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Microwave Plasma Chemical Vapor Deposition of Carbon Coatings on LiNi1/3Co1/3Mn1/3O2 for Li-Ion Battery Composite Cathodes

Description: In this paper, we report results of a novel synthesis method of thin film conductive carbon coatings on LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} cathode active material powders for lithium-ion batteries. Thin layers of graphitic carbon were produced from a solid organic precursor, anthracene, by a one-step microwave plasma chemical vapor deposition (MPCVD) method. The structure and morphology of the carbon coatings were examined using SEM, TEM, and Raman spectroscopy. The composite LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} electrodes were electrochemically tested in lithium half coin cells. The composite cathodes made of the carbon-coated LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} powder showed superior electrochemical performance and increased capacity compared to standard composite LiNi{sub 1/3}Co{sub 1/3}Mn{sub 1/3}O{sub 2} electrodes.
Date: December 10, 2008
Creator: Doeff, M.M.; Kostecki, R.; Marcinek, M. & Wilcoc, J.D.
Partner: UNT Libraries Government Documents Department

Modeling Electric Vehicle Benefits Connected to Smart Grids

Description: Connecting electric storage technologies to smartgrids will have substantial implications in building energy systems. Local storage will enable demand response. Mobile storage devices in electric vehicles (EVs) are in direct competition with conventional stationary sources at the building. EVs will change the financial as well as environmental attractiveness of on-site generation (e.g. PV, or fuel cells). In order to examine the impact of EVs on building energy costs and CO2 emissions in 2020, a distributed-energy-resources adoption problem is formulated as a mixed-integer linear program with minimization of annual building energy costs or CO2 emissions. The mixed-integer linear program is applied to a set of 139 different commercial buildings in California and example results as well as the aggregated economic and environmental benefits are reported. The research shows that considering second life of EV batteries might be very beneficial for commercial buildings.
Date: July 1, 2011
Creator: Stadler, Michael; Marnay, Chris; Mendes, Goncalo; Kloess, Maximillian; Cardoso, Goncalo; Mégel, Olivier et al.
Partner: UNT Libraries Government Documents Department

Modeling Low-Platinum-Loading Effects in Fuel-Cell Catalyst Layers

Description: The cathode catalyst layer within a proton-exchange-membrane fuel cell is the most complex and critical, yet least understood, layer within the cell. The exact method and equations for modeling this layer are still being revised and will be discussed in this paper, including a 0.8 reaction order, existence of Pt oxides, possible non-isopotential agglomerates, and the impact of a film resistance towards oxygen transport. While the former assumptions are relatively straightforward to understand and implement, the latter film resistance is shown to be critically important in explaining increased mass-transport limitations with low Pt-loading catalyst layers. Model results demonstrate agreement with experimental data that the increased oxygen flux and/or diffusion pathway through the film can substantially decrease performance. Also, some scale-up concepts from the agglomerate scale to the more macroscopic porous-electrode scale are discussed and the resulting optimization scenarios investigated.
Date: January 20, 2011
Creator: Yoon, Wonseok & Weber, Adam Z.
Partner: UNT Libraries Government Documents Department

Modeling pollutant penetration across building envelopes

Description: As air infiltrates through unintentional openings in building envelopes, pollutants may interact with adjacent surfaces. Such interactions can alter human exposure to air pollutants of outdoor origin. We present modeling explorations of the proportion of particles and reactive gases (e.g., ozone) that penetrate building envelopes as air enters through cracks and wall cavities. Calculations were performed for idealized rectangular cracks, assuming regular geometry, smooth inner crack surface and steady airflow. Particles of 0.1-1.0 {micro}m diameter are predicted to have the highest penetration efficiency, nearly unity for crack heights of 0.25 mm or larger, assuming a pressure difference of 4 Pa or greater and a flow path length of 3 cm or less. Supermicron and ultrafine particles are significantly removed by means of gravitational settling and Brownian diffusion, respectively. In addition to crack geometry, ozone penetration depends on its reactivity with crack surfaces, as parameterized by the reaction probability. For reaction probabilities less than {approx}10{sup -5}, penetration is complete for cracks heights greater than 1 mm. However, penetration through mm scale cracks is small if the reaction probability is {approx}10{sup -4} or greater. For wall cavities, fiberglass insulation is an efficient particle filter, but particles would penetrate efficiently through uninsulated wall cavities or through insulated cavities with significant airflow bypass. The ozone reaction probability on fiberglass fibers was measured to be 10{sup -7} for fibers previously exposed to high ozone levels and 6 x 10{sup -6} for unexposed fibers. Over this range, ozone penetration through fiberglass insulation would vary from >90% to {approx}10-40%. Thus, under many conditions penetration is high; however, there are realistic circumstances in which building envelopes can provide substantial pollutant removal. Not enough is yet known about the detailed nature of pollutant penetration leakage paths to reliably predict infiltration into real buildings.
Date: April 1, 2001
Creator: Liu, De-Ling & Nazaroff, William W.
Partner: UNT Libraries Government Documents Department

Modeling Population Exposures to Pollutants Emitted from Natural Gas Cooking Burners

Description: We developed a physics-based data-supported model to investigate indoor pollutant exposure distributions resulting from use of natural gas cooking appliances across households in California. The model was applied to calculate time-resolved indoor concentrations of CO, NO2 and formaldehyde resulting from cooking burners and entry with outdoor air. Exposure metrics include 1-week average concentrations and frequency of exceeding ambient air quality standards. We present model results for Southern California (SoCal) using two air-exchange scenarios in winter: (1) infiltration-only, and (2) air exchange rate (AER) sampled from lognormal distributions derived from measurements. In roughly 40percent of homes in the SoCal cohort (N=6634) the 1-hour USEPA NO2 standard (190 ?g/m3) was exceeded at least once. The frequency of exceeding this standard was largely independent of AER assumption, and related primarily to building volume, emission rate and amount of burner use. As expected, AER had a more substantial impact on one-week average concentrations.
Date: June 1, 2011
Creator: Lobscheid, Agnes; Singer, Brett C. & Klepeis, Neil E.
Partner: UNT Libraries Government Documents Department

Money for Research, Not for Energy Bills: Finding Energy and Cost Savings in High Performance Computer Facility Designs

Description: High-performance computing facilities in the United States consume an enormous amount of electricity, cutting into research budgets and challenging public- and private-sector efforts to reduce energy consumption and meet environmental goals. However, these facilities can greatly reduce their energy demand through energy-efficient design of the facility itself. Using a case study of a facility under design, this article discusses strategies and technologies that can be used to help achieve energy reductions.
Date: July 1, 2010
Creator: Drewmark Communications
Partner: UNT Libraries Government Documents Department

National Level Co-Control Study of the Targets for Energy Intensity and Sulfur Dioxide in China

Description: Since 2006, China has set goals of reducing energy intensity, emissions, and pollutants in multiple guidelines and in the Five Year Plans. Various strategies and measures have then been taken to improve the energy efficiency in all sectors and to reduce pollutants. Since controlling energy, CO{sub 2} emissions, and pollutants falls under the jurisdiction of different government agencies in China, many strategies are being implemented to fulfill only one of these objectives. Co-controls or integrated measures could simultaneously reduce greenhouse gas (GHG) emissions and criteria air pollutant emissions. The targets could be met in a more cost effective manner if the integrated measures can be identified and prioritized. This report provides analysis and insights regarding how these targets could be met via co-control measures focusing on both CO{sub 2} and SO{sub 2} emissions in the cement, iron &steel, and power sectors to 2030 in China. An integrated national energy and emission model was developed in order to establish a baseline scenario that was used to assess the impact of actions already taken by the Chinese government as well as planned and expected actions. In addition, CO{sub 2} mitigation scenarios and SO{sub 2} control scenarios were also established to evaluate the impact of each of the measures and the combined effects. In the power sector, although the end of pipe SO{sub 2} control technology such as flue gas desulfurization (FGD) has the largest reduction potential for SO{sub 2} emissions, other CO{sub 2} control options have important co-benefits in reducing SO{sub 2} emissions of 52.6 Mt of SO{sub 2} accumulatively. Coal efficiency improvements along with hydropower, renewable and nuclear capacity expansion will result in more than half of the SO{sub 2} emission reductions as the SO{sub 2} control technology through 2016. In comparison, the reduction from carbon capture and sequestration (CCS) is ...
Date: October 15, 2011
Creator: Zhou, Nan; Price, Lynn; Zheng, Nina; Ke, Jing & Hasanbeigi, Ali
Partner: UNT Libraries Government Documents Department

Natural Gas Variability In California: Environmental Impacts And Device Performance Combustion Modeling of Pollutant Emissions From a Residential Cooking Range

Description: As part of a larger study of liquefied natural gas impacts on device performance and pollutant emissions for existing equipment in California, this report describes a cmoputer modeling study of a partially premixed flame issueing from a single cooktop burner port. The model consisted of a reactive computational fluid dynamics three-dimensional spatial grid and a 71-species chemical mechanism with propane combustion capability. Simulations were conducted with a simplified fuel mixture containing methane, ethane, and propane in proportions that yield properties similar to fuels distributed throughout much of California now and in recent years (baseline fuel), as well as with two variations of simulated liquefied natural gas blends. A variety of simulations were conducted with baseline fuel to explore the effect of several key parameters on pollutant formation and other flame characteristics. Simulations started with fuel and air issuing through the burner port, igniting, and continuing until the flame was steady with time. Conditions at this point were analyzed to understand fuel, secondary air and reaction product flows, regions of pollutant formation, and exhaust concentrations of carbon monoxide, nitric oxide and formaldehyde. A sensitivity study was conducted, varying the inflow parameters of this baseline gs about real-world operating conditions. Flame properties responded as expected from reactive flow theory. In the simulation, carbon monoxide levels were influenced more by the mixture's inflow velocity than by the gas-to-air ratio in the mixture issuing from the inflow port. Additional simulations were executed at two inflow conditions - high heat release and medium heat release - to examine the impact of replacing the baseline gas with two mixtures representative of liquefied natural gas. Flame properties and pollutant generation rates were very similar among the three fuel mixtures.
Date: July 1, 2011
Creator: Tonse, S. R. & Singer, B. C.
Partner: UNT Libraries Government Documents Department

New Air Cleaning Strategies for Reduced Commercial Building Ventilation Energy ? FY11 Final Report

Description: The research carried out in this project focuses on developing novel volatile organic compounds (VOCs) air cleaning technologies needed to enable energy-saving reductions in ventilation rates. we targeted a VOC air cleaning system that could enable a 50% reduction in ventilation rates. In a typical commercial HVAC system that provides a mixture of recirculated and outdoor air, a VOC air cleaner in the supply airstream must have a 15% to 20% VOC removal efficiency to counteract a 50% reduction in outdoor air supply.
Date: October 31, 2011
Creator: Sidheswaran, Meera; Destaillats, Hugo; Cohn, Sebastian; Sullivan, Douglas P. & Fisk, William J.
Partner: UNT Libraries Government Documents Department

New Methods of Energy Efficient Radon Mitigation

Description: Two new radon mitigation techniques are introduced and their evaluation in a field study complemented by numerical model predictions is described. Based on numerical predictions, installation of a sub gravel membrane at the study site resulted in a factor of two reduction in indoor radon concentrations. Experimental data indicated that installation of 'short-circuit' pipes extending between the subslab gravel and outdoors, caused an additional factor of two decrease in the radon concentration. Consequently, the combination of these two passive radon mitigation features, called the membrane and short-circuit (MASC) technique, was associated with a factor of four reduction in indoor radon concentration. The energy-efficient active radon mitigation method, called efficient active subslab pressurization (EASP), required only 20% of the fan energy of conventional active subslab depressurization and reduced the indoor radon concentration by approximately a factor of 15, including the numerically-predicted impact of the sub-gravel membrane.
Date: May 1, 1994
Creator: Fisk, W.J.; Prill, R.J.; Wooley, J.; Bonnefous, Y.C.; Gadgil, A.J. & Riley, W.J.
Partner: UNT Libraries Government Documents Department

NUMERICAL ANALYSIS OF FLOWFIELDS GENERATED BY ACCELERATING FLAMES

Description: A numerical technique is presented for the analysis of nonsteady flowfields generated by accelerating flames in gaseous media. The problem is formulated in Eulerian coordinates and the solution is based on the extension of the floating shock-fitting technique to all the discontinuities and their interactions occurring in the flowfield. Besides shock waves, the discontinuities taken into account thus far consist of contact surfaces, deflagration, and detonation fronts. The governing partial differential equations are integrated by the use of an explicit second-order accurate, finite-difference scheme, while special algorithms are introduced for the treatment of segments of the flowfield where the influence zones of discontinuities overlap. Actual interactions between them are treated by the polar intersection method. The technique is applied to the case of a steady flame experiencing an abrupt increase in burning speed, leading either to the establishment of a new steady flame flow system or to further acceleration culminated by the transition to detonation. A demarcation line between the two regimes of solutions, depending on the value of the initial burning speed and the magnitude of its abrupt increase, is established, and the physical validity of this criterion is corroborated by experimental evidence.
Date: March 1, 1980
Creator: Kurylo, J.; Dwyer, H.A. & Oppenheim, A.K.
Partner: UNT Libraries Government Documents Department

NYSERDA's Green Jobs-Green New York Program: Extending Energy Efficiency Financing To Underserved Households

Description: The New York legislature passed the Green Jobs-Green New York (GJGNY) Act in 2009. Administered by the New York State Energy Research and Development Authority (NYSERDA), GJGNY programs provide New Yorkers with access to free or low-cost energy assessments,1 energy upgrade services,2 low-cost financing, and training for various 'green-collar' careers. Launched in November 2010, GJGNY's residential initiative is notable for its use of novel underwriting criteria to expand access to energy efficiency financing for households seeking to participate in New York's Home Performance with Energy Star (HPwES) program.3 The GJGNY financing program is a valuable test of whether alternatives to credit scores can be used to responsibly expand credit opportunities for households that do not qualify for traditional lending products and, in doing so, enable more households to make energy efficiency upgrades.
Date: January 24, 2011
Creator: Zimring, Mark & Fuller, Merrian
Partner: UNT Libraries Government Documents Department

Introduction to the Buildings Sector Module of SEDS

Description: SEDS is a stochastic engineering-economics model that forecasts economy-wide energy consumption in the U.S. to 2050. It is the product of multi-laboratory collaboration among the National Renewable Energy Laboratory (NREL), Pacific Northwest National Laboratory (PNNL), Argonne National Laboratory (ANL), Lawrence Berkeley National Laboratory (LBNL), and Lumina Decision Systems. Among national energy models, SEDS is unique, as it is the only model written to explicitly incorporate uncertainty in its inputs and outputs. The primary purpose of SEDS is to estimate the impact of various US Department of Energy (DOE)R&D and policy programs on the performance and subsequent adoption rates of technologies relating to every energy consuming sector of the economy (shown below). It has previously been used to assist DOE in complying with the Government Performance and Results Act of 1993 (GPRA). The focus of LBNL research has been exclusively on develop the buildings model (SBEAM), which is capable of running as a stand-alone forecasting model, or as a part of SEDS as a whole. The full version of SEDS, containing all sectors and interaction is also called the 'integrated' version and is managed by NREL. Forecasts from SEDS are often compared to those coming from National Energy Modeling System (NEMS). The intention of this document is to present new users and developers with a general description of the purpose, functionality and structure of the buildings module within the Stochastic Energy Deployment System (SEDS). The Buildings module, which is capable of running as a standalone model, is also called the Stochastic Buildings Energy and Adoption Model (SBEAM). This document will focus exclusively on SBEAM and its interaction with other major sector modules present within SEDS. The methodologies and major assumptions employed in SBEAM will also be discussed. The organization of this report will parallel the organization of the model itself, being ...
Date: December 31, 2010
Creator: DeForest, Nicholas; Bonnet, Florence; Stadler, Michael & Marnay, Chris
Partner: UNT Libraries Government Documents Department

Inventory of China's Energy-Related CO2 Emissions in 2008

Description: Although China became the world's largest emitter of energy-related CO{sub 2} emissions in 2007, China does not publish annual estimates of CO{sub 2} emissions and most published estimates of China's emissions have been done by other international organizations. Undertaken at the request of the Energy Information Administration (EIA) of the US Department of Energy, this study examines the feasibility of applying the EIA emissions inventory methodology to estimate China's emissions from published Chinese data. Besides serving as a proof of concept, this study also helps develop a consistent and transparent method for estimating China's CO{sub 2} emissions using an Excel model and identified China-specific data issues and areas for improvement. This study takes a core set of data from the energy balances published in the China Energy Statistical Yearbook 2009 and China Petrochemical Corporation Yearbook 2009 and applies the EIA's eight-step methodology to estimate China's 2008 CO{sub 2} emissions. First, China's primary and secondary fuel types and consumption by end use are determined with slight discrepancies identified between the two data sources and inconsistencies in product categorization with the EIA. Second, energy consumption data are adjusted to eliminate double counting in the four potential areas identified by EIA; consumption data from China's Special Administrative Regions are not included. Physical fuel units are then converted to energy equivalents using China's standard energy measure of coal equivalent (1 kilogram = 29.27 MJ) and IPCC carbon emissions coefficients are used to calculate each fuel's carbon content. Next, carbon sequestration is estimated following EIA conventions for other petroleum products and non-energy use of secondary fuels. Emissions from international bunker fuels are also subtracted under the 'reference' calculation of estimating apparent energy consumption by fuel type and the 'sectoral' calculation of summing emissions across end-use sectors. Adjustments for the China-specific conventions of reporting foreign bunkers ...
Date: March 31, 2011
Creator: Fridley, David; Zheng, Nina & Qin, Yining
Partner: UNT Libraries Government Documents Department

INVESTIGATIONS ON HYDRAULIC CEMENTS FROM SPENT OIL SHALE

Description: A process for making hydraulic cements from spent oil shale is described in this paper. Inexpensive cement is needed to grout abandoned in-situ retorts of spent shale for subsidence control, mitigation of leaching, and strengthening the retorted mass in order to recover oil from adjacent pillars of raw shale. A hydraulic cement was produced by heating a 1:1 mixture of Lurgi spent shale and CaCO{sub 3} at 1000 C for one hour. This cement would be less expensive than ordinary portland cement and is expected to fulfill the above requirements.
Date: April 1, 1980
Creator: Mehta, P.K. & Persoff, P.
Partner: UNT Libraries Government Documents Department

Isothermal Ice-Crystallization Kinetics in the Gas-Diffusion Layer of a Proton-Exchange-Membrane Fuel Cell

Description: Nucleation and growth of ice in the fibrous gas-diffusion layer (GDL) of a proton-exchange membrane fuel cell (PEMFC) are investigated using isothermal differential scanning calorimetry (DSC). Isothermal crystallization rates and pseudo-steady-state nucleation rates are obtained as a function of subcooling from heat-flow and induction-time measurements. Kinetics of ice nucleation and growth are studied at two polytetrafluoroethylene (PTFE) loadings (0 and 10 wt %) in a commercial GDL for temperatures between 240 and 273 K. A nonlinear icecrystallization rate expression is developed using Johnson-Mehl-Avrami-Kolmogorov (JMAK) theory, in which the heat-transfer-limited growth rate is determined from the moving-boundary Stefan problem. Induction times follow a Poisson distribution and increase upon addition of PTFE, indicating that nucleation occurs more slowly on a hydrophobic fiber than on a hydrophilic fiber. The determined nucleation rates and induction times follow expected trends from classical nucleation theory. A validated rate expression is now available for predicting icecrystallization kinetics in GDLs.
Date: November 11, 2011
Creator: Dursch, Thomas J.; Ciontea, Monica A.; Radke, Clayton J. & Weber, Adam Z.
Partner: UNT Libraries Government Documents Department

INTERPRETATION OF RAYLEIGH SCATTERING IN A FLAME

Description: Rayleigh scattering has become an accepted technique for the determination of total number density during the combustion process. The interpretation of the ratio of total Rayleigh scattering signal as a ratio of densities or temperatures is hampered by the changing composition and mean molecular weight through a flame. Typical values of correction factors as a function of degree of reaction, fuel, and equivalence ratio are calculated for an idealized one-dimensional flame front. The fuels considered are H{{sub 2}, CH{sub 4}, C{sub 2}H{sub 4}, C{sub 2}H{sub 6}, and C{sub 3}H{sub 8}. Errors of up to 30% can occur in the interpretation of the Rayleigh scattering as gas density for the heavier hydrocarbon fuels due, primarily, to the presence of CO as an intermediate combustion product. Conversely, using H{sub 2} as a fuel will result in a maximum error of 3%, which is within the expected experimental accuracy of a typical Rayleigh scatterinq system. The interpretation of Rayleigh scattering as temperature was found to have larger errors than the interpretation as density. Nevertheless, when corrections are applied for changes in gas composition, Rayleigh scattering provides an excellent measure of total gas density and temperature in flames.
Date: April 1, 1980
Creator: Namer, I.; Schefer, R.W. & Chan, M.
Partner: UNT Libraries Government Documents Department

Commercial and Industrial Base Intermittent Resource Management Pilot

Description: This scoping study summarizes the challenges with integrating wind and solar generation into the California's electricity grid. These challenges include: Smoothing intra-hour variability; - Absorbing excess renewable energy during over-generation periods; - Addressing morning and evening ramping periods. In addition, there are technical challenges to integrating retail demand response (DR) triggered by the wholesale conditions into the CAISO markets. The study describes the DR programs available to the consumers through the utilities in California and CAISO's ancillary services market because an integration of the wholesale and retail DR requires an understanding of these different offerings and the costs associated with acquiring them. Demand-side active and passive storage systems are proposed as technologies that may be used to mitigate the effects of intermittence due to renewable generation. Commercial building technologies as well as industrial facilities with storage capability are identified as targets for the field tests. Two systems used for ancillary services communications are identified as providing the triggers for DR enablement. Through the field tests, issues related to communication, automation and flexibility of demand-side resources will be explored and the performance of technologies that participate in the field tests will be evaluated. The major outcome of this research is identifying and defining flexibility of DR resources and optimized use of these resources to respond to grid conditions.
Date: November 30, 2010
Creator: Kiliccote, Sila; Sporborg, Pamela; Sheik, Imran; Huffaker, Erich & Piette, Mary Ann
Partner: UNT Libraries Government Documents Department

Commissioning: A Highly Cost-Effective Building Energy Management Strategy

Description: Quality assurance and optimization are essential elements of any serious technological endeavor, including efforts to improve energy efficiency. Commissioning is an important tool in this respect. The aim of commissioning new buildings is to ensure that they deliver-if not exceed-the performance and energy savings promised by their design. When applied to existing buildings, one-time or repeated commissioning (often called retrocommissioning) identifies the almost inevitable drift in energy performance and puts the building back on course, often surpassing the original design intent. In both contexts, commissioning is a systematic, forensic approach to improving performance, rather than a discrete technology.
Date: January 6, 2011
Creator: Mills, Evan
Partner: UNT Libraries Government Documents Department

COMMUNITY DEVELOPMENT IN FRESHWATER MICROCOSMS

Description: Two cylindrical freshwater microcosms with a volume of 700 {ell} were maintained under controlled laboratory conditions for 190 days. The two microcosms were identical with regard to initial chemical composition and biological inocula, with the exceptions that in one microcosm (designated Tank 2) mosquitofish (Gambusia) and herbivorous catfish (Placostomas) were added. Three distinct communities developed in the tanks: (1) a phytoplankton-zooplankton assemblage and (2) two periphyton-zoobenthos communities associated with the sides and bottom of the tank, respectively. Community development and successional patterns were similar in both tanks. Major differences between the tanks involved timing of succession of the zooplankton and zoobenthos, attributable to predation by fish, principally Gambusia. A major drawback for these microcosms as use for experimental analogs such as lakes was a luxuriant periphyton growth which eventually overwhelmed the biomass of the system. The tanks displayed a degree of successional replicability, a large number of species, and a diversity of community development. Microcosms of this size could find use as experimental systems for higher level trophic manipulation and observation of life cycles not amenable to field studies.
Date: January 1, 1978
Creator: Rees, John T.
Partner: UNT Libraries Government Documents Department

Community Wind: Once Again Pushing the Envelope of Project Finance

Description: In the United States, the 'community wind' sector - loosely defined here as consisting of relatively small utility-scale wind power projects that sell power on the wholesale market and that are developed and owned primarily by local investors - has historically served as a 'test bed' or 'proving grounds' for up-and-coming wind turbine manufacturers that are trying to break into the U.S. wind power market. For example, community wind projects - and primarily those located in the state of Minnesota - have deployed the first U.S. installations of wind turbines from Suzlon (in 2003), DeWind (2008), Americas Wind Energy (2008) and later Emergya Wind Technologies (2010), Goldwind (2009), AAER/Pioneer (2009), Nordic Windpower (2010), Unison (2010), and Alstom (2011). Thus far, one of these turbine manufacturers - Suzlon - has subsequently achieved some success in the broader U.S. wind market as well. Just as it has provided a proving grounds for new turbines, so too has the community wind sector served as a laboratory for experimentation with innovative new financing structures. For example, a variation of one of the most common financing arrangements in the U.S. wind market today - the special allocation partnership flip structure (see Figure 1 in Section 2.1) - was first developed by community wind projects in Minnesota more than a decade ago (and is therefore sometimes referred to as the 'Minnesota flip' model) before being adopted by the broader wind market. More recently, a handful of community wind projects built over the past year have been financed via new and creative structures that push the envelope of wind project finance in the U.S. - in many cases, moving beyond the now-standard partnership flip structures involving strategic tax equity investors. These include: (1) a 4.5 MW project in Maine that combines low-cost government debt with local tax ...
Date: January 18, 2011
Creator: bolinger, Mark A.
Partner: UNT Libraries Government Documents Department

A Comparison of Iron and Steel Production Energy Use and Energy Intensity in China and the U.S.

Description: Production of iron and steel is an energy-intensive manufacturing process. In 2006, the iron and steel industry accounted for 13.6% and 1.4% of primary energy consumption in China and the U.S., respectively (U.S. DOE/EIA, 2010a; Zhang et al., 2010). The energy efficiency of steel production has a direct impact on overall energy consumption and related carbon dioxide (CO2) emissions. The goal of this study is to develop a methodology for making an accurate comparison of the energy intensity (energy use per unit of steel produced) of steel production. The methodology is applied to the steel industry in China and the U.S. The methodology addresses issues related to boundary definitions, conversion factors, and indicators in order to develop a common framework for comparing steel industry energy use. This study uses a bottom-up, physical-based method to compare the energy intensity of China and U.S. crude steel production in 2006. This year was chosen in order to maximize the availability of comparable steel-sector data. However, data published in China and the U.S. are not always consistent in terms of analytical scope, conversion factors, and information on adoption of energy-saving technologies. This study is primarily based on published annual data from the China Iron & Steel Association and National Bureau of Statistics in China and the Energy Information Agency in the U.S. This report found that the energy intensity of steel production is lower in the United States than China primarily due to structural differences in the steel industry in these two countries. In order to understand the differences in energy intensity of steel production in both countries, this report identified key determinants of sector energy use in both countries. Five determinants analyzed in this report include: share of electric arc furnaces in total steel production, sector penetration of energy-efficiency technologies, scale of production ...
Date: June 15, 2011
Creator: Hasanbeigi, Ali; Price, Lynn; Aden, Nathaniel; Chunxia, Zhang; Xiuping, Li & Fangqin, Shangguan
Partner: UNT Libraries Government Documents Department

COMPARISON OF PROPORTIONAL AND ON/OFF SOLAR COLLECTOR LOOP CONTROL STRATEGIES USING A DYNAMIC COLLECTOR MODEL

Description: Common control strategies used to regulate the flow of liquid through flat-plate solar collectors are discussed and evaluated using a dynamic collector model. Performance of all strategies is compared using different set points, flow rates, insolation levels and patterns (clear and cloudy days), and ambient temperature conditions. The unique characteristic of the dynamic collector model is that it includes effects of collector capacitance. In general, capacitance has a minimal effect on long term collector performance; however, short term temperature response and the energy =storage capability of collector capacitance are shown to play significant roles in comparing on/off and proportional controllers. Inclusion of these effects has produced considerably more realistic simulations than any generated by steady-state models. Simulations indicate relative advantages and disadvantages of both types of controllers, conditions under which each performs better, and the importance of pump cycling and controller set points on total energy collection. Results show that the turn-on set point is not always a critical factor in energy collection since collectors store energy while they warm up and during cycling; and, that proportional flow controllers provide improved energy collection only during periods of interrupted or very low insolation when the maximum possible energy collection is rela= tively low. Although proportional controllers initiate flow ·at lower insolation levels than on/off controllers, proportional controllers produce lower flow rates and higher average collector temperatures resulting in slightly lower instantaneous collection efficiencies.
Date: December 1, 1979
Creator: Schiller, Steven R.; Warren, Mashuri L. & Auslander, David M.
Partner: UNT Libraries Government Documents Department