1. Introduction

Global population is still increasing, and therefore, more resources are required to fulfill people needs. The demand of energy is growing due to the population increase but also because the presence of new activities such as social networking. Nowadays, most of the vehicles utilize fossil fuels. The fossil fuels are non-renewable resources and they contribute significantly to the global pollution.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and eproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Biofuels are a propitious alternative to the fossil fuels reliance, due to their sustainable production based on using biomass as a raw material. Biomass is an organic matter derived from living or recently living beings. The production of biofuels also has some advantages from those produced from non-sustainable resources, for instance, the reduction of greenhouse emissions (GHG) such as the CO2. Another benefit of using biofuels is the development of an agricultural industry and the creation of rural jobs to produce and deliver biomass to biorefineries. Bioethanol is one type of biofuel that can be produced from organic resources such as corn stover, miscanthus, and switchgrass, among others. Bioethanol has several applications in a wide variety of industries. According to government dependencies such as the Energy Information Administration (EIA), an increment of biofuels is expected in the U.S. within the coming years as product of the Renewable Fuel Standard [1] that requires more production of fuel utilizing renewable resources (e.g., 16 billion gallons for 2022).

specific batch of biomass will be less than expected. With a shortage of biofuel, acquiring the slack from a third-party supplier to cover the demand could lead the producer to an increment

Modeling and Optimization of Quality Variability for Decision Support Systems in Biofuel Production

http://dx.doi.org/10.5772/intechopen.73111

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Biomass has many physical and chemical properties that need to be considered in order to optimize an objective such as minimization of the total cost or maximization of the profit. This chapter introduces a principal component analysis (PCA) to identify significant factors that affect the design and implementation of logistic processes and infrastructure due to the physical and chemical properties of the biomass. Moreover, the chapter presents a two-stage optimization model that take into consideration quality-related costs in order to set up the biorefinery locations and the flows of biomass from the supplier to the producer. The optimization model can be incorporated into a decision supported system (DSS) to solve several

This analysis focuses on LCB [specifically, on switchgrass (Panicum virgatum)], which is a feedstock derived from organic matter that is mainly composed of cellulose and hemicellulose. Examples of LCB are corn stover, wheat straw and switchgrass and there are many activities involved in the production and distribution of this kind of biomass such as harvesting, extracting, packaging, transporting, handling, among others. There are factors in the aforementioned activities that affect the physical and chemical properties of the biomass, and thus, their qualityrelated costs. The consideration of those factors has an effect in the design and implementation

An example of the relationship between the biomass properties and the SC design is the cellulose and hemicellulose (carbohydrates) contents in the LCB. The cellulose and hemicellulose content in the LCB is directly related to the biofuel produced in the conversion process since the carbohydrates are the main component to produce the energy. The more carbohydrates contained in the biomass, the more liters of biofuel obtained from that particular batch of feedstock. Hence, activities that affect the carbohydrate contents need to be improved to

Densification is one of the processes in the SC of biofuel production that affects some of the properties within the biomass. The densification of biomass consists in conglomerating the organic matter in the form of compact structures such as briquettes and pellets, to improve their handling, storage and transportation but also to reduce the level of dry matter loss (DML) in the feedstock. The DML is directly related with the loss of carbohydrates in the biomass. The less organic matter in the batch, the less amount of cellulose and hemicellulose to produce biofuels. Densification also affects other properties in the biomass such as the moisture content, unit density, durability index, as well as other properties specified for the conversion process according to the implemented technology. Controlling the physical and chemical properties under the specification requirements is vital for an efficient conversion. Delivering

instances of interest and aid the decision-making process.

2. A PCA in a switchgrass composition

minimize the impact on the conversion process.

in the overall cost.

of the supply chain (SC).

Biofuels are classified according to the raw material utilized to produce them: (1) the firstgeneration is related to biofuels produced from edible biomass that can be generally used for human consumption (e.g., corn, sugarcane, sugar beet, among others), (2) the secondgeneration are biofuels generated from a wide range of feedstock, including lignocellulosic biomass (LCB), such as perennial grasses, soft and hard wood, up to municipal solid waste, and (3) the third-generation commonly refers to biofuels produced from algal biomass [2]. Biofuels produced from LCB are a feasible option in the U.S. for the coming years as they utilize non-food feedstock and can be grown in marginal lands or are byproducts produced from the wood industry.

Biofuel production requires improvements in strategic areas such as conversion technologies, genetic manipulation of feedstock breeds, and supply chain management of biomass from harvesting areas to conversion facilities, among others in order to become a plausible alternative to fossil fuel production. Supply chain (SC) improvement represents an important area of opportunity in biofuel production due to the fact that environmental, geographical and economic factors are related to operations like harvesting, handling, storing as well as transportation, which have shown significant impact in biofuel yields/cost. Studies have demonstrated that some factors such as storage time affects the physical and chemical properties of the biomass [3], therefore, biomass properties have an important role in the design of the operations required for the production and distribution of biofuel [4].

There are many properties that affect the conversion efficiency depending on the type of conversion technology that is being utilized for the production of biofuels. Moisture is a property of biomass that affects both the thermochemical and biochemical conversion technologies and a drying process that diminishes the moisture content in the biomass up to the required level of humidity is needed. The drying process to meet the specification for the selected conversion technology incurs in a cost that could be reduced/controlled with the implementation of logistics processes and infrastructure design that consider the level of humidity in the feedstock. The utilization of the biomass without meeting the expected specifications could lead the production of biofuels to an inefficient conversion process. Another example of the importance of the biomass properties are the carbohydrates. If the level of carbohydrates does not meet the specification, then, the amount of biofuel derived from that specific batch of biomass will be less than expected. With a shortage of biofuel, acquiring the slack from a third-party supplier to cover the demand could lead the producer to an increment in the overall cost.

Biomass has many physical and chemical properties that need to be considered in order to optimize an objective such as minimization of the total cost or maximization of the profit. This chapter introduces a principal component analysis (PCA) to identify significant factors that affect the design and implementation of logistic processes and infrastructure due to the physical and chemical properties of the biomass. Moreover, the chapter presents a two-stage optimization model that take into consideration quality-related costs in order to set up the biorefinery locations and the flows of biomass from the supplier to the producer. The optimization model can be incorporated into a decision supported system (DSS) to solve several instances of interest and aid the decision-making process.
