AP1 - Agrarian raw material base for biogas production

Energy crops without derogation of the production of food and feedingstuff

The biogas production with agrarian raw materials significantly contributes to a renewable energy production. Even now biomass derived from fields and grassland is successfully used. Today, mostly energy crops like corn, sunflower, grass from grassland and Sudan grass are used. Various different plants might also be used for the production of biogas.

Species usually cultured for human nutrition and animal feedingstuff currently become more important for biogas production. The requirements regarding quality and composition of the plants are different in the case of biogas production. In order to optimise the methane production, such genotypes and species with a high output of methane per acreage have to be found.

Coincidentally, unidirectional crop rotation has to be avoided. The spectrum of plant species for the biogas production has to be as broad as possible. For this reason, the “Division of Agricultural Engineering” (ILT) at the “Department of Sustainable Agricultural Systems” of the University of Natural Resources and Applied Life Sciences Vienna conducts extensive research work. The research group focuses on the question of how a cultivated plant deriving from ecologically optimised crop rotation systems can be applied for the biogas production in the most suitable way. All sorts of cultivation of main crop, preceding-crop, after-crop, and adjacent-crop are considered.

Additionally, during the further processing of agrarian raw materials several by-products are formed which might also be used for the biogas production. The ILT compiles from these versatile raw materials well-balanced rations of fermentation substrate assuring a secure fermentation and high methane yields. One focal point at this moment is the development of multifaceted crop rotation systems, which are based on the following points:

  • the supply with food and feedstuff,
  • the production of material and energy,
  • the conservation, promotion and utilisation of multifarious cultural landscapes.

Also in respect of these aspects biogas production is assumed to be a key technology for the sustainable utilisation of agrarian resources. The miscellaneous targets can be linked together in a synergistic way applying the biogas technology.

The target is to achieve high biomass yields with multifaceted and healthy crop rotation systems which are adapted to their location and having a nutrient cycle which is closed to a large extent. Integration crop rotation systems allow for the production of biomass for human and animal nutrition and for the production of resources and energy. A high yield of food, material and energy per acreage can be reached. The following strategies can be used for this purpose and will be analysed:

  • switch of cultivated plants for the production of food, material and energy: “Food-Non-Food-Switch”
  • coupled utilisation of vegetative and generative parts of one plant: “cascaded utilisation”, e.g. utilisation of the maize kernel for the production of starch and utilisation of the residual plat parts for the production of biogas; or primary utilisation of sunflower seeds for the production of oil and utilisation of the remainder and the press cake for secondary biogas production.
  • usage of cropping systems with mixed or blended crops; e.g. blends of sunflower, corn and Sudan grass; e.g. cultivation of winter-rye prior to corn.
  • selection of suitable species. Genotypes for the production of biogas have to have a high yield of biomass and ingredient components in a proper composition. Various kinds of energy crops will be analysed and the best genotypes will be identified.
  • selection of the optimal harvesting time, which has a great influence on the energy yield per acreage.

Figure: Typical sorts of plants for the production of biogas: sunflower, sorghum and corn