Ofgem Approves £20 Billion Accelerating Strategic Transmission Investment Projects

Executive briefing: On November 22, 2023 Ofgem approved £20 billion in Accelerating Strategic Transmission Investment (ASTI) projects to reinforce Great Britain’s electricity network. The decision covers 17 onshore transmission upgrades—ranging from subsea HVDC links to overhead line reinforcements—needed to connect 50 GW of offshore wind by 2030.

Key policy signals

HVDC expansion. Ofgem authorised projects such as Eastern Green Links 2 and 3, delivering 4 GW of subsea capacity between Scotland and England.
Cost oversight. The regulator set cost allowances and delivery milestones, with clawbacks if transmission owners miss schedule or budget commitments.
Accelerated delivery. ASTI lets transmission owners spend ahead of the next RIIO price control, shortening lead times for critical reinforcements.

Control alignment

UK capacity planning. Update UK demand siting and power purchase strategies with the new HVDC import capacity and north–south transfer boosts.
Program governance. Align supplier management and reporting with Ofgem’s milestone tracking and clawback conditions.
Grid outage coordination. Prepare for construction-related outages on Scottish and English transmission corridors as ASTI projects mobilise.

Action checklist

Engage National Grid ESO and transmission owners to understand outage sequencing for ASTI projects affecting corporate loads.
Revisit UK renewable integration roadmaps factoring in 2030 offshore wind delivery enabled by the approved upgrades.
Monitor Ofgem’s cost adjustment mechanisms to manage exposure if project scope or timing changes.

Sources

Zeph Tech works with UK operators to integrate ASTI delivery schedules into resilience planning and offshore wind integration.