The major contribution to global warming and climate change is due to increasing emissions of greenhouse gases by fossil fuels utilization. To be more precise, globally, 32.5 Gt of emissions were registered in 2017, while carbon dioxide concentration in the atmosphere achieved a value of 404 ppm. Urgent actions are needed to face this environmental problem. In this context, carbon capture utilization and storage supply chains have been recognized as a critical measure to reduce emissions and mitigate the anthropogenic impact on the Earth. In Europe, Germany, Italy and the UK are the Countries with higher carbon dioxide emissions. Then, carbon capture utilization and storage supply chains are here designed and discussed for these European Countries. Moreover, it is interesting to analyze and study in depth the most important utilization route of carbon dioxide that can be considered inside a carbon supply chain, as reported in the literature: the hydrogenation of carbon dioxide to methanol production. These topics are investigated in this Thesis at the level of mathematical and numerical modeling, using different computational tools as AIMMS, MATLAB® and Aspen Plus®. The development of a mixed integer linear programming model (deterministic as single and multi objective optimization problem and stochastic) is thus achieved to design carbon supply chains, including its life cycle assessment analysis, and the development of a 1-D and 2-D model for a methanol reactor with the separation of methanol and water by condensation after the recycle of unconverted gases, following its equilibrium study. Results show the technical feasibility of methanol production by pure carbon dioxide and hydrogen with the best efficiencies for the above mentioned reactor configuration. Moreover, regarding carbon supply chains, optimized minimizing total costs in single optimization and minimizing total costs and maximizing total captured carbon dioxide respectively in multiple optimization, results show that these systems can reduce emissions but economic incentives and carbon tax are required to be economically feasible. The life cycle assessment analysis suggests that a net emissions reduction according to the environmental policy is achieved with these frameworks. Also, a stochastic model can provide a good design when the production costs of carbon dioxide-based products are considered as stochastic parameters. Regarding future work, it would be interesting to consider more complex CCUS supply chains taking into account, at the same time, a multiplicity of carbon sources, storage sites and utilization sites, trying to design a more realistic picture for each Country. This would imply to eliminate the assumption of only one storage site, or the restriction to only two utilization sites, with a substantial production capacity, so to keep the ratio between utilization and storage above a given threshold limit dictated by the need to establish a circular carbon economy. In addition, following the development of a supply chain model like that described in this Thesis, applied to different Countries and under different constraints, it would be interesting to extend the model to a CCUS supply chain involving the whole Europe that should achieve a reduction of CO2 emissions according the COP21 agreement. To enlarge and better characterize the basket of carbon-dioxide-based compounds, of their dynamic market demand and most convenient production processes (economically and environmentally speaking – green chemistry), realization of a comprehensive data bank would strongly help an even more reliable application of such models, as a result of combined efforts in economic and engineering research.

Reduction of CO2 emissions: strategic utilization and storage options / Leonzio, Grazia. - (2020 Jul 22).

Reduction of CO2 emissions: strategic utilization and storage options

LEONZIO, GRAZIA
2020-07-22

Abstract

The major contribution to global warming and climate change is due to increasing emissions of greenhouse gases by fossil fuels utilization. To be more precise, globally, 32.5 Gt of emissions were registered in 2017, while carbon dioxide concentration in the atmosphere achieved a value of 404 ppm. Urgent actions are needed to face this environmental problem. In this context, carbon capture utilization and storage supply chains have been recognized as a critical measure to reduce emissions and mitigate the anthropogenic impact on the Earth. In Europe, Germany, Italy and the UK are the Countries with higher carbon dioxide emissions. Then, carbon capture utilization and storage supply chains are here designed and discussed for these European Countries. Moreover, it is interesting to analyze and study in depth the most important utilization route of carbon dioxide that can be considered inside a carbon supply chain, as reported in the literature: the hydrogenation of carbon dioxide to methanol production. These topics are investigated in this Thesis at the level of mathematical and numerical modeling, using different computational tools as AIMMS, MATLAB® and Aspen Plus®. The development of a mixed integer linear programming model (deterministic as single and multi objective optimization problem and stochastic) is thus achieved to design carbon supply chains, including its life cycle assessment analysis, and the development of a 1-D and 2-D model for a methanol reactor with the separation of methanol and water by condensation after the recycle of unconverted gases, following its equilibrium study. Results show the technical feasibility of methanol production by pure carbon dioxide and hydrogen with the best efficiencies for the above mentioned reactor configuration. Moreover, regarding carbon supply chains, optimized minimizing total costs in single optimization and minimizing total costs and maximizing total captured carbon dioxide respectively in multiple optimization, results show that these systems can reduce emissions but economic incentives and carbon tax are required to be economically feasible. The life cycle assessment analysis suggests that a net emissions reduction according to the environmental policy is achieved with these frameworks. Also, a stochastic model can provide a good design when the production costs of carbon dioxide-based products are considered as stochastic parameters. Regarding future work, it would be interesting to consider more complex CCUS supply chains taking into account, at the same time, a multiplicity of carbon sources, storage sites and utilization sites, trying to design a more realistic picture for each Country. This would imply to eliminate the assumption of only one storage site, or the restriction to only two utilization sites, with a substantial production capacity, so to keep the ratio between utilization and storage above a given threshold limit dictated by the need to establish a circular carbon economy. In addition, following the development of a supply chain model like that described in this Thesis, applied to different Countries and under different constraints, it would be interesting to extend the model to a CCUS supply chain involving the whole Europe that should achieve a reduction of CO2 emissions according the COP21 agreement. To enlarge and better characterize the basket of carbon-dioxide-based compounds, of their dynamic market demand and most convenient production processes (economically and environmentally speaking – green chemistry), realization of a comprehensive data bank would strongly help an even more reliable application of such models, as a result of combined efforts in economic and engineering research.
Reduction of CO2 emissions: strategic utilization and storage options / Leonzio, Grazia. - (2020 Jul 22).
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Descrizione: Reduction of CO2 emissions: strategic utilization and storage options
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11697/149714
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