Calculate the volume of a fixed dome type biogas digester for the output of four cows. Also, calculate the thermal power available (in Watts) from biogas. Use the following data: - Retention time = 30 days - Dry matter produced = 2 kg/day/cow - Biogas yield = 0.24 m³/kg of dry matter - Percentage of dry matter in cow dung = 18% - Density of slurry = 1090 kg/m³ - Burner efficiency = 60% - Heating value of biogas = 23 MJ/m³ - Volume occupied by gas = 15% of total volume. Equal amount of water is added to cow dung for producing slurry.