Begründeter Zweifel? John L. Schellenbergs religiöse Skepsis auf dem Prüfstand

Die Dissertation untersucht die religionsskeptischen Argumente, die John L. Schellenberg in seinem Werk "The Wisdom to Doubt" entwickelt hat. In mehreren Anläufen bemüht sich Schellenberg darin zu zeigen, dass religiöse Überzeugungen aus prinzipiellen erkenntnistheoretischen Gründen nicht gerechtfertigt sein können. Diese Argumente werden detailliert analysiert und diskutiert, ins Verhältnis zueinander gesetzt und in den erkenntnistheoretischen und religionsphilosophischen Diskurs eingeordnet. Dabei wird schließlich der Nachweis erbracht, dass Schellenberg seinen Anspruch nicht einlösen kann. Darüber hinaus wird eine eingehende Analyse und Diskussion religionsphilosophischer Grundbegriffe aus Schellenbergs "Prolegomena to a Philosophy of Religion" geboten

A part-load analysis and control strategies for the Graz Cycle

Carbon capture and storage (CCS) plays a uniquely important role in the future clean and dispatchable power generation portfolio to achieve the ambitious goals set at COP21. The Graz Cycle, a zero emission oxy-combustion power plant, is one of the most promising representatives of CCS power generation plants. The present work introduces different control strategies for the Graz Cycle and the corresponding part-load performances. The process simulation is composed of a design-point (full-load) and off-design (part-load) of the cycle. In order to do this, the process simulation tool IPSEpro was used. Individual cycle components were modelled for both investigations, full load and part load, and control strategies were developed in order to achieve optimum performances and operating efficiencies by means of the assumptions given. This work distinguishes from previous studies by the development of different control strategies and comparison of corresponding part-load performances. In the simulation, the Graz Cycle operating at nominal design conditions achieved a net plant efficiency of 53.1%. The part-load simulation generated results down to 40% load by applying three different control strategies. These control operation modes differ from each other in two basic parameters, boiler pressure and turbine inlet temperature. Optimum part-load performances were achieved by control strategy, where the pressure of the heat recovery steam generator is allowed to vary. However, other parameters, e.g. costs, did not appear to be favourable for this operation mode. The comparison with a readily available technology, such as a natural gas combined cycle, showed that the Graz Cycle is more efficient as loads are reduced below 50%

Fairness and feasibility in deep mitigation pathways with novel carbon dioxide removal considering institutional capacity to mitigate

Questions around the technical and political feasibility of deep mitigation scenarios assessed by the Intergovernmental Panel on Climate Change have increasingly been raised as have calls for more directly analyzing and incorporating aspects of justice and fairness. Simultaneously, models are increasing the technical representation of novel carbon-dioxide removal (CDR) approaches to provide policy-relevant analyses of mitigation portfolios in the context of the rising number of net-zero CO _2 and GHG targets made by parties to the Paris Agreement. Still, in most cost-effective mitigation scenarios developed by integrated assessment models, a significant portion of mitigation is assumed to take place in developing regions. We address these intersecting questions through analyzing scenarios that include direct air capture of CO _2 with storage (DACCS), a novel CDR technology that is not dependent on land potential and can be deployed widely, as well as regional variations in institutional capacity for mitigation based on country-level governance indicators. We find that including novel CDR and representations of institutional capacity can enhance both the feasibility and fairness of 2 °C and 1.5 °C high-overshoot scenarios, especially in the near term, with institutional capacity playing a stronger role than the presence of additional carbon removal methods. However, our results indicate that new CDR methods being studied by models are not likely to change regional mitigation outcomes of scenarios which achieve the 1.5 °C goal of the Paris Agreement. Thus, while engineered carbon removals like DACCS may play a significant role by midcentury, gross emissions reductions in mitigation pathways arriving at net-zero CO _2 emissions in line with 1.5 °C do not substantially change. Our results highlight that further investment and development of novel CDR is critical for post-net-zero CO _2 mitigation, but that equitable achievement of this milestone will need to arrive through technical and financial transfers, rather than by substantial carbon removals in developed countries before mid-century