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Frequently asked questions and our answers to them

Questions about grid development and the future energy policy are the main focus of current public debate. The necessity to expand the power grid, the planned South-East Direct Current Passage, the future electricity market model and the evolution of grid fees are the subject of equally heated discussions by politicians and citizens alike.

In its capacity of transmission system operator, 50Hertz would like to offer a contribution to this lively political and social debate. On this site, you can find the most frequently asked questions and our answers to them.

Why do we need an expansion of the electrical grids?

The most important reason for the urgent conversion and expansion of the transmission system is the energy transition.

As a result of the development of renewable energy installations (RES installations), most electricity is no longer generated by large power plants near the consumer, but in decentralised installations in areas that offer the best conditions for the exploitation of renewable energy sources. These locations can often be found in the northern and eastern parts of Germany, especially where wind power is concerned.

Even today, many regions produce more electricity than they themselves consume. The surplus has to be transported to the consumption centres in southern and western Germany, where power is in high demand. The transmission system is tasked with the transport of this electricity. This explains the need for grid development at the 380 kilovolt level - extra high voltage - even though most RES installations are connected to lower grid levels.

50Hertz is responsible for the high voltage grid in the north and east of Germany. In this control area, a disproportionate volume is generated from renewable energy sources. That is why 50Hertz reinforces the grid and constructs new lines where necessary.

Further information can be found in our position paper on grid development, which is available on our website under the following link:

How are the grid development plans (GDP) created and what are the sources of the data used in the corresponding scenario frameworks?

Every year, 50Hertz draws up a grid development plan (GDP) together with the three other German transmission system operators: TenneT TSO, Amprion and TransnetBW. In this plan, the grid development measures are identified that are needed for the next ten years to guarantee secure and reliable grid operations. When the GDP is drawn up, the public is able to get involved by means of the consultation rounds.

The start of each GDP is the establishment of a scenario framework. This covers at least three development trajectories (scenarios) that represent a variety of probable developments in consumption and generation of electricity for the next ten or twenty years. The scenarios that were suggested by the grid system operators in January 2012 were based on selected studies by independent research institutes as well as the European Network of Transmission System Operators for Electricity (ENTSO-E). On the basis of the generation scenarios, the behaviour of the market is first simulated in the scope of the grid development plans (which producers supply their electricity to whom?), after which the need for grid expansion is determined. To this end, the load on individual lines was represented using a European network model for the nodes and lines in Germany. For each hour of the year, generation and consumption data were supplied by a general European market model that determines the use of power plants for Germany and Europe in the selected year. Additionally, the import and export from European neighbour states were taken into account. To determine the need for grid development, the NOVA principle is applied: grid optimisation before strengthening before expansion.

The GDP draft presented by the transmission system operators is reviewed and subsequently approved by the Federal Network Agency (Bundesnetzagentur). At least every three years, the German Bundestag adopts the Federal Requirements Plan Act, which stipulates the priority grid development measures. The 2012 GDP, for instance, was the basis for the Federal Requirements Plan Act adopted in 2013 that still applies today.

Can decentralised electricity generation cancel the need for grid development?

The generation of electricity from renewable energy sources is concentrated where wind or solar output is highest and the corresponding area is available. Consequently, a large share of renewable energy is generated in relatively low-populated areas with a lot of wind or sunshine.

As a rule, the decentralised producers generate more than is needed locally. At certain times, a considerable surplus is sent from the distribution level to the transmission system level, which transports it to consumption centres, some of which are located far away.

The conversion in the electricity generation sector also necessitates a conversion of the transmission infrastructure. This means that decentralised production of electricity does not necessarily lead to a lesser use of power lines - indeed, the need for grid development becomes even greater, both at the transmission and distribution level. After all, "decentralised" is not synonymous with "close to consumption".

The costs for the development of lines are also lower by several orders of magnitude than the decentralised installation of power plants and generating units in accordance with local demand. Furthermore, the self-sufficiency of individual regions is only possible in particular cases: especially the power demand by industry and commerce cannot be covered with a purely decentralised concept. This is the conclusion of a 2013 study by the Federal Environment Agency on "Modelling power generation entirely based on renewable energy sources in self-sufficient decentralised structures in 2050".

Grid development is therefore more sensible than a 100 % self-sufficient region, as it evens out the time and space fluctuations in RES supply and connects areas with a high RES potential to the load centres.

If the development of renewables slows down, do we still need grid development?

The growing need for transmission between north and south determined in the Federal Requirements Plan Act will still exist after the reform of the Renewable Energy Sources Act (EEG). It is true that according to the new EEG, the development of biomass and offshore wind power will slow down. While this leads to a smaller increase in the North Sea, the construction of wind turbines in the Baltic Sea is not expected to lessen to any significant degree. The 2012 Grid Development Plan already predicted a more surveyable growth. Furthermore, onshore wind power will play an even more important role in the future. It will for the most part be installed in northern and eastern Germany, where the potential wind output is the highest and a large surface is available. All things considered, the transmission demand from north-eastern Germany to the south-west will even increase.

Moreover, the Federal Network Agency has only approved about two thirds of the measures identified by the system operators in their 2012 Grid Development Plan (which was used as a basis for the current Federal Requirements Plan Act) because it applied additional resilience criteria. As such, the regulatory authority has already prevented changes, even to the legal framework. The Federal Requirements Plan Act, which contains the measures approved by the Federal Network Agency, therefore only includes lines that are also required after the EEG reform.

What about completely new tower types?

As far as the development of innovative tower designs is concerned, the transmission system operators have several ongoing pilot and development projects. These projects seek to design towers for alternating current transmission as these are at a further stage in the project than the planned direct current connections. The first results should be available in 2016.

50Hertz is collaborating with research and development partners on the creation of an overhead line that makes an optimal use of space. The goal is a new method of 380-kV overhead line construction for alternating current with a minimum height and corridor width. The research and development project should be concluded by 2018.

The basic conclusion is that compact lines can be constructed both as steel lattice towers and solid towers. Whether a steel lattice tower, which does not block the view as much, or a thinner but more massive solid tower is more acceptable to the public is also studied more closely using specific examples and can vary depending on the environment and landscape.

The TSOs will also apply the experiences gathered during the planned use of new tower designs for AC transmission to the specific planning of direct current lines.

How is a so-called risk of conflict analysis carried out?

The risk-of-conflict analysis is the basis of the planning and approval procedure for grid development projects. The procedure follows the directive provided by the Federal Network Agency, which you can find here: http://www.netzausbau.de/cln_1431/DE/Verfahren/Bundesfachplanung/Bundesfachplanung-node.html.

The analysis covers all aspects that might hinder or aggravate the construction of an overhead line. That is why critical locations should be identified in the early planning phase and by-passed for the further planning of the route.

To this end, the different environmental and spacial criteria are assigned to the three risk-of-conflict classes (RCC) (cfr. model application as per § 6 of the Grid Expansion Acceleration Act (NABEG) part 1: search procedure for wide and more specific corridors):

  • very high risk of conflict (RCC I) (e.g. residential areas, areas reserved for wind turbines or military use, Natura 2000 areas etc.);
  • high risk of conflict (RCC II) (open spaces near residential areas, protected landscapes, forests, priority areas for recreation etc.);
  • risks of conflict that cannot be categorised.

After different risk-of-conflict areas have been determined, the 15 kilometre wide corridors are identified. These should have as few risks of conflict of classes I and II as possible and offer possibilities for bundling with existing infrastructure (e.g. motorways or other high voltage power lines).

In a further stage, a corridor of about one kilometre in width is determined within the wider corridor. This corridor should have a minimum impact on the environment. In this stage, especially those areas of risk-of-conflict class I are considered to see whether the corridor can be moved or if there are other possibilities to limit adverse effects.

It is then evaluated whether eligible route sections (so-called corridor segments) are qualified with regard to spatial planning and the environment. Technical and economic aspects are also assessed. As a result, each corridor segment is ranked in view of possible line construction.

The objective is to search for the shortest possible route between two grid connection points along the total length, while also taking into account options to bundle it with other infrastructure (other lines, motorways, railway sections) and only crossing those areas with the lowest risk of conflict.

50Hertz and Amprion, the companies responsible for the direct current line that will connect Saxony-Anhalt and Bavaria, have not yet carried out these studies nor identified corridors, as the start and end point of the line have been altered. Possible corridors have so far been determined for the line from Bad Lauchstädt to Meitingen, given that there is a corresponding legal basis. Should the altered line be approved in the Grid Development Plan and in the Federal Requirements Plan Act, we will start planning the entire project anew.

Isn't it possible to just install the new lines underground?

There are great expectations towards underground transmission lines, especially with regard to a greater degree of local acceptance. While underground cables are more frequently used at the distribution level (110 kV and lower), they are not state-of-the-art in the extra high voltage range (380 kV).

They are also more expensive and more difficult to operate than overhead lines. In case of disturbances, recent experiences have shown that it can take months before a cable can be put into operation again, while overhead lines can often be used within a matter of days. The impact of underground cables on the environment is not lower either, as it massively affects the soil, as well as water management and landscape in certain cases.

For this reason, the decision to install a power line as an overhead line or an underground cable is always made on a case-by-case basis. Underground cables should be used where this is more advantageous to and economic for man, nature and wildlife. In our experience, cable solutions should be tested where this has a lesser impact on the landscape for close residents. However, in nature reserves, it is our experience that underground cables have a much greater impact on nature than traditional overhead lines.

The legal possibilities to test individual cable sections for larger projects are currently very limited. It is nevertheless worthwhile to make specific target-oriented analyses of special cases in consultation with all social players. The option introduced in the draft law for the new EEG that also allows partial underground cable solutions to be tested for individual cases in the scope of direct current projects (South-East DC Passage) is therefore very useful.

Should limit values for electromagnetic fields be made more strict?

The German limit values for electric and magnetic radiation are already very high compared to those of other countries and have been proven to be adequate.

Although numbers are sporadically published out of their context in other countries that might appear lower at first glance, upon closer inspection they usually refer to the average load factors of the lines. In Germany, however, the limit values are based on the maximum load factor of the installation, which is in fact only reached in the rarest of cases and only for short periods of time for reasons of system security.

Regardless, the values have to be tested continuously and adjusted to the latest research results. For this reason, first steps were taken to amend the 26th Federal Emissions Act in 2013 so that it also offers a reliable framework for direct current lines.

There is no need for further restriction of the requirements (limit values, distance rules etc.), as on the one hand, there are no indications that this would offer greater health advantages. On the other hand, it might also delay grid development, which is urgently needed at the present time, and even encumber optimisation measures meant to better blend the grid with nature and landscape (such as high-temperature conductors). The fact is that one consequence of more stringent requirements would be that many new routes have to be found and new lines have to be constructed if existing lines can no longer be optimised or reinforced despite the existing technical possibilities, because they might exceed the stricter limit values or fail to comply with the more rigorous distance rules.

Further information can be found in our position paper on electromagnetic fields, which is available on our website under the following link:


What does 50Hertz do for the cities and towns affected by grid development?

50Hertz is the first transmission system operator to pay each municipality that is directly affected by the grid expansion a legally arranged but non-mandatory financial compensation for the related encumbrances. An affected municipality can obtain a maximum of 40,000 euros in compensations per kilometre of overhead line. The exact amount of the compensation offered to municipalities directly affected by the route of the line is based on objective criteria. In this context, decisive factors are the number and the transfer capacities of the installed electrical circuits.

Furthermore, part of the investments in grid development directly benefit the affected regions: contracts for earthworks and foundation works, forestry works, activities in landscaping, tunnelling and hydraulic engineering as well as other works are granted to local companies.

In the scope of the plan approval procedure, the competent authorities of each Bundesland have determined so-called compensatory and replacement measures for environmental effects that cannot be avoided. These measures are suggested by 50Hertz and often based on information provided by the population or the local authorities. The measures are at 50Hertz's expense. Regional companies are also involved in the realisation of these measures. Furthermore, a number of young scientists are given the opportunity to develop and contribute new creative ideas to the project, e.g. for more ecological forest aisle management.

Why are storage units not promoted more?

At present, there is a high - mainly local - need to balance the supply and demand of electricity, which will decrease as a result of the planned grid development. So far, storage units have hardly been able to provide relief, as there only a limited number of them is available. In Germany, the only electrical storage units of any significance are pumped storage stations. However, even their operation is often no longer profitable, so that in general, grid development is clearly more advantageous.

In the medium to long term, however, the growing share of renewable energy will also create a greater need for storage. In addition to the balancing of short term fluctuations in the grid, long-term balancing in particular will become more important. Even if there is no feed-in of solar or wind power, it has to be possible to meet the demand. There are different storage technologies that have to prove themselves against other flexibility options (e.g. gas turbines) with regard to their profitability and contribution to system security, among other factors. Grids can also play a role in this if the regions with high storage potential (such as the Alps or Norway / Sweden) are more closely meshed with the neighbouring regions.

So far, there is no middle road. Today it is unforeseeable how the different storage technologies will evolve and which ones will be able to best meet future requirements. Here, too, there are still high economic, technical, ecological and legal challenges. There is a great need for research and pilot projects to ensure the creation of the right "storage mix" for Germany.
However, it is important that the current large storage units in Germany, particularly the pumped storage stations, can remain connected to the grid.

Further information can be found in our position paper on storage, which is available on our website under the following link: http://www.50hertz.com/Portals/3/Content/Dokumente/Medien/Positionspapiere/20140630_50Hertz-Positionspapier_Speicher.pdf

Why are the grid fees not the same for all of Germany and how can the costs be more fairly distributed?

Grid fees constitute about a fifth of the electricity price. The system operators' costs are billed to the consumers within their grid area. In some grid areas, the grid fees are clearly much higher than in others.

This is because:

  • some more thinly populated areas and less industrialised regions have fewer consumers to which the fees can be billed;
  • precisely those regions with a leading role in the field of renewables have high operating costs for the secure integration of volatile current into the electrical system, which further add to the grid fees when system operators have to frequently intervene in market activities and incur costs as a result (e.g. for so-called redispatch);
  • some regions have already modernised their grids and have higher depreciations as a result.

A unified federal grid fee should therefore be created to ensure a fair distribution of the costs for the integration of renewables into the grid, from the source to the wall socket (transmission and distribution system operators).

As an intermediary step, at least the grid fees of transmission system operators should be evenly distributed across Germany to avoid a further widening of the gap between grid fees. As a final step, the regime should abolish the avoided grid fees for volatile feed-in units borne by the distribution systems.

You can find detailed information on the subject of grid fees in our position paper on electromagnetic fields, which is available on our website under the following link: http://www.50hertz.com/Portals/3/Content/Dokumente/Medien/Positionspapiere/2014910_50Hertz-Positionspapier-Netzentgelte.pdf

How will the EEG surcharge evolve and how can it be kept stable in the future?

As per the EEG, electricity generated from renewable energy sources is currently subsidised over a period of 20 years via a surcharge that is individually assigned to the electricity bill. This instrument to support renewables was accepted very well by both investors and private persons: since 1991, 33 GW of both wind and solar power have been installed in Germany. Biomass produces some 6 GW. This is the main reason why over eleven years, the EEG surcharge has gone up from 0.35 to 6.17 cents per kilowatt-hour (kWh) in 2015. As such, the EEG surcharge constitutes one fifth of the electricity price for households.

How the EEG surcharge will evolve in the future is unclear at this point. The greatest influence on the development are fluctuations of the electricity price on the stock exchange: if the price on the exchange drops, this means less revenue from the marketing of RES power on the exchange. The amount of the payments to the RES installation operators, on the other hand, remains the same.

Fluctuations in the feed-in of RES power due to special weather conditions are considerably less influential - nevertheless, a year with plenty of wind and sunshine can also lead to a higher extra cost. The third strongest effect is the increase in RES installations. If many installations are put into operation, this also creates additional costs.

On 15 October of each year, the transmission system operators can provide a reliable outlook on the amount of the EEG surcharge for the year to come. The EEG surcharge for the following year is announced at that time.