The impact of power network congestion, its consequences and mitigation measures on air pollutants and greenhouse gases emissions. A case from Germany

The European power system will have to change significantly in next decades to meet the ambitious targets set by the upcoming European Climate Law. In particular, intermittent renewable energy will be increasingly injected in the system creating potential stability problems. Already in the last five years it has become evident that if the grid expansion does not keep pace with increasing demand for transmission capacity, congestion will happen more and more often in the European power network. To handle congestion, Transmission System Operators extensively use redispatching, requiring individual plants to alter their market-based functioning pattern in order to cope with technical limitations of the network. While the cost of redispatching actions is well known, the change in emission patterns of both greenhouse gases and air pollutants caused by these actions is not, mostly because of a lack of detailed publicly available data. This paper covers such a gap taking Germany as a case study, thanks to the quality of the available data. Following the standard methodology for estimating the direct emissions from fossil fuelled and renewable fed power plants, the study estimates the changes in the emissions of four regulated air pollutants (namely NOx, SO2, Particulate Matter and CO) together with those of CO2 related to redispatching, for the years 2015–2019. The case study of Germany shows how the management of congestions through redispatching does not necessarily imply an increase in the emissions associated with power production in a country, although it has not been possible to complete the study with a full picture of the consequences for other countries emissions because of lack of consistent data.