Potential of fast growing poplar, willow and paulownia for bioenergy production

The use of renewable energy sources is one of the possible prospects offering a real alternative to fossil fuels in combination with various eco-oriented advantages. In Bulgaria’s forests, there exists an extensive set of fast growing tree species. The most preferred are intensive forest plantations and short-rotation systems from selected clones of poplar, willow, paulownia, acacia, etc. The biomass from plantations of fast growing tree species can be an alternative and attractive base for bioethanol production. The investigation is performed for determination the potential of fast growing hardwood species from Bulgaria (paulownia (Paulownia elongata), poplar (Populus alba) and willow (Salix viminalis rubra)) as energy crops. Highest cellulose content is established in Populus alba, while the amount of lignin is lowest in Paulowniа elongata. The obtained lowest calorific value for Paulownia elongata is related with the determined content of lignin. The glucose yield after cellulase hydrolysis of steam-exploded Paulownia elongata is up to 52%. That result is approximately 24% higher in comparison with corresponding treatment of Populus alba and Salix viminalis rubra. The obtained result can be explained with the specific structure of Paulownia elongata. The chemical composition of wood and especially the cellulose content has no direct effect on the glucose yield. The plantation harvesting, the calorific value and the glucose yield from fast growing Populus alba, Salix viminalis rubra and Paulownia elongata from Bulgaria make that tree species perspective and suitable for bioenergy production.