Rising CO2 emissions in Bavaria's power supply?

Author: Marco Pruckner and Prof. Dr.-Ing. habil. Reinhard German, Chair of Computer Networks and Communication Systems, University of Erlangen-Nuremberg (as of December 2014) With the decommissioning of the nuclear power plants currently in operation by the end of 2022, the CO2 emissions balance in Bavaria will also change fundamentally. Nuclear energy accounted for 50% of Bavaria's gross electricity generation in 2012. In order to be able to compensate for the omission of nuclear energy, according to plans of the Bavarian state government, renewable energy sources are to be expanded more quickly and already have a share of around 50% of electricity demand in 2021.

Nevertheless, initial calculations with a coupled optimization, simulation and electrical network model, which is being developed at three chairs of the University of Erlangen-Nuremberg, already show that the Bavarian CO2 emissions balance will increase, taking into account rising electricity imports. While in 2012 about 80 % of the gross electricity generation was produced in low CO2 nuclear power plants and renewable generation plants, in 2023 only 50 % of the gross electricity generation will be low CO2 due to the decommissioning of nuclear power plants. The remaining 50% will be covered by fossil-fired generation plants within Bavaria, such as gas-fired power plants or coal-fired power plants, and electricity imports. Of course, much of the electricity imports will come from low-CO2 wind power from the wind-rich areas of northern and eastern Germany. However, due to the fluctuating nature of wind power and the current electricity market design, it appears that during periods of wind slack, electricity will mainly be imported from fossil-fired power plants. This electricity has an overall negative impact on the CO2 emissions balance in Bavaria, as we would like to analyze in more detail below.

In order to be able to ensure comparability of the results with the gross electricity generation from 2012, the same values are used as a basis for calculating the CO2 emissions of electricity generation. The official CO2 emission values of the Intergovernmental Panel on Climate Change (IPCC) for the holistic assessment (Life Cycle Assessment, LCA) of various generation technologies are shown in Table 1, broken down by energy carrier. In contrast to specific CO2 emissions, the holistic assessment of CO2 emissions includes the entire value chain.

Table 1: Overview of LCA of CO2 emissions of different power generation technologies

In the reference scenario, renewable energies have a share of 50% of gross electricity generation. The import share is about 30 %. It is difficult to quantify which energy sources make up the import share. For example, the share of wind power plants in electricity imports cannot be specified in detail. Nevertheless, in order to be able to make a statement on the development of CO2 emissions in Bavaria, the average CO2 emissions of both the German electricity generation mix and the Bavarian neighboring states for the year 2023 are used as a basis. In the case of Germany, a higher electricity generation from wind energy plants in 2023 is thus taken into account.

The total CO2 emissions of electricity generation in Bavaria are shown in Table 2 in an overview. For the per capita emissions of electricity generation, a population  of 12.5 million was assumed. The per capita emissions increase from 1.05 t/inhabitant today to 1.68 t/inhabitant in 2023 due to the phase-out of nuclear energy and resulting electricity imports. Interestingly, CO2 emissions from electricity generation within Bavaria decrease from 1.05 t/inhabitant to 0.88 t/inhabitant due to high electricity generation from renewable energies. However, the total CO2 emissions of electricity consumed in Bavaria are decisive for the Bavarian electricity generation balance and these increase by about 60%.

 Table 2: Overview of CO2 emissions of electricity generation

In total, it remains to be noted that the CO2 emissions of electricity consumed in Bavaria will increase in the course of the energy transition. This depends primarily on electricity imports. Further expansion of renewable energies or low-emission gas-fired power plants in Bavaria, further expansion of the transmission grid or decentralized storage facilities on a larger scale would shift the statements made here.