4. What is industrial biogas polygeneration?

Industrial biogas plants are very similar or even identical to small-scale or agricultural biogas plants as far as the digester technique is concerned. Only the input sites and the plant capacity differ. The input for industrial biogas plants is provided by the industrial food or food processing industry. Typical inputs are food waste, fats and slaughterhouse waste. These substrates have to be mixed, exempted from unsuitable matter, chopped or diluted. A lot of care should be applied when working with slaughterhouse waste, which has to be homogenized as well as sanitized. Often, the digester residues can not be used as fertilizer.

Moreover, the owner structure of the industrial biogas plant differs from that of private farm plants. The owners are mostly limited companies or associations. Industrial plants have the need for more and better organisation of work. Sometimes the biogas plants are used as disposal system, so the input supplies are contracted with the other. This global work needs a good infrastructure.

For using the biogas in combined heat and power plants, the heat should be used efficiently. 20 % up to 40 % of the generated heat can be used for the biogas plant itself, but the additional supply should be used for the industry nearby; presumably there is a demand for drying wood, pellets or grass. Also heat driven cooling is an option for using the heat surplus.