Rivarolo M.,University of Genoa |
Bogarin J.,Itaipu Binacional |
Magistri L.,University of Genoa |
Massardo A.F.,University of Genoa
International Journal of Hydrogen Energy | Year: 2012
In this paper hydrogen generation and storage systems optimization, related to a very large size hydraulic plant (Itaipu, 14 GW) in South America, is investigated using an original multilevel thermo-economic optimization approach developed by the Authors. Hydrogen is produced by water electrolysis employing time-dependent hydraulic energy related to the water which is not normally used by the plant, named "spilled water". From a thermo-economic point of view, the two main aspects of the study are the optimal definition of the plant size and the whole system management. Both of them are strongly influenced by (i) spilled water energy variability related to its time-dependent distribution during the whole year, (ii) time-dependent electricity demand of Paraguay and Brazil (the owners of the Itaipu plant) electrical grids, and (iii) the hydrogen demand profile. The system analyzed here consists of a very large size hydrogen generation plant (hundreds of MW) based on pressurised water electrolysers fed with the so called "spilled water electricity", the related H 2 storage, and the H 2 demand profile for Paraguay transport sector utilization. Since H 2 plant optimal size is strongly correlated to optimal management and vice-versa, in this paper two hierarchical levels have been considered hour by hour on a complete year time period, in order to minimize capital and variable costs. This time period analysis is necessary to properly take into account spilled energy variability to find out H 2 production system optimal size, optimal storage solution and best economical results. For the optimal storage size, two different solutions have been carefully investigated: (i) classical long time H 2 physical storage using pressurised tanks at 200 bar; (ii) hybrid one using reduced size physical storage (one day time demand) where the energy to feed electrolysers is taken from electrical grid when spilled water energy is not available [Rivarolo M, Bogarin J, Magistri L, Massardo AF. Hydrogen generation with large size renewable plants: the Itaipu 14 GW hydraulic plant case. In: 3rd international conference of applied energy (ICAE), 16-18 May 2011, Perugia; 2011.]. For both the two solutions, time-dependent results are presented and discussed with particular emphasis to economic aspects, system size, capital costs and related investments. It is worthy to note that the results reported here for this particular H 2 large size plant case represent a general methodology, since it is applicable to different size, primary renewable energy, plant location, and different H 2 utilization. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Da Silva J.R.,Itaipu Binacional |
Bastos J.P.A.,Federal University of Santa Catarina
IEEE Transactions on Magnetics | Year: 2015
The efficiency of the finite element method (FEM) for the design and improvement of electromagnetic devices has already been established several decades ago. This powerful tool is also used for the improvement of power transformer designs whose complexity can be handled by the FEM. This paper addresses the influence of simplifications to be made on the geometries of power transformers for the performance of electromagnetic and thermodynamic simulations to diminish the computational time and to obtain the electric and magnetic fields, temperatures, and heat flow in the interior of the transformer. © 2015 IEEE.
Leite Da Silva A.M.,Pontifical Catholic University of Rio de Janeiro |
De Carvalho Costa J.G.,Federal University of Itajuba |
Machado K.G.,Federal University of Itajuba |
De Souza L.L.,Electrical Company of Minas Gerais |
Gonzalez-Fernandez R.A.,Itaipu Binacional
IEEE Transactions on Power Systems | Year: 2015
This paper proposes a new probabilistic method based on chronological Monte Carlo simulation for computing optimal distribution substation spare transformers. The method allows the representation of events such as aging process, load growth, and other conditions not supported by traditional methods based on Poisson and Markov processes. The lifetimes of the transformers are represented by discrete probability distributions, determined by an algorithm that combines the aging of the insulating material, estimated by Arrhenius theory, with the loss of life caused by short-circuits, lightning and switching surges. To illustrate the importance of sizing the inventory based on reliability indices and costs, the proposed method is applied to a group of substations with 177 transformers of 138-13.8 kV, with power rating of 25 MVA. Finally, the proposed methodology is used in combination with a metaheuristic algorithm for determining the optimal timing strategy for composing of the stock of spare transformers over a pre-established planning horizon. © 1969-2012 IEEE.
Cunha D.G.F.,University of Sao Paulo |
Benassi S.F.,Itaipu Binacional |
de Falco P.B.,University of Sao Paulo |
do Carmo Calijuri M.,University of Sao Paulo
Environmental Management | Year: 2016
Artificial reservoirs have been used for drinking water supply, other human activities, flood control and pollution abatement worldwide, providing overall benefits to downstream water quality. Most reservoirs in Brazil were built during the 1970s, but their long-term patterns of trophic status, water chemistry, and nutrient removal are still not very well characterized. We aimed to evaluate water quality time series (1985–2010) data from the riverine and lacustrine zones of the transboundary Itaipu Reservoir (Brazil/Paraguay). We examined total phosphorus and nitrogen, chlorophyll a concentrations, water transparency, and phytoplankton density to look for spatial and temporal trends and correlations with trophic state evolution and nutrient retention. There was significant temporal and spatial water quality variation (P < 0.01, ANCOVA). The results indicated that the water quality and structure of the reservoir were mainly affected by one internal force (hydrodynamics) and one external force (upstream cascading reservoirs). Nutrient and chlorophyll a concentrations tended to be lower in the lacustrine zone and decreased over the 25-year timeframe. Reservoir operational features seemed to be limiting primary production and phytoplankton development, which exhibited a maximum density of 6050 org/mL. The relatively small nutrient concentrations in the riverine zone were probably related to the effect of the cascade reservoirs upstream of Itaipu and led to relatively low removal percentages. Our study suggested that water quality problems may be more pronounced immediately after the filling phase of the artificial reservoirs, associated with the initial decomposition of drowned vegetation at the very beginning of reservoir operation. © 2015, Springer Science+Business Media New York.
Kohn A.,Instituto Oswaldo Cruz |
Moravec F.,Academy of Sciences of the Czech Republic |
Cohen S.C.,Instituto Oswaldo Cruz |
Canzi C.,Itaipu Binacional |
And 2 more authors.
Check List | Year: 2011
This study presents results from several expeditions in 1985, 1991-1995 and 2003 to the Medium Paraná River in the section that begins below the Itaipu Dam and ends at the trinational border of Brazil, Argentina and Paraguay, in the lotic and lentic zones of the reservoir of the Hydroelectric Power Station of "Itaipu Binacional" (localities Foz do Iguaçu, Santa Helena and Guaira). Ninety-eight species of freshwater fishes belonging to 22 families were examined for helminths. A host-parasite list based on Acanthocephala, Cestoda, Digenea, Monogenea and Nematoda collected from the region in question is provided. New host records are presented for Digenea and Nematoda. The Monogenea and Acanthocephala are being studied and will be published in a later paper, but are referred in the host-parasite list, in order to demonstrate the parasitism in the fishes of the reservoir. The results are compared with those presented by other authors from the Upper Paraná River. © 2011 Check List and Authors.