This short briefing looks at the issue of Curtailed wind and whether it can be solved by the construction of hyperscale AI data centres
In 2025 windfarms in the UK were paid £363 million to switch off when the power generated exceeded the capacity of the grid to transmit that energy to where it was needed [Montel].
The curtailment of renewable energy happens due to the limitations of the grid infrastructure and the fact that so much energy is generated very far from the demand centres. The supply of energy needs to continually match the demand, and if too much is pushed into the system it can result in voltage and frequency spikes that may damage equipment and appliances [NESO, Margins].
Data centres can use curtailed wind when there is too much energy being produced, this is true, but the issue is that they also need to consume energy when there is no surplus energy and when the wind is not blowing. This means they need access to alternative sources of power when the wind is not blowing and this is likely to be gas and nuclear generation coming from the south.
The issue of curtailed wind is also a short term issue. The UK is building six interconnectors (see Table 1) to take energy from Scotland south, the total capacity of these will be 12GW and the first two are expected online in 2029 and will add 4GW transmission capacity between Scotland and England, thus eliminating much of the current curtailment issues.
| Link name | Power capacity | Expected completion date | Location |
| Eastern Green Link 1 (EGL1) | 2GW | 2029 | East Lothian to County Durham |
| Eastern Green Link 2 (EGL2) | 2GW | 2029 | Aberdeenshire to North Yorkshire |
| Eastern Green Link 3 (EGL3) | 2GW | 2033 | Aberdeenshire to Lincolnshire |
| Eastern Green Link 4 (EGL4) | 2GW | 2033 | Fife to Norfolk |
| Western Link 2 | 2GW | Early 2030s | Ayrshire to Wales |
| And an additional one that has just awarded a contract for initial investigations | |||
| Eastern Green Link 5 (EGL5) | 2GW | 2035 | Aberdeenshire to Lincolnshire |
Table 1: Undersea cables for energy transmission, under construction and planned
In addition to this it seems that the data centres are not being put in the right areas if their priority was to use curtailed wind energy. In Great Britain and Northern Ireland, the grid is split between 14 regions with interconnectors at the boundaries limiting the power that can be moved between areas. In Scotland, there are two grid regions, North Scotland (owned and operated by SSEN) and South Scotland (owned and operated by SPT). The key boundary for curtailment is the B4 Boundary (Figure 1) between these two regions which is limited to 4 GW by the Tealing – Westfield 275 kV circuit.
The boundary with England is B6 (Figure 2), and has a capacity of 6.7 GW at the Harker-Moffat 400 kV circuit
Figure 1: NESO map of the B4 Boundary – the boundary capability is limited to 4 GW due to thermal constraint on the Tealing – Westfield 275kV circuit
Figure 2: NESO Map of the B6 Boundary The boundary capability is limited to 6.7 GW due to thermal constraint on the Harker-Moffat 400kV circuit.
A huge amount of the wind generation capacity is located in North Scotland, including the new capacity from Seagreen, Viking and Moray East totalling around 2.5 GW, where there is very little energy demand. This means that the B4 boundary is the primary pinch point for energy transmission. [UKERH]
In 2025 In the UK 10.14TWh of energy was curtailed at a cost of £363 million with 10.06 in Scotland and only 0.18 in England and Wales. Of the Scottish Figure, 8.8TWh (87.5%) of this was in North Scotland.[Montel] See download of the report here.
However all of the proposed hyperscale data centres in Scotland’s planning system (which have a combined capacity of 7.2GW) are south of the B4 boundary [APRS Data Centre Map] (see Figure 3), so it looks like they will not be able to use the vast majority of the constrained wind produced.
Figure 3: Map from APRS Data Centre map showing data centres in Scotland’s planning system