Comparative Analysis of Dry and Wet Fermentation Processes for Biogas Production in Northernmost Norway

Abstract

This thesis investigates biogas production in northern Norway, focusing on wet and dry fermentation methods. Stemming from the Boost Nordic Biogas initiative, in collaboration with Rå Biopark, the study aims to enhance biogas production in the region. By comparing wet and dry fermentation, it seeks to identify the most suitable approach for the unique challenges of northern Norway. The objectives include researching fermentation processes, conducting a comparative assessment, and evaluating feasibility.

First, the thesis delved into existing literature on biogas in Norway, followed by research of dry and wet technologies. Subsequently, three reactors were dimensioned to compare their sizes.

The study highlights significant disparities of up to 1000 m3 between the anticipated and actual dimensions of digesters. These calculations are based on operating conditions at a mesophilic temperature of approximately 35°C, with a retention time of 25 days. For the second line, two digesters were designed: a wet technology digester with a capacity of 7686.67 m3 and a dry technology digester with a capacity of 6478.34 m3, illustrating the latter's advantage in size due to the lower water content in the feedstock.

While wet fermentation remains the preferred choice due to its maturity and efficiency, this study suggests allocating resources to further develop dry fermentation technology.