The four German TSOs have indicated that the nuclear power moratorium is having a significant impact on the German electricity supply system. Sufficient security of energy supply may not be guaranteed in southern Germany on very cold winter days with concurrent low wind power generation.
Section 11(1) of the German Energy Act (EnWG) obliges transmission system operators (TSOs) to operate a secure, reliable and capable energy transmissions system without discrimination. Furthermore, they are obliged to maintain the system, to optimize it in line with demand, to strengthen it and to expand it, to the extent this is commercially reasonable. However, as unbundled TSOs do not generate the electricity, and as recent shutdowns are limiting German generation capacity, the German TSOs are facing a challenge to comply with their obligations.
As a result of the Fukushima moratorium and scheduled revisions, only 4 of the 17 German nuclear power plants are currently online. Favourable conditions (low network load, strong solar, but rather low wind power input) and system operator interventions have so far made it possible to maintain network stability, the TSOs pointed out. Assuming no unusual events, the situation shall presumably be manageable also for the summer period, the four TSOs (Amprion GmbH, 50Hertz Transmission GmbH, EnbW Transportnetze AG and Tennet TSO GmbH) said.
However, stability will require using every possibility form of redispatch measures, interventions in the electricity markets, to postponing urgent grid maintenance and expansion projects as well as power plant revisions, they added. The TSOs also indicated that the free electricity market will be suspended for considerable periods of time. Still the risk of power failure has increased, the TSOs said.
In case input capacity remained reduced by 8,000 MW after the end of the 3-month nuclear power extension moratorium (on 15 June 2011), TSOs foresee problems in particular for the coming winter months, as the possibilities for interventions were largely exhausted. In (industrial) southern Germany the electricity demand might not be satisfied on cold cloudy winter days with a low wind power input in northern Germany. 2,000 MW of secure generation capacity would be missing in southern Germany. Demand might also not be covered by electricity imports if other countries consume their electricity output themselves. As a consequence the risk for large power outages will increase, the TSOs warned.
Frankfurter Allgemeine Zeitung quoted a spokeswoman for Environment Minister Norbert Röttgen (CDU) as saying the situation was difficult, but controllable. It required intelligent grid management. Security of supply was of utmost importance for the planned energy turnaround in Germany. It would be accorded top priority in the upcoming decisions. On 6 June the government intends to decide on a legislative package for the energy turnaround.
After the moratorium had started, the Federal Network Agency (BNetzA) asked the TSOs for information on the moratorium’s impact. BNetzA compiled the information into a report to the Federal Ministry of Economics and Technology dated 11 April 2011. In its report, BNetzA urgently advised not to order a shutdown of further nuclear power plants, in addition to the 7 +1 plants already shut down. Further decisions with effect for the transmission system or for the power plant fleet should in any event be closely coordinated with BNetzA and the TSOs.
In late April, the Federal Network Agency (BNetzA) initiated proceedings aimed at determining redispatch rules for power plants connected to the German high and extra-high voltage network. Interested parties were asked to comment on the key issue paper by 20 May 2011. The new rules shall contribute to ensuring network stability.
The TSOs intend to further verify and deepen the analysis of their findings together with the Federal Network Agency in the coming weeks.
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