BIOMETHANE YIELD FROM ENERGY PLANTS IN LATVIA

摘要

Introduction of new energy plants for biogas production is necessary for Latvia in renewable energydevelopment. Investigations were provided on sunflower, hemp and sorghum to evaluate its suitability forbiomethane production in Latvia. Sunflower (Helianthus annuus L.) is used for decades for fodder production. Hemp(Cannabis sativa subsp. sativa) is variety allowed by legislation and was sown on 59 ha in Latvia in 2006. Twovarieties were used (local hemp ‘Pūri?i’ and Polish variety ‘Bialobrzeskie’) in trial. Investigated dry matter (DM)yield was 8-11 t?ha~(-1) and 8.3-14.2 t?ha~(-1) for sunflower or hemp respectively. Sorghum-sudangrass hybrid (Sorghumbicolor Moench × Sorghum sudanense [Piper] Stapf.) is the newly introduced energy plant in Latvia and obtainedDM yields are in range 8.7-11.1 t?ha~(-1).Biomethane yield from fresh biomass was investigated in 6 laboratory digestersat constant temperature 38℃. Methane yield was 302±6 l?kgVOS~(-1), 297±9 l?kgVOS~(-1) and 294±2 l?kgVOS~(-1) fromsorghum, sunflower and hemp respectively. Investigated average methane content in biogas was 56.7%, 58.3% and55.2% for sorghum, sunflower and hemp respectively. Potential biomethane yield from unit of area is 3113 Nm~3ha~(-1) for hemp, 2627 Nm~3 ha~(-1) for sunflower and 2812 Nm~3 ha~(-1) for sorghum in agroecological conditions of Latvia.