National Grid ESO has released its Electricity Ten Year Statement (ETYS) 2023 publication, forecasting strong capacity growth for the Electricity Transmission System particularly in Scotland, North Wales and East Anglia, but also highlighting concerns over interconnector infrastructure in the South of England.
The ETYS makes recommendations to guide future investment decisions for transmission owners (TOs) and has outlined various regions where significant growth is expected to continue as the UK moves towards net zero targets.
According to the report, required transfers across Scottish boundaries are expected to almost triple from today to 2030 as the nation ramps up its efforts to achieve net zero. However ESO points out that much of the renewables generation growth seen in Scotland is often in “areas where the electricity network is limited”.
This proves an issue for the renewable sector in Scotland. Building and extending transmission lines are lengthy, complex processes which require various planning and investment decisions.
Scotland in particular needs this to be rapidly scaled. ESO stated in the ETYS that, according to current projections, Scotland will effectively cease generating power from fossil fuels between 2030 and 2035. There is a requirement for new generation projects to be catered for to ensure a stable and reliable energy system.
For this, the ESO asserts that, by 2030, all of its scenarios show an increase in wind generation of between 11 and 25GW. This could prove to be pivotal for not only Scotland but the rest of the UK with the UK and Scottish Government having established targets of 50GW for offshore wind and 20GW for onshore wind by 2030.
Despite this growing renewable capacity in Scotland, the gross demand for energy is not expected to exceed 6GW by 2030, with the ESO predicting an average embedded generation output of 1.7GW, meaning it far exceeds demand. Because of this, Scotland will be expected to export power into England most of the time.
Another area expected to see significant growth in the renewable sector is North Wales, which in turn could support the Midlands region where power plant closures are set to occur leading to a decrease in generation capacity.
According to the ESO’s Future Energy System (FES) scenarios, the total amount of transmission-connected generation capacity could rise to around 22GW to 30GW by 2030 from the current 17GW.
This growth is forecast to come mainly from future offshore wind developments in the region in addition to biomass generation. All scenarios show a decline in fossil fuel generation capacity with slight growth in interconnectors and storage and a significant growth in low-carbon technologies.
Alongside North Wales and Scotland, East Anglia is expected to see further growth in low carbon and renewable generation over the next decade, according to the ESO. The ETYS states that total installed capacity could well reach over 13GW by 2030, an increase on the current 5.5GW.
The East of England has a total of 8GW transmission-connected generation. Across all of the ESO’s FES scenarios, this is forecast to increase to between 18GW and 21GW by 2030. This growth is primarily set to be from offshore wind projects.
Peak gross demand in the East of England is also expected to remain steady or potentially rise by up to 1GW.
The ETYS report also points to potential problems affecting South Wales and the South of England. ESO believes European interconnector developments along the south coast could potentially drive very high circuit flows, causing circuit overloads as well as issues for voltage management and stability.
Under the Leading the Way scenario, over 10GW of additional interconnectors and energy storage capacity could connect to the south by 2030 for a total of over 14GW. However European interconnector developments could lead to added pressure on the UK transmission system.
Interconnectors and storage are both bi-directional and thus the South could see capacity provide up to 14GW power injection or 14GW increased demand. The ESO said this could place a “very heavy burden” on the transmission network.
“If the interconnectors export power to Europe at the same time that high demand power is drawn both into and through London, then the northern circuits feeding London will be thermally overloaded,” it said.
Along with this, “If the south-east interconnectors are importing from the continent and there is a double-circuit fault south of Kemsley, then the south–east circuits may overload and there could be significant voltage depression along the circuits to Lovedean”.
The result of this could see voltage depression in London and the south-east of the UK. The closure of conventional generation could additionally present stability and voltage depression concerns, the ESO highlighted.