EM - Escola de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6
Notícias
A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.
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6 resultados
Resultados da Pesquisa
Item Hydroelectric production from Brazil's São Francisco River could cease due to climate change and inter-annual variability.(2018) Jong, Pieter de; Tanajura, Clemente Augusto Souza; Sánchez, Antonio Santos; Dargaville, Roger; Kiperstok, Asher; Torres, Ednildo AndradeBy the end of this century higher temperatures and significantly reduced rainfall are projected for the Brazilian North and Northeast (NE) regions due to Global Warming. This study examines the impact of these long-term rainfall changes on the Brazilian Northeast's hydroelectric production. Various studies that use different IPCC models are examined in order to determine the average rainfall reduction by the year 2100 in comparison to baseline data from the end of the 20th century. It was found that average annual rainfall in the NE region could decrease by approximately 25–50% depending on the emissions scenario. Analysis of historical rainfall data in the São Francisco basin during the last 57 years already shows a decline of more than 25% from the 1961–90 long-termaverage.Moreover, average annual rainfall in the basin has been belowits long-termaverage every year bar one since 1992. If this declining trend continues, rainfall reduction in the basin could be evenmore severe than the most pessimistic model projections. That is, the marked drop in average rainfall projected for 2100, based on the IPCC highemissions scenario, could actually eventuate before 2050. Due to the elasticity factor between rainfall and streamflow and because of increased amounts of irrigation in the São Francisco basin, the reduction in the NE's average hydroelectric production in the coming decades could be double the predicted decline in rainfall. Conversely, it is estimated that wind power potential in the Brazilian NE will increase substantially by 2100. Therefore both wind and solar power will need to be significantly exploited in order for the NE region to sustainably replace lost hydroelectric production.Item Wave resource characterization through in-situ measurement followed by artificial neural networks' modeling.(2018) Sánchez, Antonio Santos; Rodrigues, Diego Arruda; Fontes, Raony Maia; Martins, Márcio Fernandes; Kalid, Ricardo de Araújo; Torres, Ednildo AndradeThis research presents a mathematical model that uses artificial neural networks for the assessment of the wave energy potential of sites, based on data recorded by wave monitoring instrumentation. The model was implemented and validated in two different sites. The first one had a dataset from an upward-looking acoustic Doppler current profiler that recorded a hindcast during 2½ years. The second consisted in data from a buoy using motion sensors that recorded continuously during 23 years. For this second site, the performance of the neural network model was compared to that of the Nearshore Wave Prediction System (NWPS), which combines SWAN, Wavewatch III and other numerical models. For the 2½ years' hindcast, the error of the neural network was significant which suggests a better use for filling missing gaps within datasets than for resource assessment. Meanwhile the performance of the neural network trained with the 23 years' hindcast was satisfactory; better than the NWPS in terms of relative bias but worse in terms of scatter index. Therefore it is concluded that neural networks can make an optimal use of the data produced by wave monitoring instrumentation and are useful to characterize the wave energy resource of a coastal site.Item Alternative biodiesel feedstock systems in the semi-arid region of Brazil : implications for ecosystem services.(2017) Sánchez, Antonio Santos; Almeida, Mateus Bastos; Torres, Ednildo Andrade; Kalid, Ricardo de Araújo; Cohim, Eduardo; Gasparatos, AlexandrosThe Northeast region of Brazil has low levels of human development and a marginal environment subject to chronic water scarcity. This paper assesses the potential impacts of bioenergy production from local varieties of castor oil plant and jatropha that could reduce the import of energy in the region, while developing its economy. Biodiesel systems based on these crops can be suitable for the Northeast region as they have low water needs, and are either indigenous or have shown excellent adaptation to the local climate. Apart from biodiesel production, the residue from their processing can be a valuable resource usable for biogas production and biofertilizers. Using the ecosystem services approach, five land management alternatives are compared: (i) Caatinga woodland (a type of dry savannah native to the region), (ii) a scheme of local jatropha varieties and vegetation for Caatinga forest restoration, (iii) a crop rotation scheme of castor oil plant and cowpeas, (iv) cowpea mono-cropping, and (v) pasture. Based on the analysis of secondary data, some provisioning and regulating services were assessed quantitatively, while others qualitatively. The results suggest that the conversion of (i) cowpea mono-cropping to a rotation of cowpeas and castor and (ii) degraded pastures to a jatropha-Caatinga forest restoration scheme can provide a bundle of provisioning, regulating and supporting ecosystem services. Feedstock for bioenergy is the most important ecosystem service derived from these multifunctional landscapes. In particular converting pasture to a jatropha-Caatinga forest restoration scheme could provide per hectare 0.7 t of oilseeds for biodiesel production and 1.8 GJ of usable energy, in the form of biogas from the residual seedcake. The castor-cowpea rotation scheme could provide per hectare 1.5 t of oilseeds for biodiesel production together with 2.2 GJ of usable biogas energy, per hectare.Item Potencial energético das ondas na costa brasileira.(2017) Sánchez, Antonio Santos; Rodrigues, Diego Arruda; Kalid, Ricardo de Araújo; Torres, Ednildo AndradeApresenta-se um modelo matemático em redes neurais para a avaliação do potencial de geração de energia elétrica mediante ondas. O objetivo é desenvolver um modelo confiável, capaz de avaliar de maneira precisa este recurso nos locais mais promissores da costa brasileira. Para validar o modelo, foi usada uma série de medições diretas, registradas durante 10 meses consecutivos por um perfilador acústico de ondas. O modelo conseguiu caracterizar o comportamento desta fonte renovável no local com um erro médio de 9,25%.Item Waste bio-refineries for the cassava starch industry : new trends and review of alternatives.(2017) Sánchez, Antonio Santos; Silva, Yuri Lopes; Kalid, Ricardo de Araújo; Cohim, Eduardo; Torres, Ednildo AndradeThe cassava starch industrial process generates very pollutant effluents that need to be treated before discharge. A series of successful experiences concerning the transformation of treatment ponds into covered lagoons have been conducted in the last years in Brazil, proving that the use of anaerobic digesters could make the worldwide cassava industry more profitable. The circular economy approach is used to add the balance of greenhouse gases, water and land use to the assessment of a set of waste-to-resource alternatives for this particular industrial process. The results point out to the convenience of upgrading the covered lagoon solution to a more complete waste bio-refinery that not only focus in electric power generation but also recovers process heat and biofertilizers as byproducts. Co-generation is very attractive for the resource recovery of this agricultural residue. It was also found that the higher efficiency that characterizes co-generation leads to the lowest level of greenhouse gases emissions.Item Integrating large scale wind power into the electricity grid in the Northeast of Brazil.(2016) Jong, Pieter de; Kiperstok, Asher; Sánchez, Antonio Santos; Dargaville, Roger; Torres, Ednildo AndradeWind power in the NE (Northeast) region of Brazil is currently undergoing rapid development and installed capacity is expected to exceed 16,000 MW by 2020. This study examines the feasibility of integrating large scale wind power into an electricity grid (the Brazilian NE subsystem) which has a high proportion of existing hydroelectricity. By extrapolating existing wind power generation data, the maximum achievable wind power penetration (without exports to other Brazilian regions) and corresponding surplus energy is determined for the NE subsystem. The viable maximum penetration of wind energy generation in the NE subsystemwas estimated to be 65% of the average annual electricity demand assuming that existing hydroelectric and gas generators have 100% scheduling flexibility. These results are compared to the actual gross penetration of wind power forecast to reach 55% in the NE subsystem by 2020. The overall LCOE (levelised cost of electricity) is calculated for various scenarios where wind power replaces all fossil fuel generators in NE subsystem. It was concluded that by 2020, wind power could feasibly reduce the overall LCOE by approximately 46e52% and reduce CO2eq emissions by 34 million tonnes per year compared to a power system with no new renewable generation.