ScottishPower Commits £1.5bn to Double Whitelee Capacity to 1 GW by 2035
The 124-turbine rebuild of Britain's largest onshore wind farm exposes the gap between Scotland's generation ambitions and transmission capacity that can carry the power south.
ScottishPower Renewables announced on Tuesday (2026-07-22) that it plans to spend £1.5 billion repowering Whitelee wind farm on Eaglesham Moor, south of Glasgow, replacing 215 ageing turbines with 124 machines standing around 250 metres tall and doubling the site's generating capacity from 539 MW to 1 GW, with full operations targeted by 2035, Montel reported.3,4
A large portion of Britain's first-generation onshore wind fleet was built in the 2000s and early 2010s, and repower decisions for that cohort are now arriving in bulk. Whitelee, as the country's largest onshore site, sets a visible benchmark for how that repowering cycle will be structured, priced and permitted.4
The turbine count falls sharply in the new design — from 215 machines to 124 — while nameplate capacity nearly doubles. That ratio reflects how far turbine technology has moved in a generation. Modern machines at around 250 metres hub-to-tip generate far more per unit than the kit they replace, and fewer foundations reduce operational maintenance costs over the asset life. The more consequential variable is the net effect on grid connection requirements, since Whitelee's existing grid access rights do not automatically carry over to a doubled capacity figure.4
Grid infrastructure is where the economics of Scottish onshore wind become contingent. A report published on 9 June 2026 by Aurora Energy Research, cited by Montel, found that prioritising Scottish onshore expansion over offshore development after 2030 could deliver system savings of around £5bn per year through lower subsidy and balancing costs — but only if transmission infrastructure kept pace, according to Phil Hewitt, director at Montel Analytics. Aurora modelled a scenario in which roughly 75% of planned Scottish offshore capacity coming online between 2031 and 2036 would shift to onshore instead. Whitelee, doubling in size on an established site with existing road and grid infrastructure, sits squarely in that arithmetic.2
But existing grid connections are not a free pass. A doubled nameplate capacity requires additional export headroom, and Whitelee sits in a part of the Scottish transmission zone already under congestion pressure. ScottishPower has not disclosed the terms of the grid connection it expects for the expanded site, and the planning and connection queue for Scottish onshore wind remains congested.4,2
The £1.5 billion capital commitment is large by onshore wind standards. For context, 124 turbines at 250-metre class size implies per-unit costs in the tens of millions of pounds each, before civil works, grid connection, and decommissioning of the existing 215-turbine fleet — a cost not separately quantified in the announcement. ScottishPower has not disclosed a funding structure, contract-for-difference assumptions, or merchant revenue strategy for the project.4
Planning consent will take years. Whitelee's original development process was lengthy even before modern visual impact and aviation radar constraints on tall turbines became as contested as they are now. At 250 metres, these machines are among the tallest structures proposed for the UK onshore environment, and consenting risk for the timeline is material. ScottishPower has not said whether it has submitted or intends to submit a planning application imminently.4,3
The Dogger Bank South offshore approval granted to Masdar and RWE earlier this year for a 3 GW offshore project confirms the UK is still consenting large-scale capacity additions, but offshore and onshore consenting regimes differ substantially in Scotland, where planning is devolved. The Whitelee repower will be decided under Scottish rather than UK government process.1
For GB power market participants, a 1 GW Whitelee delivering by 2035 adds meaningful low-marginal-cost capacity to the Scottish generation mix and would affect settlement patterns in the northern half of the GB grid, particularly Balancing Mechanism dispatch and constraint payments across the B6 boundary between Scotland and England. The system operator's ability to export that additional Scottish generation south without increased curtailment payments hinges on transmission reinforcement that has not yet been built.2,4
ICE Endex TTF front-month closed Friday (2026-07-25) at €63.76/MWh, a level at which gas-fired generation in GB retains a place in the dispatch stack. Incremental Scottish onshore wind capacity from a repowered Whitelee would compete directly for run-hours against gas-fired plant, reinforcing carbon and gas price exposure for generators holding unhedged thermal positions from 2030 onwards.
The next concrete milestone is whether ScottishPower files a formal Section 36 consent application with Scottish ministers, which would start the clock on a multi-year planning process and give the market a firmer read on whether the 2035 operational target is achievable or aspirational.3,4