Efficient Production of Biogas through Heating the Substrate with Low Temperature Solar Thermal Energy

Abstract

This research project aims to improve the production of biogas by heating the substrate (mud), with solar energy from low temperature lower than 100°C. To heat a biodegradable mass of 693 kg composed of cow dung, pennisetum clandestinum, urea and water, 6 are used. Flat collectors (CSP) with 6000 W of thermal power, oriented with 20° of inclination in south direction in a region of latitude −0.3°. Domestic hot water (DHW) enters the annular region of the digester at an average temperature of 35°C achieving maintain an aerobic fermentation during the day and night at a temperature close to 26°C, within theme sophilic range. The equipment used for the test is a digester of concentric cylinders built in carbon steel, where the substrate and the gasometer are located on the inside and hot water circulates through the annular walls of the tank which is isolated with rock wool to reduce losses to the environment. On the other hand, to determine indirectly the efficient production of biogas, a physical variable is used: the internal pressure of the container that contains the gas generated. In the course of 30 days of hydraulic retention (TRH), an increase in the internal pressure of 4.8 PSI/day is achieved, in a linear way. This new alternative to produce biogas can be useful in the agricultural sectors and live stock farmers to obtain biofuels.