Silvio Hamacher

Economic assessment of biodiesel production from waste frying oils

Waste frying oils (WFO) can be a good source for the production of biodiesel because this raw material is not part of the food chain, is low cost and can be used in a way that resolves environmental problems (i.e. WFO is no longer thrown into the sewage network). The goal of this article is to propose a method to evaluate the costs of biodiesel production from WFO to develop an economic assessment of this alternative. This method embraces a logistics perspective, as the cost of collection of oil from commercial producers and its delivery to biodiesel depots or plants can be relevant and is an issue that has been little explored in the academic literature. To determine the logistics cost, a mathematical programming model is proposed to solve the vehicle routing problem (VRP), which was applied in an important urban center in Brazil (Rio de Janeiro), a relevant and potential center for biodiesel production and consumption. Eighty-one biodiesel cost scenarios were compared with information on the commercialization of biodiesel in Brazil. The results obtained demonstrate the economic viability of biodiesel production from WFO in the urban center studied and the relevance of logistics in the total biodiesel production cost.

Managing product variety in emerging markets

Purpose – The need for an efficient provision of product variety has been widely established as a means of competing in the marketplace, yet previous studies into the management of product variety have commonly analysed products in isolated developed markets. The purpose of this paper is to investigate how firms manage their product variety in emerging markets. This paper aims to investigate the rationale underlying the restriction of variety in such settings, and define general mechanisms by which firms can adapt their product variety when operating in both emerging and developed markets simultaneously.Design/methodology/approach – The paper uses the case of a global vehicle manufacturer that offers common products across developed and emerging markets to illustrate the difference between them in terms of product variety, and examine the process that underlies its management. The paper utilises a combination of data collection techniques.Findings – The paper shows empirically how product variety (in part...

Optimization of biodiesel supply chains based on small farmers: A case study in Brazil

This article presents a methodology for conceiving and planning the development of an optimized supply chain of a biodiesel plant sourced from family farms and taking into consideration agricultural, logistic, industrial, and social aspects. This model was successfully applied to the production chain of biodiesel fuel from castor oil in the semi-arid region of Brazil. Results suggest important insights related to the optimal configuration of the crushing units, regarding its location, technology, and when it should be available, as well as the configuration of the production zones along the planning horizon considered. Moreover, a sensitivity analysis is performed in order to measure how possible variations in the considered conjecture can affect the robustness of the solutions.

A Lagrangean decomposition approach for oil supply chain investment planning under uncertainty with risk considerations

We present a scenario decomposition framework based on Lagrangean decomposition for the multi-product, multi-period, supply investment planning problem considering network design and discrete capacity expansion under demand uncertainty. We also consider a risk measure that allows us to reduce the probability of incurring in high costs while preserving the decomposable structure of the problem. To solve the resulting large-scale two-stage mixed-integer stochastic linear programming problem, we propose a novel Lagrangean decomposition scheme. In this context, we compare dierent formulations for the non-anticipativity conditions. In addition to that, we present a new hybrid algorithm for updating the Lagrangean multiplier set, based on the combination of cutting-plane, subgradient and trust-region strategies. Numerical results suggests that dierent formulations of the non-anticipativity conditions have a signicant eect on the performance of the algorithm. Moreover, we observe that the proposed hybrid approach has superior performance when compared with the traditional subgradient algorithm in terms of faster computational times for the problem addressed in this work.

Accelerating Benders Stochastic Decomposition for the Optimization under Uncertainty of the Petroleum Product Supply Chain

This paper addresses the solution of a two-stage stochastic programming model for a supply chain investment planning problem applied to the petroleum products supply chain. In this context, we present the development of acceleration techniques for the stochastic Benders decomposition that aim to strengthen the cuts generated, as well as to improve the quality of the solutions obtained during the execution of the algorithm. Computational experiments are presented for assessing the eciency of the proposed framework. We compare the performance of the proposed algorithm with two other acceleration techniques. Results suggest that the proposed approach is able to eciently solve the problem under consideration, achieving better performance better in terms of computational times when compared to other two techniques.

Optimization under uncertainty of the integrated oil supply chain using stochastic and robust programming

This paper proposes the development of a strategic planning model for an integrated oil chain considering three sources of uncertainty: crude oil production, demand for refined products and market prices. To deal with these uncertainties, three formulations are proposed: (1) a two-stage stochastic model with a finite number of realizations, (2) a robust min–max regret model and (3) a max–min model. These models were applied to Brazils oil chain, comprising 17 refineries and three main petrochemical plants, 16 groups of crude oils, 50 intermediate products, 10 final products, 13 terminals and a logistic network composed of 278 transportation arcs relative to the road, water, rail and pipeline modes. The time horizon analyzed covers 10 years. The results indicate significant financial differences between the three formulations, depending on the agents risk profile.

Petroleum refinery operational planning using robust optimization

In this article, the robust optimization methodology is applied to deal with uncertainties in the prices of saleable products, operating costs, product demand, and product yield in the context of refinery operational planning. A numerical study demonstrates the effectiveness of the proposed robust approach. The benefits of incorporating uncertainty in the different model parameters were evaluated in terms of the cost of ignoring uncertainty in the problem. The calculations suggest that this benefit is equivalent to 7.47% of the deterministic solution value, which indicates that the robust model may offer advantages to those involved with refinery operational planning. In addition, the probability bounds of constraint violation are calculated to help the decision-maker adopt a more appropriate parameter to control robustness and judge the tradeoff between conservatism and total profit.

Comparação entre as tendências e estratégias da indústria automotiva no Brasil e na Europa

A industria automotiva esta passando por transformacoes que vem provocando a diversificacao e segmentacao do mercado, a reducao do ciclo de vida de modelos de veiculos e a oferta de variedades de atributos desses modelos para os clientes. Este artigo tem por objetivos analisar essas tendencias e avaliar as principais estrategias desenvolvidas e implementadas pelas montadoras de veiculos nos mercados brasileiro e europeu, para fazer face a estas tendencias. Os resultados obtidos no Brasil pelos autores deste artigo foram analisados tendo como base a metodologia cientifica adotada em uma pesquisa similar desenvolvida na Europa. Os resultados mostram como as estrategias de plataformas, de configuracao tardia e de pacotes de opcionais estao sendo implementadas pelas montadoras, permitindo uma comparacao entre os dois mercados examinados.

Modelo de análise de cadeias de suprimentos: fundamentos e aplicação às cadeias de cilindros de GNV

In recent years, Supply Chain Management has created opportunities and challenges for competition in the world of business. As a result, chain configuration analysis has become an increasingly important theme which allows one to identify potential opportunities for improved management and decision-making in the various links in supply chains. In this context, this article presents a model which is used here to analyze supply chains based on key dimensions. The model was validated through a case study conducted in different supply chains of a large Brazilian Compressed Natural Gas cylinder manufacturer.

Literature review of oil refineries planning under uncertainty

This paper presents a literature review in the area of refinery planning models with emphasis on the main techniques to deal with optimisation under uncertainty. The studies are classified according to the segment of the oil chain (upstream, midstream, or downstream), planning level (strategic, tactical, or operational), and problem type (LP, NLP, MILP, or MINLP). The works are also categorised as deterministic or stochastic, and it is indicated whether they present an actual application or not. In addition, the stochastic models are further detailed according to the technique to account for uncertainty and the uncertainty factors considered. The conclusions point out to major literature gaps and the research opportunities in the area of refinery planning under uncertainty.