The aim of this thesis is to objectify the discussion regarding the availability of technologies related to the German energy transition. This work describes the state of development of relevant technologies on the basis of Technology Readiness Levels. Further, it points out development potentials and limits as well as the necessary power capacities needed for a certain energy system design that is mainly based on electricity. Thus, the scope is set to renewable energy sources suited to provide electricity in Germany, technologies that convert primary electricity for other energy sectors (heating and mobility) and storage technologies. Additionally, non-conventional technologies for electricity supply and grid technologies are examined. The underlying Technology Readiness Assessment is a method used to determine the maturity of these systems or their essential components. The major criteria for assessment are scale, system fidelity and environment. In order to estimate the relevant magnitudes for certain energy technologies regarding power and storage capacities, a comprehensible simulation model is drafted and implemented. It allows the calculation of a renewable, volatile power supply based on historic data and the display of load and storage characteristics. As a result, the Technology Readiness Level of the different systems examined varies widely. For every step in the direct or indirect usage of renewable intermittent energy sources technologies on megawatt scale are commercially available. The necessary scale for the energy storage capacity is in terawatt hours. Based on the examined storage technologies, only chemical storages potentially provide this magnitude. Further, the required total power capacities for complementary conversion technologies lay in the two-digit gigawatt range.:Abstract 2 Contents 3 1. Introduction 7 2. General remarks on the current state of the German energy system 12 3. Method of Technology Readiness Assessment 16 3.1. Fundamentals of the method 16 3.2. Drawbacks of TRA 19 3.3. Extended Readiness Levels 20 3.4. Conducting the Technology Readiness Assessment 21 3.5. Expert interviews 23 3.6. References 24 4. Preliminary remarks on the TRL assessment 25 4.1. Mission and environment 25 4.2. Simplifications and neglected aspects 26 4.3. References 26 5. Wind power 27 5.1. Technology description 27 5.2. Estimation of potential 32 5.3. Representation of the achieved state of expansion 37 5.4. TRL assessment 39 5.5. References 40 6. Solar energy 44 6.1. Technology description 44 6.2. Solar thermal energy 44 6.3. Photovoltaic technologies 45 6.4. Estimation of potential 48 6.5. Representation of the achieved state of expansion 52 6.6. TRL assessment 53 6.7. References 54 7. Geothermal energy 56 7.1. Technology description 56 7.2. Estimation of potential 59 7.3. Description of the current level of expansion 62 7.4. TRL assessment 63 7.5. References 64 8. Hydropower 66 8.1. Technology description 66 8.2. Estimation of potential 68 8.3. Description of the current level of development 70 8.4. TRL assessment 71 8.5. References 72 9. Biomass 73 9.1. Technology description 73 9.2. Estimation of potential 75 9.3. Representation of the achieved state of expansion 79 9.4. TRL assessment 81 9.5. References 82 10. Transmission and distribution grids 84 10.1. Technology description 84 10.2. Estimation of potential 90 10.3. Representation of the achieved state of expansion 94 10.4. TRL assessment 95 10.5. References 96 11. Power-to-heat 100 11.1. Technology description 100 11.2. Estimation of potential 104 11.3. Representation of the achieved state of expansion 107 11.4. TRL assessment 108 11.5. References 109 12. Power-to-cold 111 12.1. Technology description 111 12.2. Estimation of potential 114 12.3. Representation of the achieved state of expansion 117 12.4. TRL assessment 118 12.5. References 120 13. Power-to-chemicals 122 13.1. Technology description 122 13.2. Estimation of potential 134 13.3. Representation of the achieved state of expansion 137 13.4. TRL assessment 138 13.5. Manufacturer overview for electrolysis systems 140 13.6. References 142 14. Mechanical storage 146 14.1. Technology description 146 14.2. Estimation of potential 148 14.3. Representation of the achieved state of expansion 155 14.4. TRL assessment 155 14.5. References 158 15. Thermal storage 160 15.1. Technology description 160 15.2. Estimation of potential 164 15.3. Representation of the achieved state of expansion 169 15.4. TRL assessment 170 15.5. References 172 16. Chemical storage systems 175 16.1. Technology description 175 16.2. Estimation of potential 180 16.3. Representation of the achieved state of expansion 185 16.4. TRL assessment 186 16.5. References 188 17. Electro-chemical storage systems 191 17.1. Technology description 191 17.2. Estimation of potential 198 17.3. Representation of the achieved state of expansion 202 17.4. TRL assessment 202 17.5. References 204 18. Gas engines/gas turbines for hydrogen combustion 207 18.1. Technology description 207 18.2. Estimation of potential 208 18.3. Representation of the achieved state of expansion 211 18.4. TRL assessment 211 18.5. References 213 19. Chemicals-to-Power – Fuel cells 214 19.1. Technology description 214 19.2. Estimation of potential 218 19.3. Representation of the achieved state of expansion 221 19.4. TRL assessment 223 19.5. References 225 20. Interim conclusion for TRA 227 21. Evaluation of system integration 230 21.1. Modelling approach 230 21.2. Scenarios for a renewable energy supply 238 21.3. Results of the simulation 238 21.4. Consequences 244 21.5. References 245 22. Summary and Outlook 247 23. Abbreviations and symbols 249 24. Indices 254 25. List of Figures 255 26. List of Tables 258 27. Appendix 260 27.1. DOE TRL definition and description 260 27.2. Visualized summary of TRLs 262

The aim of this thesis is to show how much fuel can be saved in a power system based in diesel generators with integrated wind turbine (WDPS – Wind Diesel Power System) when a storage system is integrated. Diesel generator is still the most used power system for remote locations where the conventional grid doesn’t reach and its integration with wind turbine is seen as a natural combination to reduce diesel consumption. However, the wind intermittency brings some challenges that might prevent the necessary diesel savings to the level that justifies the integration with wind turbine. The introduction of a storage system can leverage the wind energy that would otherwise be wasted and use it during periods of high demand.The thesis starts by describing the characteristics of energy storage systems (ESS) and introducing the major ESS technologies: Flywheel, Pumped Hydro, Compressed Air and the four main battery technologies, Lead Acid, Nickel-Based, Lithium-ion and Sodium-Sulphur. The aim of this step it to obtain and compile major ESS parameters to frame then into a chart that will be used as a comparison tool.In the next step, wind-diesel power systems are described and the concept of Wind Penetration is introduced. The ratio between the wind capacity and diesel capacity determines if the wind penetration is low, medium and high and this level has a direct relation to the WDPS complexity. This step also introduces important concepts pertaining to grid load and how they are affected by the wind penetration.Next step shows the development of models for low, medium and high penetration WDPS with and without integrated ESS. Simulations are executed based on these models in order to determine the diesel consumption for each of them. The simulations are done by using reMIND tool.The final step is a comparative study where the most appropriated ESS technology is chosen based on adequacy to the system, system size and location. Once the technology is chosen, the ESS economic viability is determine based on the diesel savings obtained in the previous step.Since this is a general demonstration, no specific data about wind variation and consumer demand was used. The wind variation, which is used as the input for the wind turbine (WT), was obtained from a typical Weibull Distribution which is the kind of distribution that most approximate a wind pattern for long term data collection. The wind variation over time was then randomly generated from this distribution. The consumer load variation is based on a typical residential load curves. Although the load curve was generated randomly, its shape was maintained in conformity with the typical curves.This thesis has demonstrated that ESS integrated to WDPS can actually bring a reasonable reduction in diesel utilization. Even with a wind pattern with a low mean speed (5.31 m/s), the savings obtained was around of 17%.Among all ESS technologies studied, only Battery Energy Storage System (BESS) showed to be a viable technology for a small capacity WDPS. Among the four BESS technologies studied, Lead-Acid presents the highest diesel savings with the lower initial investment and shorter payback time. / O objetivo dessa tese é determinar quanto combustível pode ser economizado quando se integra um sistema de armazenamento de energia (ESS na sigla em Inglês) a um sistema gerador baseado em gerador diesel integrado com turbina eólica (WDPS na sigla em Inglês). Geradores à diesel são largamente utilizados em áreas remotas onde a rede de distribuição de eletricidade não chega, e a integração de geradores à diesel com turbinas eólicas se tornou a combinação usual visando a economia de combustível. No entanto, a intermitência do vento cria alguns desafios que podem inclusive tornar essa integração inviável economicamente. A introdução de ESS à esse sistema visa o aproveitamento da energia que seria desperdiçada para usá-la em periodos de alta demanda.A tese começa descrevendo as características de ESS e suas principais tecnologias: Flyweel, hidroelétrica de bombeamento, ar-comprimido e as quatro principais tecnologias de bateria, Chumbo-Ácido, Níquel, Íon de Lítio e Sódio-Sulfúrico. O objetivo dessa etapa é obter os principais parâmetros de ESS e apresentá-los numa planilha para referência futura.Na etapa seguinte, geradores à diesel são descritos e é introduzido o conceito de Penetração do Vento. A razão entre a capacidade eólica e a capacidade do gerador diesel determina se a penetração é baixa, média ou alta, e esse nível tem uma relação direta com a complexidade do WDPS. Nessa etapa também são introduzidos importantes conceitos sobre demanda numa rede de distribuição de eletricidade e como esta é afetada pela penetração do vento.A etapa seguinte apresenta a modelagem de WDPS com baixa, média e alta penetração, incluindo a integração com ESS. Sobre esses modelos são então executadas simulações buscando determinar o consumo de diesel de cada um. As simulações são feitas usando a ferramenta reMIND.A última etapa é um estudo comparativo para determinar qual tecnologia de ESS é a mais apropriada para WDPS, levando-se em conta sua localização geográfica e capacidade. Uma vez que a escolha tenha sido feita, a viabilidade econômica do ESS é calculada baseado na ecomonia de combustível obtida na etepa anterior.Como esta tese apresenta uma demonstração, não foram utilizados dados reais de variação do vento nem de consumo. A variação do vento foi obtida de uma distribuição Weibull típica, que é a distribuição que mais se aproxima da característica do vento coletada em logo prazo. A variação do vento no tempo foi gerada aleatoriamente baseada nessa distribuição. A curva de consumo é baseada em curvas de consumo residenciais típicas. Embora a curva de consumo tenha sido gerada aleatoriamente, o seu formato foi mantido em conformidade com as curvas típicas.Essa tese demonstrou que ESS integrado à WDPS pode trazer uma economia razoável. Mesmo usando uma distribuição de vento com baixo valor médio (5.3 m/s), a economia obtida foi de 17%.Dentre as tecnologias de ESS pesquisadas, apenas o sistema de armazenamento com bateria (BESS na sigla em Inglês) se mostrou viável para um WDPS com pequena capacidade. Dentre as quatro tecnologias de BESS pesquisadas, Chumbo-Ácido foi a que apresentou a maior economia de diesel com o menor investimento inicial e com o menor tempo de retorno do investimento.