Potential of bioethanol production from biomass of various Miscanthus genotypes cultivated in three-year plantations in west-central Poland

摘要

Production of bioethanol from Miscanthus biomass has been studied for years, yet many important aspects still remain to be evaluated and optimised. It may be assumed that the three-year yield-building phase of Miscanthus growth would be sufficient for stabilisation of biomass composition to provide suitable biomass as a bioethanol feedstock. Such early biomass harvesting could be important for the economics of newly established plantations. This study shows the gradual stabilisation of biomass production by genotypes of M. x giganteus, M. sinensis and M. sacchariflorus within the first three years of cultivation on moderately fertile soil, under the climatic conditions of west-central Poland. Photosynthesis, plant growth, biomass yield, and biochemical and elemental composition, simultaneously stabilised. The tested genotypes differed in their photosynthesis intensity and yield traits. There was little variation in the biochemical composition among genotypes; in comparison to Miscanthus cultivated in a more oceanic climate there was lower cellulose content, but higher lignin content. Aside from basal elements, the tested genotypes varied considerably in their accumulation of most macro- and especially microelements. The three-year old, winter-harvested technical biomass was used for pilot-scale bioethanol production including alkaline delignification and SSF technology. The particular biochemical components and elements in the biomass differently impacted the production process, yet for most genotypes the bioethanol produced was highly correlated with the cellulose:lignin ratio. The highest yield (g/kg DM) and efficiency (%) of raw bioethanol production were recorded for genotypes of M. sinensis (234-253 g/kg DM, 83-86%), followed by M. sacchariflorus (207-237 g/kg DM, 76-81%) and M. x giganteus (185-222 g/kg DM, 62-76%). However, biomass yield had a substantial effect on the estimated bioethanol production. The study pointed to the high potential for raw bioethanol production (4,400-5,600 L/ha) exploiting 3-year Miscanthus plantations, comparably for M. x giganteus and M. sinensis cultivated in a temperate transitional climate.