Optimal Design of Water Desalination Systems Involving Waste Heat Recovery

Water desalination appears as an attractive alternative to provide fresh water in several parts of the world. However, this process is very expensive due to the high-energy consumption, and as consequence, significant pollution is produced due to the burning of fossil fuels that yield huge emissions of CO₂. Furthermore, most of the desalination processes yield a lot of waste heat at low temperature, which can be recovered. Therefore, this paper presents an optimization approach for designing water desalination systems involving heat integration and waste heat recovery to reduce the desalination cost, energy consumption, and overall greenhouse gas emissions. The proposed approach accounts for the optimal selection of existing and emerging desalination technologies based on the heating and cooling requirements and incorporating waste heat recovery systems. The integration of the proposed systems provides power and thermal energy to the desalination task. Also, the proposed approach includes the optimal selection of fossil fuels, biofuels, and solar energy as energy sources. The proposed approach was applied to a case study, and the results show that the system that involves the multiple-effect distillation and thermal membrane distillation shows the best economic and environmental benefits involving water sales, power production, and energy savings

Analysis of Carbon Policies in the Optimal Integration of Power Plants Involving Chemical Looping Combustion with Algal Cultivation Systems

Presently, reducing the CO₂ emissions produced by electric energy generation is one of the most relevant challenges. This paper aims to address such a problem by means of proposing an integrated system including (i) chemical looping combustion systems, (ii) power generation cycles, and (iii) algae-to-biodiesel subsystems to utilize carbon dioxide. The developed approach consists of a mixed-integer linear programming model that represents the global system at a macroscopic level and allows finding the optimal design for the integrated system that involves the selection of the optimum fuel and technology for power generation (for both the combustion system and the power cycle) as well as for biodiesel production in all stages of the algae cultivation system. In addition, the impact of different values for economic penalizations and compensations associated with carbon dioxide emissions on the optimum configuration is evaluated. The results show important economic benefits and reductions in emissions, especially when considering the carbon bonus. Furthermore, the optimal trade-offs between multiple objectives (economic and environmental) are discussed through different Pareto sets

Multiobjective Optimization of Dual-Purpose Power Plants and Water Distribution Networks

This paper presents a multiobjective optimization approach for synthesizing water distribution networks involving dual-purpose power plants. The proposed model accounts for environmental, economic, and social objectives by accounting for greenhouse gas emissions, jobs, and net profit. The model considers water and energy demands for domestic, agricultural, and industrial users. Energy is provided through several alternatives including fossil fuels (i.e., natural gas and oil), biofuels (i.e., biomass, biogas, biodiesel, and bioethanol), and solar energy. Water demands are satisfied by fresh water from dams, lakes, rivers, aquifers, and artificial storage tanks. The proposed model is applied to a case study from the Mexican State of Sonora. The results show the viability of the dual-purpose power–water plants, the merits of incorporating solar energy in the system, and the economic, environmental, and social benefits of applying the proposed approach. The optimal solution yields a total annual profit of $MM 1,545.9, it generates 1.37 × 10⁷ ton CO₂ equiv/y and 19 781 jobs

A Multistakeholder Approach for the Optimal Planning of Sustainable Energy Systems

This paper presents a mathematical programming model for the optimal planning of an integrated system for producing fuels and biofuels considering the interaction with facilities capable of capturing emissions from biorefineries and refineries and receiving a monetary benefit; these facilities can be named eco-industries or forest plantations. The proposed approach is formulated as a multistakeholder scheme to consider the benefits and effects in each one of the involved supply chain entities and to determine how the interactions between the different stakeholders take place. The proposed approach takes into account the profit of biorefineries, refineries, and forest plantations as well as the emissions and jobs generated in each one of the involved entities. Additionally, it considers local and imported raw materials to satisfy the energy demand. Also, the approach considers features such as the project lifetime; the availability of resources; the amount and type of products that should be produced; and the allocation and capacity of the refineries, biorefineries, and forest plantations. The mathematical approach was applied to a nationwide case study for Mexico, considering the creation of new jobs, overall emissions, and net profit as main objectives

Total Heat Integration in the Biobutanol Separation Process

The global warming and climate change problems have become more serious because of the high consumption of fossil fuels during the past century. Recently, biofuels have attracted interest as an option to reduce the extensive use of fossil fuels; particularly, biobutanol appears as an option to replace the petroleum-based fuels. However, the separation process to produce biobutanol requires a lot of energy and yields lots of waste heat at low temperature. Therefore, there is a need to propose options to reduce the required energy in the biobutanol separation process. Consequently, this paper presents an optimization approach for designing energy integrated biobutanol separation processes. The optimization incorporates attractive separation options such as ABE fermentation using different solvents as well as incorporating several options for waste heat recovery involving integrated heat exchanger networks, stream Rankine cycles, organic Rankine cycles, and absorption refrigeration cycles. The results show significant economic and environmental benefits for the simultaneous consideration of the optimization of the separation process with the waste heat recovery for the biobutanol separation process

Involving Acceptability in the Optimal Design of Total Integrated Residential Complexes Involving the Water-Energy-Waste Nexus

This work presents a multiobjective optimization model for the design of an integrated residential complex, which incorporates the proper use of available resources and wastes through recycling and reusing networks. The proposed model involves the proper use of water accounting for rainwater harvesting and the reuse of reclaimed water. The model also includes the design of a cogeneration system to satisfy electricity demands as well as hot water demands. The treatment of the produced solid waste is also incorporated through an incineration system, and an algae system is involved for sequestering the associated emissions. The proposed model aims to satisfy the energy, heat, and water demands and the treatment for the residues with the objective to minimize the associated cost and the associated emissions. Furthermore, the proposed model includes an objective function associated with the minimization of the damage to the health of the inhabitants

Strategic Planning for Managing Municipal Solid Wastes with Consideration of Multiple Stakeholders

Management of municipal solid waste (MSW) involves multiple stakeholders such as government agencies, suppliers, consumers, providers of treatment/recycle services, and transporters. An optimal management strategy should be based on creating synergistic opportunities that benefit the multiple participants. This paper presents a multi-objective optimization approach for the strategic planning of a municipal solid waste management system. The formulation considers the involved tasks such as recycle, reuse, transportation, separation, and distribution. The proposed approach also accounts for the multiple stakeholders with the objective of maximizing the benefit to all the participating stakeholders. The Latin Hypercube sampling technique is adopted to systematically generate weights for the different stakeholders. A case study from Mexico is analyzed where three scenarios are considered. The first one considers that the separation cost is absorbed by each recycling company. The second one assumes that the government is responsible for the separation cost. The third one requires household inhabitants to carry out waste sorting. The optimization approach is used to analyze the results of the various scenarios and to deduce valuable insights on the interaction among the various stakeholders and the building blocks of the supply chain of MSW management systems

Optimization of Pathways for Biorefineries Involving the Selection of Feedstocks, Products, and Processing Steps

This paper presents a systematic approach to identify the optimal pathway configurations of a biorefinery while incorporating technical, economic, and environmental objectives. This problem is formulated as a generalized disjunctive programming model which accounts for the simultaneous selection of products, feedstocks, and processing steps. The optimal solution can involve multiproduct and multifeedstock biorefineries. The optimization model takes into account two potentially conflicting objectives, the maximization of the net profit and the minimization of the greenhouse gas emissions, while considering the number of processing steps. The environmental criterion is measured using the life cycle assessment methodology. The ε-constraint method is used to determine the Pareto curves of this multiobjective optimization problem and to show the trade-offs between the competing objectives. A case study is presented to illustrate the applicability of the proposed methodology for the optimal selection of the biorefinery configuration for the conditions of Mexico under several scenarios. The results show that the optimal combination of different feedstocks and products allows for proper trade-off between the economic and environmental objectives. Results also show that bioethanol, biodiesel, and biohydrogen usually appear as products, whereas sugar cane, jatropha, and microalgae appear as feedstocks in the optimal pathways

Strategic Planning for the Supply Chain of Aviation Biofuel with Consideration of Hydrogen Production

Substitution of petro-based aviation fuel with biomass-derived aviation fuel is an emerging strategy to reduce the carbon footprint associated with the aviation sector. There are several pathways for the production of aviation biofuel, and most of them require the use of hydrogen. Therefore, the analysis of the aviation biofuel supply chain must incorporate the production of hydrogen. This paper presents an optimization approach for the strategic planning of aviation fuel supply chains, which considers hydrogen production from fossil and renewable raw materials. The approach also considers extraction of fossil materials, growth of biomass, selection and several processing routes of the feedstock, along with the distribution of products. As a case study, the strategic planning of aviation biofuels in Mexico considering the generation of biomass and the hydrogen production is selected. The results show that significant decreases in producing costs and CO₂ emissions can be obtained if aviation fuel is generated from renewable raw materials. This finding is quite important, because in Mexico 90% of the consumed energy proceed from fossil sources. Several scenarios are addressed to assess the key factors in the design of the supply chain, reconciling the economic and environmental objectives; and also an analysis for the integration of the infrastructures of the fossil fuels and biorefineries is presented