It is true that the use of underground cables will result in higher costs. But it is also clear that, in macroeconomic terms, even if the grid is expanded using underground cables, this is still the cheapest route to a successful energy transition.

In macroeconomic terms, grid expansion which meets with local acceptance and takes place in actual fact will reduce the costs of the energy transition. At present, congestion management is causing high costs (combined costs for redispatch, feed-in management, reserve power stations). These annual costs exceeded 1 bn euros in 2015. Unless there is significant progress on grid expansion, these costs will continue to rise in the coming years.

Greater use of underground cables will cost an additional €3bn to €8 bn in investment costs (compared to the costs under the former legal situation). These are one-off investment costs which do not recur annually. These increased investment costs will be passed on in the form of grid charges.

Over, it is very difficult to arrive at a precise cost estimate in this current stage of the planning. The extent to which costs will increase due to the use of underground cables in the ultra-high voltage transmission grid will very much depend on local conditions (actual route, soil conditions, transverse infrastructure, actual cost of components, etc.).

Where major electricity highways are concerned (= new ultra-high voltage direct current transmission lines), the Act will give priority to underground cables as a principle in federal planning. Overhead cables will only be used exceptionally in certain cases, e.g. in order to protect the natural environment. To put it simply, this means that there will be an absolute ban overheard cables being used wherever people live. So overhead cables can only be used in very strict exceptions.

There will be only manageable delays caused by the change to underground cables. The largest grid development projects, such as SuedLink and SuedOstLink, were at an early stage of the planning when the changes were made. So the decision came at the right time.

In view of the fact that the new priority for underground cables has meant that the entire planning for ultra-high voltage direct current transmission system has to be changed, the Bundesnetzagentur has developed a position paper outlining the roles the transmission line operators must abide by when conducting this planning work. Public consultations were held in connection with this paper. Comments were made by authorities, associations, universities, companies and citizens' initiatives, and fed into the final version of the paper. The Bundesnetzagentur published the Position paper (in German language) (PDF, 894 KB) in April 2016.

It is hard to predict this, because it will depend on tests in the later planning stages, i.e. particularly on environmental aspects. But it is clear that the vast majority of the cabling is to be placed underground. At the same time, it is very difficult to put a precise figure on it.

Underground cabling technology is more complex where AC powerlines are concerned. So underground AC cables will only be used as part of pilot schemes.

As far as new ultra-high-voltage AC cables are concerned, the Act expands the criteria and the number of pilot projects for this type of underground cable to allow for experience to be gained more quickly. The number of pilot AC projects (allowing for partial underground cabling) is being increased from three to four and ultimately to a total of eleven.

Under the new legislation, the Requirements Plan has been brought into line with the Power Grid Expansion Act, and the Federal Requirements Plan with the Federal Requirements Plan Act. This was done on the basis of the Network Development Plan for 2024, which was approved by the Bundesnetzagentur in September 2015.

In this document, the Federal Network Agency confirmed which powerlines will be urgently needed in the coming ten years. According to this, a total of approx. 5,800 km of new powerlines will have to be built by 2024; of which optimisation and upgrading of existing routes account for approx. 3,050 km. New calculations have shown that a total of 6,100 km of new powerlines (of which optimisation and upgrading of existing routes account for 3,050 km) will be needed by 2025.

In one of the key expansion projects – the SuedOstLink, formerly known as the Süd-Ost DC passage – the starting and finishing points were altered as a result of the relevant consultations. This outcome of the consultations has now been anchored in statute, making Wolmirstedt the starting point of SuedOstLink and Isar the finishing point.

It is important to note that at the stage of grid development planning, only the starting and end points are defined. The exact geography of the lines, in between the starting and finishing points, will be further specified in the future. But the starting and finishing points of essential powerlines have been bindingly stipulated by the legislator in the Federal Requirements Plan.