RESUMO A importância do emprego de fontes alternativas de energia, que sejam renováveis e provoquem menores danos ao meio ambiente, como menor poluição atmosférica e estabilidade do ciclo do carbono, traz em destaque a biomassa florestal. Nesse contexto, avaliou-se a produção de briquetes, produzidos a partir de resíduos florestais encontrados nas diversas fases de produção das fábricas de celulose, os quais foram analisados quimicamente, bem como suas propriedades físicas e mecânicas. Foram realizados dez tratamentos a partir de quatro classes de resíduos amostrados, utilizando delineamento estatístico inteiramente casualizado (DIC), com 10 repetições por tratamento. Para a análise estatística, realizou-se teste Tukey de comparação de médias e análise de componentes principais para explicar a estrutura da variância. Os tratamentos 4 e 10 apresentaram maior poder calorífico devido ao seu maior percentual de lignina, bem como obtiveram os melhores resultados de densidade energética. Quanto a densidade e a resistência mecânica, os valores encontrados foram adequados e condizentes aos citados na literatura, sendo que a última variável não diferiu estatisticamente entre os tratamentos. A análise dos componentes principais foi adequada, sendo os teores de extrativos, umidade, lignina, e a densidade energética as variáveis mais importantes na análise, com os mais elevados coeficientes da componente principal 1, a qual representa 70,9% da variância total explicada. O tratamento 4, contendo apenas casca de Pinus taeda, se destacou pelas suas melhores características para energia.

ABSTRACT The importance of using alternative sources of energy, which are renewable and cause less damage to the environment, such as lower atmospheric pressure and carbon cycle stability, highlights a forest biomass. In this context, the production of briquettes, produced from forest residues found in the various production phases of pulp mills, was evaluated and chemically analyzed, as well as their physical and mechanical properties. Ten treatments were performed from four sampled residue classes, their analysis was performed by a completely randomized design, with 10 repetitions per treatment. For the statistical analysis, Tukey's test of comparison of means and analysis of main components was performed to explain the structure of variance. Treatments 4 and 10 showed higher calorific power due to its higher lignin percentage, as well as obtained the best energy density results. Regarding the density and mechanical strength, the values found were adequate and consistent with the literature, and the last variable did not differ statistically among the treatments. The principal components analysis was adequate, with the contents of extractives, moisture, lignin, and energy density the most important variables in the analysis, with the highest coefficients of the main component 1, which represents 70.9% of the total variance explained. Treatment 4, containing only Pinus Taeda bark, stood out for its best characteristics for energy.

ABSTRACT The tobacco production requires annually a large volume of firewood used in the cure process of tobacco leaves, representing up to 10% of its production cost. An alternative is the use of agroindustry residues, such as sawdust or pellets. The objective of this study was to analyze the consumption and to characterize forestry biomass used in the tobacco cure process in farmers from Candelária, Southern Brazil, aiming the culture energetic efficiency. Forestry biomass consumption, residues formation after combustion and biomass quality were verified. In terms of available energy, the consumption for each kilogram of dry tobacco was 77.23 MJ for firewood, 61.40 MJ for sawdust and 37.51 MJ for pellets. Pellets presented the best physicochemical characteristics for use as energy, as well as the lowest consumption and the lowest organic fraction present in combustion residues.

ABSTRACT Economic and environmental aspects of residues energetic use in Brazil are extremelly important. In one hand, the country is today a recognized bioenergy producer in a global scenario; on the other, it is still struggling to provide a reliable renewable energy supply to rural communities. Local demand could be supplied through small investments using local forest mill residues as feedstock to produce value-add bio-based energy fuels. Therefore, this work aims at evaluating wood pellets production as an alternative source for supplying regional heat demand for drying grains and tobacco in the Rio Pardo Watershed (RPW), Brazil. It presents techno-economic analysis and risk assessment for a pellet plant supplied by sawmill residues available at the RPW. The results showed the economic feasibility of pellets production in the RPW. The pellets can be a clean, renewable alternative energy source to firewood for supplying farms demand for drying grains and tobacco.

RESUMO O trabalho teve como objetivo geral avaliar a demanda de madeira para as serrarias no Vale do Rio Pardo e, ainda, analisar a viabilidade financeira de implantar uma base florestal que supra a capacidade ociosa de processamento dessa região. O estudo foi desenvolvido na área central do Rio Grande do Sul, abrangendo 13 municípios que compõem a Bacia Hidrográfica do Rio Pardo. Para a obtenção dos dados foram realizadas entrevistas semiestruturadas com proprietários de serrarias da região. Essas foram avaliadas quanto ao seu consumo e capacidade instalada, que, respectivamente, foram de 7.005 m3.mês-1 e 12.330 m3.mês-1, apresentando uma capacidade ociosa na ordem de 63.900 m3.ano-1. O abastecimento de 30.336 m3.ano-1 ocorre através de fornecedores de fora da região. Com isso, verificou-se a necessidade de 1.836 ha para suprir a demanda anual destas serrarias. A substituição da importação de matéria-prima e o incremento da capacidade ociosa seriam responsáveis por gerar 55 empregos nas atividades de produção florestal e 471 empregos na indústria. Conforme análise financeira pelo Método de Monte Carlo, a receita anual gerada pelo empreendimento seria na ordem de R$ 1.756.347,00, correspondente a uma área de colheita estimada em 122,40 ha, distribuída nos municípios da região.

ABSTRACT The general objective of this study is to evaluate the demand for timber from the sawmills and to analyze the financial feasibility of establishing a forest base that meets the idle processing capacity. The study was conducted in the central portion of Rio Grande do Sul state, comprising 13 municipalities that constitute the Rio Pardo watershed. Data collection was done through interviews with farmers and sawmill owners. The sawmills of the region were evaluated as to their timber consumption and installed capacity, respectively amounting to 7,005 m3.month-1 and 12,330 m3.month-1, with an idle capacity of approximately 63,900 m3.year-1. The supply of 30,336 m3.year-1 is carried out by suppliers from other regions. This shows the need for 1,836 hectares for meeting the annual demand. The replacement of raw material imports and a better use of the idle capacity would translate into the creation of 55 jobs in forest production activities and 471 jobs in the industries. According to the financial analysis by Monte Carlo Method, the annual income generated by the enterprise would reach approximately R$ 1,756,347.00, corresponding to a harvest area estimated at 122.40 hectares, across the municipalities of the region.