Stephan Raths

An option for stranded renewables: electrolytic-hydrogen in future energy systems

Future energy systems will likely be challenged by large quantities of stranded renewable electricity that cannot be used in the conventional electrical grid. Using surplus electricity for electrolysis and thereby producing hydrogen is seen as a valuable solution functioning as an energy storage and transport medium and providing other sectors, such as transport or industry, with required feedstocks at the same time. In this study, we suggest using a set of assessment tools to highlight the quantitative potential, cost and environmental performance of electrolytic hydrogen production, transmission and storage. Our approach employs power sector modeling for Germany with three sequential elements: (i) a market model, (ii) power flow modeling, and (iii) re-dispatch modeling. The results were then used to identify suitable locations for large scale electrolysis plants. Electrolysis, large-scale gas storage, a transmission pipeline and other system components were scaled-up and the total cost was calculated. In a final step, we looked at greenhouse gas emissions as one of the major aspects regarding the environmental performance of the hydrogen delivered. Based on our analysis, annual hydrogen production rates of up to 189 kilotons have been determined for the state of Schleswig-Holstein, which exhibits the largest potential for utilizing surplus power from renewables. The economic analysis reveals a hydrogen cost of 3.63–5.81€ kg−1, including installations, for large-scale storage and transmission. If surplus power from renewables is used for hydrogen production, the total greenhouse gas emissions of hydrogen provision were determined to be up to 435 gCO2-eq. kg−1. Using grid electricity, this value increased to some 17 000 gCO2-eq. kg−1.

Analysis of alternative transition paths for the German energy system

On EU-level and especially in Germany there are strong efforts to meet the targeted climate goals. However, finding the most efficient transition path from todays energy system to a sustainable one remains a challenge. Therefore, in this paper different transition paths for the German energy system based on gas instead of lignite power plants are presented and discussed. Those paths are compared with the most likely development of the German energy system based on todays energy policy (baseline scenario). The assessment is based on a model, the European Multimodal Market Simulation (EMMS). Without lignite power plants, Germany will always comply with the climate goals. Most investigated scenarios lead to higher total system costs than the baseline scenario. Cost reductions are only achieved in case of a low gas price and a high reduction of renewable capacities.

Analysis of future power generation structures with a multi-period, multi-objective expansion model

The politically initiated energy turnaround in Germany changes the existing decision-making structures concerning the development of the power generation sector. In this context a future energy system has to fulfil the multiple criteria of the sustainability principle. In this paper we propose a multi-period, multi-objective optimization method based on a Genetic Algorithm for determining the optimal expansion planning and regionalization of power generation structures for Germany. This work considers changes in the generation side. The developed genetic operators are described in detail and novel methodical approaches are presented. Finally exemplary results are shown and evaluated.