Papers by Osvaldo Venturini
Sugar Industry, 2008
Ethanol production via sugar juice fermentation has a serious problem related to the quantities a... more Ethanol production via sugar juice fermentation has a serious problem related to the quantities and high organic content of its main residue i.e. vinasse or stillage. Awareness of the impact of vinasse disposal by fertirrigation caused the environmental agencies in Brazil to implement more rigorous conditions regarding this practice. In this paper, as possible disposal alternatives, the following were defined: conventional fertirrigation (base reference case); vinasse biodigestion and biogas use as fuel in factory boilers, vinasse dewatering up to 40–50% and its direct combustion in boilers; vinasse dewatering up-to 60% before fertirrigation in order to reduce transport costs. At the same time, environmental impacts characterization and weighting of the vinasse fertirrigation life cycle and the advantages and disadvantages of each alternative are presented. Graphs of normalized environmental effects for the evaluated alternatives are also presented.
Journal of Cleaner Production, 2018
Brazilian steel industry based on charcoal is unique in the world, making Brazil the largest worl... more Brazilian steel industry based on charcoal is unique in the world, making Brazil the largest world charcoal producer and the only one that produces green pig iron in large scale, a low-carbon and economic option to the traditional pig iron produced from coal coke. The renewable charcoal originates from the slow pyrolysis of eucalyptus wood produced in high productivity reforestation farms thought traditional batch reactors. Unfortunately, the state-of-the-art of charcoal making in Brazil do not comprise the pyrolysis gases utilization, wasting more than 30% of wood energy decreasing air quality and producing environmental and social impacts. Therefore, in this sense, the goal of this work is to evaluate the possibility to recovery this energy to produce electricity, and issues the topics related to the use of a very lean fuel, with flammability problems, which varies its composition over time, and the lack of water to be used as cooling mean for the thermodynamic cycles in the eucalyptus farms. The gases Lower Flammability Limit (LFL) was analyzed by the Calculated Adiabatic Flame Temperature (CAFT) method showing that in the first half of pyrolysis, the gases are generally under the LFL line, what could be solved by the gases pre-heating or mixing with richer fuel produced by kilns in advanced carbonization stage. Results showed an average gas Lower Heating Value (LHV) of 1,323 kJ/kg. To overcome gas production instability a cluster system of 120 rectangular carbonization kilns working in synchrony was accessed through a computational tool, where it was found a minimum thermal power available of 57.5 MW th or 25.6% of initial wood energy content. Three energy conversion technologies were evaluated: the Steam Rankine Cycle (SRC), the Externally Fired Gas Turbine (EFGT) and the Organic Rankine Cycle (ORC). In this work, it was found that the efficiency of the SRC, EFGT and ORC conversion technologies are 24.0%, 19.3% and 23.7%, respectively. An economic analysis indicated the SRC as the most viable technology with a potential to generate 0.93 MWh el per ton of charcoal ACCEPTED MANUSCRIPT produced. Brazil has as estimated energy loss of 2.5 Mtoe (million tonne of oil equivalent) annually in the form of carbonization gases, which could be used to produce up to 5,644 GWh el of electricity and reduce the Greenhouse Gases (GHG) emissions up to 15 Mton CO 2-eq.
Renewable and Sustainable Energy Reviews, 2009
Resources, Conservation and Recycling, 2014
With recent emphasis on environmental protection, electric vehicles (EVs) have gained popularity ... more With recent emphasis on environmental protection, electric vehicles (EVs) have gained popularity in regions such as Europe, America, China and Australia; due to their 'zero tail-pipe emission' and low maintenance cost. This paper aims to investigate the feasibility of introducing EVs into the Brunei market using life cycle cost analysis, as well as identify dominant factors that influence its feasibility. Although local data have been used, methodologies adopted in this paper are applicable and directly transferable for analysis of other markets. Our analysis has shown that EV is currently still expensive as compared to Internal Combustion Engine Vehicles (ICEVs) and Hybrid Electric Vehicles (HEVs) in the market; with its acquisition cost contributing much to its Life Cycle Cost (LCC). In order to promote EVs and make other types of vehicles less desirable, it is proposed that a direct government subsidy to be introduced as well as the current gasoline price to be increased. It has been shown that initial subsidy of USD$4100 and increasing gasoline price to USD$0.70/litre, would allow EVs to compete comfortably in the market. This subsidy can be gradually reduced with time, as EV becomes cheaper due to the expected reduction in battery price. Environmentally, however, current Greenhouse Gas (GHG) emissions from EVs turn out higher than ICEVs, considering the energy chain. In this regard, cleaner renewable energy sources need to be considered and improvement in power plant efficiency needs to be made, to make EVs more environmentally competitive to conventional vehicles. In conclusion, the government needs to look into financial incentives such as subsidy and increasing gasoline price to improve the feasibility of EVs in the market, as well as to improve efficiency of the energy generation and transmission to derive the full benefit of EVs.
Energy, 2011
A thermodynamic information system for diagnosis and prognosis of an existing power plant was dev... more A thermodynamic information system for diagnosis and prognosis of an existing power plant was developed. The system is based on an analytic approach that informs the current thermodynamic condition of all cycle components, as well as the improvement that can be obtained in the cycle performance by the elimination of the discovered anomalies. The effects induced by components anomalies and repairs in other components efficiency, which have proven to be one of the main drawbacks in the diagnosis and prognosis analyses, are taken into consideration owing to the use of performance curves and corrected performance curves together with the thermodynamic data collected from the distributed control system. The approach used to develop the system is explained, the system implementation in a real gas turbine cogeneration combined cycle is described and the results are discussed.
Energy, 2011
and System Analysis www.itas.kit.edu KIT-Universität des Landes Baden-Württemberg und nationales ... more and System Analysis www.itas.kit.edu KIT-Universität des Landes Baden-Württemberg und nationales Forschungszentrum in der Helmholtz-Gemeinschaft www.kit.edu
Energy, 2011
Biofuels world production has increased sharply in recent years. Oil reserves depletion, the oil ... more Biofuels world production has increased sharply in recent years. Oil reserves depletion, the oil high price and the confidence in biofuels "carbon neutrality" are the main causes of this phenomenon. However, claims related to the negative consequences of biofuel programs are frequent; mainly those related to the biofuels/food competition and sustainability. This paper aims to contribute for the development of a framework for sustainability indicators as a tool for performance assessment. The most used indicators to measure the biofuels sustainability are: Life Cycle Energy Balance (LCEB), quantity of fossil energy substituted per hectare, co-product energy allocation, life cycle carbon balance and changes in soil utilization. On the other hand, existing assessment tools, such as Life Cycle Assessment (LCA) and Integrated Environmental Assessment (IEA), are compared emphasizing their advantages and disadvantages. Main constraints related to the studied frontiers, as well as the lack of reliable data and their effects are also discussed. Discussions are held on the basis of real life cycle studies carried out by the authors about palm oil biodiesel and different alternatives for the stillage treatment and disposal. Finally, suggestions and recommendations are made to improve existing methodologies for biofuels sustainability evaluation, all this from a south perspective.
Resumo. As usinas termelétricas típicas nos Sistemas Isolados são compostas por conjuntos de grup... more Resumo. As usinas termelétricas típicas nos Sistemas Isolados são compostas por conjuntos de grupos geradores a diesel operando em paralelo. Somente no Brasil, os sistemas isolados possuem em torno de 230 usinas termelétricas com um consumo diesel de 1,08 bilhão de litros/ano. Assim, como forma de reduzir o consumo de óleo diesel nas usinas dos Sistemas Isolados, nos últimos anos e, principalmente, a partir de 2014, a Agência Nacional de Energia Elétrica (ANEEL) vem restringindo os limites de consumo específico de combustível definidos para as usinas dos sistemas isolados. Esta medida obriga as usinas a adotarem unidades geradoras mais eficientes, ou seja, com baixo consumo de combustível, e procedimentos de operação e manutenção para que o consumo mensal de combustível das usinas esteja abaixo do limite máximo permitido. Este artigo estuda a aplicação de alternativas para redução de consumo de combustível em uma usina de 1,8MW de potência instalada. Esta usina foi escolhida por pos...
Proceedings of the 23rd ABCM International Congress of Mechanical Engineering, 2015
Proceedings of the 23rd ABCM International Congress of Mechanical Engineering, 2015
Applied Thermal Engineering, 2013
ABSTRACT This paper deals with the thermodynamic analysis, of both the first and second law of th... more ABSTRACT This paper deals with the thermodynamic analysis, of both the first and second law of thermodynamic of two different technologies, (ORC and Kalina cycle) for power production through an enhanced geothermal system (EGS). In order to find a better performance of both thermal cycles it were evaluated 15 different working fluids for ORC and three different composition of the ammonia–water mixture for the Kalina cycle. In this work, the Aspen-HYSYS software was used to simulate both thermal cycles and to calculate the thermodynamic properties based on Peng–Robinson Stryjek–Vera (PRSV) Equation of State (EoS). At the end the two cycles was compared using an economic analysis with the fluid that offers the best performance for each thermal cycle which are R-290 for ORC and for Kalina cycle a composition of the mixture of 84% of ammonia mass fraction and 16% of water mass fraction. For this conditions the Kalina cycle produce 18% more net power than the ORC. A levelized electricity costs of 0.22 €/kW h was reached for ORC and 0.18 €/kW h for Kalina cycle. Finally a sensitivity analysis of the EGS LCOE was carried out for a few economic parameters to determinate how is the variation of LCOE for a % change from the base case.
The imminent decline of the world's oil production, its high market prices and environmental ... more The imminent decline of the world's oil production, its high market prices and environmental impacts have made the production of biofuels reach unprecedented volumes over the last ten years. This is why there have been intense debates promoted by international organizations and political leaders in order to discuss the impacts of the biofuel use intensification. Besides assessing the causes of the rise in the demand and production of biofuels, this paper also shows the state of the art of its world's current production. It also discusses different vegetable sources and technological paths to produce biofuels, as well as issues regarding production cost and the relation of its economic feasibility with oil international prices. The environmental impacts of programs that encourage biofuel production, farmland and requirements and the impacts on food production are also discussed, considering the life cycle analysis as a tool. It is concluded that the rise in the use of biofuel...
ASME 2021 Power Conference, 2021
In order to increase the flexibility and performance of gas turbines, generally their manufacture... more In order to increase the flexibility and performance of gas turbines, generally their manufacturers and research centers involved in their development are constantly seeking the expansion of their operational envelope as well as their efficiency, making the engine more dynamic, less polluting and able to respond promptly to variations in load demands. An important aspect that should be considered when analyzing these prime movers is the assessment of its behavior under transients due to load changes, which can be accomplished through the development of a detailed, accurate and effective computational model. Considering this scenario, the present work aims to develop a model for the simulation and analysis of the dynamic behavior of stationary gas turbines. The engine considered in this analysis has a nominal capacity of 30.7 MW (ISO conditions) and is composed by a two-spool gas generator and a free power turbine. The model was developed using T-MATS, an integrated Simulink/Matlab t...
The Present work aims to study, by mean of the first and second law of the thermodynamic, the per... more The Present work aims to study, by mean of the first and second law of the thermodynamic, the performance of low-temperature Enhanced Geothermal Systems (EGS) including efficiency, working fluids, mass flow rate consumption, electric power production and the irreversibilities of the ORC system to establish the thermodynamics conditions of the cycle and the thermo physical conditions of the working fluids to achieve the better performance of the conversion process of the thermal energy into electrical energy. In this work, the ASPEN-HYSYS software was used as a tool to simulate the thermal system and PengRobinson Stryek-Vera (PRSV) equations of state (EoS) for the 15 analyzed working fluids
As usinas termeletricas tipicas nos Sistemas Isolados sao compostas por conjuntos de grupos gerad... more As usinas termeletricas tipicas nos Sistemas Isolados sao compostas por conjuntos de grupos geradores a diesel operando em paralelo. Somente no Brasil, os sistemas isolados possuem em torno de 230 usinas termeletricas com um consumo diesel de 1,08 bilhao de litros/ano. Assim, como forma de reduzir o consumo de oleo diesel nas usinas dos Sistemas Isolados, nos ultimos anos e, principalmente, a partir de 2014, a Agencia Nacional de Energia Eletrica (ANEEL) vem restringindo os limites de consumo especifico de combustivel definidos para as usinas dos sistemas isolados. Esta medida obriga as usinas a adotarem unidades geradoras mais eficientes, ou seja, com baixo consumo de combustivel, e procedimentos de operacao e manutencao para que o consumo mensal de combustivel das usinas esteja abaixo do limite maximo permitido. Este artigo estuda a aplicacao de alternativas para reducao de consumo de combustivel em uma usina de 1,8MW de potencia instalada. Esta usina foi escolhida por possuir car...
Q As an expert in land-based feedstock development, what would you regard as the major advances i... more Q As an expert in land-based feedstock development, what would you regard as the major advances in this field to date? In sharp contrast to food crops, which people have been growing and breeding for millennia, research on most energy crops is still in its infancy. Yet even in a relatively short period of time, we have seen breeding programs increase yields of energy crops such as switchgrass and willow by 30–50% [1,2]. We are just beginning to see results from the application of crop biotechnology to dedicated energy crops, but initial indications are promising. Of particular importance are increased tolerance to stress (e.g., water, nutrients and pests), control of invasiveness (through sterile lines and delayed flowering) and enhanced energy characteristics (e.g., by modifying cell wall constituents such as cellulose, hemicellulose and lignin). Along with these advances in genetics and agronomic practices, there have also been considerable advances in the use of remote sensing, e...
Biofuels for a More Sustainable Future
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Papers by Osvaldo Venturini