Biogas typically refers to a biologic gas produced by anaerobic fermentation of materials that occurs spontaneously in landfills or is produced in anaerobic digestion plants for sewage sludge, urban solid waste and other types of organic waste.
The components capable of producing biogas are the organic substances present in waste, characterized by various biodegradation rates according to their nature. Food, paper, cardboard, textile, etc. wastes have a higher degradation rate. Plastic, glass, metals and inert materials generally represent non-biodegradable substances.

Biogas is generated by waste decomposing under anaerobic conditions and presents a concentration of methane exceeding 55% in volume. This characteristic makes it possible to use it as a fuel in electricity production plants. On the basis of theoretical analyses and experimental data, a ton of urban solid waste (USW) can be estimated to generate from 150 to 250 m3 of biogas with a time period that ranges from 5 to 20 years.
The use of biogas in electricity production plants reduces the environmental impact of urban solid waste disposal deriving from uncontained emissions into the atmosphere of high levels of greenhouse gases (methane and CO2) and contributes to fuel consumption reduction objectives.

In various different Italian regions, the ICQ Group has built over 50 plants supplied by biogas from landfills and presently manages approximately 20 of these plants with different levels of shareholding.
The plants’ power varies from 500 to 5,000 kWe. In 2010, ICQ also planned building four new plants: Modena 2mW, Voltana 600 kW, Zocca 600 kW, Corno di Rosazzo 600kW.