Bioethanol Potential From High Density Short Rotation Woody Crops on Marginal Lands in Central Chile

Abstract

Cellulosic ethanol is one of the most important biotechnological products to mitigate the consumption of fossil fuels and to increase the use of renewable resources for fuels and chemicals. Short rotation woody crops (SRWC) have been proposed as the most promising raw material for cellulosic ethanol production, as a result of its several advantages over traditional crops. In order to analyze the potential as crops for lignocellulosic bioethanol production in Chile, SRWC were established with the following species: Acacia melanoxylon, Eucalyptus camaldulensis, Eucalyptus globulus and Eucalyptus nitens. These crops were established in two contrasting environments and in three plantation densities. The average theoretical ethanol yield at 48 months reached 395.9 L . t -1 for A. melanoxylon, 348.7 L . t -1 for E. camaldulensis, and 363.9 L t -1 for E. nitens. It can be concluded that there are significant differences in polysaccharides yield between species and time. On the other hand, significant differences were found between environments.In conclusion, this study has shown that the choice of SRWC species used as a source of polysaccharides must take into account the percentage content in biomass and, crucially, the species, planting density, harvest cycle and site must be carefully selected to ensure a high biomass yield per unit area. POTENCIAL DE BIOETANOL DE CULTURAS LENHOSAS CONDUZIDAS EM ALTA DENSIDADE E CURTA ROTAÇÃO EM TERRAS MARGINAIS NO CHILE CENTRALRESUMO: Etanol celulósico é um dos mais importantes produtos biotecnológicos para reduzir o consumo de combustíveis fósseis e a aumentar a utilização de recursos renováveis para combustíveis e produtos químicos. Culturas lenhosas de curta rotação (CLCR) têm sido propostas como a mais promissora matéria prima para produção de etanol celulósico, devido às suas várias vantagens sobre culturas tradicionais. Para analisar o potencial de culturas para produção de bioetanol lignocelulósicos no Chile, CLCR foram estabelecidos com as seguintes espécies: Acacia melanoxylon, Eucalyptus camaldulensis, Eucalyptus globulus e Eucalyptus nitens. Estas culturas foram estabelecidas em dois ambientes contrastantes e em três densidades de plantio. O rendimento teórico médio de etanol em 48 meses atingiu 395,9 L . t -1 para A. melanoxylon, 348,7 L . t -1 para E. camaldulensis e 363,9 L . t -1 para E. nitens. Foi concluído que existem diferenças significativas no rendimento de polissacarídeos entre as espécies e o tempo. Por outro lado, foram encontradas diferenças significativas entre ambientes. Em conclusão, este estudo mostrou que a escolha da espécie usada na CLCR como fonte de polissacarídeos deve levar em conta sua percentagem na biomassa e, crucialmente, a espécie, densidade de plantio, ciclo de colheita e sítio devem ser cuidadosamente selecionados para garantir um rendimento elevado de biomassa por unidade de área.

Insights for the Valorization of Biomass from Portuguese Invasive Acacia spp. in a Biorefinery Perspective

“…for the production of bioethanol, considering also an autohydrolysis pretreatment (liquid to solid ratio of 6:1 (v/w), a heating rate of 3 • C/min and cooking at 194 • C for 1 min), followed by simultaneous saccharification and fermentation of the remaining cellulose-and lignin-enriched solid. A. melanoxylon outstands with a high average theoretical ethanol yield, after 48 months of plant growth, that reached 396 L of ethanol per ton of wood [153]. This estimation must be interpreted in the context of the referred work, that considered a plantation in marginal lands, with the sites presenting serious nutritional and hydric deficits, leading to low yields of wood production [153].…”

“…The liquid phase contains saccharides (including monosaccharides and sugar oligomers suitable as ingredients of functional foods or as carbon sources for chemical or biotechnological processes), sugar-degradation compounds (furfural) and acetic acid [166]. Acuña et al [153] investigated the potential of wood from A. melanoxylon and several Eucalyptus spp. for the production of bioethanol, considering also an autohydrolysis pretreatment (liquid to solid ratio of 6:1 (v/w), a heating rate of 3 • C/min and cooking at 194 • C for 1 min), followed by simultaneous saccharification and fermentation of the remaining cellulose-and lignin-enriched solid.…”

Short Rotation Wood Crops in Latin American: A Review on Status and Potential Uses as Biofuel

“…However, these recommended rotations were put forward before 2010, when the concepts of high density and short rotations in SRWCs were not developed [43]. With the new concepts in SRWCs for densities above 5000 trees/ha, a rotation of less than 5 years is to be expected, as is the case of Populus [92,93], E. globulus [85], A. melanoxylum [87], and Gmelina arborea [51] (Table 2).…”

“…Another important parameter related to production is the increase of the biomass, which for the few species reported is moderately high. For example, an increment of 9.2 to 11.5 Tn/ha/yr was found for Populus deltoides [93]; several species of Eucalyptus report a range from 17 to 50 Tn/ha/yr [87], from 18.1 to 33.4 Tn/ha/yr has been observed in Acacia mangium and Acacia auriculiformis in Brazil [83], and from 12 to 64 Tn/ha/yr was found for G. arborea in Costa Rica [52].…”

“…Data on the costs of SRWCs use in Latin America are limited to data available for Chile and Brazil [154,155]. In the Chilean case, Acuña et al [87,154] presented a detailed analysis of the production costs for the first two years for different plantation densities of Eucalyptus globulus. This analysis indicated that the main cost is incurred in the first year, during the SRWC establishment (plantation, fertilization and irrigation system), and then due to fertilization and weed control.…”