Planning and purchase of a mini biogas plant up to 75 kW

Since the EEG amendment in 2012 and the historically highest subsidy for a size class of biogas plants, the mini biogas plants up to 75 kW have moved into the awareness of many farmers and communities. Even if I am not aware of any mini biogas plant that was designed in accordance with Section 27 b EEG 2012 and that has started successful operation, we are working flat out on the development of functioning concepts. I am convinced that the first mini BGAs according to EEG 2012 will soon enrich the biogas landscape. Therefore, today there is an article that deals with the purchase of a mini biogas plant and shares previous experiences on this topic with you. What should you watch out for if you intend to buy and operate a mini biogas plant?

In previous articles I'm already on the Economy of the new mini biogas plants received and have a large part of the Provider of mini biogas plants presented in Germany.

In this article, the information is even more specific and the first experiences of plant planners, investors and farmers are incorporated. The aim is to create a decision-making aid for the purchase of a mini-biogas plant and to support the new type of plant, which has to overcome some initial difficulties.

You can find the entry to the article here Download the EEG 2012 (PDF) in a consolidated version and thus the legal text which nevertheless forms the legal basis for the new asset class.

Event on CARMEN eV mini biogas plants

Community of bioenergy is growing steadily and I am pleased that Germany is taking a global leadership role in the development of biogas technology.

For this article I also refer to lectures at an event on mini-biogas plants, which was carried out by CARMEN eV

For all readers to those of CARMEN eV is still unknown, I would like to briefly introduce the association. Most readers will Ccentral-AharshRohmMarketing-and-EdevelopmentNetzwerk for the promotion of renewable raw materials. With 20 employees and 70 members, the association in Straubing, founded in 1992, is one of the largest and oldest associations dedicated to promoting the material and energetic use of biomass.

Many thanks to CARMEN eV for making the lectures available. A further increase in cooperation between the various players in the bioenergy industry (e.g. at Facebook) would be very happy.

Planning before buying a mini biogas plant

Economy of a mini biogas plant

A major advantage of the mini-biogas plants according to § 27 b EEG 2012 is the comparatively simple remuneration structure for the bioenergy plants of the smallest performance type so far. With the flat-rate payment of 25 cents / kWh, the splitting of the remuneration rate into the basic remuneration and the feedstock remuneration is eliminated (see Compensation calculator with ESK 0 - ESK 2), as it has applied to larger biogas plants since the beginning of the year.

The following graphic from the presentation by Dipl-Geogr. Melanie Arndt from CARMEN eV shows a first compilation of the various cost factors for a 75 kW mini-biogas plant that is operated 85 percent with liquid manure. The complete presentation with statements about the various cost factors (substrate costs, investment costs, heat recovery, annual utilization rate etc.) is linked to the graphic.

Table costs mini biogas plant 75 kW
What costs can you expect when building and operating a mini biogas plant with 75 kW?

The creation of a detailed and medium-term economic concept is certainly one of the most important steps before buying a mini biogas plant. Good planning of income and expenditure minimizes the occurrence of financial surprises during construction and operation.

Financing for the purchase of a mini biogas plant

If you plan to purchase a mini biogas plant, you can rarely pay for the plant out of your own pocket. After all, an investment volume of between 5.000 - 8.000 € per kW system output should be planned.

The majority of the plant operators are financed on a mix of equity, subsidies (e.g. KfW funding program for renewable energies) and have to draw on a loan.

The ratio of the equity capital brought in and the debt capital required also determine the general conditions for the design of the bank loan when purchasing a mini biogas plant.

The financing of a mini biogas plant in the Straubing-Bogen region could look something like this, according to Franz Binder (Raiffeisenbank).

Overview of total costs of the mini-biogas plant 75 kW
Example of financing a mini biogas plant with 75 kW

This concept uses loans from the Landwirtschaftliche Rentenbank.

Selection of the right provider for the purchase of a mini biogas plant

The choice of the system manufacturer should not be underestimated when purchasing a mini biogas system and can make it easier to deal with any operating problems that may arise due to the services offered by the selected provider.

Here you will find one Overview of manufacturers of mini biogas plants from which you can obtain offers.

Not just the ideal fermenter (e.g. a Wooden fermenter) and the secondary fermenter must be carefully selected, but also the purchase of the right one Biogas CHP in the necessary performance class contributes to the economic success of your own mini biogas plant. The EEG 2012 stipulates for the 75 kW plants that the biogas must be converted into electricity directly on site, which clearly excludes the use of satellite CHP.

Partnerships in substrate purchase and heat sales make it easier to buy a mini biogas plant

As you know, together you are strongest and you can hope for synergy effects. Finding regional partners can bring the decisive cost advantage for a successful concept for operating a decentralized mini-biogas plant.

The possibilities for cooperation have already been discussed in the article "Win-win situation for communities thanks to micro biogas plants"Reports. Partnerships are particularly promising in the following areas:

  • Purchase of liquid manure or 20 percent renewable raw materials
  • Sales of heat
  • Use of a common digestate storage
  • Use of the digestate

Construction and operation of a mini biogas plant according to EEG 2012

Plant safety in the construction and operation of the mini biogas plant

After the planning, the construction and finally the operation of the mini biogas plant follow. The following steps are necessary for these steps:

  • Building permit according to building law
  • Taking plant and occupational safety into account
  • Measures for water and soil protection
  • Construction: power connection, foundations, trenches for gas, liquid manure and heat pipes, construction of the system parts (feeder, fermenter, CHP plant, digestate storage, etc.)
  • Liquid manure has been an animal by-product since 01.06.2012!

In addition, by the end of 2013, each biogas plant (including existing plants) must have a gas torch that is large enough to burn the entire amount of biogas produced in an emergency. In this way, it is to be avoided that methane, which is harmful to the climate, can escape into the atmosphere unused or that accidents at work can be risked due to released methane (explosive) or hydrogen sulfide (very toxic).

Substrate selection and quantity for your own mini biogas plant

Before a plant can be operated, a solid concept must be drawn up that justifies the purchase of a mini biogas plant from an economic point of view. A crucial point is a guaranteed substrate procurement for 20 years. How many livestock units (LU) or how many tons of manure do I need per year so that I can successfully operate a mini biogas plant?

In order to receive the fixed remuneration rate of 25 cents / kWh, the microbiogas plants have to use 80 percent of the following substrates:

  • Cattle manure
  • Pig manure
  • Beef crap
  • Pig manure
  • Horse manure
  • Goat manure
  • Sheep manure
  • Poultry manure is not one of them!

These substrates correspond to numbers 9 and 11 to 15 of Appendix 3 Biomass Ordinance (Download). Through this broad spectrum, very interesting partnerships can be constructed, at least in theory, if the farm's own manure quantities should not be sufficient. It will be seen in the coming months whether these partnerships for the procurement of liquid manure and the additional work involved in balancing will continue to exist in practice.

Classification of manure as waste entered into force on June 1, 2012 (amendment to the Recycling Waste Act). Even if this measure is not exactly popular with the operators of biogas plants, the use of liquid manure and waste in biogas plants has been further enhanced by the EEG 2012.

The amount of slurry required depends heavily on whether a mini biogas plant should be operated with 100 percent slurry or whether up to 20 percent of a higher-energy NawaRo substrate is used instead.

Slurry accumulation slurry quantities of mini biogas plants up to 75 kW
How much liquid manure or livestock units (GVE) do you need to operate a mini biogas plant?

Markus Niedermeier from Office for Food, Agriculture and Forests Regen (AELF Regen) calculates that the amount of around 75 tons of cattle slurry (14.000 percent slurry system) is necessary for a 100 kW biogas plant. For an 80 percent slurry plant that is supplemented by a 20 percent maize silage portion, only around 5.000 tons of cattle slurry are required to ensure the operation of the 75 kW mini biogas plant at 8.200 full load hours.

The details for the large livestock units required are very fluctuating and Mr. Niedermeier assumes a requirement of 600 - 700 LU for a 75 kW system for the calculated slurry quantities. In my opinion, these GVE quantities are conservatively estimated and can also be lower for plants that do not use 100 percent of liquid manure.

The following graphic shows the amount of substrate required, which is indicated by the Schmack Biogas belonging to the Viessmann Group.

Table with manure and Nawaro maize needs for mini biogas plant
Demand for liquid manure, maize and arable land for various operating concepts of a mini biogas plant

Heat demand and heat use of a mini biogas plant

Knowing the heat flows of your own mini-biogas plant as precisely as possible and recording the heat input and heat discharge is of great importance for cost savings, especially for plants operated thermophilically, with temperatures above 50 ° C.

According to Robert Wagner from CARMEN eV, at Improvement of the heating concept of a mini biogas plant taking measures for heat insulation (concrete ceiling), heat recovery (heat exchanger) and heat storage (heating pockets on the fermenter etc.) is particularly efficient.

Especially during the winter months, the heat requirement is very high, just like with the larger biogas plants. The strong seasonal fluctuations in self-consumption of heat and the remaining free heat capacities pose a challenge for system planning that should not be underestimated. For the operation of larger biogas plants, dealing with the heat fluctuations between winter and summer is an even more difficult problem to solve than for mini biogas plants. This applies in particular to the stricter framework conditions of the EEG 2012, which stipulate that 60 percent of the new heating systems are mandatory.

Handling liquid manure and digestate in mini-biogas plants

Since the amended Recycling Management Waste Act (KrWG) came into force on June 1, 2012, the use of liquid manure in biogas plants has been used to deal with an animal by-product. Accordingly, the transportation, use and spreading of manure falls within the scope of the KrWG (Section 2 Paragraph 2 No. 2) and the effort for handling manure becomes more complex. However, the final decision on the specific classification of the manure for a regional biogas project rests with the responsible authority.

Dipl.-Ing. In his interesting presentation, David Wilken from the Biogas Association pointed out that the following legal texts must be taken into account when using liquid manure in biogas plants:

  • Animal By-Products Disposal Act (TierNebG)
  • Animal By-Products Disposal Ordinance (TierNebV)
  • Veterinary classification according to hygiene regulation (EG) No. 1069/2009
  • Implementing Regulation (EC) No. 142/2011 (Annex V biogas plants, Annex XI slurry)
  • Fertilization Act (DüG)
  • Fertilizer Ordinance (DüV)
  • Farm fertilizer transfer ordinance (WDüngV) for mini-biogas plants only of limited relevance

In addition, a residence time of 150 days in the gas-tight (!) Sealed fermentation residue storage facility is stipulated, whereby the time of 150 days is not a prerequisite for pure slurry plants in order to receive funding according to EEG 2012.

Advice on the purchase and operation of a mini biogas plant

If you have a second opinion about buying a mini biogas plant or one Consulting I look forward to hearing from you.

I am in regular contact with manufacturers, operators and biogas associations and know the strengths and weaknesses of the systems between 30 and 150 kW that are currently being discussed. I would be happy to advise you on the following topics and support you in the implementation of your “Mini-Biogas Plant Project”.

  • Creation or testing of the concept for your mini biogas plant
  • Second opinion for the profitability calculation (necessary for lenders)
  • Development of partnerships (substrate procurement, heat sales, etc.)
  • Advice on existing providers of mini biogas plants and biogas CHP
  • And many more functions

You can also download the monthly newsletter of the bioenergy blog order if you would like to be informed about further developments in the field of mini-biogas plants free of charge.

Many thanks to the speakers and the team of CARMEN eV for the successful event on the topic of mini biogas plants. You can find them all here Presentations of the event for download. Hopefully, plant manufacturers, project planners, investors, the media and politics will continue to work well together to overcome the remaining obstacles, which are primarily in the area of ​​the economics of small systems.

Do you have experience with the mini biogas plants or do you plan to build your own? And what aspects of mini biogas plants would you like to read more about in the future on BiomassMuse?

3 comments on “Planning and buying a mini biogas plant up to 75 kW”

  1. Paulmaier Thomas

    Hello, Mr. Kirchner read your contribution to 75 kw plants, very interesting. That would be something for our dairy farm, I have little experience with biogas. Maybe you can get in touch. Paul Paul Thomas

  2. I think the table (substrate use of a biogas compact system according to EEG 2012) is good, but it does not quite reflect reality. As a rule, the TS contents are higher than stated here. The liquid manure yields are also somewhat higher, so that with a pure liquid manure plant, less LU can be assumed and some farmers can therefore opt for a pure liquid manure finishing plant (because they already have enough work). Personally, I would also neglect the safety discount of 2% because safety has already been incorporated into the manure quantities. The TS contents of the cattle slurry should be checked in each individual case, since the breed of cattle, housing conditions, feed etc. have an impact on the TS content and thus influence the size of a plant and its economy. Pure slurry systems are offered as a complete kit in stages 30/40/50 / 75KW.

    Best regards Tom

  3. On Annual biogas conference in Leipzig I learned that some mini-biogas plants have already been put into operation. If the federal government does not put a spanner in the works, then after the initial hesitation it could now really start with the addition of the small biogas plants. The complete systems with 30/40/50/75 kW are certainly particularly popular due to their modular design. I am looking forward to the first practical reports!

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