From farmer to energy farmer with 75 kW mini-biogas plants based on liquid manure

The EEG amendment 2012 gives the biogas market impulses for a course change. This also includes the promotion of mini biogas plants, for example based on liquid manure. For the operation of a small biogas combined heat and power plant connected with this, correspondingly less substrate is required to feed the biogas plant. What space requirements (former NawaRo bonus) or how many cows (former liquid manure bonus) are required to ensure the operation of a micro biogas plant? The above graphic and article address this question and include the data from the most recent agricultural census of the Federal Statistical Office.

New remuneration class for micro biogas plants up to 75 kW in the amended EEG 2012

With the valid from January 2012 Renewable Energy Law (EEG) and the additional funding of micro biogas plants up to 75 kW, the biogas landscape in Germany will change again. The previous trend towards larger biogas plants will be supplemented by a development trend for micro biogas plants. 80% of these have to be operated with liquid manure so that the subsidy rates can be fully utilized and the investments in the required biogas technology pay off as quickly as possible.

In the new performance class for biogas plants up to 75 kW, a tariff of 27 cents per kilowatt hour of electricity produced is paid if the requirements are met (see Section 2012b in the EEG 25). This high remuneration payment for the new mini biogas plants is not tied to the newly added "remuneration classes" (see article Remuneration classes in the EEG 2011), but basic remuneration and feedstock bonus payment are covered together by the 25 cents / kWh.

In addition to a changed remuneration structure, the new EEG 2012 primarily promotes the direct marketing of the electricity produced by biogas plants. See also the article on Introduction of the market and flexibility premium.

Here you can find more articles on economic Operation of a biogas plant according to the EEG.

Download the EEG amendment 2012 as PDF

This one Link to download a consolidated version of the Renewable Energy Sources Act 2012. The topic of bioenergy is dealt with from § 27 and all changes to the previous version are shown in bold as usual.

First agricultural census in Germany in 10 years

In order to gain an overview of how many farms this subsidization of small biogas plants could be of interest, below is a small insight into the latest agricultural census.

The first agricultural census in Germany in 10 years shows a total of 2010 agricultural holdings for 300.700. Together they cultivate an arable area of ​​almost 17 million hectares. This corresponds to an average farm size of 56 hectares.

17% of the 71 million hectares are used for cultivating arable land and 28% for permanent pasture. With 3,3 million hectares, winter wheat remains the most frequently cultivated crop in 2010. This is followed by the cultivation of silage maize with a total area of ​​1,8 million hectares.

1,1 million people are employed in agriculture, which corresponds to a declining trend based on the last count.

You can get detailed information on the agricultural census in a published Federal Statistical Office article.

Mini-biogas plants need micro-biogas CHP

Even if the data from the agricultural census are only averages, an average farm has 56 hectares of land.

Is this space enough to think about building a mini biogas plant, including a biogas CHP? What space requirements should be planned for the construction of a 75 kW biogas plant? The graphic above should serve as the basis for the following suggestions.

Operated on a slurry basis, the new mini-biogas plant can theoretically be operated from a power of 1 kW and still receive the subsidy rates according to EEG 2012. That would correspond to a necessary manure quantity of 7 dairy cows. There are at least cogeneration plants, which are delivered with an output of 1 kW. These include, for example, the following 3 micro CHP units:

  • the “Dachs Stirling” micro CHP from SenerTec with 1 kWel, released in spring
  • the WhisperGen with 1 kWel
  • the micro-CHP ecoPOWER 1.0 from Vaillant

The combined heat and power plants are also available with a modular and higher performance range. It is problematic, however, that none of the manufacturers of the micro-CHP units, apart from the use of bio natural gas, also gives biogas as a possible fuel. A lack of information in the technical instructions can also simply be due to the market for micro-biogas CHP plants that has hardly existed up to now.

The website also offers a good overview with manufacturer-neutral information on mini and micro CHP units "CHP Prince".

Space requirements for mini biogas plants

The construction and economical operation of a 1 kW biogas plant is more challenging than finding a suitable micro CHP! At least I have never heard of such a small and very decentralized biogas plant. Do you know of such mini biogas plants?

Here is a possible scenario for a farm with an integrated mini-biogas plant.

Assuming the average farm in Germany (56 hectares), which cultivates 60% maize and 40% grassland, a biogas plant with an output of at least 68 kWel could operate. The following "equation" shows how this value came about.

  • 60% of 56 hectares = 34 hectares x 0,5 hectares of maize (per 1 kW BGA) = biogas plant with 68 kW

The remaining 22 hectares can be used as permanent grassland for dairy cattle grazing. With a high stocking, the grassland can be used for a livestock of 55 dairy cows.

  • 2,5 cows / hectare x 22 hectares = 55 cows

The manure of these 55 cows in turn provides the manure for the operation of an 8 kW biogas plant.

There are many ways to combine dairy farming and biogas and energy production.

Conversion of 1 hectare (ha)

A farmer or planner, of course, does not need to be told the area "hectares". In order to give a somewhat broader audience an idea of ​​1 hectare, finally some conversion information.

  • 1 hectare = 100 x 100 m = 10.000 square meters
  • 1 hectare = 100 ares
  • 1 hectare = 1 football fields measuring 5 x 105 m (FIFA standard)

Advice on mini biogas plants

BiomassMuse specializes in the planning of mini biogas plants according to § 27 b EEG 2012. I am happy to support you with your "Mini-Biogas Plant Project" and offer consultations for the construction and operation of small systems between 30 and 150 kW.

Here you can order the monthly newsletter from BiomassMuse.

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7 comments on “From the farmer to the energy farmer with 75 kW mini biogas plants based on liquid manure”

  1. Get Tickets here! the link to an interesting forum discussion on the subject of mini biogas plants between 10 - 25 kW on the agrarheute website.

    During this discussion, some practical suggestions for the installation of a mini biogas plant (especially based on liquid manure) are given.

  2. Liquid manure biogas plants have the advantage that they come from what the farmer has on the farm and that should be enough. If the manure is only rich for 20 kw = good.

    But everyone is talking about 75 kW systems with what should the remote meter be "fed". Know an example that has 450 GVE is probably the exception?

    At the beginning of the biogas plant you also looked at what the farmer had on the farm and then came the request for a high "kw number"! And the substrate food = corn

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