Strategische Planung von Wertschöpfungsnetzwerken zur Produktion von synthetischen Kraftstoffen auf Basis erneuerbarer Energien : ein Ansatz unter Berücksichtigung saisonaler Schwankungen der Inputs

  • Strategic supply chain planning of synthetic fuels based on renewable energies : an approach considering seasonal supply fluctuations of the inputs

Doré, Larissa Alexandra; Walther, Grit (Thesis advisor); Fröhling, Magnus (Thesis advisor)

Aachen : RWTH Aachen University (2021)
Dissertation / PhD Thesis

Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2021

Abstract

The present PhD thesis develops an approach for strategic supply chain planning of synthetic fuels based on renewable energies (wind, solar, biomass) and validates this approach with a European case study. To conceptualise the planning approach, the regulatory, economic, ecological, technical and logistical framework conditions, which determine the design of supply chains for synthetic fuels based on renewable energies, are analysed as a first step. Based on this analysis, the following requirements for the planning approach are derived: Synthetic fuels can be produced by the three process pathways Biomass-to-Liquid, Power-to-Liquid and Power and Biomass-to-Liquid, which differ in terms of processed inputs as well as type and number of process steps. In order to determine the economically preferred process pathways with respect to geographically and temporally limited input potentials, all three pathways have to be considered simultaneously in one planning approach. The inputs biomass and renewable electricity are characterised by a seasonally fluctuating supply pattern, which is why storages within the supply chain network have to be taken into account. For storing and transporting inputs, intermediates and fuels within the network, different storage technologies and transport modes exist, which have to be modelled accordingly in the planning approach. Economies of scale can be realised for production plants, storages and the transport mode pipeline and also have to be considered in the planning approach. Furthermore, dynamic developments on a strategic as well as tactical level have to be modelled in order to account for both the future increase in demand for synthetic fuels and the seasonal fluctuations of the inputs. As a second step, existing approaches in the field of supply chain planning of synthetic fuels based on renewable energies are analysed. Based on this analysis, suitable modelling options to meet the requirements of the present planning problem are identified. Furthermore, the analysis reveals that no approach in literature meets all requirements defined in this thesis. Based on the derived requirements and the identified modelling options, a planning approach for the design of supply chains for synthetic fuels based on renewable energies is developed. The planning problem is formulated as a mixed-integer linear programming model. The objective function of the model maximizes the net present value of the supply chain. Strategic and tactical time periods are modelled in order to consider both long-term developments and seasonal supply fluctuations. To reduce model complexity, several years are aggregated into one strategic time period. The material and energy transformations in the production plants are modelled by an activity analysis approach. Subsequently, the developed planning approach is validated on the basis of a case study for the European Union for the planning period 2025 to 2050. Thereby, five scenarios are examined in order to account for uncertainties in terms of input supply, fuel demand and economic parameters of the production technologies. The case study reveals that all three production pathways Biomass-to-Liquid, Power-to-Liquid and Power and Biomass-to-Liquid are of significance in the future. This highlights the importance of an integrated planning of all three process pathways. Furthermore, this implies the need for politicians, potential investors as well as stakeholders from research and development to stay open to all technologies and to enhance all technological pathways. However, the results also indicate that synthetic fuel production based on renewable energies is – considering the current framework conditions – not economically advantageous for any scenario. This holds also for very optimistic assumptions in terms of electricity price and economic parameters of the production technologies. Thus, political incentives, e. g. subsidies or CO2 emission limits, have to be implemented to foster the investment in synthetic fuel production plants. In the context of the underlying thesis, an approach for the supply chain planning of synthetic fuels based on renewable energies is developed, which adequately considers all characteristics of the present planning situation. In particular, all three process pathways are analysed integrated for the first time. Therefore, the developed approach provides an important basis for the integration of supply chain models of synthetic fuels based on renewable energies with models of the electricity system.

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