Effects of Shoot Size and Genotype on Energy Properties of Poplar Biomass in Short Rotation Crops

Abstract

Eight poplar genotypes grown in a short rotation forest plantation established in an acid soil in South Europe were sampled at the age of 7 years to determine the energy properties regarding thermochemical conversion. The goal was to address the effect of selection of genotypes or shoot size at harvest on the energy quality of biomass. Between 34 and 50 biomass samples were obtained for each genotype: three disks were systematically sampled along the stem and were pooled together with a subsample of leafless branches representative of the biomass share of this component. Several energy properties were determined: higher calorific value, net calorific value, fresh moisture content, basic density, ash, volatile matter, fixed carbon content and elemental composition. Genotype had a significant effect on most of these properties, and the balsam genotypes displayed superior quality parameters and also higher biomass yield than the Euramerican genotypes. As a covariate, shoot basal diameter had a significant effect on the moisture content, basic density, ash content and on the concentrations of the elements N, K, Ca, Mg, S, Na and C. It was concluded that genotypes with low nutrient requirements planted at low density (<8000 cuttings ha−1) and harvested at a long enough rotation (7 years) produce good yields and high chip quality. Poplar short rotation crops can be grown to produce chips of A2 quality for non-industrial heating use (according to UNE-EN ISO 17225-4), able to be combusted in domestic thermal facilities of <1 MWth power.

Poplar Short Rotation Coppice Plantations under Mediterranean Conditions: The Case of Spain

“…In Spain, several studies have addressed the characterization of poplar biomass for thermal use [148,231,292,293] as biofuels [294][295][296][297] or for new bioproducts [298,299]. The lower heating value, which is used to calculated the available energy, is usually around 18-20 MJ kg −1 in poplar wood on a dry basis [300,301].…”

“…The humidity content can be as high as 48-50% at winter harvesting [231,303], but poplar biomass has shown a good ability for air drying [303]. The specific density is known to be low [304][305][306][307], thus deriving in low bulk density chips (150-260 kg m −3 , [231]), corresponding to low energy densities. Densification to produce pellets is therefore an option.…”

“…The ash content, which is negatively related to the energy value and associated with the risk of boiler corrosion [308], varies broadly (1-4%), depending on genotype and site conditions [117,137,231,303]. The fouling and slagging risk derived from ash compositions are known to be very low [308][309][310].…”

The Bioenergetic Potential of Four Oak Species from Northeastern Mexico

“…In addition, Lerma-Arce et al [14] found values of 0.46% for logs with diameters greater than 20 cm of Pinus pinaster with bark. Eimil-Fraga et al [100] and Werkelin et al [101] mentioned that the basal diameter has a significant effect on the ash content mainly because the bark content increases with smaller diameters [38]. In addition, Miranda et al [40] reported for Quercus pyrenaica branches that lower diameters correspond to higher ash content.…”

Bacterial Canker Disease on Populus × euramericana Caused by Lonsdalea populi in Serbia

“…It is an important tree species in many European countries. Populus × euramericana is characterized by rapid growth rates, ease of clonal propagation, coppice regeneration, high biomass production and carbon sequestration, potential for phytoremediation, and suitability for multiple industrial uses, e.g., sawn timber, veneers, and fuelwood [1][2][3].…”