La cadena de suministro sostenible: conceptos, modelos de optimizaci´on y de simulaci´on y tendencias

Context: The environmental and social dimensions of performance are of great importance, given that they must be incorporated into strategic, tactical, and operational objectives in companies and supply chains to minimize negative impacts on the environment and society. Method: After reviewing the Scopus, Web of Science, and ScienceDirect databases for the topics of sustainability and supply chain management, a state of the art of green and sustainable supply chain management is presented, aiming to guide readers towards a synthesis of related concepts and future lines of research. Results: The reader is introduced to concepts and trends around the field of green and sustainable supply chain management to raise interest in new research and practices to guide the implementation of sustainability in organizations and their supply chains. Conclusions: Sustainable supply chain management still faces several academic and practical challenges in terms of implementation, performance measurement, and how models can capture a dynamic and uncertain social and environmental context. There are latent research issues such as management of the circular supply chain, applications in emerging economies, or the application of 4.0 technologies.Contexto: Las dimensiones ambiental y social del desempeño son de gran importancia, puesto que deben ser incorporadas a los objetivos estratégicos, tácticos y operativos de las empresas y cadenas de suministro para minimizar los impactos negativos sobre el medio ambiente y la sociedad. Método: Tras haber consultado los temas de sostenibilidad y gestión de la cadena de suministro en las bases de datos Scopus, Web of Science y ScienceDirect, se presenta el estado del arte en gestión de la cadena de suministro verde y sostenible, esperando guiar a los lectores hacia una síntesis de conceptos relacionados y futuras líneas de investigación. Resultados: Se introduce al lector a conceptos y tendencias en el campo de gestión de la cadena de suministro verde y sostenible para despertar el interés en nuevas investigaciones y prácticas para guiar la implementación de la sostenibilidad en organizaciones y sus cadenas de suministro. Conclusiones: La gestión sostenible de la cadena de suministro aún enfrenta varios retos académicos y prácticos, desafíos en términos de implementación, medición del desempeño y la manera en que los modelos pueden capturar un contexto social y ambiental dinámico e incierto. Hay cuestiones de investigación latentes como la gestión de la cadena de suministro circular, las aplicaciones en economías emergentes o la aplicación de tecnologías 4.0

Modeling and optimization of the palm oil (Elaeis guineensis) supply chain in Colombia

The aim of this research is to develop a quantitative tool that supports decision-makers in the strategic planning of supply chains (SC). The problem to be solved consists in determining the optimal configuration of the palm oil SC, including decisions associated to the number, location and capacity of all the facilities of the SC in a given country; its expansion policy in the planning horizon, means of transportation, production rates, material flow, waste management, and its potential environmental impact. Bearing this in mind, two mathematical models are presented to address this problem. The first one is a mixed integer linear programming (MILP) model applied to the oil palm industry in Colombia that aims to maximize the net present value of its SC in a specific planning horizon. On the other hand, the second model solves a multi-objective optimization (MOO) MILP problem. It combines the first model with the Life Cycle Assessment (LCA) methodology to optimize the palm oil SC in Colombia. The MOO model aims at maximizing the economic benefit of this SC and simultaneously minimizing its environmental impact (measured in “eco-points”). The MOO problem was solved using the epsilon constraint method. Pareto optimal solutions provide valuable information for the optimal design and configuration of the palm oil SC, in particular the compensations or trade-offs resulting from economic profit, and its environmental impact. The solutions obtained through this model show a more rational distribution of productive units, including the establishment of renewable power plants.DoctoradoDoctor en Ingeniería Industria

Understanding the Implications of Alternative Bioenergy Crops to Support Smallholder Farmers in Brazil

Smallholders constitute more than three quarters of the world’s farmers, and despite their numbers, they commonly lack opportunities to advance their development status. Bioenergy production and consumption can help sustain smallholders’ energy needs and generate employment and income, but it also raises concerns over social justice and equity, especially where crops used for bioenergy could also be used for food. This perspective paper is grounded in a literature review related to three different crops in Brazil: sugarcane, landrace maize and sweet potato. It seeks to determine if these crops offer the potential to support smallholder farmers’ development in a more equitable way, focusing on opportunities for their use in bioenergy. We review the literature to identify policies shaping the smallholder development context in relation to these crops, assessing whose knowledge informs policy and institutional decision making, and highlighting the policy attention afforded to the different crops from different sectors. We further evaluate the literature on each crop in relation to water use and calorific value (i.e., food and energy). Our review indicates that while sugarcane has received the most policy and institutional attention, its development is largely anchored in research and development investments that support large-scale commercial farms and agri-businesses. Smallholders have not benefited or had the opportunity to engage in relevant policy decision making for sugarcane cultivation. At the same time, smallholders hold valuable untapped knowledge on the cultivation of sweet potato and landrace maize, both of which have the potential to generate development opportunities for smallholders. Our review suggests that the environmental impact of landrace maize and sweet potato in terms of water use is significantly lower than sugarcane, while they can generate more calories for energy or food consumption and offer diversification opportunities. Despite that these alternative crops offer considerable untapped potential to support rural development, more research is still needed to harness these benefits. Changes are needed to address inequities in policies, institutions and the types of knowledge informing decision making. Such changes need to afford smallholder farmers greater recognition and participation in decision making, so that the distribution of benefits from the three study crops can reach them to support their development better

Anaerobic digestion in sustainable biomass chains

This thesis evaluates the potential contribution of anaerobic digestion (AD) to the sustainability of biomass chains. Results provide insights in the technological potential to recover energy and valuable by-products from energy crops and residues, and evaluate biomass cascades involving AD technology for their feasibility and desirability. Embedding AD in biomass chains addresses current constraints towards increased use of biomass for energy production considering land competition and environmental pollution. In this context, so far the major advantages of AD to improve energy efficiency and closing material cycles have received, thus far, limited attention. As part of the experimental research an Oxitop® protocol was refined for screening plant material suitable for anaerobic digestion based on their energy content. Environmental factors influencing the test outcome are the use of NaOH pellets for CO2 scavenging, substrate pretreatment, microbial culture, and type of buffer. The use of NaOH pellets and substrate pretreatments were most influential on the results. By means of the developed Oxitop® protocol the relationship between plant ligno-cellulosic composition and the Biochemical Methane Potential (BMP) and first-order hydrolysis constant (kh) was researched. The Acid Detergent Fibre (ADF) and the Neutral Detergent Fibre (NDF) as analyzed by the van Soest method were proposed as suitable plant characterization techniques for predicting BMP and kh, respectively. The model proposed was further used to predict the biodegradability of 114 European plant samples identifying interesting crops and crop residues suitable for anaerobic digestion. Batch experiments on digestate quality during codigestion of maize silage and manure showed an increase of 20-26% and 0-36% in solublised NH4+ and PO43-, respectively, after 2 months of digestion. The largest fraction of the inorganic nutrients was found in the liquid fraction of the digestate, i.e. 80-92% NH4+ and 65-74% PO43-. Increase in manure content in the mixture showed a positive effect in the methane production rate. Digestion time and increased proportion of maize silage in the mixture positively influenced the availability of PO43-. The added value of AD within different biomass cascades was evaluated by means of a sustainability framework developed for the purpose. The sensitivity analysis of the energy balance of an AD facility showed that the most important energy loss when a high value substrate such as energy maize is employed are heat losses induced by restricted reuse possibilities within the cascade. In contrast, when low energy substrates such as manure are used, indirect energy inputs embedded in infrastructure become significant. The developed sustainability framework was applied for the Colombian case. Results show that production of bio-ethanol from cassava is only sustainable from an energy and greenhouse gas (GHG) perspective when energy recovery from the process residues, using AD, is part of the process. The exact outcome of the evaluation largely depends on variables like substrate drying, type of fuel used, reuse possibilities for the digestate and type of applied AD system. During the study of other Colombian biofuel cascades the contribution of by-products was shown to be crucial, constituting 41-68% of the sum of all energy flows. For oil palm, sugarcane, panelacane and cassava, the estimated energy contribution of the by-products to the different biofuel systems fluctuate between 51-158, 122-290, 71-170, and 36-71 GJ.ha-1yr-1, respectively. AD had also a positive impact on nutrient recovery and water savings in the studied chains. The energy, nutrient and water benefits were set in perspective by giving an indication on the economic benefits and land savings potentially attainable under Colombian conditions. <br/

Supply Chain Network Design of Perishable Food in Surplus Periods

Research on the design of the perishable food supply chain network has increased in recent years. However, little attention has been given to those seasonal foods that generate periods of oversupply and, particularly, to their impact on the sustainability of small producers in developing countries. This research proposes and develops a multi-objective mixed linear programming model for perishable fruits in a south American country at oversupply periods. It minimizes losses and transportation costs and maximizes the inclusion of farmers. It considers four echelons of the supply chain: farms, collection centers, distribution centers and the demand, which is represented by the agroindustry, wholesalers, shopkeepers, and hypermarkets. The Epsilon constraint method is used to solve the multi-objective model. A set of Pareto optimal solutions helped evaluate tradeoffs between the three objectives and find the location of collection and distribution centers. The proposed generic mathematical model is applicable to any food supply chain, as it allows for the improvement of the established performance measures and the distribution flows for the different echelons. The model considers the losses in perishable food from the impacts caused by changes in temperature (T0) and humidity level (RH) at different thermal floors of mountain ranges

Towards a sustainable biobased economy in Colombia: integrated environmental and economic analyses of land use and biomass value chains

This thesis aims to analyses different scenarios for the implementation of a biobased economy in Colombia integrating environmental and economic analyses of land use and biomass value chains. Through the thesis, the main lacks for the implementation of a sustainable economy in this country are identified by answering three research questions. The first one is related to management practices and scenarios considering the environmental and economic impacts of some productions systems. The second one analyzes the most important measures to improve biomass production in the future, and the third one is related to the design of frameworks for the regional application and impacts of land-use change and bioenergy use in a specific area in Colombia. The thesis is divided into 5 chapters where the research questions are answered, and the solutions are proposed and analyzed. I think that this thesis should be addressed to policymakers as a guideline for the implementation of the bioeconomy in Colombia. The benefits are tangible and can help the country to meet its environmental goals in the medium and long term