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Papers by Ralph-Uwe Dietrich

Journal of Fundamentals of Renewable Energy and Applications, Jan 30, 2017

Greenhouse gas emissions in the transport sector can significantly be reduced by replacing fossil... more Greenhouse gas emissions in the transport sector can significantly be reduced by replacing fossil based fuels with biomass-based alternatives. Several promising fuel production paths of the second generation made from residues and waste wood had already been developed

Conversion of CO2 to fuels is one of the long-term solutions to reduce dependence on fossil fuels... more Conversion of CO2 to fuels is one of the long-term solutions to reduce dependence on fossil fuels and mitigate climate change. Our previous study has already assessed the Power-to-Liquid (PtL) process by means of water electrolysis, reverse water-gas shift (RWGS) reaction and Fischer-Tropsch (FT) synthesis. However, the source of CO2 supply has not been identified and the net production cost (NPC) of such synthetic fuels remains much higher than that via conventional petrochemical process. In this work, we have extended our study with advanced CO2 capture technologies and optimised process integration. Several commercial acid gas separation technologies such as amine scrubbing and Selexol® as well as novel methods using phase change solvents have been evaluated and adopted for PtL process. To reduce the energy demand, various process designs and heat integration concepts have been conducted. For example, using process heat from FT reactor for solvent regeneration in the thermal desorber can save more than 80 % of the total energy requirement for the entire CO2 capture system. Aspen Plus® process simulation of the optimised system design has been implemented and the in-house assessment programme TEPET (Techno-Economic Process Evaluation Tool) has been employed for the detailed analysis. The capital expenditure (CAPEX), operational expenditure (OPEX) and fuel NPC are hence estimated upon industrial standards, literature data and simulation results. Cost estimation according to class III and IV of the ICEAA is achieved, offering an 30 % accuracy. To minimise the cost of the overall CO2-to-Fuels process, the potential of using low price industrial CO2 sources with novel carbon capture technologies and improved system integration of all process units has been extensively evaluated. The sensitivity analysis has also been carried out to predict the possibility of future NPC reduction.

International Journal of Hydrogen Energy, Jul 1, 2022

Large-scale hydrogen production facilities will be required to supply the chemical energy demand ... more Large-scale hydrogen production facilities will be required to supply the chemical energy demand of certain industries in the future. The case for such production plants based on individual adapted PV and wind farms has been addressed in several studies. However, most studies focus on an island solution of the evaluated plant and therefore, do not allow grid assistance which significantly reduce the installed capacity of the corresponding units. To address this issue, we developed a tool with a linear programming approach to evaluate any location around the world for its renewable hydrogen production costs and the influence on the plant layout depending on its interaction with the grid. A detailed techno-economic evaluation has been performed for five locations where hydrogen production costs in the range of 4 – 6 €(2020)/kg have been retrieved. Furthermore, it is shown that with perspective cost data the costs can further be reduced to 2.50 €(2020)/kg.

Energy Conversion and Management, Oct 1, 2023

In this work, the techno-economic and exergy analyses of two gasification technologies with integ... more In this work, the techno-economic and exergy analyses of two gasification technologies with integration into heat and power combined cycles are presented: i). Circulating fluidized bed (CFB) and ii). Dual fluidized bed (DFB) systems. As feedstock, lignocellulosic biomass (sugarcane bagasse, SCB) was considered. The gasification process of the fluidized-bed systems (circulating and dual bed) and the syngas conversion were performed using Aspen Plus® software. The process design includes biomass drying and gasification, syngas cleaning, combustion, power generation, and heat recovery. The SCB-DFB system has the lowest irreversibility rate and, as a result, the highest overall performance and power generation (achieving 32% in the gasification system and 53% of exergy efficiency when coupled with the combined cycle). From the techno-economic assessment, the SCB-DFB system has the lowest total production costs per unit of energy. Hence, the dual fluidized bed systems could be a more competitive technology for the agro-industrial sector to generate power from lignocellulosic materials.

Chemie Ingenieur Technik, 2018

Der vorliegende Beitrag skizziert einen möglichen zukünftigen Bedarf an erneuerbaren flüssigen Kr... more Der vorliegende Beitrag skizziert einen möglichen zukünftigen Bedarf an erneuerbaren flüssigen Kraftstoffen, bewertet mögliche Prozessrouten zu deren Erzeugung im großen Maßstab unter Einsatz von erneuerbarem Strom, Biomasse und anderen Kohlenstoffquellen und diskutiert systemische Effekte eines entsprechenden Infrastrukturausbaus. Die in einer Fallstudie erfolgte technische, ökonomische und ökologische Bewertung basiert auf detaillierten Prozesssimulationen verknüpft mit dem Kostenberechnungstool TEPET und ermöglicht so eine größtmögliche Transparenz aus wissenschaftlicher Sicht.

International Journal of Hydrogen Energy, 2018

ECS transactions, Apr 25, 2011

Solid oxide fuel cell systems (SOFC) can improve the efficiency of electrical power generation fr... more Solid oxide fuel cell systems (SOFC) can improve the efficiency of electrical power generation from biogas compared to small scale CHP units. The SOFC requires a reforming step converting biogas into synthesis gas (hydrogen and carbon monoxide). . Dry reforming of methane with the carbon dioxide contained in biogas is a promising approach to produce high caloric SOFC fuel gas, but carbon formation is predicted for all typical biogas compositions. To avoid carbon formation and to compensate fluctuating biogas compositions additional supply of steam is essential leading to a combined dry and steam reforming. The paper describes the system approach, upfront analysis, biogas monitoring results, process unit design and evaluation as well as the system setup to demonstrate a biogas to electricity route with a gross efficiency of 45 % using a commercial 1 kW SOFC stack.

Fuel, Jun 1, 2022

Four types of adverse events resembling immunological reactions have been reported in patients un... more Four types of adverse events resembling immunological reactions have been reported in patients undergoing chronic maintenance hemodialysis: anaphylaxis [1], hypereosinophilia [1-5], asthmatic attacks [4-6], and pulmonary leukostasis with compromised pulmonary function [7-10]. We evaluated three successive chronic dialysis patients who had developed acute hypersensitivity reactions manifested by increased airway obstruction in response to hemodialysis. Each patient also had a non-acute reaction to dialysis, hypereosinophilia, and one patient had urticaria. All dialyzers were ethylene oxide sterilized and none were reused. In these three patients the adverse reactions abated after changing from dialyzers containing Cuprophan (ENKA Ag, Wuppertal, Germany) to dialyzers not containing Cuprophan. In each patient a second exposure to Cuprophan caused recurrence of one or more of the adverse reactions. These case studies and our re-examination of previous observations [1-61 suggest that in some patients both acute and chronic adverse reactions may be related to the use of Cuprophan. Methods and Results. Patient 1. A 50-year-old black female with renal failure secondary to hypertension began chronic hemodialysis in December 1975. It is uncertain which dialyzers were used during the first 10 months of dialysis, but during her ninth and tenth months of dialysis differential counts showed 18 and 20% eosinophils (Fig. 1). In October 1976, a one antigenmatched cadaver kidney transplant was attempted but was rejected and, 3 weeks later, removed. Hemodialysis was continued using coil dialyzers containing Cuprophan (ENKA Ag)

Journal of Fundamentals of Renewable Energy and Applications, Jan 30, 2017

Greenhouse gas emissions in the transport sector can significantly be reduced by replacing fossil... more Greenhouse gas emissions in the transport sector can significantly be reduced by replacing fossil based fuels with biomass-based alternatives. Several promising fuel production paths of the second generation made from residues and waste wood had already been developed

Conversion of CO2 to fuels is one of the long-term solutions to reduce dependence on fossil fuels... more Conversion of CO2 to fuels is one of the long-term solutions to reduce dependence on fossil fuels and mitigate climate change. Our previous study has already assessed the Power-to-Liquid (PtL) process by means of water electrolysis, reverse water-gas shift (RWGS) reaction and Fischer-Tropsch (FT) synthesis. However, the source of CO2 supply has not been identified and the net production cost (NPC) of such synthetic fuels remains much higher than that via conventional petrochemical process. In this work, we have extended our study with advanced CO2 capture technologies and optimised process integration. Several commercial acid gas separation technologies such as amine scrubbing and Selexol® as well as novel methods using phase change solvents have been evaluated and adopted for PtL process. To reduce the energy demand, various process designs and heat integration concepts have been conducted. For example, using process heat from FT reactor for solvent regeneration in the thermal desorber can save more than 80 % of the total energy requirement for the entire CO2 capture system. Aspen Plus® process simulation of the optimised system design has been implemented and the in-house assessment programme TEPET (Techno-Economic Process Evaluation Tool) has been employed for the detailed analysis. The capital expenditure (CAPEX), operational expenditure (OPEX) and fuel NPC are hence estimated upon industrial standards, literature data and simulation results. Cost estimation according to class III and IV of the ICEAA is achieved, offering an 30 % accuracy. To minimise the cost of the overall CO2-to-Fuels process, the potential of using low price industrial CO2 sources with novel carbon capture technologies and improved system integration of all process units has been extensively evaluated. The sensitivity analysis has also been carried out to predict the possibility of future NPC reduction.

International Journal of Hydrogen Energy, Jul 1, 2022

Large-scale hydrogen production facilities will be required to supply the chemical energy demand ... more Large-scale hydrogen production facilities will be required to supply the chemical energy demand of certain industries in the future. The case for such production plants based on individual adapted PV and wind farms has been addressed in several studies. However, most studies focus on an island solution of the evaluated plant and therefore, do not allow grid assistance which significantly reduce the installed capacity of the corresponding units. To address this issue, we developed a tool with a linear programming approach to evaluate any location around the world for its renewable hydrogen production costs and the influence on the plant layout depending on its interaction with the grid. A detailed techno-economic evaluation has been performed for five locations where hydrogen production costs in the range of 4 – 6 €(2020)/kg have been retrieved. Furthermore, it is shown that with perspective cost data the costs can further be reduced to 2.50 €(2020)/kg.

Energy Conversion and Management, Oct 1, 2023

In this work, the techno-economic and exergy analyses of two gasification technologies with integ... more In this work, the techno-economic and exergy analyses of two gasification technologies with integration into heat and power combined cycles are presented: i). Circulating fluidized bed (CFB) and ii). Dual fluidized bed (DFB) systems. As feedstock, lignocellulosic biomass (sugarcane bagasse, SCB) was considered. The gasification process of the fluidized-bed systems (circulating and dual bed) and the syngas conversion were performed using Aspen Plus® software. The process design includes biomass drying and gasification, syngas cleaning, combustion, power generation, and heat recovery. The SCB-DFB system has the lowest irreversibility rate and, as a result, the highest overall performance and power generation (achieving 32% in the gasification system and 53% of exergy efficiency when coupled with the combined cycle). From the techno-economic assessment, the SCB-DFB system has the lowest total production costs per unit of energy. Hence, the dual fluidized bed systems could be a more competitive technology for the agro-industrial sector to generate power from lignocellulosic materials.

Chemie Ingenieur Technik, 2018

Der vorliegende Beitrag skizziert einen möglichen zukünftigen Bedarf an erneuerbaren flüssigen Kr... more Der vorliegende Beitrag skizziert einen möglichen zukünftigen Bedarf an erneuerbaren flüssigen Kraftstoffen, bewertet mögliche Prozessrouten zu deren Erzeugung im großen Maßstab unter Einsatz von erneuerbarem Strom, Biomasse und anderen Kohlenstoffquellen und diskutiert systemische Effekte eines entsprechenden Infrastrukturausbaus. Die in einer Fallstudie erfolgte technische, ökonomische und ökologische Bewertung basiert auf detaillierten Prozesssimulationen verknüpft mit dem Kostenberechnungstool TEPET und ermöglicht so eine größtmögliche Transparenz aus wissenschaftlicher Sicht.

International Journal of Hydrogen Energy, 2018

ECS transactions, Apr 25, 2011

Solid oxide fuel cell systems (SOFC) can improve the efficiency of electrical power generation fr... more Solid oxide fuel cell systems (SOFC) can improve the efficiency of electrical power generation from biogas compared to small scale CHP units. The SOFC requires a reforming step converting biogas into synthesis gas (hydrogen and carbon monoxide). . Dry reforming of methane with the carbon dioxide contained in biogas is a promising approach to produce high caloric SOFC fuel gas, but carbon formation is predicted for all typical biogas compositions. To avoid carbon formation and to compensate fluctuating biogas compositions additional supply of steam is essential leading to a combined dry and steam reforming. The paper describes the system approach, upfront analysis, biogas monitoring results, process unit design and evaluation as well as the system setup to demonstrate a biogas to electricity route with a gross efficiency of 45 % using a commercial 1 kW SOFC stack.

Fuel, Jun 1, 2022

Four types of adverse events resembling immunological reactions have been reported in patients un... more Four types of adverse events resembling immunological reactions have been reported in patients undergoing chronic maintenance hemodialysis: anaphylaxis [1], hypereosinophilia [1-5], asthmatic attacks [4-6], and pulmonary leukostasis with compromised pulmonary function [7-10]. We evaluated three successive chronic dialysis patients who had developed acute hypersensitivity reactions manifested by increased airway obstruction in response to hemodialysis. Each patient also had a non-acute reaction to dialysis, hypereosinophilia, and one patient had urticaria. All dialyzers were ethylene oxide sterilized and none were reused. In these three patients the adverse reactions abated after changing from dialyzers containing Cuprophan (ENKA Ag, Wuppertal, Germany) to dialyzers not containing Cuprophan. In each patient a second exposure to Cuprophan caused recurrence of one or more of the adverse reactions. These case studies and our re-examination of previous observations [1-61 suggest that in some patients both acute and chronic adverse reactions may be related to the use of Cuprophan. Methods and Results. Patient 1. A 50-year-old black female with renal failure secondary to hypertension began chronic hemodialysis in December 1975. It is uncertain which dialyzers were used during the first 10 months of dialysis, but during her ninth and tenth months of dialysis differential counts showed 18 and 20% eosinophils (Fig. 1). In October 1976, a one antigenmatched cadaver kidney transplant was attempted but was rejected and, 3 weeks later, removed. Hemodialysis was continued using coil dialyzers containing Cuprophan (ENKA Ag)