GRC are to improve design approaches and analysis tools and to recommend practices and test methods resulting in improved design standards for wind turbine gearboxes that lower the cost of energy (COE) through improved reliability. The GRC uses a combined gearbox testing, modeling and analysis approach, along with a database of information from gearbox failures collected from overhauls and investigation of gearbox condition monitoring techniques to improve wind turbine operations and maintenance practices. Testing of Gearbox 2 (GB2) using the two-speed turbine controller that has been used in prior testing. This test series will investigate non-torque loads, high-speed shaft misalignment, and reproduction of field conditions in the dynamometer. This test series will also include vibration testing using an eddy-current brake on the gearbox's high speed shaft.
Date: April 1, 2013
Creator: Link, H.; Keller, J.; Guo, Y. & McNiff, B.
Partner: UNT Libraries Government Documents Department

Installation, Operation, and Maintenance Strategies to Reduce the Cost of Offshore Wind Energy

Description: Currently, installation, operation, and maintenance (IO&M) costs contribute approximately 30% to the LCOE of offshore wind plants. To reduce LCOE while ensuring safety, this paper identifies principal cost drivers associated with IO&M and quantifies their impacts on LCOE. The paper identifies technology improvement opportunities and provides a basis for evaluating innovative engineering and scientific concepts developed subsequently to the study. Through the completion of a case study, an optimum IO&M strategy for a hypothetical offshore wind project is identified.
Date: July 1, 2013
Creator: Maples, B.; Saur, G.; Hand, M.; van de Pieterman, R. & Obdam, T.
Partner: UNT Libraries Government Documents Department

Investigation of Response Amplitude Operators for Floating Offshore Wind Turbines: Preprint

Description: This paper examines the consistency between response amplitude operators (RAOs) computed from WAMIT, a linear frequency-domain tool, to RAOs derived from time-domain computations based on white-noise wave excitation using FAST, a nonlinear aero-hydro-servo-elastic tool. The RAO comparison is first made for a rigid floating wind turbine without wind excitation. The investigation is further extended to examine how these RAOs change for a flexible and operational wind turbine. The RAOs are computed for below-rated, rated, and above-rated wind conditions. The method is applied to a floating wind system composed of the OC3-Hywind spar buoy and NREL 5-MW wind turbine. The responses are compared between FAST and WAMIT to verify the FAST model and to understand the influence of structural flexibility, aerodynamic damping, control actions, and waves on the system responses. The results show that based on the RAO computation procedure implemented, the WAMIT- and FAST-computed RAOs are similar (as expected) for a rigid turbine subjected to waves only. However, WAMIT is unable to model the excitation from a flexible turbine. Further, the presence of aerodynamic damping decreased the platform surge and pitch responses, as computed by both WAMIT and FAST when wind was included. Additionally, the influence of gyroscopic excitation increased the yaw response, which was captured by both WAMIT and FAST.
Date: July 1, 2013
Creator: Ramachandran, G. K. V.; Robertson, A.; Jonkman, J. M. & Masciola, M. D.
Partner: UNT Libraries Government Documents Department

Long-Term Probability Distribution of Wind Turbine Planetary Bearing Loads (Poster)

Description: Among the various causes of bearing damage and failure, metal fatigue of the rolling contact surface is the dominant failure mechanism. The fatigue life is associated with the load conditions under which wind turbines operate in the field. Therefore, it is important to understand the long-term distribution of the bearing loads under various environmental conditions. The National Renewable Energy Laboratory's 750-kW Gearbox Reliability Collaborative wind turbine is studied in this work. A decoupled analysis using several computer codes is carried out. The global aero-elastic simulations are performed using HAWC2. The time series of the drivetrain loads and motions from the global dynamic analysis are fed to a drivetrain model in SIMPACK. The time-varying internal pressure distribution along the raceway is obtained analytically. A series of probability distribution functions are then used to fit the long-term statistical distribution at different locations along raceways. The long-term distribution of the bearing raceway loads are estimated under different environmental conditions. Finally, the bearing fatigue lives are calculated.
Date: April 1, 2013
Creator: Jiang, Z.; Xing, Y.; Guo, Y.; Dong, W.; Moan, T. & Gao, Z.
Partner: UNT Libraries Government Documents Department

National Skills Assessment of the U.S. Wind Industry in 2012

Description: A robust workforce is essential to developing domestic wind power projects, including manufacturing, siting, operations, maintenance, and research capabilities. The purpose of our research is to better understand today's domestic wind workforce, projected workforce needs as the industry grows, and how existing and new programs can meet the wind industry's future education and training needs. Results presented in this report provide the first published investigation into the detailed makeup of the wind energy workforce, educational infrastructure and training needs of the wind industry. Insights from this research into the domestic wind workforce will allow the private sector, educational institutions, and federal and state governmental organizations to make workforce-related decisions based on the current employment and training data and future projections in this report.
Date: June 1, 2013
Creator: Levanthal, M. & Tegen, S.
Partner: UNT Libraries Government Documents Department

NREL Collaborative Improves the Reliability of Wind Turbine Gearboxes (Fact Sheet)

Description: Gearbox failures have a significant impact on the cost of wind farm operations. To help minimize gearbox failures, in 2007 the National Renewable Energy Laboratory (NREL) initiated the Gearbox Reliability Collaborative (GRC), which consists of manufacturers, owners, researchers, and consultants. Based on all the lessons learned from the past five years, the GRC has now produced a new and improved design, which is projected to yield an operating lifetime of 12 years, more than triple that of the previous redesigned gearbox. The GRC findings will result in increased gearbox reliability and an overall reduction in the cost of wind energy.
Date: September 1, 2013
Partner: UNT Libraries Government Documents Department