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Predicting formation energies of crystals is a common but computationally expensive task. In this work, it is therefore investigated how a neural network can be used as a tool for predicting formation energies with less computational cost compared to conventional methods. The investigated model shows promising results in predicting formation energies, reaching below a mean absolute error of 0.05 eV/atom with less than 4000 training datapoints. The model also shows great transferability, being able to reach below an MAE of 0.1 eV/atom with less than 100 training points when transferring from a pre-trained model. A drawback of the model is however that it is relying on descriptions of the crystal structures that include interatomic distances. Since these are not always accurately known, it is investigated how inaccurate structure descriptions affect the performance of the model. The results show that the quality of the descriptions definitely worsen the accuracy. The less accurate descriptions can however be used to reduce the search space in the creation of phase diagrams, and the proposed workflow which combines conventional density functional theory and machine learning shows a reduction in time consumption of more than 50 \% compared to only using density functional theory for creating a ternary phase diagram.

La autoproducción es un nuevo mecanismo de oferta en el mercado de electricidad que permite al usuario ser a la vez generador de electricidad, consumir su producción e inyectar los excedentes, haciéndose acreedor de un derecho de compensación futura. La investigación desarrolla las implicancias regulatorias que impactan a los usuarios, a las empresas generadoras, a las distribuidoras y a los usuarios, estableciendo que no representa mayor riesgo que una competencia a menor escala, que el usuario tiene derecho a autoabastecerse, sin dejar de lado su responsabilidad por la red a la que se encuentra conectado y no tomando ventajas respecto de los usuarios que no entren en el régimen del autoconsumo. Entre las ventajas de la autoproducción se identifica un ahorro por el consumo de la generación propia, la mitigación de la dependencia de las fuentes convencionales de generación, la reducción de los costos en las pérdidas por el transporte de electricidad, la promoción de energías limpias. Como desventajas se evalúa la necesidad de contar y remunerar el respaldo energético por la intermitencia de la generación eléctrica con fuentes renovables no gestionables, la posible afectación a las inversiones en las redes de distribución, los costos iniciales de inversión y de administración de las unidades de generación dispersas, el trámite y acceso a la conexión. Desde el punto de vista regulatorio, habiendo demostrado la rentabilidad del proyecto con una evaluación de costos, la medición neta, como mecanismo de para la autoproducción, puede ser desarrollada en nuestro país y en la presente investigación se plantea las reformas normativas para hacerlo viable con probabilidad de éxito, consistentes entre otros, en establecer un límite individual de capacidad efectiva (instalada), un límite acumulado de capacidad a nivel país como primera etapa, la necesidad de establecer un pago fijo por la confiabilidad y posibilidad de inyecciones de energía a la red, y un neteo de derechos energéticos a ser compensados en un periodo de doce meses, luego de lo cual, el derecho pasará a favor de la distribuidora; que junto a las reglas claras y simples de los trámites para ser autoproductor, conllevaría a un beneficio parar el sector y la sociedad en su conjunto. / Self-production is a new supply mechanism in the electricity market, through which the consumer produces his own electricity, consume it, and inject the surpluses into the grid, becoming a creditor of the right to future compensations for those surpluses. This paper explains the regulatory impacts of self-production on users and electricity companies. Net metering represents a competition on a smaller scale, where users have the right to self-supply electricity without having advantages over other users who aren't in the self-consumption regime. Among the advantages of net metering, as a mechanism for self-production, this thesis identifies savings from the consumption of own electricity, the reduction of dependence on conventional sources of power generation, the reduction of losses in the transport of electricity, the promotion of clean energy. As disadvantages, the need to count on and remunerate energy support with conventional sources due to the intermittency of electricity generation, with non-manageable renewable sources, the possible impact on distributor’s incomes, initial investment and administration costs of the dispersed generation equipment, the procedure and access to connection. We propose to establish an individual limit of effective capacity for self-generation, an accumulated limit of self-production capacity in the national system as the first stage, a fixed payment for the reliability and possibility of energy injections to the grid, and a netting of energy rights to be compensated in a period of twelve months. / Trabajo de investigación

Within the present work, the main objective is to identify interactions between flexibility demand and flexibility supply. Therefore, three research fields regarding the future transformation of the European energy system are addressed. First, an expansion of intermittent renewable energy sources (iRES) is discussed taking the potentials of wind and PV technologies into account. The analysis is based on fundamental considerations of generation characteristics as well as available potentials across 17 countries in central-western Europe. To emphasis the differences in electricity generation between wind and PV, an iRES expansion model is developed coping for geographically highly resolved weather data as well as for limitations of iRES potentials due to land-use restrictions and for energy-policy constraints. Three scenarios with varying Wind-PV ratio in total iRES electricity generation are evaluated. Second, the options to provide flexibility to balance the flexibility demand are introduced and mathematically implemented in ELTRAMOD. Therefore, the model was adjusted to represent multiple flexible technologies for upward, downward and shifting flexibility provision to cover the residual load. In a system perspective and a greenfield approach, the linear electricity market model enables the analysis of cost-optimal combinations of flexibility options against the background of scenarios with different flexibility demands. In addition, the third research field addresses the emerging developments of sector coupling by including selected Power-to-X technologies. A second scenario dimension analyses the role of energy storages in the energy end-use sectors for a more flexible sector coupling. The results underline the importance of the Wind-PV ratios in electricity generation when assessing flexibility demand and flexibility supply in model-based energy system analysis. Due to the higher seasonality of PV, the residual load parameter indicate higher iRES integration challenges in terms of flexible capacity requirements. Particularly the provision of spatial and temporal balancing flexibility is significantly influenced by a higher wind or a higher PV share in the iRES mix. With sector coupling, the value of temporal shifting is increasing. Hourly storages are not only highly sensitive to the Wind-PV ratio, but in addition strongly impacted by sector coupling. In both dimensions, a higher PV share is increasing the value for short-term shifting. Furthermore, sector coupling increases the need for additional electricity generation. Thereby, for peak-load capacity provision gas-fuelled power plant are optimal in the present work increasing the total emissions especially with higher PV shares. The sensitivity analysis shows the value of additional iRES capacities as well as of storage cost reductions to further reduce emissions.

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