The four German transmission system operators 50Hertz, Amprion, TenneT and TransnetBW today presented the findings of the second grid stress test (second special analysis for winter 22/23). On behalf of the Federal Ministry for Economic Affairs and Climate Action, they undertook a special analysis between mid-July and early September 2022 of the security of the power grid this winter in the face of worsened external conditions. The background to this was that, in view of the drought in the summer, the low river levels, the fact that roughly half of France’s nuclear power plants are down, and the generally tense situation on the energy markets in the wake of the Russian war of aggression against Ukraine, there are a number of uncertainties which, in certain circumstances, can result in an accumulation of risks. The second stress test is therefore looking into various scenarios and the grid situation, including in particular the interplay with neighbouring European countries, since Germany’s situation is particularly affected by developments across Europe in view of its geographical location and the fact that it has interconnectors to eleven other European countries.

The second grid stress test finds that hourly crisis situations in the power system are very unlikely in the coming winter, but cannot be entirely excluded. For this reason, a number of additional measures are recommended so that even these very unlikely scenarios do not result in a short-term shortfall of supply or blackouts due to stress situations in the grid. Some the measures recommended in the stress test, such as the use of reserve power stations and the return to the market of coal-fired power plants, have already been implemented or are currently being rolled out. Further measures are now being prepared and will be implemented in the third revision of the Energy Security of Supply Act (EnSig 3.0), such as additional power generation from biogas plants and measures to increase the capacity utilisation of the grid / to improve transport capacities.

Federal Minister for Economic Affairs and Climate Action Robert Habeck commented on the findings as follows: “We have a very high level of security of supply in our electricity system in Germany. We have enough energy in and for Germany; we are an electricity exporter. But we are part of a European system, and this year is a special year right across Europe. The Russian attack on Ukraine has led to a tense situation on the energy markets, and we are doing our utmost to avoid a shortage of gas. Roughly half of France’s nuclear power plants are currently off the grid. The drought in the summer has reduced the water levels in rivers and lakes, affecting hydropower in neighbouring countries and making it more difficult for us to transport coal to the power stations we need to use because of the difficult gas situation. And the roll-out of renewable energy and the expansion of the power grid were very much slowed down in recent years, something that is having a particularly severe impact in the south of our country. The major crises – war and climate crises – are having very tangible effects. So we have a number of uncertainties, made much worse by the dry summer. In certain circumstances and very specific situations, we can face a combination of these risks. Given all these risks, we cannot rely on our neighbouring countries having enough power stations available to help stabilise our power grid at short notice in the event of grid congestion,” Habeck said.

He stressed this point: “It remains highly unlikely that we will face a crisis or an extreme scenario. But as the minister responsible for energy security, I am doing everything it takes to ensure that we have full security of supply. We have therefore already put in place many of the measures which the stress test believes to be necessary, such as the return of the coal-fired power plants to the market. We will address other measures in the grid sector, such as in particular improving the transport capacities in the grid, in a third revision of the Energy Security of Supply Act, and will launch coordination of this in the course of this week.”

The Minister stated: “The results of the stress test also mean that, in order to cover ourselves for emergencies this winter, we will need a new deployment reserve for a specific period and specific situations which will consist of the two nuclear power plants in the south of Germany, Isar 2 and Neckarwestheim. These two nuclear power plants are to remain available until mid-April 2023 so that they can, if necessary, make an additional contribution to the power grid in southern Germany this winter. This also means that all three of the nuclear power plants currently still on the grid in Germany will be taken off the grid as planned at the end of 2022. We are sticking to the nuclear phase-out stipulated in the Atomic Energy Act. New fuel elements will not be used, and the deployment reserve will be terminated in mid-April 2023. Nuclear power is and continues to be a high-risk technology, and the highly radioactive waste will be a problem for many future generations. You can’t play around with nuclear power. It would therefore be wrong to simply delay the nuclear phase-out, not least in view of the safety status of the power plants. By setting up the deployment reserve, we are taking account of the risks of nuclear technology and the special situation in the coming winter. This will enable us to act if necessary. The nuclear power deployment reserve is a targeted response.”

Habeck highlighted this point: “The situation in the electricity sector this winter cannot be compared with that in the winter of 2023-24. Next year, the fundamentals will be different, because the measures we are taking will have had more time to work, and further responses can be made. We are boosting our import capacities for gas via floating LNG terminals (FSRUs) to such an extent for the winter of 23-24 that we will not need to worry about a potential shortage of fuel for the gas-fired power stations. By then, we will have made more electricity available from biogas and renewable energy plants. The same goes for the capacity of the grids and the power stations, and for flexible loads. This means that the uncertainties facing us this winter will be much reduced by the winter of 2023-24, and the supply situation will be better.”

Further details of the stress test:

The second stress test was carried out by the four transmission system operators from mid-July until early September 2022. In comparison with the first special analysis (March to May 2022), the assumptions made about the effects on the energy market of the Russian war of aggression against Ukraine were much more demanding and were gradually scaled up. Also, the calculations take account of other possible bottlenecks in power plant availability.

The analysis covers three critical scenarios (critical scenario +, very critical scenario ++ and extreme scenario +++), which deviate substantially from the reference scenarios in the statutorily prescribed analyses of power supply security from the end of April 2022. In comparison with the first stress test of May 2022, the assumptions about power plant availability and fuel prices were made much higher and scaled up for the respective scenario. This means that a total of five scenarios now form the basis of the overall evaluation of the electricity supply situation – from the base scenario of the needs analysis required by law to the extreme scenario in this second stress test.

Possible effects of differing critical energy market situations on the electricity sector in Germany and Europe were examined step-wise for the three scenarios of the second stress test. The new calculation was based not least on the following assumptions:

  • A large proportion of the French nuclear power plants do not return to the market before the winter. In the extreme scenario (+++), output is available from just under two-thirds of the French nuclear power plants.
  • Only some of the power stations potentially available under the Act on the Maintenance of Substitute Power Stations return to the market – to differing degrees, depending on the scenario.
  • The low river levels continue to restrict hard-coal shipments. This means that, even at times of peak consumption, the hard coal-fired power stations can only produce far less electricity (the smallest amount being assumed in the extreme scenario).
  • One quarter (+) to one half (+++) of the generating capacity in the grid reserve is not operationally ready.
  • In the critical scenario, one quarter of the gas-fired power stations in southern Germany are not available, rising to half in the extreme scenario.
  • The demand for power from fan heaters results in gigawatt-scale increases in the peak consumption levels.
  • The gas price assumed in the calculations was increased uniformly to 300 €/MWh for all three scenarios.

The second stress test shows the following: An hourly crisis situation in the power system in the winter of 22/23 is very unlikely, but cannot be entirely excluded at present. Additional measures to improve grid security need to be taken in order to ensure that there is no shortfall of supply or blackouts due to grid stress situations.

Specifically, the outcomes of the calculations show that, in some scenarios, demand cannot be fully covered in some regions of the European electricity market without additional measures being taken. In the very critical scenario (++) and the extreme scenario (+++) such situations also arise in Germany for very brief periods, i.e. just a few hours a year.

A special focus in the stress test was placed on the question of whether and to what extent there will be congestion in the grid. The finding here is that – caused by the delayed grid expansion and the lack of generation capacities in the south of Germany – there can be grid congestion in all three scenarios. Nuclear power stations located outside Germany (redispatch power stations) are needed to tackle this congestion, to some extent to a much greater extent than previously calculated and planned. Since the supply situation throughout Europe is tense, not least due to drought, low river levels and the problems with French nuclear power plants, it is extremely uncertain whether this power plant capacity can actually be provided by our European partners.
The second stress test therefore finds that a package of precautionary measures is needed to avoid grid congestion. Further to this, a number of ways to mitigate critical situations are recommended; these should be implemented in combination, as stand-alone measures will not be enough. Important contributions to grid security include higher capacity utilisation of the existing grids by accelerating the planned weather-dependent overhead line operation, better use of various power stations and reserve power stations, and contractual demand side management. These measures need to be implemented as a matter of urgency.

For the very critical scenario ++, an additional calculation studies the possible effect on the grid of an availability of the three nuclear power plants at Emsland, Isar and Neckarwestheim. The findings show that keeping the three nuclear power plants available can only be of limited assistance for the electricity grid in stress situations. In a very critical scenario, having all three nuclear power plants in operation would reduce the need for foreign redispatch power stations not by the nominal capacity of the three plants, but only by 0.5 GW. There will continue to be a need for 4.6 GW of redispatch capacity from outside Germany (in the scenario ++, the calculated need for foreign redispatch is 5.1 GW). Redispatch power stations are power stations that can quickly provide the German market with electricity to offset grid congestion. Also, in terms of total gas consumption, only a minimal amount of gas would be saved. In general, nuclear power plays a lesser role than the other urgent measures which need to be taken to ensure grid security in critical situations. Even if the three remaining nuclear power plants were to be used, significant intervention in the power plant fleet would be needed to ensure grid security.

Further details about the deployment reserve:

Since, according to the calculations of the second stress test, the potential contribution of nuclear power is limited and nuclear power continues to be a high-risk technology, any approach must be particularly careful and targeted, not least in order to take account of the high constitutional barriers imposed by Article 20a of the Basic Law. For example, this article requires that the state assume its responsibility for future generations by protecting the natural environment and animals in line with the constitution. The risks resulting from the use of nuclear energy to generate electricity and the burden placed on future generations by the nuclear waste are therefore only acceptable if interests are precisely weighed up and the reason for the use of nuclear power is explained in detail.

For this reason, Minister Habeck would like a targeted deployment reserve of nuclear power plants which is limited both in time and scope. The deployment reserve of nuclear power plants takes account of the risks of nuclear power and of the special situation in the coming winter, and is therefore limited in time to mid-April 2023. The scope is limited to the southern German nuclear power plants, Isar 2 and Neckarwestheim. A narrowly defined emergency deployment of the nuclear power plants is permitted only for this period, and only for the two southern German nuclear power plants, where this is needed to avert a specific danger to security of supply, meaning that the deployment is a reasonable decision by the legislature within the constraints of the constitution. In contrast, other, less risky instruments can be deployed for the north German region. For example, additional oil-fired power stations can be quickly deployed in the form of oil-fired power barges. These are not available in the case of Isar 2 and Neckarwestheim.

Furthermore, the deployment reserve consisting of Isar 2 and Neckarwestheim is to be designed as a reserve, deployed only when it seems likely that the other instruments will be insufficient to avert a supply crisis. The design of the deployment reserve will take account of the necessary technical requirements of nuclear power. An extension beyond mid-April 2023 or renewed deployment in the winter of 2023-24 is not possible due to the safety status of the nuclear power plants and the fundamental considerations about the risks of nuclear power.

The rules governing the deployment reserve are to be set out in the Energy Security of Supply Act. Also, it will be subject to the proviso that the normal safety standards are fully upheld. A robust inspection of the safety status is therefore needed.

The decision as to if and when the reserve is deployed will be based on monitoring by the Bundesnetzagentur (Federal Network Agency) to assess the electricity market and grid situation, which will identify the developments in the electricity system (coal reserves, power station availability, gas availability, etc.) at an early stage. This will permit an analysis of the security of supply on the generation side on the basis of various indicators. The outcome of this will serve as a basis for a decision on any activation of the nuclear power plant deployment reserve. Not least, the parameters will be monitored which, according to the stress test scenarios, can result in critical market and grid situations. The aim should be an assessment of the overall situation and early assessment of alternative measures.

Any critical or dubious developments will immediately result in an in-depth analysis with the Bundesnetzagentur and the transmission system operators. If necessary, and in response to a proposal from the Federal Ministry for Economic Affairs and Climate Action, the Bundesnetzagentur is to make the recommendation that the reserve be deployed; the decision is then to be taken via a government ordinance with the possibility for the Bundestag to challenge it. The competent nuclear supervisory authority is responsible for issuing the licence to recommence generation.