Reader Question: Can I Upgrade a Small Biogas Plant for My Power Supply?


Question: “I have a 75 kW biogas plant based on liquid manure. Since I have enough manure with 500 cows and offspring, I can scale up the system to 100 kW. I am getting 200,000 for my electricity supply in the company kWh of additional generated power, as we have a power consumption of 250,000 kWh per year. Is this legally possible and what should I consider regarding top-up and self-consumption?”

Answer: Attorney Dr. Helmut Loibli

The assessment depends very precisely on when such a small liquid composting plant was commissioned: legislators have made very different specifications in individual renewable energy laws (EEGs) and allow older plants to use the newer ones. opportunity is neglected (or intentionally omitted). Regulations.

Depends on EEG

His vote:

  • EEG 2012: Maximum (installed) power 75 kW,
  • EEG 2014: Maximum (installed) power 75 kW,
  • EEG 2017: Maximum installed power 150 kW, rated power 75 kW (note: “double superstructure” is required from 100 kW)
  • EEG 2021: Maximum installed capacity 150 kW, but also here: a double superstructure from 100 kW is required. It makes sense to install here only 99 kW, since up to this output power can be fed completely. From 100 kW, only half of the electricity produced can be fed into the grid.

This includes self-consumption

Whereas before EEG 2012 it always depended on the amount of electricity, from EEG 2012 the output is based on the kWh generated, i.e. the power itself used is also part of the system output. Results for systems according to EEG 2012 and 2014: If more than 75 kW is installed here to use the electricity as self-power, then the entire small-scale liquid composting system remuneration no longer applies!

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In EEG 2017 you can expand to 99 kW, but own power reduces the maximum permissible amount to 75 kW, so that expansion will ultimately be nothing or you will have to accept a huge loss in remuneration. Example: If you add 25 kW to your 75 kW system (which is easier to calculate than 24 kW), you will exceed the allowed amount by a quarter. Accordingly, you will receive remuneration only for 56 kW. Reason: Network operators always impose proportionate overruns. It is also conceivable that the network operator will forfeit the entire claim of remuneration if the rated output (including own power) exceeds 75 kW. We have never had such a case in practice.

Exception: new systems from 2021

With the system to generate electricity according to EEG 2021, you can increase the installed capacity to 99 kW and then produce it, whether it is put into the electricity grid or used on its own. With more than 100 kW of installed power, you should only be producing half of the installed power. However, this only applies to systems newer than 01.01.21. You have to check on a case-by-case basis whether self-consumption is more economical than feed-in tariffs.

Conclusion: Even if your ideas make sense from an operational and energy-efficient point of view, expanding the old 75 kW system is not feasible.

Dr. Helmut Loibal, Paluka Lawyer


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