Notice

GGSS budget caps, production factors, and inflation forecasts for 2024-2025

Updated 20 December 2024

Applies to England, Scotland and Wales

This page covers the Green Gas Support Scheme (GGSS) budget caps and their supporting information effective for the 2024-2025 financial year (1 April 2024 to 31 March 2025).

The Department for Energy Security and Net Zero (DESNZ) is required to publish this information under the Green Gas Support Scheme Regulations (reg. 4(13)).

The GGSS has 2 budget caps, which are shown in Table 1: the Application Budget (AB), which limits estimated spend by acting as a cap against which all applications to the scheme are checked, and the Overall Scheme Expenditure Budget (OSEB), which sits above the AB, and is used to set the Green Gas Levy rate.

This page also contains the production factors (Table 2) and inflation forecast (Table 3) used to set the budget caps for the 2024-2025 financial year, which are used in the assessment of applicants’ estimated annual payments against available budget when they apply for a tariff guarantee.

Following the extension of the scheme closure date to March 31 2028, this page has been updated to include budget caps and inflation forecasts for years 2028/2029 and 2029/2030.

Further information on GGSS budget caps and the production factors and inflation forecasts used to set them is published on the GGSS Budget Management Guidance page.

Budget caps

Table 1: GGSS budget caps (set 22 December 2023, effective from 1 April 2024)

Year 2024/25 2025/26 2026/27 2027/28 2028/29 2029/30
AB (£M) 51.7 80.3 124.9 174.2 203.8 214.3
OSEB (£M) 54.6 92.3 143.6 200.3 234.4 214.3

Production factors

Production factors are used to estimate the proportion of a plant’s total registered capacity that we expect to be used to produce eligible biomethane in any given quarter of a plant’s time on the scheme.

Table 2: Production factors used to estimate AB commitments from 1 April 2024

Quarter following registration Production factor
Q1 48%
Q2 61%
Q3 64%
Q4 69%
Q5 71%
Q6 72%
Q7 73%
Q8 75%
Q9 76%
Q10 77%
Q11 80%
Q12 81%
Q13 81%
Q14 80%
Q15 80%
Q16 83%
Q17 85%
Q18 86%
Q19 87%
Q20+ 88%

Inflation Forecast

The inflation forecast used to calculate budget caps effective from 1 April 2024 to 31 March 2025 was based on the Office of Budget Responsibility’s Consumer Price Index (CPI) forecast published in November 2023. Each financial year’s figure is set at the OBR’s forecast for Q4 for the preceding calendar year.

Ofgem is responsible for uprating GGSS tariffs annually on 1 April, starting on 1 April 2023, using the actual CPI rate from the previous December. This covers inflation for that calendar year and is published by ONS each January. The forecast used from the OBR to set budget caps is used as the closest available for the figure that Ofgem will use – the forecast rate for Q4 for each calendar year is the closest to the December rate.

Table 3: Inflation forecast used to estimate AB commitments from 1 April 2024

Financial year 2024/25 2025/26 2026/27 2027/28 2028/29 2029/30
Estimate of CPI inflation 4.8% 2.8% 1.5% 1.5% 1.8% 2.0%