Biogas Plants and Battery Storage for Greater Flexibility
Why Battery Storage as a "Green Co-Location" Is the Future of Flexibility for Biogas Plants
EEG subsidies (subsidies under the Renewable Energy Sources Act) have been instrumental in driving the expansion of renewable energy in Germany, particularly for biogas plant operators. But for many pioneers in the biogas industry, a critical date is approaching: the end of the 20-year EEG subsidy or the subsequent follow-up subsidy. Without the fixed feed-in tariffs, many biogas plant operators are faced with the question of how they can continue operations. One innovative option is to integrate biogas plants with battery storage systems.
The End of EEG Subsidies
In the past, operating a biogas plant was more predictable: produce and feed electricity into the grid, no matter what time of day. But as subsidies phase out, biogas plants are becoming market participants. Those who feed electricity into the grid when the sun is shining and the wind is blowing often receive only minimal—or even negative—prices. To remain economically viable, flexibility is essential.
Co-located Battery Storage as an Alternative Revenue Model
A battery storage system can be one way to increase flexibility, allowing electricity generation to be decoupled from the time of sale. There are two main approaches to this, which differ both legally and technically:
Green Co-Location: Focus on Biogas-Generated Electricity
In a green co-location setup, the battery storage system is powered exclusively by the biogas plant (and, if applicable, other on-site renewable sources). The battery storage system enables cross-market optimization—that is, selling electricity in various electricity markets. The battery can thus supply electricity to the spot market, as balancing power, or through intraday trading.
Gray co-location: Maximum market freedom
Gray co-location eliminates the strict distinction between green and gray electricity. In this scenario, the battery storage system can draw electricity from both the biogas plant and the public grid.
What should I keep in mind when choosing a battery storage system for my biogas plant?
A common mistake in planning is sizing the battery storage system too small. As a general rule, the battery should have a capacity greater than the output of the biogas plant (CHP). Why? Only if the storage capacity can accommodate the CHP plant’s entire output over several hours can production be shifted entirely to the most attractive time slots of the day on the intraday market.
If the storage capacity is too small, the biogas plant operator is forced to feed electricity into the grid even when prices are low, as soon as the battery storage is full. This prevents the operator from fully leveraging the system’s flexibility and, consequently, maximizing profits.
Conclusion: Battery Storage as an Opportunity for Biogas
The combination of biogas and batteries is an innovative way to enable the continued operation of a biogas plant in an economically viable and profitable manner, independent of fixed feed-in tariffs.
Would you like to know what storage capacity would be ideal for your specific CHP plant output? Or whether it’s worth selling the excess power from your flexible biogas plant? Feel free to schedule an appointment with our colleague Matthias Mengler:
