Renewable Energy Sources Act: Flexibilisation potential for existing plants

06.06.2025

A monitoring programme regularly examines the effectiveness of the Renewable Energy Sources Act. In the current evaluation report, previously untapped potential for flexibilisation was identified with the collaboration of the DBFZ.

The feed-in of electricity from renewable energy sources was first regulated in 2000 by the then newly introduced Renewable Energy Sources Act (Erneuerbare-Energien-Gesetz, EEG). After several years of its effectiveness and an increase in the feed-in of electricity from various sources over time, the need arose to analyse the effect of the regulated measures and any necessary adjustments and readjustments in more detail. To this end, an annual report has been published since 2011 to monitor the impact of the Act. This report shows not only the quantities of energy fed into the grid and the installed capacity, but also other parameters such as the costs per energy source. The DBFZ has been directly or indirectly involved in the preparation of the monitoring report for biogas, sewage gas, landfill gas and mine gas for many years. This also covers the biomethane sector and the resulting increase in sector coupling with the heating, gas and transport sectors.

The DBFZ is currently supporting the Federal Ministry for Economic Affairs and Energy (BMWE) in a joint project with the Fraunhofer IEE Kassel (project management) and ESE with sound and comprehensive scientific information on electricity generation from biomass plants, which can be used as a basis for the draft of the Renewable Energy Sources Act report.

The current evaluation report was published in February 2025. The report documents the development of biomass plants in Germany and contains, among other things, cost analyses on the design of the future funding regime. Existing plants in particular show relevant potential for flexibilisation. Possible adjustments to the tendering design were considered for selected plant concepts, which can be used to further develop the flexibility instruments in the Renewable Energy Sources Act. The results of the cost analyses show that a variant with 3-fold overbuilding (~ 3,000 operating hours/year) results in a necessary flexibility surcharge of at least €100/kW, while a variant with 4-fold overbuilding (~ 2,500 operating hours/year) requires a minimum flexibility surcharge of €125/kW. A switch to lower operating hours should be accompanied by an increase in the flexibility surcharge in order to adequately compensate for cost increases. If an annual gradual reduction in operating hours is aimed for, it is recommended that the level of the flexibility surcharge be aligned with the targeted degree of flexibilisation in order to create stronger incentives to make the systems more flexible.

In order to determine the maximum values for biomass plants in the tendering rounds of the Federal Network Agency (BNetzA), reference was made to the cost considerations of the evaluation report, among other things.

Detailed information can be found in the report from February 2025 at the following link: EEG monitoring project report (in German).