Early-stage decision making approach for the selection of optimally integrated biorefinery processes

Lignocellulosic biorefineries are the best non-petroleum alternatives for a sustainable development. In the biorefinery process design, it is important to implement an algorithm that allows the systematic generation and the evaluation of energy conversion chains and making comparison of different pathways, ranking them according to different performance criteria. To achieve these goals, a methodology has been proposed to systematically define an ordered set of solutions using mixed integer linear programming models with integer cut constraints. In this study, we apply a systematic approach which adopts thermo-environomic optimization together with heat integration to assess the economic performance, environmental impact and energy requirement of several process options. Both sugars and syngas platforms are compared considering multiple products (energy services, valuable chemicals, fuels). A hybrid superstructure of different processes is developed and the heat recovery in the systems is represented using pinch analysis. Different pathways are evaluated and ranked according to different objective functions to understand the best combination of products and the synergies between them. The results of this work provide a set of candidate solutions considering benefit of heat integration between different pathways to obtain energy efficient biorefinery systems with improved process economics and reduced environmental impacts.

Ayse Dilan Celebi, François Maréchal, Shivom Sharma, Adriano Viana Ensinas

Lignocellulosic biorefineries are the best non-petroleum alternatives for a sustainable development. In the biorefinery process design, it is important to implement an algorithm that allows systematic generation, evaluation of energy conversion chains and making comparison of different pathways, ranking them according to different performance criteria. To achieve these goals, a methodology has been proposed to systematically define an ordered set of solutions using mixed integer linear programming models with integer cut constraints. In this study, we apply a systematic approach which adopts thermo-environomic optimization together with heat integration to assess the economic performance, environmental impact and energy requirement of several process options. Both sugars and syngas platforms are compared considering multiple products (energy services, valuable chemicals, fuels). A superstructure of different processes is developed and heat recovery potentials in the systems are analyzed using pinch analysis. Different pathways are evaluated and ranked according to different objective functions to understand the best combination of products and the synergies between them. Our results provide a set of candidate solutions according to minimum total cost and environmental impact as objective functions, considering benefit of heat integration between different pathways to obtain energy efficient biorefinery systems with improved process economics and reduced environmental impacts.

2017

Integration of Life Cycle Assessment in the conceptual design of renewable energy conversion systems

Léda Gerber

Life Cycle Assessment (LCA) is a well-established methodology that has been extensively used for the environmental evaluation of emerging technologies in the field of renewable energy conversion systems. In order to identify effective solutions for impact mitigation already at the conceptual process design stage, it is necessary to take into account the environmental aspects in the process design procedure, in consistency with economic and thermodynamic criteria. This thesis presents a systematic methodology for the integration of LCA in the conceptual design of renewable energy systems, using process design, process integration and multi-objective optimization techniques. The developed methodology is illustrated by three application case studies. The first one concerns the evaluation of different candidate technologies for the combined production of Synthetic Natural Gas and electricity from lignocellulosic biomass by thermochemical conversion. The second case study treats of the environomic optimal configurations of Enhanced Geothermal Systems for combined heat and power production, considering different potential conversion technologies. The third case study deals with the design and the synthesis of an urban energy system, accounting for the different energy services to be supplied, the different potential resources, the candidate conversion technologies, and the waste to be treated. In this last case study, the overall supply chains from resources or wastes to services are synthesized, accounting for the industrial ecology possibilities. A first major outcome of these application case studies is that accounting for the process integration in the evaluation of the environmental impacts leads to an important impact reduction. Secondly, the developed methodology allows for calculating the trade-offs between the environmental criteria and the thermo-economic ones. Therefore, the optimal promising configurations of an emerging technology or of a system considering its environmental performances can be identified. Finally, it is demonstrated that integrating the environmental impacts in the process design procedure leads to a different decision-making than if only thermo-economic criteria are considered.

EPFL2012

Methodology for the identification of promising integrated biorefineries

Ayse Dilan Celebi

Steady increase in global energy consumption, greenhouse gas emissions, and depletion of fossil energy resources, together with increased attention towards sustainable development has prompted researchers to discover economical and environmentally competitive non-petroleum alternatives and biomass is considered to be one of the most promising renewable sources of energy and carbon of this matter to address the aforementioned issues within a biorefinery platform. A biorefinery is an integrated processing facility that converts biomass into transportation fuels, value-added chemicals, heat, and electricity via biochemical and thermochemical conversion routes. Integrated biorefineries are capable of mimicking petroleum refineries via application of advanced process synthesis methods including modeling, simulation, integration and optimization techniques. This thesis presents a comprehensive synthesis methodology for the integration of bioprocessing technologies in biorefineries by addressing techno-economic and environmental sustainability analysis. The proposed systematic design approach combines advanced process modeling approaches, process integration techniques, and multi-objective optimization algorithms to assess the performance of the overall system with respect to economic, environmental, and energetic indicators. The design strategy is applied based on different case studies. Results indicate that multi-product processes can yield significant cost and environmental benefits. Additionally, the integration of biochemical and catalytic processes with thermochemical conversion pathways results in increased carbon efficiency and economic and environmental competitiveness. Synergies between biorefineries and energy system are assessed by integrating industrial plants with a cogeneration system producing biofuels and process heat. In doing so, system efficiency is increased by coupling the proposed cogeneration system with carbon capture and sequestration (CCS) and power-to-gas technologies to store the renewable intermittent electricity in the form of biofuels. The results exhibit that through system expansion, integrated biorefinery systems allow us to imitate fossil refineries with a large spectrum of bio-based products. This further increases the resource efficiency while offering a promising solution to mitigate CO2 emissions and hence reaching the longer-term decarbonization target set by the Paris Agreement.

EPFL2019

Methodology for the identification of promising integrated biorefineries

Ayse Dilan Celebi

EPFL2019

Integration of Life Cycle Assessment in the conceptual design of renewable energy conversion systems

Léda Gerber

EPFL2012

Early-stage decision making approach for the selection of optimally integrated biorefinery processes