Teknisk undersökning : Rötgaskammare för småskalig biogasproduktion

Biogas mainly consists of methane and carbon dioxide, where methane is theenergy-rich gas, and is naturally created when organic matter breaks down in absenceof oxygen, also known as anaerobic digestion. A biogas plant re-creates the anaerobicconditions inside a digester where the organic substrate is fed into and digests toproduce biogas. The gas is then used to produce energy by combustion and can beseen as a completely renewable fuel.Today, energy from biogas is used primarily by major stakeholders such asmunicipalities and thus the plants become very large with high investment- andconstruction costs. There are currently few small plants in Sweden, even though thepotential for agriculture and medium-sized to smaller farms to become self-sufficientin terms of electricity and heat is great. Farms have a natural stock of digestibleorganic material in form of manure or crops for example, which are constantlyavailable. A reason that only a few small plants exists are the large investment costs.A study focusing on the actors who supply these smaller plants today was made withthe intention to find out where the large investment costs are and what techniquesare most profitable and efficient to use. The survey was conducted through field visits,interviews and contact by phone and internet with active companies and peoplefamiliar with the modern production of biogas.The survey was compiled and the various techniques and concepts were presented,evaluated and discussed to give the client a good basis for further development ofsmall-scale biogas plants.The investigation revealed that there are no barriers for biogas production in smallerfacilities, given that the same conditions in terms of temperature, acidity and nutrientis created just like in the larger facilities. It also showed that active heating and stirringof the substrate in the digester is of utmost importance to have a functioning processand maximum gas exchange