Decarbonisation of decentralised energy infrastructures

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The phase-out of coal-fired power generation by 2038 at the latest is a central element in meeting the climate protection targets of the Federal Republic of Germany for 2030 and 2050. A shutdown of coal-fired power plants is also associated with challenges and opportunities for district heating: one opportunity is to achieve a largely climate-neutral heat supply for end consumers. In 2018, hard coal-fired cogeneration plants at more than 45 locations and lignite-fired cogeneration plants at more than ten locations in Germany produced electricity and heat simultaneously. In total, lignite and hard coal account for about 27 % of district heating generation. This means that coal is currently the most important energy source in district heating generation in Germany alongside natural gas.

Exploitation of small-scale potentials enables the achievement of the objectives

A long-term climate-neutral heat supply requires that the locally available renewable potentials are exploited and integrated into the existing heating networks. For this purpose, several small-scale potentials must be tapped in many places depending on the availability of renewable heat sources (multivalent heating networks). Renewable energies and waste heat can often only be used to a limited extent, because bottlenecks exist due to the availability and higher investment costs, as well as due to the characteristics and design of the existing networks. In existing networks, the high temperature level, which is required to supply existing buildings, complicates the integration of renewables. In addition, the specific challenges of the individual networks vary considerably - depending on different customer structures, the topology of the network and the existing generation capacities.

Development and evaluation of possible transformation paths

The project investigates at least five heating networks currently connected to coal-based cogeneration plants in order to create an empirical-analytical basis. Our focus is on the technical characteristics of producers, distribution network systems and heat consumers on the one hand, and on the socio-economic, planning, ecological and institutional framework conditions on the other. Furthermore, we develop and evaluate possible transformation paths towards a 100 % reduction of greenhouse gas emissions in two scenarios. Based on the results of the case study analysis, we derive the necessary overarching support framework for the actors involved in district heating network transformation. For each of the technologies for decarbonising heating grids, we identify the economic and financial obstacles and gaps in the support framework for their widespread application. Furthermore, we show what obstacles exist for the target technologies with regard to the framework conditions for the promotion of district heating plants (especially the KWKG). For both the overarching framework and the technology-specific framework conditions, we make proposals for improving the support instruments and summarise them in four coherent support frameworks, which should lead to an effective decarbonisation of the heating networks in two different scenarios.