Spain: Real Decreto 917/2025 changes the specific regime for renewables, including biogas and biomass

Spain published Real Decreto 917/2025 in the BOE of 16 October 2025. It amends Real Decreto 413/2014, which regulates electricity generation from renewables, cogeneration and waste under the specific regime. The amendment concerns, among other things, the calculation of equivalent operating hours for hybrid installations with energy storage. The specific regime is the one under which biogas and biomass installations are also supported.

Why the rules were changed

The preamble of the decree states that the electricity sector is undergoing a deep transformation: according to the preamble, renewable sources contributed more than 50% of annual electricity generation for the first time. According to the text, the adjustments are meant to allow installations with economic rights to adapt to the current mix and to remove barriers to energy storage hybridised with such installations.

Equivalent hours

Annual revenue under the specific regime is reduced when an installation's number of equivalent operating hours falls below the minimum, and if it falls below the threshold set for the standard installation, the owner may lose the right to the regime in a given year. Equivalent hours are the quotient of energy sold on the market and installed capacity. So that generation modules without self-consumption do not lose revenue after being combined with storage, the decree clarifies the definition in art. 21 para. 2, and in art. 11 para. 6 it guarantees operating support for energy produced by a renewable module, regardless of whether it goes to the market or to a storage module.

Historical background

The text recalls that over the last decade the regime has required targeted interventions: measures under Real Decreto-ley 23/2020 during the pandemic for installations dependent on fuel prices, changes under Real Decreto-ley 6/2022 and 10/2022 after the energy price crisis in Europe, and the change under Real Decreto 376/2022 introducing sustainability and emission-reduction criteria for biofuels, bioliquids and biomass fuels, together with a system of guarantees of origin for renewable gases. The most recent change to the operating support methodology was Orden TED/526/2024 (see the article on that order).

Significance for biogas and biomass

The rules apply to all installations under the specific regime, including biogas and biomass power plants, provided they are operated by entities entitled to that regime. Hybridisation with storage makes it possible to shift energy sales over time, and the new definition of hours is meant to prevent penalising installations that direct part of their output to batteries.