• Required transfers across Scottish boundaries are expected to almost triple from today to 2030. The coordinated approach of the Holistic Network Design (HND) provides additional transfer capability to these boundaries, especially B6, and will relieve some of the constraints across Scottish boundaries from 2030 by providing new routes for power flows. Offshore wind generation projects considered by the HND and HND Follow-up Exercise (HNDFUE) are factored into the ETYS’s generation background (as per FES 2022). 

• Required transfers across North Wales boundaries are expected to quadruple between 2027 and 2032 to a maximum of 11GW in the Leading the Way scenario. Large amounts of generation, including new offshore wind generation is expected to connect in this region. 

• In the East Anglia region, growth in low-carbon and renewable generation over the next decade will continue, potentially reaching a total installed capacity of over 13GW by 2030, up from 5.5GW today, across all FES scenarios. 

• Interconnector and storage capacity is anticipated to reach a total 9 – 12GW in the South of England by 2030. Network flows in the region will be driven largely by market conditions and the direction of interconnector flow, and large swings in power transfer are possible as these interconnectors move from exporting to importing (or vice-versa). The south coast region will therefore require careful network management. 

The ETYS describes the network capability by looking at the maximum secured power transfer between two regions or the power transfer across a boundary. 

To operate the network safely, we must make sure that the power flow across the boundary do not exceed the capability of the system between the two regions. To prevent this, we must take actions to constrain generation which can incur significant costs. 

The two heatmaps below illustrate the impact of the network reinforcement options recommended in the NOA Refresh 2021/22, showing how these options can significantly reduce constraints by increasing the power transfers across boundaries. 

It is vital that both onshore and offshore reinforcements are developed in a timely and coordinated manner to maximise the network benefits and ensure that the transmission network can provide power to demand centres in a safe, reliable, and economic manner. 

We welcome Ofgem’s decision to accelerate strategic onshore electricity transmission projects through the new Accelerated Strategic Transmission Investment (ASTI) regulatory framework. This recognises the scale and pace required to deliver the Government’s 2030 renewable energy ambitions. Ofgem expect this will have a net benefit to consumers of up to £2.1bn in reduced constraint costs and carbon savings, contingent on timely project delivery.

_{Chart uses the NOA 2021/22 Refresh recommendations following the Leading the way scenario against FES 2022 flows}

The ESO is also proactively developing non-build solutions for regions where a short-term requirement has been identified. For example, the EC5 Constraint Management Intertrip Service (CMIS) is being launched to reduce constraint costs across the EC5 boundary (found in East Anglia) for the 2025 – 2030 period by offering additional network management options during real-time network operation. This follows the success of our Constraint Management Intertrip Service now in operation for the B6 boundary.

The past year has sparked recognition of the importance of a faster transition to net zero and an increasing focus on Great Britain’s, as well as the rest of the world’s, energy security. This highlights the need for the ESO and the wider industry to secure the network against a wider range of conditions. 

Currently, the ETYS process focuses on securing the network against a winter-peak scenario for thermal or low-voltage constraints. With the ongoing rise in intermittent and converter-based technology on the transmission system we need to expand our view of system needs to a wider range of requirements including voltage and stability needs across a range of scenarios over the year.  

We have continued to develop our year-round thermal analysis tool (Power Uncertainty Year-round Adviser – POUYA) to help us evaluate year-round network flows. The ESO is developing new enduring processes to assist us in identifying and managing system needs relating to voltage and stability. We are also working with our transmission and distribution partners to determine how system needs across the transmission-distribution interface could be communicated. 

We will value your feedback on our latest ideas and would like to hear your thoughts on how we can continue to enhance ETYS to communicate a wider range of year-round system needs. Read more in Improving the ETYS to integrate a wider range of system needs.