In the course of the energy transition, distributed, hybrid energy supply concepts, such as the combination of photovoltaic and battery storages, are increasingly being used for economic and ecological reasons. However, electricity generation is highly weather-dependent and the storage capacity of batteries is limited. Nowadays, a new component is emerging for distributed energy supply: the Power-to-Gas-to-Power (PtGtP) technology which stores electricity as hydrogen even over longer periods of time. As this is still a relatively new application, there is still a lack of valid assessments of its usefulness and prospects. In order to be able to give such an assessment under the current German market conditions, a methodology is being developed that optimises the sizing and operation of such a PtGtP as part of a hybrid energy system. The evaluation is based on a multi-criteria approach optimising for both costs and CO2 emissions. In order to gain further insights into this energy supply concept and its future prospects, a sensitivity analysis is carried out, where key parameters are identified and their effects on the results are described. The methodology is used to examine the case study of a dairy and shows that PtGtP is not yet profitable but promising.

This publication devises a method which formulates a national strategy for the renovation of single family houses by treating each era of initial construction independent of all the others, and applies a universally adoptable procedure to evaluate the cost efficiency of carbon emission reduction. A multi-objective optimization was conducted which varied the building envelope and energy systems while optimizing for annual cost and carbon emissions. The optimization was carried out in oemof.solph and PyGMO on typical German building stocks from 11 different construction eras between 1860 and 2020. The buildings were modelled in TEASER using TABULA building stock data. The results indicate that post-war era construction has the greatest improvement potential by saving over 16 tons of CO2/yr with respect to its business as usual case. The recommended solutions for each construction era have an investment cost to emission reduction ratio which is 25% better than those of the current efficiency subsidies.

The optimal combination of energy conversion and storage technologies with local energy demand is a key but in its result not obvious challenge of distributed energy. Although a variety of possible approaches to the optimal design of limited technology selections can be found in the literature, the previous design step, the actual technology selection, and the subsequent step, the selection of the optimal operating strategy, are often neglected. We develop and demonstrate a methodology, which can optimise energy systems with arbitrary technology selection and under multi-criteria optimality definitions. The energy system modelled in oemof.solph is optimised using a MOEA/D approach with regard to economic, ecological and technical key performance indicators. The aim is to find trends and tendencies with a methodology that is as generalised as possible in order to integrate it into the decision-making process in energy system planning. We demonstrate the method by means of a German district for which an integrated supply concept is being sought. Different evaluation and visualisation possibilities are presented and the chances and limitations of the developed methodology are identified. We show that not only the choice of technology, but especially its sizing and operational strategy have a decisive influence on the optimality.