UBC Theses and Dissertations
Optimization of forest-based biomass logistics at the operational level Malladi, Krishna Teja
Logistics cost and emissions are important factors affecting the utilization of forest-based biomass. While numerous studies optimized biomass logistics at the tactical level, those at the operational level are limited. The focus of most of the previous studies was on cost minimization, while emission reduction from biomass logistics received less attention. Few recent studies analyzed the impact of carbon pricing policies on the optimum cost and emissions of biomass logistics. However, due to the focus on specific case studies, the results obtained in these studies may not be generalized. Moreover, these studies combined the cost and the emissions into one objective function resulting in the loss of information about the trade-off between the two objectives. The overall goal of this dissertation is to optimize biomass logistics at the operational level considering biomass storage, pre-processing and transportation decisions, and to analyze the impacts of carbon pricing policies on biomass logistics optimization models independent of the underlying case study. First, optimization models are developed to minimize the total cost of biomass logistics considering all logistics operations. The models are applied to the case study of a large logistics company. The results indicated a potential to save up to 12% of the total cost compared to the actual plans implemented by the company. Next, several properties of the optimal cost and emissions of case-independent logistics models under different carbon pricing policies are proposed and proved mathematically. The properties are numerically verified using the case study of a biomass-fed district heating plant. The results indicate that the carbon tax and the carbon cap-and-trade models result in equal emissions for equal carbon prices. The carbon cap-and-trade model is more cost-effective than the carbon tax model only if the carbon price is more than the price of initial allowances. Finally, the optimization model developed for the biomass-fed district heating plant is extended to incorporate cost and emissions as two separate objectives. A new algorithm is proposed to solve bi-objective optimization models considering carbon pricing policies to overcome the computational complexity involved in solving these models. Being case-independent, the algorithm can be applied to other cases.
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