Spain’s environment ministry has put a draft Royal Decree out for consultation that would, for the first time, oblige gas suppliers to blend a rising minimum share of biomethane into national natural gas and LNG sales, starting at 0.5% in 2028 and climbing each year to 6% by 2035. The obligation is backed by biomethane Guarantees of Origin, carries the legal weight of a “very serious infraction” for non-compliance, and on the ministry’s own arithmetic the 2035 target equates to close to 10 TWh of biomethane against the gas demand the PNIEC and CNMC project. Comments are open until 11 June.
This converts Spanish biomethane from a subsidy-and-voluntary story into a compliance one. The measure derives from Royal Decree-law 7/2026 of 20 March, the package assembled in response to the Middle East supply crisis, which frames the mandate squarely as import substitution rather than climate policy alone. Secretary of State for Energy Joan Groizard announced it. Obligated parties are the gas retailers and direct market consumers, who will have to surrender biomethane GoOs to demonstrate compliance, with the ministry to set the monitoring and reporting procedure separately.
What the carve-outs reveal
The exemptions matter more than the headline percentage. Gas burned in combined-cycle and cogeneration plants is excluded, as is consumption in the island territories and all gas used in road, maritime and air transport, the last because it falls under the separate renewable-energy-in-transport rules still in transposition. The 6% therefore applies to a deliberately narrowed base, essentially industrial and buildings heat demand on the peninsula.
The read here is that Madrid is segmenting biomethane demand into three non-overlapping pools so that no molecule is claimed twice across regimes: the grid-blending obligation for heat and industry, the transport sub-mandate for mobility, and the power market left to electricity-side instruments. That is clean from a double-counting standpoint and it is why the ministry’s 10 TWh equivalent sits well below a percentage applied to total gas throughput. It also caps the addressable volume the mandate can pull.
A demand signal the supply base cannot yet meet
Spain entered 2026 with 23 biomethane plants, 21 of them injecting into the grid, and total production capacity near 1.4 TWh a year. Getting to roughly 3 TWh by 2030, the 1.8% step, implies something like a doubling of today’s capacity, and the 2035 endpoint near 10 TWh implies close to a sevenfold increase over the decade. Resource is not the constraint. Sedigas puts national potential at around 163 TWh a year, equivalent to nearly half of gas demand, and ranks Spain among Europe’s top three by potential. The binding limits are project pipeline, permitting and capital, and an independent Comillas estimate of 9.71 TWh achievable by 2030 against a 10.41 TWh reference shows how tight even the near-term numbers are once you move from potential to deliverable.
The genuinely useful provisions are the ones getting least attention. The draft reclassifies reverse-flow equipment as regulated assets of the gas system, defines the connection installations needed for injection, and creates direct connection lines for plants producing non-natural-gas combustible gases. Most Spanish biomethane potential sits in rural, agricultural settings wired to distribution rather than transmission, where the economics of injection have been killed by connection cost and seasonal flow mismatches. Socialising reverse-flow capacity into the regulated asset base is the supply-side unlock that actually moves the buildout, more than the quota line itself. Sitting alongside it is a national excellence seal covering social, territorial and environmental criteria, which projects must hold to count toward the quota.
What this means for Spanish biomethane GoOs and developers
The mandate manufactures obligated demand for Spanish biomethane GoOs from 2028 into a market where physical supply is years behind the curve. That points to firm and potentially spiky certificate prices in the early compliance years, with the effective ceiling set by whatever sanction regime attaches to a “very serious” breach once defined. The single most price-relevant unknown in the text is what it does not say: whether GoOs from biomethane injected in other member states will be recognised toward the Spanish obligation. The draft’s emphasis on injection into the national grid and on a domestic excellence seal points toward a ringfence. If that holds, Spanish GoOs decouple from fungible European biomethane certificates and trade at a domestic premium, which is bullish for local developer economics and turns the seal into a de facto non-tariff barrier protecting the home pipeline.
The non-obvious risk runs the other way. The same scarce domestic molecules can be sold into the transport sub-mandate, which under the EU framework carries multipliers and double-counting that the blending obligation does not. Faced with a thin supply base and two compliance buyers, producers will route GoOs to whichever pays the higher effective price, and the transport mechanism is structurally built to outbid. Unless the blending decree and the transport rules are calibrated together, the new heat-and-industry quota could find itself competing for, and losing, the very biomethane it was written to mobilise. Watch the relative pricing between the two obligations as the leading indicator of whether the 6% path is deliverable or merely declarative.
