SUStainable Computer Aided Process Engineering


Sustainable processes


The use of new sources of energy like fuel cells, solar energy or biofuels has recently become a priority. Biofuels in particular share some of the storage and distribution advantages of traditional fuels, as opposed to other energy carriers like hydrogen. For this reason, their production is expected to increase in the next years all over the world and specially in Europe. Here, the European Union has intensively promoted their use, as it is clearly stated in the Directive 2003/30/CE that sets a consumption standard of biofuels.

In close collaboration with University of Tucumán, we are developing quantitative tools that can be useful at different decision-support levels in the area of bioethanol and biodiesel production. At the supply chain level, we are investigating the use of multi-objective mixed integer linear programming models where the environmental concerns are explicitly described through algebraic equations. At the process operation level, we are developing mixed-integer nonlinear programming formulations that allow for the systematic generation and assessment of process alternatives that may lead to significant environmental improvements. 

Selected publications

  • Kostin, A., Guillén-Gosálbez, G., Mele, F., Bagajewicz, M., Jiménez, L. A novel rolling horizon
    strategy for the strategic planning of supply chains. Application to the sugar cane industry of
    Argentina. Computers & Chemical Engineering, doi:10.1016/j.compchemeng.2011.04.006, 2011.
  • Kostin, A., Guillén-Gosálbez, G., Mele, F., Bagajewicz, M., Jiménez, L. Design and planning of
    infrastructures for bioethanol and sugar production under demand uncertainty. Chemical Engineering Research & Design, 10.1016/j.cherd.2011.07.013, 2011.
  • Mele, F., Kostin, A., Guillén-Gosálbez, G., Jiménez, L. Multi-objective model for more sustainable fuel supply chains. A case study of the sugar cane industry in Argentina. Industrial & Engineering Chemistry Research, 50 (9), 4939-4958, 2011.

Environmentally conscious energy systems

Nowadays a high percent of the total human-originated environmental impact is energy related. For this reason, there has been extensive research on the area of design and planning of efficient energy systems considering both financial and environmental objectives. A typical energy production system consists of (1) storage tanks to store raw materials, (2) boilers that convert fuel into steam at high pressure, (3) turbines that expand higher pressure steam into lower pressure steam in order to generate electricity and (4) mixing equipments for mixing compatible materials originated from different sources in the system. We are investigating the use of multi-objective mixed-integer linear programming (mo-MILP) techniques that allow to identify solutions that reduce the environmental impact of these systems through appropriate changes in the energy network.

Selected publications

  • Guillén-Gosálbez, G., Türkay, M. Life Cycle Assessment coupled with multi-objective optimization for environmentally conscious planning of energy production systems , AIChE Annual Meeting 2008.

Absorption cycles

Today, it seems clear that a drastic change in the energy structure should be made in the developed countries, and at the same time, renewable energies have to be more promoted. Spain is not an exception, and also, its emissions are too high to achieve the CO2 reduction scheduled in its adherence to the Kyoto agreement. Moreover, in the last years, the Spanish air conditioner market has been growing very quickly and most of the installed units are based on the mechanical vapor compression systems driven by electrical motors. As a consequence, the electrical demand has been rising, which worsens the trouble for both the generation and distribution networks, along with the associated environmental issues.

A more sustainable concept, known as thermal solar refrigeration, is based on the use of an absorption unit driven by solar thermal panels. This idea is not new at all, as there are some pilot installations already in the world. However, even with the enormous interest due to their benefits, both environmental and economical (for their low operating cost), their deployment in the market is null. The reason for such a low market impact could be attributed to their high purchase costs and the low integration of the devices involved in such installations.

In this area, different approaches as exergy and thermoeconomic analysis coupled with multi-objective optimization are being studied with the aim to develop more competitive and sustainable absorption systems.

Selected publications

  • Gebreslassie, B., Guillén-Gosálbez, G., Jiménez, L., Boer, D. A systematic tool for the minimization of the life cycle impact of solar assisted absorption cooling systems. Energy, 35(9), 3849-3862, 2010.
  • Gebreslassie, B., Guillén-Gosálbez, G., Jiménez, L., Boer, D. Economic performance optimization of an absorption cooling system under uncertainty. Applied Thermal Engineering, 29(17-18), 3491- 3500, 2009.
  • Gebreslassie, B., Guillén-Gosálbez, G., Jiménez, L., Boer, D. Design of environmentally conscious absorption cooling systems via multi-objective optimization and life cycle assessment. Applied Energy, 86(9), 1712-1722, 2009.

Hydrogen supply chains

The use of hydrogen as an alternative fuel and energy carrier has been the focus of a growing research interest in the last years. This trend has been mainly motivated by the need to reduce the CO2 emissions and mitigate global warming. In this area, we are studying the optimal design and operation of hydrogen networks for vehicle use. Mixed integer formulations that incorporate LCA principles are being developed along with efficient solution methods based on hierarchical decomposition techniques.

Selected publications

  • Sabio, N., Kostin, A., Guillén-Gosálbez, G., Jiménez, L. Holistic minimization of the life cycle
    environmental impact of hydrogen infrastructures using multi-objective optimization and principal component analysis. International Journal of Hydrogen Energy, Accepted, 2011.
  • Sabio, N., Gadalla, M., Guillén-Gosálbez, G., Jiménez, L. Strategic planning with risk control of hydrogen supply chains for vehicle use under uncertainty in operating costs: A case study of Spain. International Journal of Hydrogen Energy, 35 (13), 6836-6852, 2010.
  • Guillén-Gosálbez, G., Mele, F., Grossmann, I. E. A bi-criterion optimization approach for the design and planning of hydrogen supply chains for vehicle use. AIChE Journal, 56 (3), 650-667, 2010.

Susutainable supply chains

Nowadays, there is a substantial inter-regional trade in petrochemicals of all kinds. In an environment of this type, the demands are satisfied by dispersed facilities that act as entire petrochemical supply chains. A novel modeling framework and solution strategy are being developed to address the optimal design of such complex networks taking into account economic and environmental concerns. Our approach integrates multi-criteria mixed integer linear programming (MILP) and LCA principles (Eco-Indicator 99) within a single modeling and optimization framework. Efficient solution strategies based on parametric programming are also being studied to expedite the computation of the Pareto solutions of these formulations.

Selected publications

  • Grossmann, I. E., Guillén-Gosálbez, G. Scope for the application of mathematical programming techniques in the synthesis and planning of sustainable processes. Computers & Chemical Engineering, 34 (9), 1365-1376, 2010.
  • Guillén-Gosálbez, G., Grossmann, I. E. A global optimization strategy for the optimal design and planning of sustainable chemical supply chains under uncertainty in the damage assessment model. Computers & Chemical Engineering, 34 (1), 42-58, 2010.
  • Guillén-Gosálbez, G. A novel MILP-based objective reduction method for multi-objective
    optimization: application to environmental problems. Computers & Chemical Engineering, 35(8),
    1469-1477, 2011.
  • Guillén-Gosálbez, G., Grossmann, I. E. Optimal design and planning of sustainable chemical supply chains under uncertainty. AIChE Journal, 55(1), 99-121, 2009.


Systems biology

Systems biology addresses the study of biological systems dealing with them as a whole instead of focusing on their individual components. Particularly, the construction of reliable models of metabolic networks is a key issue in systems biology. This field has recently emerged as an active area of research given its potential applications in biotechnological and evolutive studies, For instance, the optimization of metabolic pathways to maximize the production of an intermediate metabolite is an important issue in biotechnological applications. On the other hand, the identification of feasible biological parameter regions of a metabolic network constitutes a major challenge in evolution studies. Optimization methods, in particular, offer a general framework to accomplish these tasks. The aim of this work is to develop a systematic modeling framework and solution strategy based on advanced optimization techniques that are useful for the aforementioned applications. The capabilities of our method have been illustrated through its application to different case studies. The approach presented has provided valuable biological insights, and has been shown to be very efficient in solving medium/large size problems, performing much better than standard optimization packages.

Selected publications

  • Pozo, C., Guillén-Gosálbez, G., Sorribas, A., Jiménez, L. Outer approximation-based algorithm for biotechnology studies in systems biology. Computers & Chemical Engineering, 34 (10), 1719-1730, 2010.
  • Pozo, C., Marín-Sanguino, A., Alves, R., Guillén-Gosálbez, G., Jiménez, L., Sorribas, A. Steadystate global optimization of metabolic non-linear dynamic models through recasting into power-law canonical models. BMC Systems Biology, 5, 137, 2011.
  • Pozo, C., Guillén-Gosálbez, G., Sorribas, A., Jiménez, L. A spatial branch-and-bound framework for the global optimization of kinetic models of metabolic networks. Industrial & Engineering Chemistry Research, 50 (9), 5225-5238, 2011.
  • Guillén-Gosálbez, G., Sorribas, A. Identifying quantitative operation principles in metabolic
    pathways: a systematic method for searching feasible enzyme activity patterns leading to cellular adaptive responses. BMC Bioinformatics, 10 (386), 2009.


Application of new teaching methodologies and popular science

When the word “chemistry” comes to our minds, automatically we make negative associations, as pollution, toxics, additives, wastes or toxicity. The attributes associated to “chemistry” are always opposite to “natural”. We believe that this vision is outdated, as the benefits of the chemistry surpass the potential risks that entails. In addition, other areas (pharmaceutical, medical, food technology, synthetic fibers…) have a high social prestige, and we haven’t succeeded in communicating the chemistry-based advantages to the society.

Chemistry is not a boring discipline reserved for a few researchers dressed in white coat, that work in an isolated laboratory. Chemistry can be displayed in an enjoyable and good-humored way, and it can transmit positive aspects.

Through short videos (5-8 minutes each), we contribute to eradicate the Chemofobia that affects the society. The tone of the videos is amusing, entertaining and loutish, to connect with a juvenile public. Also, the format is agile to favor dynamism. The structure of each videos is:

  • Start with an initial anecdote that stimulates curiosity, as closely related with daily life aspects (Why you can not prepare salty iced cubes?).
  • Develop a short story with scientific aspects embedded that shows how chemistry contributes to the welfare and how it helps to solve problems.
  • End with the technical explanation. The idea is to raise open-questions that foster critical discussion and analyze the scientific content.

The objective of the videos is to provide an interesting, motivating and attractive tool to promote curiosity, and just then, when curiosity is up and doing, provide technical knowledge to clarify concepts that, in most occasions, are known superficially. A brief introduction of each video is:

  1. The hard-boiled egg of the Everest -I-. Wolfram has an appointment. His aim is to seduce a girl by impressing her with a romantic dinner: a salad decorated with a hard-boiled egg. And he begins to prepare the egg …
  2. The hard-boiled egg of the Everest -II-. After preparing the hard-boiled egg he eats it, and he must find a faster method, since the girl is coming!!! Now he is trying to boil the egg in the conditions of the top of the Everest (is it better in the conditions of the sea bed?)…
  3. Coolbito. Wolfram popularity is extremely low, and to improve it he decides to organize a party and prepare the fashionable drink: tequila & lemon & salt. Since he is very scrupulous, he decides to prepare salty ice cubes...
  4. Sauces. Wolfram has an appointment and wants to prepare a sauce to dress his romantic dinner. He decides to prepare mayonnaise, since it explains his dual personality: egg (very energetic) and oil (it warms up easily). In addition, to mix both ingredients you need a suitable third component...
  5. The burnt omelet. Wolfram has a terrible sore throat, which will prevent him from a impressive success in the karaoke. He decided to call a nurse. Since for nurses neatness is fundamental, he is cleaning the lab-apartment. While waiting, he cooks an omelet for his throat...