ESO says £54bn required to upgrade grid for offshore wind

Up to £54 billion worth of new grid infrastructure will be required to deliver the government’s target to increase UK offshore wind generation capacity to 50GW by 2030, National Grid Electricity System Operator (ESO) has calculated.

In a landmark report, published on Thursday (8 July), the ESO outlined the pathway for the transmission network upgrades that it said will be needed to enable this anticipated increase in offshore wind generation.

This includes the Holistic Network Design (HND), which is intended to provide a more co-ordinated approach to developing the network than the point-to-point connections with the onshore grid that offshore wind farms currently rely on.

This “radial” model is “no longer fit for purpose without potentially risking avoidable impacts on consumers, the environment and communities”, according to the ESO document.

The document estimated that £54 billion of total investment will be required to upgrade the grid to cope with the extra offshore wind generation due to come on stream by the end of this decade.

This total includes 94 reinforcements of the onshore transmission network, worth £21.7 billion by 2030.

Another £32 billion will be required for offshore infrastructure, including £7.6 billion of additional capital costs for delivering co-ordinated rather than radial connections.

The additional offshore transmission infrastructure includes four new subsea cables to connect wind farms off the eastern coasts of Scotland and England with the biggest sources of demand in London and the South East.

However, this additional £7.6 billion of additional capital expenditure will be outweighed by £13.1 billion of savings as a result of offshore wind generation not being constrained by grid limitations.

These savings will result in consumers saving approximately £5.5 billion, which works out as £2.18 per household per annum, according to the ESO.

Key reinforcements

Other benefits identified in the report include a 32TWh increase in the availability of offshore wind on the system over a ten-year period from 2030.

Less need for gas-fired generation will cut CO₂ emissions by 2 megatonnes between 2030 and 2032, which the report said is the equivalent to the UK’s entire domestic air transport emissions.

In addition, greater sharing of infrastructure by wind farms will mean a 30% reduction in the footprint for the cables required to bring the electricity onshore.

However, the transmission network upgrades proposed in the pathway document will not be achieved unless the planning process is speeded up, according to the ESO.

Greater coordination of connections will also require “significant changes” to industry codes and standards, which the ESO said it will progress during the second half of 2022.

Responding to the report, Renewable UK’s director of future electricity systems, Barnaby Wharton, said: “Today’s publication of the Holistic Network Design is the first step towards a more co-ordinated approach for designing and developing an electricity network to deliver our offshore wind ambitions. Rather than taking a piecemeal approach to connecting wind farms, by looking instead at the whole picture we can find efficiencies and reduce impacts on communities and the environment.

“There is still a lot of work to be done, and we’re looking forward to working with the ESO and industry to connect more projects faster and provide further solutions to enable cost-effective grid upgrades”.

Paul Cooley, director of offshore wind at SSE Renewables described it as “a welcome first step in identifying the supporting infrastructure needed to help enable Britain’s transition to net zero through the delivery of 50GW offshore wind by 2030”.

He added: “It must be highlighted though that there is a significant volume of offshore wind capacity still without certainty of their connection date and location which needs to be urgently resolved.”