Biogas is a term used to describe a mixture of gases containing mostly Methane (CH¬¬4) (50 – 70 %), and some of other gases like Carbon dioxide (CO2) (30 – 40 %), Hydrogen (H2), and Hydrogen Sulphide (H2S) produced by microbial activity which may be used as fossil fuel and natural gas substitute. During growth certain microbes can produce certain gases as waste of their metabolism, the gas produced depends on the type of microbes and what organic matter digested by them. For example at the making of kombucha, Acetobacter xylinum is used to ferment tea which will produce CO¬2 as metabolism waste of digesting sugar, however certain anaerobic bacteria which can be found in cellulosic material can produce a significant amount of methane. Bacteria with this trait are classified as Methanogens, a common example for methanogens is Methenobacterium which can be found in cow’s rumen or in sewage sludges, but before the organic matters can be metabolized by these Methanobacterium, it has to go through several processes involving digestion of organic matter by Hydrolitic bacteria, Acidogens, and Acetogens to make it suitable for Methanogenesis.Based on book written by Prakash S. B. (2012), Organic matters in use are generally composed of complex polymers such as lipids, proteins, cellulose, hemicelullose and lignin, these complex polymers have to be broken down into simpler soluble monomers by catabolizing it with the help of water, enzymes and facultative anaerobic bacteria such as Cellulomonas sp, Eubacteria sp, Clostridium sp, and Ruminococcus sp, which are usually be found inside cow’s digstion system or in sewage sludge, these bacteria turns the organic matter into a slurry composed of simpler soluble monomers that can be easily digested by other bacteria this process is called Hydrolysis, and this process takes place inside an anaerobic bioreactor or digester which the organic matter is sterilized at 70 oC to kill pathogenic microorganisms and then cooled inside with temperature of 35 – 38 oC for optimal mesophilic environment or 52 oC for optimal thermophilic environment. According to Yuni Erlita this process starts roughly in the first 8 day in traditional in-home bioreactor and the gas produced are mainly Carbon Dioxide (CO2), which should be thrown away.According on book written by Prakash S. B (2012), the next process utilizes acid-producing facultative anaerobic bacteria such as Escheria coli, Clostridium sp, Actinomyces sp, and Corynebacterium sp, turning the soluble monomers in the slurry into acids such as, Hydrogen (H2), Carbon Dioxide (CO2), Ammonia (NH3), Hydrogen Sulphide (H2S), shorter fatty acids, carbonic acids, alcohols, as well as trace of other byproducts, this process is called Acidogenesis, according to Yuni Erlita, this process occurs at the same time and environment of Hydrolysis, and done by bacteria classified as Acidogens. Based on book written by Paul Singleton and Diana Sainsbury (2006), before Methanoges can produce methane, it has to went into digestion that turns derivative of carbons, and other energy source matters by catabolism and acidogenesis into Acetic Acid (CH3COOH), some traces Carbon Dioxide (CO2), and Hydrogen (H2), this catabolism is done by Acetogens and produced necessary products which will be digested and used by Methanoges to produce methane needed to make biogas.According to Thauer and Shima (2006), Methanogens are a group of anaerobic microorganism that produce a significant amount of Methane (CH¬¬4) and other gasses as metabolic byproduct. Methanogens can easily digest acetic acid (CH3COOH), and produce Methane (CH¬¬4) and a trace of Carbon dioxide (CO2), Methanogens then will digest Carbon dioxide (CO2) and Hydrogen (H2), producing Methane (CH¬¬4) and Water (H2O). According to IPCC, 1 Kilogram manure can produce 0.24 m3 per kilogram or roughly 250 gram Methane (CH¬¬4) (50 – 70 %), with traces of other gases like Carbon dioxide (CO2) (30 – 40 %), Hydrogen (H2), and Hydrogen sulphide (H2S) (20% – 30%) over a 24 hour period of time, this result depends on microbial activity, dry matter, organic matter, and time.According to an expository text written by Chitlange Sahas (2016), biogas can be produced at household level with simple self made digester made of plastic containers and plastic pipes as a digester. This digester can produce biogas in 12 hour to fuel burner for 20 – 30 mins from 5 kilogram of manure. Based on a text written by Dr. Ann C. Wilkie, biogas can used as natural gas substitute, which can be used to power generators to produce electricity and to produce heat for cooking, drying, room heater without compressing the gas, if compressed, biogas can be used to fuel gas run light and heavy vehicles.