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Publicações

Publicações por Maria João Santos

2016

Least-cost 100% Renewable Electricity Scenarios

Autores
Santos, MJ; Ferreira, P; Araujo, M;

Publicação
2016 13TH INTERNATIONAL CONFERENCE ON THE EUROPEAN ENERGY MARKET (EEM)

Abstract
Renewable energy sources (RES) are becoming the main players for the sustainability of the planet and achieving a 100% RES energy system has been attested as a good strategy to go forward in many countries. This target however defies the system to integrate highly variable RES in a system that does not allow for shortage on the energy supply. This work presents a possible 100% RES scenario for an electricity system close to the Portuguese estimating and analysing the economic and technical impacts. The sensitivity of the results to aspects related to RES availability, electricity demand, peak load and interconnection capacity for electricity trading were also analysed. The results highlighted the excess of electricity produced in 100% RES systems and the importance of including interconnection capacity to contribute to overcome this problem.

2020

Integrated planning of inbound and outbound logistics with a Rich Vehicle Routing Problem with backhauls

Autores
Marques, A; Soares, R; Santos, MJ; Amorim, P;

Publicação
OMEGA-INTERNATIONAL JOURNAL OF MANAGEMENT SCIENCE

Abstract
This paper addresses the integration of the planning decisions concerning inbound logistics in an industrial setting (from the suppliers to the mill) and outbound logistics (from the mill to customers). The goal is to find the minimum cost routing plan, which includes the cost-effective outbound and inbound daily routes (OIRs), consisting of a sequence of deliveries of customer orders, pickup of a full truck-load at a supplier, and its delivery to the mill. This study distinguishes between three planning strategies: opportunistic backhauling planning (OBP), integrated inbound and outbound planning (IIOP) and decoupled planning (DIOP), the latter being the commonly used, particularly in the case of the wood-based panel industry under study. From the point of view of process integration, OBP can be considered as an intermediate stage from DIOP to IIOP. The problem is modelled as a Vehicle Routing Problem with Backhauls, enriched with case-specific rules for visiting the backhaul, split deliveries to customers and the use of a heterogeneous fleet. A new fix-and-optimise matheuristic is proposed for this problem, seeking to obtain good quality solutions within a reasonable computational time. The results from its application to the wood-based panel industry in Portugal show that IIOP can help to reduce total costs in about 2.7%, when compared with DIOP, due to better use of the delivery truck and a reduction of the number of dedicated inbound routes. Regarding OBP, fostering the use of OIRs does not necessarily lead to better routing plans than DIOP, as it depends upon a favourable geographical configuration of the set of customers to be visited in a day, specifically, the relative distance between a linehaul that can be visited last in a route, a neighboring backhaul, and a mill. The paper further provides valuable managerial insights on how the routing plan is impacted by the values of business-related model parameters which are set by the planner with some degree of uncertainty. Results suggest that increasing the maximum length of the route will likely have the largest impact in reducing transportation costs. Moreover, increasing the value of a reward paid for visiting a backhaul can foster the percentage of OIR in the optimal routing plan.

2020

A robust optimization approach for the vehicle routing problem with selective backhauls

Autores
Santos, MJ; Curcio, E; Mulati, MH; Amorim, P; Miyazawa, FK;

Publicação
TRANSPORTATION RESEARCH PART E-LOGISTICS AND TRANSPORTATION REVIEW

Abstract
The Vehicle Routing Problem with Selective Backhauls (VRPSB) aims to minimize the total routing costs minus the total revenue collected at backhaul customers. We explore a VRPSB under uncertain revenues. A deterministic VRPSB is formulated as a mixed-integer programming problem and two robust counterparts are derived. A novel method to estimate the probabilistic bounds of constraint violation is designed. A robust metaheuristic is developed, requiring little time to obtain feasible solutions with average gap of 1.40%. The robust approach studied demonstrates high potential to tackle the problem, requiring similar computing effort and maintaining the same tractability as the deterministic modeling.

2020

The vehicle routing problem with backhauls towards a sustainability perspective: a review

Autores
Santos, MJ; Amorim, P; Marques, A; Carvalho, A; Povoa, A;

Publicação
TOP

Abstract
The vehicle routing problem with backhauls (VRPB) allows to integrate inbound and outbound routes, which is an efficient strategy to reduce routing costs and also to reduce the environmental and social impacts of transportation. In this paper, we analyze the VRPB literature with a sustainability perspective, which covers environmental and social objectives, collaborative networks and reverse logistics. First, to better understand and analyze the VRPB literature, all related works are characterized according to a common taxonomy provided for routing problems. This taxonomy is extended to differentiate between economic, environmental and social objectives. After identification of all VRPB papers that include sustainability issues, these are analyzed and discussed in more detail. The analysis reveals that research on VRPBs with sustainability concerns is recent and relatively scarce and the most popular aspects investigated are the minimization of fuel consumption andCO2 emissions. Future research lines driven by sustainability concerns are suggested for the VRPB as a promoter of green logistics.

2017

Scenarios for the future Brazilian power sector based on a multi criteria assessment

Autores
Santos, MJ; Ferreira, P; Araujo, M; Portugal Pereira, J; Lucena, AFP; Schaeffer, R;

Publicação
JOURNAL OF CLEANER PRODUCTION

Abstract
The Brazilian power generation sector faces a paradigm change driven by, on one hand, a shift from a hydropower dominated mix and, on the other hand, international goals for reducing greenhouse gas emissions. The objective of this work is to evaluate five scenarios for the Brazilian power sector until 2050 using a multi-criteria decision analysis tool. These scenarios include a baseline trend and low carbon policy scenarios based on carbon taxes and carbon emission limits. To support the applied methodology, a questionnaire was elaborated to integrate the perceptions of experts on the scenario evaluation process. Considering the results from multi-criteria analysis, scenario preference followed the order of increasing share of renewables in the power sector. The preferable option for the future Brazilian power sector is a scenario where wind and biomass have a major contribution. The robustness of the multi-criteria tool applied in this study was tested by a sensitivity analysis. This analysis demonstrated that, regardless of the respondents' preferences and backgrounds, scenarios with higher shares of fossil fuel sources are the least preferable option, while scenarios with major contributions from wind and biomass are the preferable option to supply electricity in Brazil through 2050.

2015

Multicriteria Scenario Analysis on Electricity Production

Autores
Santos, MJ; Ferreira, P; Araujo, M;

Publicação
2015 12TH INTERNATIONAL CONFERENCE ON THE EUROPEAN ENERGY MARKET (EEM)

Abstract
Energy planning is a complex process involving multiple and conflicting objectives with many agents able to influence decisions. This complexity is frequently addressed with the use of multicriteria tools, relying on a set of criteria and different methods to aggregate all the information in a final ranking of the available alternatives. This paper describes the application of a multicriteria decision tool for the analysis of Portuguese electricity scenarios. A set of criteria is proposed aiming to include social, economic, environmental and technical aspects. Criteria weighting was directly addressed considering 5 approaches: equitable weights, financial, technological, social and environmental perspectives. Results indicate that close to 100% RES scenario is the best option under a social perspective, base scenario represents the best option on a technical approach and scenarios relying on natural gas and wind power units are the best options for the electricity system under equitable weights, economic and environmental approaches.

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