Why use Biomass?

From an economic and ecological point of view, technologies based on regenerative energy are not entirely without problems, since they are strongly influenced by existing environmental conditions (e.g., solar intensity, daily length of solar radiation, wind, etc.). Therefore, these technologies can only be viewed as supplementary energy sources, not as substitutes. Biomass plants offer a true alternative. One of their main advantages is the fact that the use of biomass for the production of heat, electric power or as a fuel source enables an even CO² balance, since the CO² emission is restricted to the amount of CO² previously bound biochemically.

The main economic advantage lies in the fact that the substrates required for operation of the biomass plant can be stockpiled cheaply and easily (e.g., in silos, simple storage yards), thus guaranteeing the continuous operation of the plant.

Working Principle of a Biogas Plant

Raw materials (e.g., biological waste, liquid manure, sludge, grease or plant matter) are fed into an airtight fermenter. The processes of anaerobic digestion (fermentation) and decomposition lead to the production of biogas, which, depending on the base materials, consists of 40-75% methane, 25-55% carbon dioxide, up to 10% water vapor, and additional minute amounts of nitrogen, oxygen, hydrogen, ammonia and hydrogen sulfide.

The substrate is heated in the fermenter under the exclusion of air, which leads to the development of microorganisms that convert most of the substances into biogas. The gas is collected in the gas storage tank, while the fermentation waste is channeled through an overflow from the fermenter into the storage container.

The fermented manure and silage are almost odorless and high in nutrients. They can be used as high-quality fertilizer on agricultural fields.

Currently, biogas is used primarily for the decentralized, coupled generation of electrical power and heat in cogeneration plants (power-heat-coupling). In this case the gas mixture is dried by reducing the proportion of water in the biogas. By blowing in small amounts of fresh air, the mixture is desulfurized and subsequently fed into a combustion engine, which drives a generator. The resulting electricity is fed into the power grid. The waste heat contained in the exhaust and in the cooling water of the engine is recovered in heat exchangers. Part of this heat is required for the heating of the fermenters.