Capacity inputs

GB will have 400 GW of connected generation by 2050

The capacity stack reflects the total installed capacity of all power generators connected to the GB National Grid, including interconnectors.

The GB Electricity System Operator (ESO) has committed to having the capability to run a zero carbon grid by 2025; and a fully green grid, all the time, by 2035. The UK government has committed to the UK being net zero by 2050. These dates influence the growth of renewables in our capacity stack.

Here's the full capacity stack from 2024 to 2050, which we break down bit by bit below. Note that EVs are not included here.

Overall wind capacity at 120 GW by 2050 with 90 GW of it offshore

Offshore wind

From now until 2035, we get individual offshore wind farm capacities from our wind buildout pipeline, constructed using the Renewables Obligation, Contract for Difference (CfD) registers, and RenewableUK project list.

The pipeline accounts for the lack of offshore wind in CfD AR5, and the latest results from the AR6 auction. There are currently 20 GW of offshore wind capacity assigned to projects without a commissioning date. These are the projects granted seabed leases as part of 'Scotwind'. We assume these sites come online between 2035 and 2040, i.e. after the expected commissioning of those that do have dates. After 2040, informed by the FES and taking a modest view on as-yet unscoped projects coming online between 2040 and 2050, we estimate a total of 87 GW of offshore wind by 2050 in our central scenario.

In our Low scenario, we assume a more modest offshore wind buildout which gets to 65 GW by 2050 (see Macro Scenarios for detail).

Offshore wind

To 2035 we get individual onshore wind farm capacity from Renewables Obligation, Feed-in-Tariff, Contract for Difference (CfD) registers, and RenewableUK project list. We use the expiry date of these various subsidies to get a subsidized and unsubsidized pipeline. After 2035, we take onshore wind numbers from FES 2024 Electric Engagement as these agree with our pipeline.

The wind Contract for Difference round impacts the short-run marginal cost so is modelled separately

We assume all new CfDs going forward are floored at £0/MWh, and early rounds (labelled AR1 in the figure) are priced at £100/MWh. Onshore wind and solar PV were not eligible for CfDs in AR2 or AR3.

Subsidised solar retires whilst domestic and unsubsidised utility PV gets to 80 GW by 2050

For solar, from now until 2035, we use the Renewable Obligation and Feed-in-Tariff registers. We extract these numbers from those in the FES to get an unsubsidised and subsidised pipeline to 2050.

Gas: low-efficiency CCGT goes by 2041, with CCS picking up after 2031

The capacities of gas CCGT, OCGT, and recip engines are determined by our Capacity Expansion model (which flexes the build-out of each technology in response to economic signals).

Low-efficiency CCGT plants will retire by 2038. Mid-efficiency CCGTs, OCGTs, and Gas CHP will retire by 2044. High efficiency Gas CCGTs retire by 2045, and 2GW of Gas Recips remain online in 2050.

These retirements are sensitive to the role of carbon in the Capacity Market. More on how we approach this here.

We forecast 21 GW of CCGT CCS by 2050.

Low carbon baseload provided by biomass and new nuclear

We take biomass numbers from the FES, and separate out Drax from this capacity as their public accounts give extra information (particularly around CCS).

Old nuclear consists of Hartlepool, Heysham 1 and 2, Torness, and Sizewell B. New nuclear consists of Hinkley Point C (online in 2029 and 2031), Sizewell C (in 2033 and 2036), along with 8.8GW of other new nuclear from 2035.

We have updated our models according to the announcement (Jan 2024) of the delay to Hinkley Point C.

Low carbon peaking generation: DSR and hydrogen peakers

The FES provides a guide on hydrogen capacity but doesn't dictate what it is. We assume it's all peaking as we don't think a hydrogen CCGT makes economic sense. More on that next.

Demand Side Response (DSR) is given three subtypes: Low, Mid and High price. This indicates the cost of using it (i.e. how easily it can be used) at times of system stress. Low is priced at £250/MWh, Mid at £500/MWh, and High at £1500/MWh.

Low-priced DSR might be automatically turning down electric heating or cooling in response to a high price. High-priced DSR might require more manual intervention, that has a cost - like shutting off a factory supply line, suspending manufacturing for a few hours.

Battery, EV, Pumped and Other Storage