​Ofgem announced its Minded-to decision on Long Duration Energy Storage (LDES) on July 21 2026. Subject to consultation, this awarded 7.6 GW and 136.9 GWh of Cap and Floor contracts across 16 projects, with 79% of the energy capacity awarded in North Scotland.

By 2030, the operational timeline Window 1 requires, we expect 1 GW / 8.5 GWh of projects online. In our firm scenario, made of projects with planning, land and grid in place, Modo Energy expects the LDES cap and floor to deliver 2.5 GW / 55 GWh by 2035. In our probable scenario, delivery is 5.6 GW / 99 GWh by 2036.

Key takeaways

• Of the 16 “minded-to” LDES projects, 8 currently hold planning permission.
• Of the Planning consents awarded, these are typically for larger projects by MW, but smaller by MWh. Schemes will have to amend their planning permissions accordingly, which could present additional challenges - particularly where initial consents were difficult to come by.
• The five Field projects have a high density of GWh per hectare of site, indicating they intend to use 9MWh BESS containers which are not currently available - but could be by 2033.
• None of the sites hold Gate 2 offers, and 7 sites hold Gate 1. The TEC register shows LDES grid capacity could reach 4.4GW by 2030 and 7.2GW by 2035.
• We provide several buildout scenarios. The firm scenario, made up of sites which currently have planning, grid and land has 2.5 GW / 55 GWh of LDES online in 2035. The probable scenario adds sites which we consider likely to secure these by 2030, and has 5.6 GW / 99 GWh in 2036.

For any comments, suggestions or follow-ups on this analysis, please get in touch with robyn@modoenergy.com.

If built, the LDES batteries will be the largest batteries in the world

The Window 1 minded-to projects feature 11 lithium-ion batteries. If built, these assets will be among the biggest battery sites in the world, and by a long way the largest in Great Britain. The chart shows the LDES batteries as compared to the largest operational BESS sites in the markets that Modo Energy track.

Given planning, grid and land available, the detailed analysis below gives sensitivities on how likely we think these sites (as well as the non-battery LDES bids) are to become operational, and when. It does not consider individual project economics.

How many LDES sites do we think will get built, and when?

We separate the LDES projects into four buckets of likely delivery: firm, probable, possible and speculative.