Biogas to Clarke Energy (2014), sewage gas
Biogas is a renewableenergy.
Biogas is produced by putrefactive bacteria that breaks down organicmatter under airless conditions and is used in energy production. It can be called as anaerobic digestion.Biogas is composed of methane gas, carbon dioxide, and trace amounts ofnitrogen, hydrogen, and carbon monoxide. Any organic wastes can be used toproduce biogas. The common sources to produce biogas are animal and plantwastes. Not just from animal and plant wastes, biogas can also be produced fromwood waste, wastewater, and regular waste as raw materials. Thereare a lot of types ofbiogas and three of them aresynthetic gas, sewage gas, and landfill gas.
The first type of biogas issynthetic gas. Synthetic gas is formed from the wood biomass. Accordingto Paul Scherrer Institut (2009), to generate methane from wood, wood chips arefirst turned into gas using hot vapour. The gas is purified by removing sulphurand converted into a mixture of methane and carbon dioxide by using a nickelcatalyst. Thegas enables the utilization ofenergy for combined heat and power. This energy will make a combustible gas toconsumers, like industry, residential areas, and tourist resorts. Thecombustible components of the gas are predominantly hydrogen, carbon monoxideand methane, and higher hydrocarbons. The process also produces waste heatwhich is useful to generate electricity for the demand of industrial heat or tofeed district heating networks.
The second type of biogas issewage gas. According to Clarke Energy (2014),sewage gas is formed fromwastewater by the anaerobicsludge stabilization, which the separated sludge can produce biogas. Sewage iscollected and sent to wastewater treatment plant, and then sent to sewagedigesters. In digestion progess, hydrolysis, the process where the organicmaterial is solubilised into the digestion liquid, occurs. Then, acidogenesisand acetogenesis create the precursos molecules for methanogenesis.
Methanogensfeed off precursors and produce methane as a cellular waste product. Sewage gasis considered to be very effectivesince harmful wastesare used to generate heat and power.Sewage gas can be used to maximizes renewable energy output and smoothens gasproduction fluctuations by seamless dual fuel mixing.
The efficiency is ensured by maintaining thetemperature, pH, stirring, removing oxygen and toxic substances.Highelectrical efficiencies help generate more electricity per unit of sewage gasused.The third type of biogas islandfill gas. Landfill gas is formed from regular wastes (raw garbage). Accordingto Green Group (2013), humansproduce 300—400 kg of waste per person per year. This garbage is collected anddisposed of in safe sanitary landfills. The garbage will decompose under theinfluence of microorganisms (bacteria) under anaerobic conditions. Too muchlandfill gas is also very dangerous for the environment since it containsmethane that is very explosive at some conditions.
To remove the negativeeffects of uncontrolled proliferation of landfill gas, collection is carriedout and forcibly burned. One of the uses of the burning is for energy purposeswhile creating economic benefits. Such as, over a compressor plant, landfillgas is sucked out, compressed, dried and directed to the gas engine (CHPengine). The heat can be applied in heating buildings or processing foodproducts. The by-product heat engine at moderate temperatures can be used forcooling. To conclude, biogas can begenerated by any raw organic materials under an anaerobic process, such aswastes.
The waste can be from wood biomass that will create synthetic gas thatwill make a combustion gas. Wastewater will create sewage gas that will maximize renewableenergy output. Raw garbagewill create landfill gas that will provide energy for machines to heat andprocess food.
The different types of biogas might have different sources, butit all eventually will have the same purpose, generating heat and power for thesake of a better human life. It shows that biogas can be produced from anythingorganicdue to many available sources.