Germany's grid regulator Bundesnetzagentur (BNetzA) said Wednesday that it has decided against keeping one idled nuclear reactor on standby as reserve capacity for the coming two winter seasons to ensure power grid stability after the government permanently closed eight older reactors in the wake of the Fukushima disaster in March.
"Our investigations have shown that even in exceptional contingencies the transmission system will remain operational without the dispatch of a reserve nuclear power plant," BNetzA President Matthias Kurth said in a statement.
Instead, BNetzA secured 1,075 MW of reserve capacity from Austria and picked older conventional power plants in Germany with a total capacity of 1,009 MW to secure energy supply in extreme weather situations during the coming two winter seasons.
Those plants include the coal-fired GKM3 unit in Mannheim and Ensdorf C as well as the gas-fired unit 2 at Mainz-Wiesbaden, which have all been in cold reserve mode, the statement said.
"The situation this winter will remain tight, but controllable," Kurth said. "A complete back-up for any kind of risk is impossible on a technical as well as economical level."
BNetzA said it is aware that, even under normal conditions, transmission system operators increasingly will have to ask plant operators to dispatch their plants according to grid stability criteria rather than in a market-driven way.
BNetzA also recommends extending the operating licenses for E.ON's coal-fired units Datteln 1-3 until Datteln 4 becomes operational as well as extending the Staudinger 3 license for three months from the current expiry at the end of 2012.
The government has asked the grid regulator to investigate the need for a nuclear reserve capacity during the winter after transmission system operators in May warned of possible blackouts during extreme winter weather should the eight older reactors remain shut permanently, removing at least 5,000 MW of nuclear capacity from the market.
Based on first estimates by Germany's four TSOs, BNetzA said in its second assessment of the nuclear moratorium scenario for the government on May 26 that a strong demand/strong wind scenario may overload the grid in the Frankfurt area, while a low wind/strong demand scenario could endanger grid stability in the Hamburg region. Based on this report, the TSOs asked for extra capacity between 1,400 MW and 2,000 MW in southern Germany.
BNetzA said Wednesday that it could not confirm such a deficit, that around 1,000 MW reserve capacity may be needed in southwestern Germany under certain conditions.
Nuclear power contributed 23% to Germany's energy mix in 2010, according to energy lobby group BDEW, with lignite adding another 23% and the rest being made up from coal, gas and renewable sources.