The main goal of this project consists in the generation of a substitute for natural gas using a novel process for biogas treatment. For this purpose, researchers designed a mobile testing facility in a container with a two-stage gas separation unit using membranes. Researchers tested the practicability of this innovative and highly efficient method of extracting methane from biogas generated in an energy crop digester. Investigations also addressed issues relating to analysis and safety.
Pre-studies conducted by the project team have shown that membranes technology permits to simultaneously remove harmful biogas components such as CO2 and water vapor and that methane enrichment can reach levels slightly above 96% at relatively low pressures. One still unsolved problem consisted in unacceptably high methane losses in conventional one- or two-stage operation. Therefore, researchers developed a new approach relying on a two-stage gas permeation process; this method uses modified membrane modules for the individual separation stages and a system that requires only one compressor. This concept was put into practice in cooperation with partners in the industry within the scope of the “Energy Systems of Tomorrow” subprogram.
At the end of 2004, the first pilot plant for biogas upgrading to natural gas specifications started trial service at St. Martin in the province of Burgenland. The plant uses a process where, after compression, H2S is removed in a pre-treatment stage. The membrane separation unit then reduces CO2 concentration in the gas to less than 2%. At the same time, moisture is completely removed from the gas, which then reaches a dew point below –50°C. These values comply with the required specifications.
Researchers participating in the project also developed and tested a photo-acoustic measuring method for analysis of the upgraded biogas. This online method permits real time monitoring of important quality parameters of the generated gas.
