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Energy efficiency indices for lignocellulosic biomass production: Short rotation coppices versus grasses and other herbaceous crops

Stolarski, Mariusz J., Krzyżaniak, Michał, Warmiński, Kazimierz, Olba-Zięty, Ewelina, Penni, Dumitru, Bordiean, Anna
Industrial crops and products 2019 v.135 pp. 10-20
Helianthus salicifolius, Miscanthus sacchariflorus, Miscanthus sinensis, Salix, Sida hermaphrodita, Spartina pectinata, biomass production, coppicing, crop rotation, energy efficiency, environmental factors, genotype, grasses, industrial crops, lignocellulose, plantations, straw, willows, wood
Plantations of perennial industrial crops (PIC) could be important sources of lignocellulosic biomass. These crops can be classified into three groups: short rotation coppice (SRC) – wood, herbaceous crops (semi–wood) and grasses (straw). Comparing various PIC genotypes directly under similar environmental conditions over many successive harvest rotations is necessary to accurately determine the yielding potential and energy efficiency of lignocellulose biomass production. Therefore, the aim of this study was to determine the energy input, energy yield value and the energy efficiency indices of biomass production for 26 PIC genotypes (fifteen SRC, six herbaceous crops and five grasses) harvested in six successive annual rotations.The significantly highest energy yield value throughout the experiment (2012–2017) was obtained from the Ekotur willow variety (1857 GJ ha–1). Among the 26 PIC, the top ten for energy yield value and energy gain in the six successive rotations included five SRC willow (Salix spp.) genotypes: (Ekotur, Start, Żubr, Turbo, UWM 095), three grass genotypes: Miscanthus sacchariflorus ((Maxim.) Hack.), M. sinensis ((Thunb.) Andersson), Spartina pectinata Bosc ex Link and two herbaceous crops: Sida hermaphrodita Rusby L., Helianthus salicifolius A. Dietr. The significantly highest energy ratio (22.3) was obtained for the production of M. sacchariflorus. The next three places were occupied by willows, Ekotur, Żubr and Start and the index for them was 8–10% lower than for M. sacchariflorus. This research should be continued for the entire lifetime of a plantation, which is set up for at least 15 years even though some SRC may be exploited for more than 20 years. Therefore, it is important to assess individual PIC genotypes in later years of their cultivation in terms of their productivity and energy efficiency indices.