Initial situation

According to the legal plans, nuclear energy and coal power will be abolished in Germany, nuclear energy by 31 December 2022, coal on a declining path until 2038 or even as early as 2030. In return, gas-fired power plants are currently being added as a "transitional technology" to support the grid, which is also to be significantly expanded and accelerated in accordance with the coalition agreement of the German government. In view of the current war situation in Ukraine and the potentially critical, perhaps even longer-lasting energy supply situation in Europe, the feasibility and usefulness of the latter goal must be called into question, especially as the German and European electricity grid was already on the verge of collapse several times before the current situation and natural gas will probably no longer be available in the future as planned or as before. Politicians and the energy supply industry are now faced with the question of whether and to what extent existing conventional power plants must continue to support and secure the supply. The following remarks are intended to show that German nuclear power plants can play a decisive role here.

Power requirement

Irrespective of the current potential crisis situation, the demand for electricity, which is generally between 40 and 80 gigawatts (GW), will continue to exist or even gradually increase due to electromobility and numerous heat pumps in new buildings, among other things. This applies not only to the total annual demand, but also to the maximum electricity demand in the hour of the year with the highest consumption, as assumed in load coverage analyses. In the transmission system operators' 2021 system analysis for 2021/2022, this maximum load was assumed to be 87.9 GW (excluding grid losses at transmission grid level of approx. 4 per cent). The chart below shows this maximum load and the development of the installed net generation capacity of conventional power plants according to the Federal Network Agency's 2021 monitoring report.

Available power

Based on the experience of past decades, the hour with the maximum load falls on an early evening hour in a winter month with cold winter weather, so that generation from photovoltaics should be assumed to be zero. In a calm situation, a maximum of 5 per cent of the installed capacity should be assumed to be available for wind power, i.e. around 3.3 GW of around 66 GW onshore and offshore. In calm periods, however, the actual output of wind turbines can fall well below 5 per cent of installed capacity for significant periods of several days. Run-of-river power plants (5.6 GW) and electricity generation with biomass (7.8 GW) can in principle contribute to meeting demand in a similar way to conventional power plants, although some of the hydropower plants and currently most of the biomass power plants cannot provide any system services to stabilise the electricity grid.

As with all technical systems, unplanned unavailability must also be assumed for power plants and other electricity generators, for example due to defects or planned unavailability even in the critical winter months, for example because extensive maintenance or repair measures are required that also extend over the winter. To take this into account, a technical unavailability of 5 per cent is assumed for conventional generation technologies (cf. VGB, UBA). For run-of-river power plants and electricity generation with biomass, the unavailabilities from the last power balance report of the transmission system operators from 2020 are assumed in accordance with historical experience, i.e. 72 per cent and 40 per cent respectively. These aspects are shown in the figure below.

Gas shortage problem

As can be seen, even without a gas shortage situation from January 2023, the maximum electricity demand is no longer covered by domestic German generation if the conditions regarding the nuclear and coal phase-out remain unchanged; there is a deficit of 4.9 GW. In the event of a gas shortage, which is conceivable at any time as a result of the war against Ukraine and the resulting geopolitical and energy industry upheavals, as currently documented by the German government's declaration of the first stage of the gas emergency plan, the situation will change significantly for the worse.

Unlike private consumers or combined heat and power plants in the public heating supply, the so-called uncoupled plants for the exclusive generation of electricity with gas and an installed capacity of (currently) 9.4 GW (BDEW) as well as the gas-fired industrial power plants with an installed electrical capacity of 5.3 GW (BDEW) do not belong to the so-called protected consumers within the scope of the gas emergency plan. In the event of a gas shortage, it can therefore be assumed that these plants will not be available.

This results in a calculated shortfall of 19.6 GW compared to the demand measured against this year's assumed maximum load. This can theoretically be covered by imports, as the total physical capacity of all cross-border interconnectors is more than 23 GW (BNetzA). However - and apart from possible unavailability here too - a gas shortage caused by an import ban or embargo on Russian gas supplies would not only affect Germany, but the whole of Europe, including Austria, which is particularly important for securing the electricity supply in southern Germany (gas production 16 per cent, in winter 20 to 30 per cent; gas import share of Russia: 80 per cent) or Italy (gas production 43 per cent, electricity imports: 12 per cent; gas import share of Russia: 40 per cent), which would then also be dependent on increased electricity imports.

In such a stressful situation, which is exacerbated by the EU's planned ban on the purchase of Russian hard coal, it cannot be ruled out that the integrity of the European electricity network cannot be maintained and that the network will break down into several separate zones, which would then have to ensure their supply independently for a certain period of time. Such a scenario already materialised in January 2021, even without a general stress situation due to the failure of grid components in south-eastern Europe, albeit only for a short time at the time.


In an acute stress situation for the power supply, the installed capacity of nuclear power plants that continue to operate can make the difference between maintaining the power grid and its collapse, especially when the particular regional vulnerability in southern Germany is taken into account. In such a stressful situation, when grid voltage AND frequency have to be kept within the narrow specified limits, EVERY large-scale non-volatile power generator (and this includes nuclear energy) is urgently needed to stabilise the grid. Nuclear power plants can certainly be the "tip of the scales" here. It is irresponsible to simply switch off these power plants in the grid in order to secure the electricity supply for the German population in the event of a crisis, as is the case now.

With regard to the question of security in the event of a conflict, which is currently raised from time to time, it has long been known that nuclear facilities are among the best-secured industrial facilities of all and therefore offer good protection against terrorist attacks, for example, which would also be effective in a hypothetical case of hostilities in the vicinity of a nuclear power plant. A possible shutdown would not result in any significant increase in security in the event of a deliberate and targeted military attack in violation of international law due to the above-ground interim storage facilities that already exist at the sites.

Last but not least, the continued operation of nuclear power plants in Germany - even in the short or medium term - also contributes to the achievement of climate protection goals through its practically CO2-free electricity generation - and this without new investments, approval and construction times and supply risks for new gas-fired power plants. The additional radioactive residues resulting from the limited continued operation of nuclear power plants are small compared to the existing inventories from decades of nuclear energy utilisation.

Berlin, 07 April 2022

Press contact: Nicolas Wendler, Phone: +49 172 237 91 84, E-Mail:

Nuclear Technology Germany e.V. (KernD)

Berliner Straße 88 A, 13467 Berlin

Chairman of the Management Board: Thomas Seipolt

Managing Director: Dr Thomas Behringer

Registered office: Berlin, Charlottenburg Local Court, VR 21055 B

Current relevance of nuclear power plants for security of supply

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