The efforts required to achieve the climate targets set in the Paris Agreement and the associated transition of energy generation and supply necessitate the implementation of new energy technologies. In addition, the remaining carbon budgets involved in reaching these targets require early and effective action. Therefore, policy- and decision-makers must rely on comprehensive assessments to identify the economic viability and effectiveness of climate change mitigation of emerging energy technologies. Thus, they must be able to set supportive measures and regulations or decide on corresponding investments. In terms of the energy transition, apart from electrification, the demand for renewable gases, such as hydrogen or synthetic natural gas (SNG), is substantial. Therefore, power-to-gas (PtG) is a fundamental cornerstone of future renewable and sustainable energy systems. However, the corresponding technologies are still in a relatively early stage of technological maturity, especially regarding implementations at industrial scale. On one hand, this leads to hesitancy in their implementation, while on the other, the hydrogen demand of >1500 TWh/a identified for the EU suggests an early and rapid expansion of capacities. Hence, this thesis provides a prospective techno-economic assessment (TEA) of today¿s most promising and mature PtG technologies to estimate their short- and long-term competitiveness, allowing for the identification of the required measures. To estimate the development of technology costs, economies of scale were considered by implementing a disaggregated experience curve model. This model allows for an effective assessment of scaling effects over all investigated technologies. In addition, it shows the importance of considering spillover learning effects between technologies to avoid overestimating the individual effects of technological learning. According to these investigations, the technology costs for PtG applications are expected to decrease by 30¿75 % solely through technological learning induced by the non-energetic industrial demand for hydrogen by 2050. With the additional consideration of increasing system scales above 50 MW, overall cost reductions for all technologies are calculated with >75 %. Consequently, the product generation costs for hydrogen and SNG from PtG were found to decrease significantly for corresponding large-scale implementations. Depending on the source of electricity, hydrogen production costs are evaluated to reach values well below 100 ¿/MWh H¿ in the long term. Owing to the additional efforts required for the methanation process, the identified general production costs for SNG relate to approximately 150 ¿/MWh SNG. However, in that context, the elaborated assessments show that significantly better performance can be achieved if synergistic effects between the processes are appropriately utilized. Therefore, an integrated system within an industrial application scenario can achieve an effective product cost of <50 ¿/MWh SNG. Furthermore, studies have shown that the competitiveness of PtG is widely affected by its consideration as an integral part of future energy systems, and thus, its capabilities regarding sector coupling. The utilization of byproducts, namely oxygen and waste heat, not only contributes to the economic viability of the process but can also have a significant impact on systemic energy efficiency by reducing diverse supply efforts. Finally, the elaborated assessment methods and performed analysis also represent a generic outline of the capabilities of prospective techno-economic methods to identify the potential of early-stage technologies to contribute to the energy transition. Therefore, these methods allow for early identification of the technical and economic risks involved, as well as potential bottlenecks regarding resource and demand potentials, thus ena