196,028 research outputs found
Long-term power-to-gas potential from wind and solar power: A country analysis for Italy
No full textChallenges related to variability of renewable energy sources (RES) recently arose in many countries and several solutions based on energy storage were proposed; among them, a promising option is Power-to-Gas (P2G), able to recover excess and unbalanced electrical energy. In this work, an assessment of long-term P2G potential is performed on a country scale, based on the analysis of electrical system historical data series, rescaled in order to consider the evolution of load and installed wind and solar capacity. In a long-term perspective, it is assumed the complete exploitation of the technical potential of the RES, which represents an upper deployment boundary with current technology. Once satisfied the electric load, residual energy to the P2G system and hydrogen production are calculated on a hourly basis; P2G installed capacity is a consequence of the assumed target on minimum operation on a yearly basis. The Italian case is analyzed, evidencing that the recovered excess energy from RES could substitute nearly 5% of current natural gas consumption or about 7% of national fuel consumption when used for hydrogen mobility. A range of options and a sensitivity analysis on assumptions is presented, showing scenarios with up to 200 GW of installed RES and a 50% additional load with respect to current one. In addition, the extension of the model to a zonal grid structure evidences the impact of transmission lines saturation that may increase gas production up to 50%. Results are compared with the German case, considered in a previous work, evidencing differences due to the diverse energy production mix
Effect of cascade storage system topology on the cooling energy consumption in fueling stations for hydrogen vehicles
No full textOne of the main obstacles of the diffusion of fuel cell electric vehicles (FCEV) is the refu-
eling system. The new stations follow the refueling protocol from the Society of Auto-
motive Engineers where the way to reach the target pressure is not explained. This work
analyzes the thermodynamics of a hydrogen fueling station in order to study the effects of
the cascade storage system topology on the energy consumption for the cooling facility. It
is found that the energy consumption for cooling increases, expanding the total volume of
the cascade storage system. Comparing the optimal and the worst volume configurations
of the cascade storage tanks at different ambient temperatures, the energy saving is
approximately 12% when the average ambient temperature is 20 C and around 20% when
the average ambient temperature is 30 C. The energy consumption for cooling is signifi-
cantly influenced by the topology of the cascade storage system and it is particularly
relevant in the case of low daily-dispensed amount of hydrogen
Clean mobility infrastructure and sector integration in long-term energy scenarios: The case of Italy
No full textAs main contributors to greenhouse gas emissions, power and transportation are crucial sectors for energy system decarbonization. Their interaction is expected to increase significantly: plug-in electric vehicles add a new electric load, increasing grid demand and potentially requiring substantial grid upgrade; hydrogen production for fuel cell electric vehicles or for clean fuels synthesis could exploit the projected massive power overgeneration by intermittent and seasonally-dependent renewable sources via Power-to-Hydrogen. This work investigates the infrastructural needs involved with a broad diffusion of clean mobility, adopting a sector integration perspective at the national scale. The analysis combines a multi-node energy system balance simulation and a techno-economic assessment of the infrastructure to deliver energy vectors for mobility. The article explores the long-term case of Italy, considering a massive increase of renewable power generation capacity and investigating different mobility scenarios, where low-emission vehicles account for 50% of the stock. First, the model solves the energy balances, integrating the consumption related to mobility energy vectors and taking into account power grid constraints. Then, an optimal infrastructure is identified, composed of both a hydrogen delivery network and a widespread installation of charging points. Results show that the infrastructural requirements bring about investment costs in the range of 43–63 G€. Lower specific costs are associated with the exclusive presence of FCEVs, whereas the full reliance on BEVs leads to the most significant costs. Scenarios that combine FCEVs and BEVs lie in between, suggesting that the overall power + mobility system benefits from the presence of both drivetrain options
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Dr. Glendon Swarthout
No full textHosted by Roger M. Busfield, MSU Assistant Professor of Speech and Theater, Meet the Author is designed to introduce a general audience to a contemporary author and their work through in-depth interviews. This episode features a conversation between Dr. Glendon Swarthout, prolific author and English professor at MSU, and assistant professors Sam S. Baskett and Theodore B. Strandness
An Energy Concept to Supply the Transport Sector with Hydrogen from Renewable Energy Sources
No full text21st World Hydrogen Energy Conference 2016. Zaragoza, Spain. 13-16th June, 2016An Energy Concept to Supply the Transport Sectorwith Hydrogen from Renewable Energy SourcesM. Robinius1*, S. Schiebahn oder T. Grube2 and D. Stolten31Forschungszentrum Jülich GmbH, Electrochemical Process Engineering (IEK-3), D-52425 Jülich, Germany2 Forschungszentrum Jülich GmbH, Electrochemical Process Engineering (IEK-3), D-52425 Jülich, Germany3 Forschungszentrum Jülich GmbH, Electrochemical Process Engineering (IEK-3), D-52425 Jülich, Germany(*) [email protected] minimize the anthropogenic impact of the climate system the increase of the global temperature should be below2 degrees Celsius. Therefor all sectors have to be decarbonated to a specific value. In Germany for example thegreenhouse gases have to be decreased overall sectors by 80 to 95 % by 2050 compared to 1990. Hence there is a needfor an energy concept in which not only one sector for example the electrical energy sector is considered. For thisreason the IEK-3 developed an energy concept as well as a model in which two of the biggest sectors in terms ofgreenhouse gases can be implemented: the electrical energy and the transport sector. This paper gives an overviewabout this concept and shows selected results of the model. The concept is driven by the increasing amount of variablerenewable energy sources (VRES). The VRES feed-in from wind turbines and photovoltaic systems depends onweather and is only partially predictable. As a result, to decarbonize this sector the installed capacity of VRES has to beabout the factor 3 over the peak load. This is leading to a changing regime in which the VRES producing temporarilymore energy than is needed from the conventional load as well as can be transported from the electrical grid. Thissurplus energy can be used to produce hydrogen via electrolysis and can then supply the transport sector.Introduction and OverviewThe energy concept relies on a high share of VRES and the so called “power-to-gas” approach. This approach usesthe surplus of the Renewable Energy Sources (RES) to produce hydrogen and oxygen via electrolysis. The hydrogencan then for example been used in the transport sector by fuel cell cars. Schiebahn et al. (2015) [1] and Robinius (2015)[2] showing the potential as well as a technological overview for this approach. While Baufume et al. (2013) [3]describing the calculation for a nationwide German hydrogen pipeline infrastructure Robinius et al. (2014) [4] analyzingthe optimal placement of electrolysis. Both papers and models have no interconnection at all and therefor the goal ofthis paper is to combine both models and show by analyzation of the energy concept the capability of this combination.The Electrical Energy SectorThe model calculates the hourly residual load for 11,268 municipalties in Germany. Therfore the VRES as well as theload has been deatailed analyzed and integrated. Futhermore the high voltage grid (380 and 220 kV) can be considered.Figure 1 shows an example of the installed capacity, theproduced electricity and the full load hours in Germany bythe year 2050 in the model. For this the user has to setinitially the installed capacity and the choosen weather year.Afterwards the model calculates the produced electricity aswell as the residual load for each hour under considerationof the high voltage grid. The residual load will be thencalculated by:87601P P P PDemand ,t RES ,t Im port ,t Export ,tt Where Demand ,t P is the hourly demand of each municipality,RES ,t P is the hourly production of electricity from all RES,Im port ,t P is the imported power to Germany and Export ,t P isthe exported power from Germany. This means if theresidual load is negative there is suplus energy and if theresidual load is positive there is a need for conventional power plants.Table 1. Sections of the abstract to be changed01000200030004000500060007000050100150200250300350400Full load hours [h]Produced electricity [TWh]Installed capacity [GW]Installed capacity [GW] Produced electricity [TWh]Full load hours [h]Figure 1. Example of the installed capacity, producedelectricity and full load hours by the year 2050in Germany21st World Hydrogen Energy Conference 2016. Zaragoza, Spain. 13-16th June, 2016Figure 2 shows the accumulated residual energy for one year in 11,268 municipalties in Germany with the data from figure 1. The negative residual energy which can be used to produce hydrogen is especially located in the north of Germany. This is due to the high amount of on- and offshore wind which are also located mainly in the north in Germany.The Transport SectorFigure 3 (left) shows the possible amount of fuel cell vehicles in Germany and the summarized hydrogen demand in the model as well as the demand from an agent based model after Keles et al. (2008) [5]. For the model of the IEK-3 among others a geospatial model has been developed which distributes the summarized hydrogend demand to 413 counties in Germany. Therfore different indicators for each county like the GDP was taken into considertation. The peak demand is in the year 2052 with 2.93 million tons. Afterwards the demand decreases because of the more efficient fuel cell cars. Figure 3 (right) shows the location of the electroysis (red stars), the transmission grid (red lines), the distribution grid (black lines) as well as all 9,968 hydrogen fuel stations to supply Germany with hydrogen from RES. Futhermore a detailed econmic analysis waReferences[1] Schiebahn, S., Grube, T., Robinius, M., Tietze, V., Kumar, B., und Stolten, D.; Power to gas: Technological overview, systems analysis and economic assessment for a case study in Germany. International Journal of Hydrogen Energy, 2015. 40(12): p. 4285-4294.[2] Robinius, M.; The German Energiewende and the Potential for Power to Gas. 2015. DOI: 10.13140/RG.2.1.4569.2641.[3] Baufumé, S., Grüger, F., Grube, T., Krieg, D., Linssen, J., Weber, M., Hake, J.-F., und Stolten, D.; GIS-based scenario calculations for a nationwide German hydrogen pipeline infrastructure. International Journal of Hydrogen Energy, 2013. 38(10): p. 3813-3829.[4] Robinius, M., Rodriguez, R.A., Kumar, B., Andresen, B., Stein, F.T., Schiebahn, S., und Stolten, D.; Optimal placement of electrolysers in a German power-to-gas infrastructure, in World Hydrogen Energy Conference,2014: Gwangju, Korea.[5] Keles, D., Wietschel, M., Möst, D., und Rentz, O.; Market penetration of fuel cell vehicles – Analysis based on agent behaviour. International Journal of Hydrogen Energy, 2008. 33(16): p. 4444-4455.01230102030402015202020252030203520402045205020552060Hydrogen demand [Mil. t]Fuel Cell Vehicles [Mil. units]BrennstoffzellenfahrzeugeWasserstoffbedarfResidual energy[MWh/km²]-3.000.000 - 2.500-2.500 - -1.700-1.700 - -1200-1.200 - -830-830 - -460-460 - -120-120 - 175175 - 545545 - 1.5351.535 - 50.600Peak H2-demand 2,93 Mil. tFigure 2. Residual energy in 11,268 municipalities in GermanyFigure 3. Left: Quantity of fuel cell cars and hydrogen demand in Germany related to Keles et al. (2008) and IEK3. Right: Dedicated hydrogen pipeline grid to supply the German transport sectorFuel Cell Vehicles Lead Scenario[5] Scenario 3[5] Hydrogend demand Sources Transmission HUBs Distribution Hydrogen fuel stations Countie
Simulation of thermal plant optimization and hydraulic aspects of thermal distribution loops for large campuses
No full textFollowing an introduction, the author describes Texas A&M University and its utilities system. After that, the author presents how to construct simulation models for chilled water and heating hot water distribution systems. The simulation model was used in a $2.3 million Ross Street chilled water pipe replacement project at Texas A&M University. A second project conducted at the University of Texas at San Antonio was used as an example to demonstrate how to identify and design an optimal distribution system by using a simulation model. The author found that the minor losses of these closed loop thermal distribution systems are significantly higher than potable water distribution systems. In the second part of the report, the author presents the latest development of software called the Plant Optimization Program, which can simulate cogeneration plant operation, estimate its operation cost and provide optimized operation suggestions. The author also developed detailed simulation models for a gas turbine and heat recovery steam generator and identified significant potential savings. Finally, the author also used a steam turbine as an example to present a multi-regression method on constructing simulation models by using basic statistics and optimization algorithms. This report presents a survey of the author??s working experience at the Energy Systems Laboratory (ESL) at Texas A&M University during the period of January 2002 through March 2004. The purpose of the above work was to allow the author to become familiar with the practice of engineering. The result is that the author knows how to complete a project from start to finish and understands how both technical and nontechnical aspects of a project need to be considered in order to ensure a quality deliverable and bring a project to successful completion. This report concludes that the objectives of the internship were successfully accomplished and that the requirements for the degree of Degree of Engineering have been satisfied
Economically-Limited Onshore Wind Capacity and Production in European Nations
No full textICREN Conference:Title: Economically-Limited Onshore Wind Capacity and Production in European NationsAbstract:In the context of meeting CO2 emission reduction targets to fulfill climate action plans, expansion of renewable energy sources into future energy systems represents a common research theme. Onshore wind turbines currently hold one of the highest shares in renewable electricity generation worldwide, with the second highest growth over the last 25 years [1], which will surely continue in the future. It is well known that electricity generation from wind turbines is characterized by spatially-sensitive intermittency, and furthermore that the placement of turbines is strongly influenced by the sociotechnical criteria; such as proximity to settlements, terrain suitability, and conservation efforts. Nevertheless, wind scenario studies commonly do not account for all of these concerns in detail; typically over simplifying the impact of sociotechnical criteria on the final distribution of a desired capacity across a study region. To improve upon this deficiency, the work described here incorporates contemporary techniques for the simulation of hourly wind turbine performance at large spatial scales in coordination with land eligibility concerns. Using the European continent as the study region, the applied method proceeds as follows. First, every 1 km2 location in Europe is simulated at the hourly level considering multiple turbine models and 36 weather years (Figure 1). A previous land eligibility result [2] is used along with a turbine placement algorithm to identify the maximal number of turbines which can be placed in the available areas with a minimal distance of 850 meters enforced between turbines. The placements are then matched to their expected FLH, and a cost model [3] is used to determine the best turbine model and the associated levelized cost of electricity (LCOE) for each placement following the approach of Robinius et. al[4]. Ordering by cheapest LCOE, the average FLH and LCOE of each country is determined as a function of installed capacity (sample trends displayed in Figure 2). By choosing an economically-constrained average LCOE of 11, 9, 7, and 5 Euro-ct/kWh, it finally becomes possible to determine the economically-limited capacity and production within each of the evaluated countries, shown in Table 1. References:[1] IEA. “Renewables Information 2017”. 2018. ISBN: 978-92-64-27811-0. url:https://www.iea.org/publications/freepublications/publication/renewables-information---2017-edition---overview.html[2] Ryberg, D. S., Robinius, M., & Stolten, D. (2017). Methodological Framework for Determining the Land Eligibility of Renewable Energy Sources. arXiv preprint arXiv:1712.07840.[3] Fingersh, L., Hand, M., & Laxson, A. (2006). Wind turbine design cost and scaling model (No. NREL/TP-500-40566). National Renewable Energy Lab.(NREL), Golden, CO (United States).[4] Robinius, M., Otto, A., Syranidis, K., Ryberg, D. S., Heuser, P., Welder, L., ... & Stolten, D. (2017). Linking the power and transport sectors—Part 2: Modelling a sector coupling scenario for Germany. Energies, 10(7), 957
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