North Wales and the Midlands boundaries

The Western transmission region includes boundaries in the Midlands and the north of Wales. This includes the lower midlands boundary B9 and the north Wales boundaries NW1, NW2 and NW3.

West ETYS map

The figure above shows the general pattern of power flow directions expected to occur most of the time in the years to come up to 2031, i.e. power will generally flow from north to south. The arrows in the diagram illustrate power flow directions and are approximately scaled relative to the winter peak flows.

Regional drivers

Future offshore wind and biomass generation connecting in North Wales have the potential to drive increased power flows eastward into the Midlands where power plant closures are set to occur, and demand is set to remain fairly high.

By 2030, the scenarios suggest a total amount of transmission-connected generation capacity of between 17GW to 21GW, from the current 17GW. At present, this region has significant levels of fossil fuel (about 14GW). All scenarios show a decline in fossil fuel with slight growth in interconnectors and storage and a significant growth in low-carbon technologies. For all scenarios other than Steady Progression, fossil fuel generation is not present in the region by 2050.

A new 0.5GW interconnector to Ireland will be connecting in this region from 2024 and in additions there will be between 1 – 3.5 GW of additional storage connecting in this region by 2030.

All scenarios show a decline in fossil fuel with slight growth in interconnectors and storage and a significant growth in low-carbon technologies.

West demand

The graph shows that the gross demand as seen from the transmission network in the region will increase across all scenarios. As with other regions, this is driven by the adoption of technologies such as electric vehicles, heat pumps and embedded storage.

In a high decentralised scenario like Leading the Way, local generation capacity connected at the distribution level in this western region could reach 23GW by 2030. Of that capacity, a typical embedded generation output on average might be around 7GW. This will vary depending on factors like wind speeds, and how other local generators decide to participate in the market.

The need for network reinforcement to address the potential capability issues will be evaluated in the NOA 2021/22 CBA.

Boundary regions

Click on the regions below to expand the boundary and understand its capability and challenges.

If you would like to learn how to interpret the graphs, click the button below.

 

Interpreting boundary graphs

The graphs show a distribution of power flows for each of our Future Energy Scenarios, in addition to the boundary power transfer capability and NETS SQSS requirements for the next twenty years. ​

Each scenario has different generation and demand so produces different boundary power flow expectations. From applying the methodology in the NETS SQSS for wider boundary planning requirements (as discussed in chapter 2), we determine for each scenario:

  • The economy criteria - solid coloured line

  • Security criteria - dashed coloured line

  • Current boundary capability – solid black line

Due to the NOA being published after the ETYS, the boundary capability line (red line) is prepared from the 2020/21 (previous year’s) NOA optimal path released in January 2021 which uses the 2020/21 FES and ETYS data. This is the best information available at the time of publication and will change annually and over time as the network, generation, demand and more importantly the NOA optimal path changes. More information about the NOA methodology can be found here. The 50%, 90%, Economy RT and Security RT are calculated from the 2021/22 FES and ETYS processes. Where the NOA transfer capability is not available, there is a black line that provides the current ETYS 2021/22 transfer capability​.

Note: Boundary capability line is affected by the generation and demand profiles within each FES background. Therefore, the graphs are provided for indicative purposes only and cannot be directly compared. ​

The calculations of the annual boundary flow are based on unconstrained market operation, meaning network restrictions are not applied. This way, the minimum cost generation output profile can be found. We can see where the expected future growing needs could be by looking at the power flows in comparison with boundary capability.​

On each graph, the two shaded areas provide confidence as to what the power flows would be across each boundary:

  • The darker region shows 50% of the annual power flows

  • The lighter region shows 90% of the annual power flows​

From the regions, we can show how often the power flows expected in the region split by the boundary are within its capability (red line). If the capability of the boundary is lower than the two regions over the next 20 years, there might be a need for reinforcements to increase the capability. However, if the line is above the shaded regions, it shows that there should be sufficient capability here and that potentially no reinforcements are needed from a free market power flow perspective until the shaded regions exceed the capability (red line).

Boundary B9 – Midlands to South of England

 

Boundary B9 separates the northern generation zones and the southern demand centres.​

Developments in the east coast and the East Anglia regions, such as the locations of offshore wind generation connection and the network infrastructure requirements, will affect the transfer requirements and capability of boundary B9.​

Boundary Flows and Base capability

The capability line (in red) is based on the recommendations from the NOA 2020/21 optimal path which uses the 2020/21 FES and ETYS data as inputs. The 50%, 90% Economy RT and Security RT lines are based on FES 2021/22.

The current boundary capability is limited to 12.5GW due to a voltage constraint for a fault on the Enderby-Ratcliffe on Soar double-circuit​.

In all four scenarios, the requirements gradually increase to above the boundary capability for B9. The increase is more than last year showing a need for additional boundary capability in the future for three out of the four scenarios.

The generation expected behind B9 is a combination of offshore wind generation and biomass generation.​

North Wales – overview

The onshore network in North Wales comprises a 400kV circuit ring that connects Pentir, Connah’s Quay and Trawsfynydd substations.​

A 400kV double-circuit spur crossing the Menai Strait and running the length of Anglesey connects the now decommissioned nuclear power station at Wylfa to Pentir. A short 400kV double-circuit cable spur from Pentir connects Dinorwig pumped storage power station. In addition, a 275kV spur traverses north of Trawsfynydd to Ffestiniog pumped storage power station.

Most of these circuits are of double circuit tower construction. However, Pentir and Trawsfynydd within the Snowdonia National Park are connected by a single 400kV circuit, which is the main limiting factor for capacity in this area. The area is studied by analysing the local boundaries NW (North Wales) 1 to 3.​

 

Boundary regions

Click on the regions below to expand the boundary and understand its capability and challenges.

If you would like to learn how to interpret the graphs, click the button below.

Interpreting boundary graphs

The graphs show a distribution of power flows for each of our Future Energy Scenarios, in addition to the boundary power transfer capability and NETS SQSS requirements for the next twenty years. ​

Each scenario has different generation and demand so produces different boundary power flow expectations. From applying the methodology in the NETS SQSS for wider boundary planning requirements (as discussed in chapter 2), we determine for each scenario:

  • The economy criteria - solid coloured line

  • Security criteria - dashed coloured line

  • Current boundary capability – solid black line

Due to the NOA being published after the ETYS, the boundary capability line (red line) is prepared from the 2020/21 (previous year’s) NOA optimal path released in January 2021 which uses the 2020/21 FES and ETYS data. This is the best information available at the time of publication and will change annually and over time as the network, generation, demand and more importantly the NOA optimal path changes. More information about the NOA methodology can be found here. The 50%, 90%, Economy RT and Security RT are calculated from the 2021/22 FES and ETYS processes. Where the NOA transfer capability is not available, there is a black line that provides the current ETYS 2021/22 transfer capability​.

Note: Boundary capability line is affected by the generation and demand profiles within each FES background. Therefore, the graphs are provided for indicative purposes only and cannot be directly compared. ​

The calculations of the annual boundary flow are based on unconstrained market operation, meaning network restrictions are not applied. This way, the minimum cost generation output profile can be found. We can see where the expected future growing needs could be by looking at the power flows in comparison with boundary capability.​

On each graph, the two shaded areas provide confidence as to what the power flows would be across each boundary:

  • The darker region shows 50% of the annual power flows

  • The lighter region shows 90% of the annual power flows​

From the regions, we can show how often the power flows expected in the region split by the boundary are within its capability (red line). If the capability of the boundary is lower than the two regions over the next 20 years, there might be a need for reinforcements to increase the capability. However, if the line is above the shaded regions, it shows that there should be sufficient capability here and that potentially no reinforcements are needed from a free market power flow perspective until the shaded regions exceed the capability (red line).

Boundary NW1 – Anglesey

Boundary flows and base capability

The capability line (in black) is based on the ETYS transfer capability using FES 2021/22 data, shown below.

The current boundary capability is limited by the infrequent infeed loss risk criterion set in the SQSS, currently 1.8GW​.

For all scenarios in the FES, the requirements increase to above the boundary capability for NW1. Last year, only the System Transformation and Consumer Transformation scenarios did so. This increase suggests a need for additional boundary capability in the near future for NW1 to support the increasing amounts of generation behind it.​

Boundary NW2 – Anglesey and Caernarvonshire

Boundary flows and base capability

The capability line (in red) is based on the recommendations from the NOA 2020/21 optimal path which uses the 2020/21 FES and ETYS data as inputs. The 50%, 90% Economy RT and Security RT lines are based on FES 2021/22.

The current boundary capability is limited to 1.4GW due to a thermal constraint on the Pentir - Trawsfynydd single circuit​.

Across all four FES scenarios, the SQSS economy required transfer is higher than the current capability. The expected power flows only see significant changes from around 2033 when they increase very sharply as large new offshore wind projects come online.

The scenarios show a similar requirements until 2033 where they diverge due to different assumptions of connection time and dispatching of potential offshore wind and biomass generation behind this boundary.​

Boundary NW3 – Anglesey and Caernarvonshire and Merionethshire

Boundary flows and base capability

The capability line (in black) is based on the ETYS transfer capability using FES 2021/22 data, shown below.

The current boundary capability is limited to 1.4GW due to a thermal constraint on the Connah’s Quay - Bodelwyddan -Pentir circuit​

Across all four FES scenarios, the SQSS economy required transfer grows beyond the present boundary capability only after 2033 onwards. The expected power flows only see significant changes from around 2033 when they increase very sharply as large new offshore wind projects come online.

The scenarios show a similar requirement until 2033 where they diverge due to different assumptions of connection time and dispatching of potential offshore wind and biomass generation behind this boundary.