The energy efficiency of Virginia fanpetals biomass production for solid biofuel

Virginia fanpetals is a highly versatile energy crop, and its biomass is converted mainly to solid biofuels and biogas. The aim of this study was to determine the biomass yield, energy inputs, and energy efficiency of Virginia fanpetals produced for solid biofuel during 13 successive years. Three types of propagating material were used to establish the plantation: seeds, root cuttings (rhizomes), and seedlings. Seeds were sown at a density of 1.5 or 4.5 kg ha-1, whereas rhizomes and seedlings were planted at a density of 20,000 or 60,000 plants ha-1. The average annual yield of S. hermaphrodita biomass reached 7 Mg ha-1 DM. The highest yield was noted where seedlings were planted at a density of 60,000 plants ha-1. Biomass yields continued to increase until year 4-5 and decreased in successive years until year 10. Yields were maximized when seeds were sown at a density of 4.5 kg ha-1. In the above treatment, total and average annual yields were only 3% lower than the highest value noted during the 13-year experiment, whereas energy inputs were 31% lower, energy gain was comparable, and the average energy efficiency ratio was higher.