Ricardo Morales-Rodriguez

Financial Risk Assessment and Optimal Planning of Biofuels Supply Chains under Uncertainty

Biofuels provide an attractive alternative for satisfying energy demands in a more sustainable way than fossil fuels. To establish a biorefinery, an optimal plan must be implemented for the entire associated supply chain, covering such aspects as selection of feedstocks, location, and capacity of biorefineries, selection of processing technologies, production amounts and transportation flows. In this context, there are several parameters, including the availability of biomass, product demand, and product prices, which are difficult to predict because they might change drastically over the different seasons of the year as well as across years. To address this challenge, this work presents a mathematical programming model for the optimal planning of a distributed system of biorefineries that considers explicitly the uncertainty associated with the supply chain operation as well as the associated risk. The potential of the proposed approach is demonstrated through its application to the production of biofuels in Mexico, considering multiple raw materials and products.

Multiobjective optimization for the socio-eco-efficient conversion of lignocellulosic biomass to biofuels and bioproducts

This work focuses on a way to integrate the social, environmental and economic aspects (socio-eco-efficient aspects) together in the decisions concerning the sustainable process synthesis of a lignocellulosic (Agave bagasse) biorefinery. This challenge is addressed by the formulation and solution of a multiobjective optimization model of a process superstructure for the lignocellulosic biomass conversion into biofuels and products, where social (human toxicity potential), economic (cost), environmental (environmental impact) and socioeconomic (product demand) criteria are included in the formulation of the objective function. The optimization resulted model is a MINLP (Mixed Integer Non-Linear Programing) problem. To solve this problem, a process synthesis methodology is proposed, which includes the epsilon constraint (ε-constraint) method, the use of the GAMS software and a benchmarking using Aspen Plus process simulator to include the energy balance of the different processes. As results, four feasible configurations of biorefineries were obtained, including the best configuration selected after the benchmarking using energy requirements, reduced use of energy after integration and water used as indicators. With the approach proposed in this paper, it was possible to evaluate in a short time a vast number of options included in the superstructure, as well as to select the best option that fulfills the three aspects of sustainability.

Enhancing Xylitol Bio-Production by an Optimal Feeding Policy during Fed-Batch Operation

Abstract The xylitol production has become an important process to investigate given the diverse product applications, especially in the food industry. The biotechnological xylitol production has been assessed mainly through an experimental approach via batch and fed-batch operation. This study presents an analysis for optimal operation of the fed batch process following a systematic methodology. The model based approach includes the collection, validation and calibration of the mathematical model, followed by the proposal of some operation scenarios. The implementation of such methodology allowed to increase 20% the yield of xylitol compared with the obtained previously in some experiments. Moreover, an analysis for the diauxic phenomenon was also performed, allowing to determine an optimal feeding ratio between substrates.

Process integration for the supercritical production of biodiesel and the production of lignocellulosic bioethanol

Abstract Biodiesel and bioethanol are among the most studied biofuels. For the production of biodiesel, the use of supercritical alcohols has been reported as an alternative with some advantages over the traditional base-catalyzed processes. Nevertheless, due to the high pressure and temperature conditions under which the supercritical process operates, the energy demand can be considerably high. On the other hand, production of bioethanol through lignocellulosic biomass is a topic of interest, because it avoids the competence with food industry derived of using first-generation biomass. In such processes, several reaction steps are required, with water as one of the main resources. Therefore, the integration of both production processes could be advantageous in terms of energy costs and environmental impact. In this work, the feasibility of mass and energy integration between the supercritical biodiesel production process and a lignocellulosic bioethanol process is evaluated, as a strategy to reduce external energy requirements and mass agents. By this approach, reductions on the utilities costs are expected if compared with the individual processes.

Process Intensification in Biotechnology Applications

This chapter presents an overview on how process intensification has influenced biotechnology applications from a multidisciplinary perspective. Initially, the process intensification philosophy is contextualized into biotechnology due to the particular challenges of these processes. This leads to a conceptual map analyzing the disciplines’ interaction to achieve bioprocesses intensification. Subsequently, intensification is explored mainly from transforming biomass into chemicals point of view as an integrated solution addressed within the biorefinery concept. The chapter focuses into revising and presenting representative examples from process engineering perspective. First, how to enhance raw materials utilization in fermentations and enzymatic systems is presented. Secondly, advances on in situ product removal/recovery in order to enhance the reaction environment are presented, emphasizing on membrane bioreactor technologies. Finally, some current and future challenges are assessed to achieve bioprocess intensification. We strongly believe that developing bioprocess intensification philosophy will bring new perspectives to increase the cost-effectiveness of industrial applications towards a more sustainable future.

Exergy Analysis of an Extractive Distillation Column for Reducing Energy Consumption in a Bioethanol Production Process

Abstract This work focuses on the exergy analysis of an extractive distillation column in the second-generation bioethanol production process. The study of the exergy performance of the separation and purification section is relevant from a thermodynamic point view due to the large amount of the energy consumed by their unit operations. A sensitivity analyses of the separation section, the location of the feeding stages for the solvent and the ethanol-water azeotropic mixture, the reflux ratio and solvent/feed ratio were performed for obtaining the minimum energy consumption in the column reboiler. Finally, the profiles of exergy components, irreversibilities and the exergy efficiency for the base case and enhanced case were compared. The results show a 29.21 % decrease on the irreversibilities and a corresponding increase of 22.82 % in the exergy efficiency for the separation section. The simulation as well as the sensitivity analyses were done using a connection between the process simulator Aspen Plus v 8.8 and Excel.

Computer-aided process simulation, design and analysis: lactic acid production from lignocellulosic residues

Abstract Lactic acid (LA) is a compound with a considerable range of application in industry, where its use as precursor of diverse products is currently relevant. Thus, it is important to complement experimental efforts to investigate the design of the lactic acid production relying in computer-aided tools using a process system engineering approach. This work presents the implementation of a computer-aided processing platform and the analysis of a possible industrial production route of LA from the waste of sugar industry. The process configuration consisted on a pretreatment stage to extract the raw material from the residues. Subsequently, the LA fermentation is included using a more realistic design and analysis considering the combination of batch and continuous operations based on a scheduling plan. Finally, the separation and purification stages using reactive distillation are included, aiming to obtain an LA solution above 95 % mass fraction and a production of 14,448 kg/hr from 28,886 kg/h of sugarcane bagasse. The process was evaluated to determine its economic feasibility based on a price of 1.5 US/kg of LA. It was estimated that the process has a recovery time of 3.6 years.

A Framework for an Optimized Sustainable Product and Process Design: Acetone-Butanol-Ethanol Separation and Purification

The biobutanol production have gained special attention due to diverse positive characteristics compared with bioethanol, but one of the paramount problems is found at the downstream processes section. In order to tackle that issue, a systematic framework for sustainable product and process design including the optimization of the problem considering economic and environmental aspects, could be identified as a supportive solution. Thus, this study proposes and implements a framework consisting of organized steps combining methods and tools, using as a case study the acetone-butanol-ethanol separation. The process configuration included a liquid-liquid extraction unit that allowed the molecular design of the extracting agent, followed by the process design of the required equipment, and finally by an optimization step using a hybrid stochastic optimization method, the differential evolution with tabu list. The results allowed to reduce the total annual cost by 22 % and the environmental impact by 28 % relying on the eco-indicator.

Multi-objective optimization for the biotechnological conversion of lingocellulosic biomass to value-added products

Abstract The increasing attention toward sustainable developments as alternative solutions for the climate change problems have generated the interest to propose optimal synthesis configurations of biorefineries. These kind of challenges have been partially addressed employing mathematical optimization of superstructures, which mostly includes economic and environmental aspects. However, the social aspects are also important and must be included for the correct selection of the sustainable process topology. Therefore, this work presents a multi-objective optimization model for the lignocellulosic biomass conversion into products. The economic, environmental and social aspects are considered in this study. The superstructure is mathematically modelled giving a MINLP problem. First, the mathematical model is solved for four criteria separately, maximizing yields, Y; maximizing demands D; minimizing costs, MC; and minimizing environmental impact, EI. The results of three of the previous criteria (D, MC and EI) where used together adding a social criteria (minimizing human toxicity, HTP) in a multi-objective optimization problem. The solution of the multi-objective optimization problem showed that furfural, bioethanol and biogas are the most promising products to be considered when implementing a sustainable biorefinery that satisfies the formulated multi-objective MINLP.

Model-based framework for enhanced and controlled operation of a fed-batch bioreactor: xylitol production

Abstract Experimental work in dynamic fermentations is challenging mainly due to the sensitive nature of the biological system, the time variant conditions along the experiments and low automation of the process. Therefore, tremendous experimental effort is needed in order to identify optimal operation conditions useful to be scaled up. In this contribution, a model based framework is proposed in order to assist the experimental design. Firstly performing a sensitivity and uncertainty analyses to identify the most important parameters in the mathematical model, followed, by the design of optimal controlled experiments that can provide quality data close to the best performance identified scenario. A control structure designed for disturbance rejection during fedbatch fermentations can potentially lead to a substantial reduction in experimental work.