The UK biomethane subsidy cliff

2026-06-17 · 6 min read

Nearly every operational UK biomethane plant earns the bulk of its revenue from one of two government support schemes — and both have a hard end date. Understanding when that date falls, plant by plant, is the single most important input to valuing the asset class.

Two schemes, two clocks

The Non-Domestic Renewable Heat Incentive (NDRHI) supported biomethane injected to the grid with a tiered tariff for 20 years from accreditation. Its successor, the Green Gas Support Scheme (GGSS), supports the post-2021 cohort for 15 years. Both tariffs are RPI-indexed, so a plant's subsidy income rises with inflation — right up until the window closes, when it drops to zero and the plant is left selling gas at the merchant price.

When the cliff actually arrives

The UK's first grid-injection biomethane plant came online in 2012, and the bulk of the NDRHI fleet was commissioned between 2012 and 2014. Add the 20-year support window and the cliff for that cohort lands in 2032–2034. (Across the full NDRHI + GGSS fleet, the single busiest cliff window computes slightly later — the live cliff tracker shows the current figure.) In other words: in 2026, essentially no real plant is at its cliff. The cliff is a forward-planning horizon — a refinancing and exit-timing question — not a present-day distress event. Treating it as an emergency today misreads the data; ignoring it entirely misprices the asset.

Why it drives value

A biomethane plant's enterprise value is dominated by the discounted subsidy income to the cliff, plus a thinner merchant-gas tail beyond it. Two otherwise-identical plants can be worth very different amounts purely because one has twelve years of subsidy left and the other has four. For a buyer, the years-of-subsidy-remaining is the first number to establish; for an owner, the approaching cliff is the clock on a refinancing or sale.

The data problem

Computing a plant's exact cliff requires its accreditation date — which is not cleanly published per installation. InfraValue tracks commissioning years from curated public sources and flags where a date is an estimate, so the cliff horizon is transparent rather than asserted. The Subsidy Cliff Tracker shows the year-by-year exposure across the fleet.

InfraValue maps every UK biomethane plant to its owner, distress signals and subsidy-cliff exposure from public-register data. Screening tool only — not investment advice. See plans →