Conference article

The paper quantifies the synergy-effects of an areal combination of biogas-plants with plants of the building materials industry (e.g. cement plants) from the energetic and economical point of view. Therefore a model biogas and cement plant are defined and the effects of a combination of both plants in terms of energetic efficiency; investment and operating costs; greenhouse gas emission reduction and overall energy production costs are quantified. The main benefits of this combination are the utilisation of low temperature excess heat sources from the cement plant for fermenter heating and the direct thermal utilisation of unprocessed biogas as a valuable; CO2-neutral fuel for combustion processes for instance clinker burning. Due to the combination; the energetic efficiency of the biogas plant; defined as utilisable energy output in relation to the energy content of the produced biogas; significantly increases from 63.0% to 83.8%. Concurrently the energy production costs are reduced; turning biogas into a competitive source of energy without the need for federal sponsorship. Calculations show; that from a plant size of around 90 m³STP/h biogas production costs in combined plants are even lower than the actual market prize of natural gas.

Biogas; cement plant; thermal utilisation; excess heat recovery