e-Highway 2050: Grid architectures for 2050

Challenge
Where and how to locate the necessary grid reinforcements that overcome the weak points of the 2030 transmission system when facing the challenging conditions expected for the energy system in 2050?

Background and assumptions 
The methodologies and assumptions to identify the grid bottlenecks and the progressive construction of the Transmission Requirements (TR) by an iterative approach aiming at minimizing the effects of grid limitations at least cost are described here.

In brief, the implemented grid development process aims to find an optimal solution between two extreme situations: (i) no further reinforcements are implemented after 2030. The grid investments are then minimal but the operating costs of the power system are high because grid congestion can prevent the use of the cheapest generation units; (ii) virtually infinite capacities are built between all the clusters of the starting grid (the so-called “copper plate” assumption). The grid investments are then extremely expensive, but the operating costs of the power system are minimal because the cheapest generation can always be used wherever its location.

The resulting efficient grid architecture from a European techno-economic perspective is scenario dependent following the e-Higwhay2050 scenarios and over a simplified European transmission system (about 100 nodes built upon 100 geographical clusters). The granularity of the results is thus not as accurate as in a study that would tackle a closer time horizon and use a full grid model. The approach gives the priority on the detection of a major electric energy transportation needs between clusters.

1. Overview of the proposed new transmission reinforcements at 2050, per scenario
When observing the needed transmission reinforcements at 2050 resulting from the project simulations, major “North – South” corridors appear in all scenarios with several reinforcements that connect the North of the pan-European electricity system (North Sea, Scandinavia, UK, Ireland), and southern countries (Spain and Italy), to the central continental area (northern Germany, Poland, the Netherlands, Belgium and France).


Figure 1 : Transmission requirements identified in each scenario (GW): upper line ”Large scale RES” (green), “Fossil and nuclear” (brown), “100% RES” (blue), 2nd line “Big & Market” (red), “Small & local” (orange)

The number of liaisons requiring reinforcements according to the e-Highway2050 assumptions amounts to 150 links out of the 247 identified inter-cluster links candidate for reinforcements (56 submarine and 191 terrestrial).  These 150 links are split according to their type and the morphology of the corridor (terrestrial or submarine) as follows.


Table 1: Breakdown of the 150 links on identified non-zero Transmission Reinforcements

The amount of links should however be adjusted to take into account the scenario dependency as shown in the two tables below (respectively in absolute number and in the form of a metric capturing the order of magnitude of the related investment in in GW*000’km).


Table 2: Overview of the number of links with non-zero Transmission Requirements, per scenario


Table 3: Overview of the Transmission Requirements (TR) needs index, per scenario

All scenarios show significant transmission need. The scenarios “100% RES” and “Large Scale RES” lead to “heavier” transmission requirements than the “Small & Local” and “Fossil Fuel & Nuclear” scenarios. “Large scale RES” and “100% RES” show important needs for major infrastructures in the middle of the continental system, on top of the peripheral network investments required by all the scenarios: the volumes of renewable in both scenarios, especially coming from the North Sea, are such that all the corridors from these sources to the major load centers need to be reinforced.

2. Generic reinforcements at 2050 whatever the scenarios  
Even if the five scenarios are extremely different, some major corridors remain common to all of them. They are robust to the large uncertainties at 2050 and constitute thus good candidates for mid-term grid investments.
Figure 2 pinpoints the similarities between scenarios, emphasizing only the corridors that have been reinforced in at least two of the covered scenarios. The ranges of size of the corridors to be developed is also displayed.


Figure 2 : Common reinforcements (widths are according to average reinforcement capacity and the color represents the number of scenarios where the reinforcement is needed)

The identified major common corridors relate to important changes in the generation capacities with respect to their 2012 values.


Table 4 : Main drivers for major common corridors

3. Overview of costs and benefits
The figure below gives the total investment costs for each scenario as well as their corresponding annuities. For the three less critical scenarios (Big & market, Fossil & nuclear, Small & local), the total cost ranges between 120 and 220 b€ depending on the public acceptance of new overhead lines and therefore the available reinforcement technologies. In the scenarios Large Scale RES and 100% RES, the architectures are almost twice as expensive with a total cost around 250 b€ in the case of new grid acceptance and around 390 b€ with DC cables in case of status quo.


Figure 3: Investment costs and annuities of the final architectures for each scenario

When analysing the impacts of the architectures in each scenario, with a focus on security of supply and optimal dispatch, it can clearly be seen in the figure below that the grid reinforcements provide a large benefit.


Figure 4: Unsupplied energy, extra spillage and increase of operating costs in the different scenarios, before and after grid reinforcements

For all scenarios, almost all ENS has been solved, and generation redispatch has been drastically reduced. The total annual benefits in each scenario can be compared to the annuities of investment. Even with the strategy “status quo” in which only refurbishment of existing lines or new DC cables can be implemented due to a strong public opposition to new OHL infrastructures and with an ENS cost of 1000 €/MWh, the architectures identified in each scenario are profitable.

When assuming a cost of ENS of 10 000 €/MWh, the architectures in the scenarios Large Scale RES and 100% RES are even profitable within one year, what is explained by the tremendous amount of congestions. The reinforcements are more significant in those two scenarios - the investment cost is doubled compared to the others, but they are also much more profitable: their benefits are three to nine times higher.

These investments don’t take into account the additional reinforcements inside clusters which will be necessary for the proper functioning of the system. Nevertheless, these additional reinforcements will be significantly less expensive than the reinforcements between clusters and so they should only slightly reduce the profitability.

References
[1]    B. H. Bakken, M. Paun, R. Pestana, G. Sanchis, “e-Highway2050: A Modular Development Plan on Pan- European Electricity Highways System for 2050”, Cigre Lisbon, April 2013
[2]    G. Sanchis, RTE et alia, “A methodology for the development of the pan-European Electricity Highways System for 2050”, CIGRE Paris, August 2014  
[3]    Thomas Anderski, Amprion et alia, deliverable D2.3 System simulations analysis and overlay-grid development – Digest.
[4]    T. Anderski, Amprion; F. Careri, RSE; N. Grisey, RTE; G.Migliavacca, RSE; D. Orlic, EKC; G. Sanchis, RTE. e-Highway2050: a research project analysing very long term investment needs for the pan-European transmission system. Cigre Paris. Submitted to Cigre Paris, August 2015
[5]    http://www.e-highway2050.eu
[6]    Thomas Anderski, Amprion et alia, deliverable D2.4 Contingency Analyses of Grid Architectures and Corrective Measurements, to be published end of 2015
[7]    ENTSO-E, “Ten-Year Network Development Plan (TYNDP)”, www.entsoe.eu/major-projects/ten-year-network-development-plan/, 2014