Power-to-heat heats Leipzig apartments

08.01.2025

Source: E & M powernews

Leipziger Stadtwerke and the transmission system operator 50 Hertz have put a power-to-heat plant into operation. It supplies district heating from green electricity during surplus periods.

Leipziger Stadtwerke and transmission system operator 50 Hertz have jointly commissioned a power-to-heat (PtH) plant at the Nord-Ost heating plant. 50 Hertz invested around four million euros in the project. The power-to-heat plant has an electrical output of ten MW. It is the eighth PtH plant to be installed and commissioned in the 50 Hertz grid area. Others are located in Halle/Saale and Berlin, for example.

"With the expansion of electricity generation from renewable energies, there will be more and more times when, depending on sunshine and wind, there will be an abundance of electrical energy that cannot be fully transported via the electricity grids," explained Karsten Rogall, Managing Director of Leipziger Stadtwerke. Power-to-heat uses this electricity from wind power or photovoltaic systems to produce renewable district heating.

"Our 50 Hertz system management near Berlin will be able to use the PtH plant in the north of Leipzig together with the power plant in Eutritzscher Straße for congestion management via the control center of Leipziger Stadtwerke," said Dirk Biermann, Chief Operations Officer (COO) of 50 Hertz. This relieves the power grid twice over: through additional power consumption in the power-to-heat plant and simultaneously lower power and heat production in the power plant.

Kettle XXL

The generation of heat in a PtH system is comparable to the principle of an immersion heater or kettle - only in XXL format. A large tank contains electric heating elements around which water flows. These heating elements can be switched on as required and heat the water using electricity from renewable energy sources, which at this point in time generate more electricity than can be transported away by the power grid.

As heat generation and heat consumption do not always coincide, the heated water can be temporarily stored in Leipziger Stadtwerke's two heat storage facilities and fed into the district heating network at a later date. "20 years ago, nobody would have given a damn about this idea," said Stadtwerke project manager Thomas Walther. But times have changed. It is both sensible and sustainable to go back to the tried and tested.

"As the use of power-to-heat systems can reduce the consumption of fossil fuels for heating purposes, this technology will play an increasingly important role in Leipzig's heating supply and in achieving Leipzig's climate targets in the future," said Walther. Stadtwerke is already planning a second power-to-heat plant with a capacity of 60 MW at the power plant site in Zentrum-Nord, he announced.

Less curtailment of green electricity

According to the Federal Network Agency, around 10 billion kWh of electricity from renewable energies was curtailed in Germany in 2023 in order to avoid bottlenecks in the electricity grid. This meant that 96% of the total generation from renewable energies could be transported to consumers via the electricity grids. However, four percent of potential generation was lost because the grids are currently insufficient for this. Storage is therefore of crucial importance.

In addition, the expansion of the electricity grids, sector coupling (use of surplus electricity to generate heat or to electrify means of transport) and demand management should result in fewer curtailments in future. Demand management means that plannable industrial processes will run when there is a lot of renewable electricity in the grid.

Author: Susanne Harmsen