Water integration in eco-industrial parks using a multi-leader-follower approach.

The design and optimization of industrial water networks in eco-industrial parks are studied by formulating and solving multi-leader-follower game problems. The methodology is explained by demonstrating its advantages against multi-objective optimization approaches. Several formulations and solution methods for MLFG are discussed in detail. The approach is validated on a case study of water integration in EIP without and with regeneration units. In the latter, multi-leader-single-follower and single-leader-multi-follower games are studied. Each enterprise's objective is to minimize the total annualized cost, while the EIP authority objective is to minimize the consumption of freshwater within the ecopark. The MLFG is transformed into a MOPEC and solved using GAMS® as an NLP. Obtained results are compared against the MOO approach and between different MLFG formulations. The methodology proposed is proved to be very reliable in multi-criteria scenarios compared to MOO approaches, providing numerical Nash equilibrium solutions and specifically in EIP design and optimization

Game theoretic optimisation in process and energy systems engineering: A review

Game theory is a framework that has been used by various research fields in order to represent dynamic correlation among stakeholders. Traditionally, research within the process and energy systems engineering community has focused on the development of centralised decision making schemes. In the recent years, decentralised decision-making schemes have attracted increasing attention due to their ability to capture multi-stakeholder dynamics in a more accurate manner. In this article, we survey how centralised and decentralised decision making has been facilitated by game theoretic approaches. We focus on the deployment of such methods in process systems engineering problems and review applications related to supply chain optimisation problems, design and operations, and energy systems optimisation. Finally, we analyse different game structures based on the degree of cooperation and how fairness criteria can be employed to find fair payoff allocations

Targeting economic and environmental benefits associated with the integration of regeneration units in water systems

Water treatment is traditionally seen as an "end-of-pipe" solution to deal with contaminated water satisfying discharge regulations at a minimum expense. However, the reuse of treated water as regenerated water is a promising strategy to counteract water scarcity. This approach to transform waste into resources is motivated by the circular economy paradigm. This study presents a mathematical programming approach to target both the environmental and economic benefits of water systems by introducing additional regeneration units to close the loop. In addition to water users and authorities, the approach also considers operators and dealers, which are revealed as key stakeholders. Hence, the feasible region of the regeneration units design specifications is determined and visualized through a multi-objective optimization approach targeting the systems operating cost and freshwater consumption. Its application is demonstrated on a benchmark case study from the literature, revealing a potential economic benefit of 37.5% and a freshwater reduction of 80.9% over the case without regeneration units. Furthermore, we show that a cooperative exchange strategy leads to higher benefits compared to the solutions presented in the literature. Finally, we demonstrate how the barrier plots introduced in this work can be used by different stakeholders in the water market to support their decision-making.Peer ReviewedPostprint (published version

Bilevel optimization of Eco-Industrial parks for the design of sustainable resource networks

This work presents a bilevel programming framework for the design of sustainable resource networks in eco-industrial parks (EIP). First, multiobjective optimization methods are explored in order to manage the multi-criteria nature of EIP network design problems. Then, different case studies are modeled in order to minimize and maintain in equilibrium participating plants operating costs while minimizing resource consumption. Thus, the structure of the model is constituted by a bilevel programming framework where the enterprises’ plants play a Nash game between them while being in a Stackelberg game structure with the authority. This structure defines a model which, in order to be solved, has to be transformed into a MOPEC (Multiple Optimization Problems with Equilibrium Constraints) structure. Regarding the case studies, monocontaminant water networks in EIP are studied first, where the influence of plants operating parameters are studied in order to determine the most important ones to favor the symbiosis between plants. The water network is composed of a fixed number of process and water regeneration units where the maximal inlet and outlet contaminant concentrations are defined a priori. The aim is to determine which processes are interconnected and the water regeneration allocation. Obtained results highlight the benefits of the proposed model structure in comparison with traditional multiobjective approaches, by obtaining equilibrate different plants operating costs (i.e. gains between 12-25%) while maintaining an overall low resource consumption. Then, other case studies are approached by using the bilevel structure to include simultaneously energy networks in a multi-leader-multi-follower formulation where both environmental authorities are assumed to play a noncooperative Nash game. In the first case study, economic gain is proven to be more significant by including energy networks in the EIP structure. The second industrial case study explores a supply-demand utility network model where the environmental authority aims to minimize the total equivalent CO2 emissions in the EIP. In all cases, the enterprises’ plants are encouraged to participate in the EIP by the extremely favorable obtained results

Application of industrial symbiosis principles to the management of utility networks

Utility exchanges between different plants have shown to produce large energy savings, extending the potential advantages of Energy/Process Integration through Industrial Symbiosis principles. Systematic approaches to determine such exchanges in industrial networks have been already proposed, although some of them are only applicable to specific situations and some others introduce the figure of a central authority. However, assuming such a figure in non-cooperative situations may restrict the economic benefit of some companies involved, thus discouraging their participation and preventing eventual agreements. The aim of this work is to develop an optimization model that allows analyzing the different symbiosis alternatives in different conflicting situations, even without the presence of any authority. Scenarios inspired by Game Theory have been considered. The problem has been modelled using a Mixed Integer Linear Programming (MILP) formulation and its capacities are illustrated through a particular case from the literature. Results show that the method allows establishing utility exchanges between different plants, which can improve the energetic, economic and environmental efficiency of all of them, as well as the whole set. Considering cooperative scenarios may allow determining solutions producing total energy savings and cost reductions, but without taking the specific interests of individual companies into account. On the other hand, considering non-cooperative scenarios ensures desirable outcomes from the eventual agreements for each company. Furthermore, the model is able to identify the economic barriers of the companies for participating, thus, being a useful and applicable tool that may improve decision-making support for managing utility networks in such situations.Peer ReviewedPostprint (published version

Utility network optimization in eco-industrial parks by a multi-leader follower game methodology

A multi-leader-follower game (MLFG) model for the design of the utility network in an eco-industrial park (EIP) is studied and implemented by introducing the concept of an environmental authority. The methodology also considers the flowsheet simulation of each enterprise involved in the EIP in order to obtain utility consumption of each enterprise operating by itself. The approach is validated on a case study of a potential Norwegian EIP. In the latter, multi-leader-single-follower and single-leader-multi-follower game models are studied. Each enterprise's objective is to minimize the total annualized cost, while the EIP authority objective is to minimize the equivalent CO2 consumption related to utility consumption within the ecopark. The MLFG is transformed into a MOPEC and solved using GAMS® as an NLP. The methodology proposed is proven to be reliable in multi-criteria scenarios compared to traditional multiobjective optimization approaches, providing numerical Nash/Stackelberg equilibrium solutions and specifically in EIP planning and optimization

Benefits analysis of optimal design of eco-industrial parks through life cycle indicators

Industrial symbiosis offers to companies the possibility to make economic benefits and to minimize environmental impacts by sharing flows and increasing inter-enterprise exchanges. However, even if some studies have demonstrated the benefits of the development of eco-industrial parks (EIP), there is no consensus to evaluate their benefits in a global point of view and there is a lack of integrated indicators for the assessment of EIPs. The aim of this study is to propose a holistic approach to evaluate the global impacts of an EIP. To reach this goal, the potential eco-industrial park of Mongstad in Norway has been chosen. Several steps are considered: a simulation through Aspen Properties®, then the superstructure optimization problem solved within GAMS® environment by minimizing the total cost of the EIP is done. Finally, an evaluation of the optimal solution through a life cycle approach is carried out. The results show that companies included in the EIP have environmental impacts reduced from 45% to 80% compared to the impacts of stand-alone companies

Growth, Conventional Production and Tourism Specialisation: Technological Catching-up Versus Terms-of-Trade Effects

This paper extends the ’expanding-varieties’ growth model in a two-countries-two-goods setup, and describes the dynamics of growth rates and terms of trade when the industry-based economy is the innovation leader, while the tourism-based economy is the follower (i.e. increases the number of intermediate inputs by readapting innovations developed abroad). Two types of transitional dynamics may exist: technological catching-up and technological falling-behind. Contrary to the standard result, technological catching-up by the follower is associated with lower growth rates with respect to the leader, whereas terms-of-trade effects guarantee positive growth differentials for the tourism-based economy when the technological gap with the leader increases over time. The underlying principle of ’increased relative demand’ might explain the good economic performance observed in tourism-dependent economies.Endogenous growth, Two-country models, Technology diffusion, Trade specialization

A circular economy approach to the design of a water network targeting the use of regenerated water

Increasing water demand by the process and allied industries coupled with global water stress and scarcity have underlined the importance of water as a crucial resource and increased the need for widespread adoption of water reuse and recycle. Early research based on water-pinch analysis addressed the use of systematic methods to identify the most promising opportunities for water reuse within a process plant. More recent work has addressed similar concepts in the framework of industrial symbiosis and Eco-Industrial Parks (EIP) under the assumption of the leadership of an EIP authority. However, many wastewater plants continue processing wastewater to condition water for disposal, which means meeting the limits given by regulations at a minimum cost. These wastewater treatment plants may play a role in a growing market of regenerated water in which an increasing number of businesses and public services would be demanding water with different quality specifications. Hence, this work is presenting an MINLP model aimed at exploiting the flexibility of a wastewater treatment plant and maximizing its profit within this market. Results and discussion are provided in regard of a case study based on a wastewater treatment plant nearby Barcelona.Peer ReviewedPostprint (published version