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Hydrogen is widely considered to play a pivotal role in successfully transforming the German energy system, but the German government's current “National Hydrogen Strategy” does not specify how hydrogen utilization, production, storage or distribution will be implemented. Addressing key uncertainties for the German energy system's path to greenhouse gas-neutrality, this paper examines hydrogen in different scenarios. This analysis aims to support the concretization of the German hydrogen strategy. Applying a European energy supply model with strong interactions between the conversion sector and the hydrogen system, the analysis focuses on the requirements for geological hydrogen storages and their utilization over the course of a year, the positioning of electrolyzers within Germany, and the contributions of hydrogen transport networks to balancing supply and demand. Regarding seasonal hydrogen storages, the results show that hydrogen storage facilities in the range of 42 TWhH2 to 104 TWhH2 are beneficial to shift high electricity generation volumes from onshore wind in spring and fall to winter periods with lower renewable supply and increased electricity and heat demands. In 2050, the scenario results show electrolyzer capacities between 41 GWel and 75 GWel in Germany. Electrolyzer sites were found to follow the low-cost renewable energy potential and are concentrated on the North Sea and Baltic Sea coasts with their high wind yields. With respect to a hydrogen transport infrastructure, there were two robust findings: One, a domestic German hydrogen transport network connecting electrolytic hydrogen production sites in northern Germany with hydrogen demand hubs in western and southern Germany is economically efficient. Two, connecting Germany to a European hydrogen transport network with interconnection capacities between 18 GWH2 and 58 GWH2 is cost-efficient to meet Germany's substantial hydrogen demand.

In the framework of the Paris Agreement, the European Union (EU) will have to firmly set decarbonization targets to 2050. However, the viability on these targets is an ongoing discussion. The European Commission has made several propositions for energy and climate ""roadmaps"". In this regard, this paper contributes by analyzing alternative pathways derived in a unique modelling process. As part of the SET-Nav project, we defined four pathways to a clean, secure and efficient energy system-taking different routes. Two key uncertainties shape the SET-Nav pathways: the level of cooperation (i.e. cooperation versus entrenchment) and the level of decentralization (i.e. decentralization versus path dependency). All four pathways achieve an 85-95% emissions reduction by 2050. We include a broad portfolio of options under distinct framework conditions by comprehensively analyzing all energy-consuming and energy-providing sectors as well as the general economic conditions. We do this by applying a unique suite of linked models developed in the SET-Nav project. By linking more than ten models, we overcome the traditional limitation of models that cover one single sector while at the same time having access to detail sectoral data and expertise. In this paper, we focus on the implications for the energy demand sectors (buildings, transport, and industry) and the electricity supply mix in Europe and compare our insights of the electricity sector to the scenarios of the recent European Commission (2018a) report ""A clean Planet for all"".

China’s energy system is based mainly on coal power plants, which held a share of 69% in 2017. Large numbers of coal power plants lead to air pollution and high CO2 emissions. China has high potentials for renewable energies, which could bring about the transformation of the energy system in the future. The transition of the energy system from coal-based to renewables-based is a huge challenge. A carbon–neutral energy system is based mainly on fluctuating renewable energies like wind and solar power. In order to meet the hourly demand, flexibility options are needed to balance volatile energy production. In this paper, we construct two scenarios to analyse a carbon–neutral Chinese energy system in 2060. The first scenario focusses on electricity in order to decarbonise the energy system. The second scenario uses hydrogen for the decarbonisation. We found that storage possibilities like batteries and hydrogen play a major role in both scenarios. However, the number of installed batteries was lower in the hydrogen scenario although the installed capacity of renewable energies is higher. This is due to the increased hydrogen production in this scenario, which flattens the high solar photovoltaic (PV) peak at noon. Our results highlight the importance of flexibility options in a decarbonised energy system with a high share of renewables.

Reducing CO2 emissions, as targeted by the European Union, requires the substitution of fossil fuels with renewable energies. This reduces the CO2 intensity of electricity generation and this low carbon electricity can then be used in other sectors, e.g. to decarbonize heating. Besides contributing to emission savings, this so-called sector coupling provides additional flexibility in the electricity sector and fosters the integration of renewable energies. We assess how heat pumps in district heating grids contribute to renewable electricity integration. We analyze different scenarios using the Enertile model, which optimizes capacities and dispatch of electricity and heat generation simultaneously. The results show that, the higher the achieved levels of decarbonization and renewable electricity, the more competitive heat pumps become in heating grids. Keywords: European energy system, Optimization model, Renewable electricity integration, Sector coupling, District heating grid, Heat pump

Decarbonizing the energy supply by substituting fossil fuels with renewable energy sources (RES) is a key task for the coming decades in order to achieve the EU's ambitious climate protection targets. Information about the possible development and marketability of RES in the electricity sector is essential for assessing future funding needs. However, rising shares of fluctuating RES generation in the energy system reduce the average market prices and increase price volatility. Balancing price variations requires a considerable degree of flexibility. Additional flexibility in the electricity market through closer interconnection between the electricity sector and other demand sectors makes it possible to keep the market values of RES closer to the general market price level, irrespective of their shares. Such sector coupling can thus contribute to a cost-efficient transition to a low-carbon energy system. This paper examines the impact of efficient sector coupling on the market values of RES in a European energy system with ambitious decarbonization. We analyze different scenarios by applying the Enertile model, which uses an integrated cost optimization approach with flexibility options due to sector coupling and provides a detailed future development of RES. In our analysis, we examine three flexibility options: smart charging of electric vehicles, decentralized heat pumps in buildings, and multivalent district heating grids. We show that the flexible use of electricity in district heating has a significant impact on market values, while the impact of both flexible electric vehicle charging and flexible heating with heat pumps is rather small. Short-term flexibility due to load shifting of the charging or heating process shows only a limited effect on market values. Fuel switching in district heating, however, offers the possibility to change the absolute demand for electricity in direct response to RES feed-in and drastically reduces the curtailment of RES.

Short version of the conference paper "Modelling of heat pumps in heating networks and analysis of the effects on the German power generation system" presented in the15. Symposium Energieinnovation, held on 14 - 16 February 2018, in Graz, Austria.