When the 20-year payment under Germany’s Renewable Energy Sources Act (EEG) ends for a biogas plant, operators essentially have five routes: follow-on support through the biomass tenders of the Federal Network Agency (Bundesnetzagentur), switching to biomethane, conversion to a smaller plant, continued operation without support, or closure. For most farm plants the tender is the obvious route, but it requires flexible operation and therefore investment. Everything here reflects the situation in October 2026. The EEG rules for biogas were last overhauled in February 2025 with the so-called biomass package (Biomassepaket), and further changes are possible.
When support ends
The statutory payment is generally made for 20 years. For many older plants the commissioning year is added, so payment ends on 31 December of the twentieth following year. Many German biogas plants were built between 2004 and 2012, so support is running out for a large part of the fleet during these years.
Plan the decision several years ahead. Follow-on support requires a valid permit for the new term, an expert certificate on flexibility and often investment in the combined heat and power (CHP) unit, gas storage and heat storage. These steps often take more than a year.
Follow-on support through tenders
Under section 39g EEG, biomass plants commissioned before 1 January 2017 may take part in the biomass tenders. The tender dates are 1 April and 1 October each year. Key points:
- Maximum value: for existing plants it was 19.83 cents per kWh at both 2026 tender dates. You bid a value up to this limit, and the lowest bids win.
- Small plants: plants up to 150 kW installed capacity receive the highest successful bid of the same round as their award value.
- Switch date: the new entitlement replaces the old one from a month you choose between the third and the 42nd month after the award is announced.
- Evidence: an environmental verifier must certify technical suitability for demand-oriented operation, and the permit must run until at least the end of the 13th calendar year after the tender date.
- Feedstocks: for awards in 2026 to 2028, cereal grain and maize together may make up no more than 25 per cent by mass. Biomethane may not be used in the plant.
At the 1 April 2026 tender date around 727 MW were on offer. Bids totalled 637 MW, and 491 MW received an award. The results of the 1 October 2026 round had not yet been published at the time of writing. Under section 28c EEG, the annual tender volume falls from 1,126 MW in 2026 to 326 MW in 2027 and 76 MW in 2028.
Flexible operation as a requirement
Since the biomass package, follow-on support only covers electricity from a limited number of operating quarter hours, namely those with the highest output. The rules are set out in section 39i EEG:
| Plant size | Supported operating quarter hours per year | Roughly equivalent to |
|---|---|---|
| up to 350 kW installed capacity | 16,000 | 4,000 hours |
| above 350 kW | 11,680 | 2,920 hours |
Under section 39i EEG the number falls in steps of 500 quarter hours in later years of support. If you want to keep converting the same amount of gas into electricity, you therefore need to increase CHP capacity considerably (overbuilding) and store gas during periods of low power prices. This usually requires larger gas storage, a heat store and suitable controls.
In return, section 50a EEG provides a flexibility premium (Flexibilitätszuschlag) of 100 euros per kilowatt of installed capacity per year. For the share of capacity that already received a flexibility premium in the past, it is 50 euros. Check with a planner whether the necessary investment pays off over the term of follow-on support.
Biomethane as an alternative
Instead of generating electricity on site, the gas can be upgraded to biomethane and injected into the natural gas grid or sold as vehicle fuel. Buyers include heat suppliers, biomethane CHP units at other sites and the transport sector. Because of the high cost, upgrading usually only pays off for larger gas volumes. Several farm plants can pipe their raw biogas to a shared upgrading unit. Details are in the guide to biomethane upgrading.
Conversion to a small manure plant
For livestock farms it is tempting to switch the old plant to mainly manure and use the payment under section 44 EEG. Legally this is not straightforward: the section 44 values apply to newly commissioned plants. If existing digesters and gas storage remain in use, the plant usually keeps its original commissioning date, even if a new CHP unit is installed. Have your specific case checked legally before investing, for example through an enquiry to the EEG and CHP clearing body (Clearingstelle EEG|KWKG) or by agreement with the grid operator.
Regardless of this, scaling down to a smaller output with a high manure share can also make sense in the tender, because plants up to 150 kW benefit from uniform pricing. How a small manure plant works is explained in the guide to the small manure biogas plant.
Continued operation without support, or closure
Without support you can sell electricity on the exchange through a direct marketer, under a long-term supply contract, or use it yourself. Exchange revenue is generally not enough for biogas plants to cover feedstock, maintenance and labour. This becomes interesting mainly where a heat network must continue to be supplied or where electricity and heat replace expensive purchases on your own farm.
If no option is economic, closure follows. This involves:
- Informing the grid operator and any heat customers in good time.
- Registering the closure in the market master data register.
- Emptying tanks properly, flaring residual gas safely and using digestate correctly.
- Informing the competent authorities; for plants permitted under immission control law, the cessation of operation must be notified.
- Planning demolition or reuse of the tanks, for example as slurry stores.
Making the decision
Run all options with the same assumptions: revenue under follow-on support, investment in flexibility, feedstock costs, heat revenue and demolition costs. The biogas calculator helps with an initial assessment.
If you plan to take part in a tender, clarify early on:
- whether the permit covers the planned term and higher CHP capacity or needs amending
- whether the grid connection and transformer can take the additional capacity
- which gas and heat storage is needed for flexible operation
- how heat customers will be supplied when the CHP unit only runs at certain times
- which environmental verifier will issue the certificate and what documents they need
Agree your bid with your bank, because the investment in flexibility has to pay back within the new support period. Because tender volumes fall sharply from 2027, operators whose support is ending should prepare early for the remaining tender dates. Planning offices experienced in flexible operation and tenders are listed under planning and engineering.
Frequently asked questions
When does my biogas plant's EEG payment end?
The payment is generally made for 20 years. For older plants the year of commissioning is added, so support ends on 31 December of the twentieth year after the commissioning year. The exact date is in your records with the grid operator and in the German market master data register (Marktstammdatenregister).
How early can I take part in a tender?
Existing plants can bid once their current payment entitlement has only a limited remaining term at the time of the tender. After winning, you choose when to switch to the new support within a set time window. Check the current version of section 39g EEG and take advice.
Can I convert my old plant into a small manure plant?
Conversion is often technically possible. Whether the converted plant receives the payment under section 44 EEG for new plants depends on whether it legally counts as newly commissioned. If existing digesters continue in use, this is usually not the case. Clarify this in advance with the grid operator or the EEG and CHP clearing body (Clearingstelle EEG|KWKG).
What happens if my bid is unsuccessful?
You can bid again at a later tender date as long as your plant meets the requirements. Without an award, the options are selling electricity without support, switching to biomethane or closure. Because tender volumes fall sharply from 2027, later chances become scarcer.
How much power and revenue could your livestock deliver? Run the numbers with open assumptions.
Open the biogas calculator