Development of a Mathematical Model and Validation for Methane Production Using Cow Dung as Substrate in the Underground Biogas Digester

Abstract

South Africa is highly dependent on conventional fuels from non-renewable energy sources such as coal and fossil fuels. The methane from biogas is a renewable energy source for generating electricity using a combined heat and power plant. Therefore, the aim of the study is to develop and validate a mathematical model for predicting methane production in an underground biogas digester. The developed model was able to predict the production of methane gas as separate entity differing from other models. A total of 286 datasets were used as a trained dataset for the model development, and 144 datasets served as test data for the validation of the model, making a total of 430 measured datasets of all the predictors. The determination coefficient (R2) and the p-value of the predicted and calculated methane yield were 0.962 and 0.920, respectively. The high R2 in the present study confirms a good correlation between the model and experimental value. Hence, the model is of significance because it is applicable in predicting the performance of methane production of systems of the same design used in different locations, thereby arriving at the same constant values. From the study, the ambient weather factors (ambient temperature, relative humidity, and global horizontal irradiance) affected the methane production. Additionally, the indoor parameters (pH, gas temperature, slurry bottom and slurry top temperature) impacted on the yield of the methane production because the scaling factors associated with these quantities are non-zero real numbers. Hence, the scope of the study did not consider the volume of the biogas digester as an input parameter to the response.

Qualitative and Quantitative Means of Production of Biogas from Biodegradable Waste (Cow Dung) for Sustainable Energy

“…The solids reported in the study were digestible and degradable; hence, the values of the TS and VS in the post digested sample (PDS) were much lower than the predigested sample (PRDS). These findings were similar to the report of [12] who reported lower TS and VS in the post digestion sample and higher pre-digestion samples(PRDS) The results on total solids were correlated to the quantity and quality of biogas in the cow dung This observation is correlated to the report of [13][14] who reported higher quantity of biogas yield from reactors with TS 7.4% and 9.2% as against rectors with TS 2.65%, 4.6% and 6.2% .This study was carried out to investigate the best ratio of water to cow dung (based on the moisture content of the cow dung) for biogas production. The production of flammable biogas commenced within 78 hours of charging.…”

Optimal Design and Performance Analysis of a Digitally Controlled Biogas Power Generation System Suitable for DC Microgrid

“…The biogas fermenter can be modeled considering its volume and the required rate of generation of gas based on the amount of sludge. The volume of the biogas fermenter (V d ) can be written as [51],…”

Economic Analysis of Biogas Production via Biogas Digester Made from Composite Material

“…The following parameters were examined and reported as follows: pH: 7.83 at 30 • C; total solids: 130,800 g/L; volatile solids: 110,467 g/L; chemical oxygen demand: 42,583 g/L [9].…”