The analysis of biodegradable waste as renewable resource for alternative energy production in Estonia

The process of anaerobic digestion is well known for digestion of wastewater and sludge, but now it has been widely implemented for production of renewable energy worldwide. Biogas from anaerobic digestion process is one of the most perspective alternative energy sources. Directive EU for renewable energy targets has been determined to 25% in 2020 for Estonia. Presently (2010) in Estonia the share of renewable ener­gy rose to approximately 21%. The annual of municipal solids waste (MSW) generated in Estonia accounts for 0.5 million tons or, taking into account the urban population (1.344 million inhabitants), 372 kg per capita. Up to 56% of total municipal solids waste generated in Estonia is easily biodegradable and can be used for biogas production. The volumes and qualities of different types of biodegradable fraction of municipal waste, industrial waste and waste of landscaping, agricultural waste and sewage sludge generated in Estonia during the period from 2002 to 2011 were analysed and their energy potential was estimated. The obtained data demonstrates that the main sources for biogas production are sewage sludge and animal manure. Also wastes of food industry, biodegradable municipal waste, and herbaceous biomass and agriculture products may be used. Special attention is paid to agricultural products and waste. The minimum energy potential from waste in Estonia may be estimated as 306.69 GWh per year, but this is only 3% from total energy production in Estonia. For the achievement of the recommended level of using renewable energy in Estonia in 2020, other natural sources of energy such as solar, wind, rain, etc. will be used.