Analysis of Feasibility of Producing and Using Biogas in Large Cities, Based on the Example of Krakow and Its Surrounding Municipalities

Abstract

In Poland, mixed municipal waste, municipal sewage and agricultural waste are used to produce biogas. Biodegradable green waste and kitchen waste generated in households are not used for this purpose. In the cogeneration process, the produced biogas is burned in a gas generator, resulting in electricity and heat. Electricity is sold in its entirety to the energy operator, but there are no heat consumers. The solution may be the construction of municipal biogas plants in urban areas, using kitchen and green biowaste from households located in cities and surrounding municipalities. Thanks to this location, the surplus heat can be used by the local district heating network to heat the buildings in the city. The aim of the article is to assess the possibilities of producing biogas and energy from municipal bio-waste generated in households in Krakow and surrounding communes. To achieve the goal, a simulation was carried out for a biogas plant with a capacity of 1 MW. Two types of substrates were used as inputs, i.e., biowaste from households and green biowaste. The data for analysis came from the Marshal’s Office of the Małopolskie Voivodeship, to which municipalities submit reports on the amount of municipal waste collected, and the Central Statistical Office, which has data on municipal waste collected in municipalities in Poland. The collected data were used to conduct five simulations. The most advantageous method is to produce biogas from kitchen waste and silage from green waste mixed in the appropriate C:N ratio. Assuming the optimal proportions of mixed substrates, a 1 MW biogas plant can produce 4.1 million m3 of biogas, from which electricity can be produced for 2.5 thousand houses and heat for 1.1 thousand houses. The article ends with conclusions and recommendations on how to collect biodegradable municipal waste, which should be treated as a valuable source of energy.