Juan Martinez-Gomez

A multi-objective optimization approach for the selection of working fluids of geothermal facilities: Economic, environmental and social aspects

The selection of the working fluid for Organic Rankine Cycles has traditionally been addressed from systematic heuristic methods, which perform a characterization and prior selection considering mainly one objective, thus avoiding a selection considering simultaneously the objectives related to sustainability and safety. The objective of this work is to propose a methodology for the optimal selection of the working fluid for Organic Rankine Cycles. The model is presented as a multi-objective approach, which simultaneously considers the economic, environmental and safety aspects. The economic objective function considers the profit obtained by selling the energy produced. Safety was evaluated in terms of individual risk for each of the components of the Organic Rankine Cycles and it was formulated as a function of the operating conditions and hazardous properties of each working fluid. The environmental function is based on carbon dioxide emissions, considering carbon dioxide mitigation, emission due to the use of cooling water as well emissions due material release. The methodology was applied to the case of geothermal facilities to select the optimal working fluid although it can be extended to waste heat recovery. The results show that the hydrocarbons represent better solutions, thus among a list of 24 working fluids, toluene is selected as the best fluid.

Optimal Reuse of Flowback Wastewater in Shale Gas Fracking Operations Considering Economic and Safety Aspects

Abstract This work presents a mathematical programing formulation for the optimal management of flowback water in shale gas wells considering economic and safety aspects. The proposed formulation accounts for the time-based generation of the flowback water, as well as the options for treatment, storage, reuse, and disposal. The economic objective function is aimed at determining the minimum cost for the fresh water, treatment, storage, disposals and transportation. The safety objective accounts for the risk associated to a failure in the treatment units and its consequence in human deaths. In this regard, the proposed method is able to consider different treatment units with different operating efficiency factors, costs and risks. To carry out the water integration, a recycle and reuse network is proposed. A given scheduling for the completion phases of the wells is required to implement the proposed method. Finally, an example problem is presented to show the applicability of the proposed method.

An Optimal Planning for the Reuse of Municipal Solid Waste Considering Economic, Environmental and Safety Objectives

Abstract Nowadays, the waste generation is a serious problem mainly in the countries with inefficient waste management systems. However, some waste can be reused as raw material for several products using a set of available technologies. In this context, several options to attack this problem have been implemented, but just a few alternatives consider the waste management as an integral part in the supply chain. This way, several technical, environmental and economic aspects have been taken into account for the assessment of the entire supply chain; although, the incorporation of safety criteria into the assessment of the supply chain focused in municipal solid waste have not been implemented in previous papers. Therefore, in this paper is proposed a mathematical programming model for the optimal planning of the reuse of municipal waste to maximize the economic benefits considering sustainability and safety criteria simultaneously. This methodology considers several phases: the separation of waste, distribution of waste to processing facilities, processing of waste to obtain useful products and distribution of products to consumers. Additionally, the safety criteria are based on the fatalities associated with the supply chain for the waste management. The problem is formulated as a multi-objective problem that considers three different objectives: the net annual profit, the amount of reused waste and the total fatalities generated with the considered risks. Results show that it is possible to implement a distributed processing system to reuse municipal waste in an economically attractive way. In addition, results can be used for governments to take decisions about the waste disposal and define the amount of waste that must be reused to obtain several products. It should be noted that results include the supply chain configuration. In addition, in future works this methodology can be extended to problems focused in supply chain design and retrofit simultaneously.

A quantitative risk analysis for the vegetable oil industry in Mexico

In industrializing countries, the rapid population growth frequently tends to reach the vicinity of the industrial parks, yielding an imminent hazard to the residents in the case of the occurrence of an accident. In the case of Mexico, particularly in the city of Morelia, the industries associated to the vegetable oil and margarine, originally located far from the city, have been absorbed by the city due to the high population growth. It should be noticed that this industry represents a high hazard because it uses huge amounts of hydrogen and LP gas. Therefore, to determine the potential impact of an accident for the people within and around these industries, this paper presents a quantitative risk analysis applied to the vegetable oil refining industry in Morelia. The main objective is the identification of the facilities with the highest hazard, as well as the risk analysis to the personnel inside and the people leaving around the plant. According to the quantitative risk analysis, the hydrogen processing and storage units are the most dangerous facilities inside the plant. Moreover, the identified potential accidents were boiling liquid expanding vapor explosion, flash fire, jet fire, and vapor cloud explosion, which were evaluated through the software SCRI. Furthermore, an inherent approach was applied to propose alternatives for risk reduction.