Against the background of the destruction of the Japanese nuclear power station Fukushima the German government decided on the 14th March 2011 to take 8 nuclear units with 8,422 MW out of service for 3 months for comprehensive security tests. These plants have been commissioned between 1975 and 1984 [1].

On the 6th June 2011 the German minister of Economics and Technology, Philipp Rösler, announced that the 8 units will be out of service permanently and that the remaining nuclear units will be phased out until 2022. A declaration in 39 points clarifies the government's decision. [2]

At the end of 2009 the installed capacity in Germany was 153 GW of which 22 GW was nuclear power, 26 GW was wind power and 10 GW was photovoltaic (PV). The secured capacity is assumed to be 90 GW. The maximum load is about 80 GW. [3]

In 2010 the production was 141 TWh from nuclear power, 37 TWh from wind power and 12 TWh from PV. The total production was 625 TWh and the gross consumption 608 TWh.

Distribution of German electricity production in 2010 [4]:

Lignite	23.2%
Nuclear	22.5%
Coal	18.8%
Natural gas	13.4%
Oil etc.	5.7%
Renewables	15.4%
- of which	Biomass	4.6%
	Waste	0.8%
	Hydro	3.1%
	Wind	6.0%
	PV	1.9%

The impact on economy and environment of the sudden decision has not been quantified. It is doubtful if it will ever be known.

From one day to the next Germany changed from being a net exporter of electricity to being a net importer. This is valid also for the exchange between Denmark and Germany, but at this border the large rainfall in 2011 was a contributory factor by filling up the Norwegian water storages.
 

The electricity market responded by increasing prices of financial products by 10-20%.

Infrastructure for electricity, gas, communications, mail services and railways in Germany is under surveillance by Bundesnetzagentur (The Federal Network Agency).

A number of direct consequences of the moratorium are presented in a report published by Bundesnetzagentur on 11th April 2011 [1]. The conclusion of the report is that sufficient reserves are estimated to be available for the summer 2011 and for the winter 2011/12.

The report is strikingly marked by worry and uncertainty. The first point of the summary says says that simultaneous and unforeseen closure of power plants of a 5 GW magnitude never occurred before. The agency advises against further uncoordinated steps in this direction. The report also mentions that the risk of cascading failures has increased. The increased risk may also affect neighbouring countries.

On 26th May Bundesnetzagentur published a continuation of the report [5]. The observations for the period from 11th March to 8th May seem to confirm the predictions in the report of 11th April. The four transmission system operators in Germany are urged to continue the comprehensive analyses of the stability of selected extreme scenarios.

However, experiences from previous disturbances are decisive to the high operational security of the interconnected power systems rather than theoretical analyses. The variability of the high large German share of wind power and PV will create situations, which have not yet occurred. This creates a unique challenge to the German system operators.

The calculations have shown that it may be difficult to maintain the system voltage in the south western part of Germany. Voltage problems have been decisive in several large blackouts, including USA on the 14th August 2003 and East Denmark on the 23rd September 2003. Therefore the German system operators are considering the use of generators at the closed nuclear power plants as synchronous compensators in order to stabilize voltage. Synchronous compensators exist in Denmark at the terminals of the HVDC links in Vester Hassing and Tjele.

California is also a net importer of electricity. A routine grid switching operation in Arizona caused a major interruption of supply on the 8th September 2011 affecting about 5 million people in Arizona, Mexico and the southern California for up to 12 hours.

The German grid is a European backbone. Insufficient co-ordination between two German grid operators caused on 4th November 2006 the European grid to be split up into 3 parts and 15 million households to be without electricity.

Apparently Energinet.dk has not yet found reasons for an adjustment of the Danish criteria for operating reserves.

It will be interesting to study future operational results.