Micro-Biogas-Plant

The micro-biogas-plant is intended to utilize organic waste as biogas.

The organic waste is brought into fermentation in an anaerobic environment - that is, without the presence of oxygen - by means of heat. In this biological process, bacteria decompose the waste and thereby separate a gas mixture containing a high proportion of methane. This gas mixture is the biogas and it can be used as an additive to the fuel for the engine in the PowerCube.

The remaining solid residue of the waste is removed via a separator and can be used as fertilizer (compost).

What can be fed?

In principle, all types of organic waste. (Originally, the micro biogas plant was designed to dispose of food waste from a number of production facilities, each with several hundred employees.)

Organic waste can be exemplary:

• Leftovers, for example from (large) kitchens or canteens
• Expired groceries
• Old, hard or inedible pastry (bread, …)
• Fish waste
• Old fruits and vegetables
• and so on

The list could be continued endlessly. Even residues such as manure (cattle manure, chicken droppings, …) or residues from food production (pomace, pressed cake, …) and many more are among the organic waste.

The point, however, is that almost all organic waste consists partly of water. Some more, some less. And the proportion of water does not ferment, no biogas can be derived from it. Only the solid, organic fraction can be converted to biogas. (There is still a mineral content that is ignored here for the sake of simplicity.)

A small example

A tomato consists to about 90% to 95% of water. The pulp accounts for only 5% to 10% of the total weight. If, for example, you bring in 100 kilograms of tomatoes into the microbiogas plant, that means that only 5 to 10 kilograms of bacteria are processed. The remaining 90 to 95 kilograms are water that does not produce gas but takes away the space for more profitable waste.

If you take, for example, old bread it’s exactly the other way around. There is very little to almost no water in the old bread and a very high proportion of it can be converted into biogas.

Note: The proportion without water is called dry substance and expressed in percent dry substance (abbreviated DS). In our example, the tomato has 5% to 10% DS.

It’s all about the mixture

It does not work without any water or liquids. A certain proportion is always present. This has the advantage that the waste inside the biogas plant comes in a more or less liquid form, and therefore can be transported via simple pumping technology.

Another small Example

The decisive factor is the freshness of the waste. Food leftovers, which are already in the bin for several days, plus summery temperatures, have already been fermenting continuously. Various bacteria have already decomposed a large part of the waste at this time, and the result of this decomposition is the odor that comes to mind when opening this trash can.

To put such waste into the micro-biogas plant makes little sense because the fermentation is already well advanced. The gas yield will be insignificant. The waste should always be introduced as fresh as possible.

What can NOT be fed?

Basically, everything that is NOT organic.

In particular:

• All types of packaging materials
• All types of disinfectants or cleaning agents
• All types of medicines
• All types of mineral oils
• and so on

Especially for packaged food our industrial biogas plants are responsible and in charge. Among other things, they also have the necessary technologies to separate the packaging residues (glass, metal, plastic, wood, cardboard, paper, etc.) and to sort them out separately.

Special Case: Slaughterhouse Waste in Biogas Plants

The micro-biogas plant is NOT intended for this purpose. Only our industrial biogas plants meet these requirements:

For slaughter waste specific legal regulations apply. These differ from country to country.
In Austria, Category 3 slaughterhouse waste may be introduced into biogas plants with its own regulatory approval. However, special provisions with regard to incorporation, processing, sanitation and others must be taken into account. Compliance with these regulations is regularly checked by the official authorities.

Technical Description

Like the PowerCube, the micro biogas plant is completely installed in a 20-foot container.

Organic waste such as food waste (without packaging material) can be fed with an amount of 100 kg per day up to a maximum of 1,000 kg per day (per fermenter).

Up to 100 m3 of biogas per day can be directly generated, depending on the type of organic waste introduced. This amount corresponds to an energy equivalent of 200 kWh of electrical energy.

The micro-biogas plant includes a thermally insulated fermenter, a shredding unit, a pumping station, a separation unit, and a gas storage (mounted on the top of the container and secured against wind).

The remainder of the micro biogas plant can be reused as a valuable fertilizer (compost).

There is also the possibility to provide the biogas for cooking purposes (gas cooker).

The supply of electrical energy as well as the required heat should be undertaken via the PowerCube to maintain the energy efficiency of the whole unit.

The commissioning of the micro-biogas plant must be carried out by us, a self-commissioning is not recommended.

A detailed technical description is here available for download.