Cluster I: Net-Zero-2050. Project 1.2 Integrated Scenario Analyses. In: Helmholtz Climate Initiative Final Report 2022.

Kurzfassung

The integrated scenario analysis consists of three major tasks – a synthesis study on existing research on a CO2- neutral Germany; the development of an energy transition pathway which is limited by a total CO2 budget; and the multicriteria assessment of energy transition pathways. The budget approach was developed in close cooperation with Project 1.1. which lead to an allocation of < 7 Gt to the German energy system for 2021 until 2050.

The synthesis study summarizes the key findings from three recent publications that describe a transformation of Germany into a CO2- or, respectively, climate-neutral economy and society by the middle of this century at the latest, including the climate policy instruments and measures required to achieve this goal. The main objective of this synthesis study within Net-Zero-2050 is to show which key climate policy steps need to be focused on and implemented, especially in the years up to 2030, which are at the same time mandatory prerequisites for achieving the goal of a CO2- or climate-neutral Germany.

This synthesis is then integrated into a newly developed energy scenario. We apply a normative backcasting approach for scenario building, relying on historic data and assumptions from existing scenario studies. Additionally, a new energy and LCA-focused modeling was developed for the industrial sector, providing insights on hard to avoid or residual CO2 emissions from the steel and cement sectors. The energy system modeling approach was successfully extended by a model coupling: The energy system model based on an accounting framework (ESM) was integrated with REMix, a cost minimizing optimization model for power, heat and sector coupling. To achieve the necessary CO2 reduction, the scenario focuses on electrifying all end use sectors until 2030. Thus, the scenario envisages a doubling of power demand by 2050, with power supplying also for electric vehicles, heat pumps for space heat and the production of synthetic fuels (e.g. H2) which will be required for heavy duty transport, aviation & navigation and the transformation of industrial processes. The results indicate a significant regional focus of hydrogen production in the North Western Germany, including all necessary infrastructures.

Next the modeling results were provided to the multicriteria assessment framework for further analysis of regional heterogeneity and stakeholder aspects. Stakeholders have differing interests and goals and tend to support the transformation pathway that suits their best interests and show resistance to pathways that do not. By applying an MCDA approach, we show that attitudes of stakeholders (incl. private households and utilities) differ with respect to the preferred transformation pathways. In particular, we show that transformation pathways with a higher share of biomass in combination with CCS face a lower level of preference among all stakeholders. Since biomass in combination with CCS and similar technologies will be necessary for reaching the net-zero goals, measures have to be taken quickly to reduce resistance, e.g. among households.

Regions differ greatly in their geological, geographical as well as regional economic conditions. This also affects the potential for mitigation measures for greenhouse gases. Thus, it is to be expected that some regions will benefit more from decarbonization measures than others, while individual regions run the risk of economic losses. Accordingly, the question arises as to what extent benefits and losses need to be redistributed regionally. A successful energy transition which will be supported by at least a majority of stakeholders has to take heterogeneity across scales, resources, technologies, and regions into consideration.