Optimization of methane production - the Methane Energy Value Model

Status

completed

Summary

This project serves to promote biogas production from energy plants. The energy plants: sunflowers, meadow grass, wheat, triticale, rye and maize were investigated. All energy plants were harvested in the course of the vegetation period at four to six different dates. At each harvest, yield measurements were carried out, as well as biomass sampled for silaging and the subsequent ingredient analyses. Following, laboratory investigations for the determination of the specific methane yield were carried out with the help of Eudiometer-instrumentation. The methane hectare yield and the optimal harvest times were determined for all of the investigated energy plants.

Of all the energy plant species investigated in this project, maize showed the highest biomass yields and methane yields per hectare. Sunflowers achieved approximately 30% of the methane hectare yield obtained by maize, cereals or intensive farmed meadow grass on average 26.5%. Variations of 6 to 38% in methane hectare yield appeared within the examined energy plant species depending on the variety, the place of cultivation, the management intensity or the harvest time. The effect of pretreatment measures (acidifying, heat treatment, microwave irradiation and addition of clay minerals) on the specific methane yield of energy plants was examined. With the exception of the clay minerals which increased the specific methane yield for all energy plants, it appeared that the pretreatment measures had a different effect on the different energy plants.

The optimal hydraulic retention times, determined in this project, lay between 20 days (cereal silage from whole plant) and 42 days (sunflower silage). Besides the energy plant type, the hydraulic retention time also appear to be influenced by the harvest year and the assigned pretreatment measure. These results must be verified in further investigations with dynamic systems.

In order to achieve long-term success, the cultivation of energy plants must be organized using sustainable crop rotation principles. Locally adapted biological and conventional crop rotations were developed in this project with the prospects of energy plant cultivations as main and intermediate crops.

With the data from the project, the Methane Energy Value Model for maize could be continued so far that it can now be used in practice. The database for the estimation of the methane energy value of cereals, sunflowers and meadow grass is however still too small and requires further investigations.

Energy ratio of mixtures of energy plants on the specific methane yield and on the biogas quality was examined with the help of protein-rich clover grass silage and energy-rich maize silage.

Guidelines for optimized biogas production from energy plants, efficient fertilization with fermentation residues of fermented energy plants as well as different uses of biogas are given.

The results of this project show that the potentials of biogas from energy plants are larger than have been assumed so far.

Project leader (Contact address)
Ao.Univ.Prof. Dipl.-Ing. Dr. Thomas Amon
BOKU Wien, Department für Nachhaltige Agrarsysteme, Institut für Landtechnik
Peter-Jordan-Strasse 82
A-1190 Wien
Tel: +43 (0) 1/47654-3502
Fax: +43 (0) 1/47654-3527
E-Mail: amon@boku.ac.at
Internet: Division of Agricultural Engineering

Institute
BOKU Wien, Department für Nachhaltige Agrarsysteme, Institut für Landtechnik

Project partners
Institut für Nutztierwissenschaften (Projektpartner)
Institut für ökologischen Landbau (Projektpartner)
BAL Gumpenstein (Projektpartner)
AGES - Agentur für Gesundheit und Ernährungssicherheit (Projektpartner)
IPUS GmbH (Finanzierungpartner)
Jenbacher AG (Finanzierungpartner)
Monsanto Agrar Deutschland (Finanzierungpartner)
Limagrain Nickerson GmbH (Finanzierungpartner)
Pioneer Saaten GmbH (Finanzierungpartner)
Schmack Biogas (Finanzierungpartner)
Nawaros GmbH (Finanzierungpartner)
Raiffeisen Ware Austria (Finanzierungpartner)