ENERGY DENSITY MODEL FOR FOREST SPECIES FROM CERRADO

ABSTRACT Wood is the main source of energy in the energy matrix of underdeveloped countries, in addition to having a significant participation in developing countries, ranking fourth in Brazil. Thus, this study aimed to determine a model for determining the energy density of forest species from the Cerrado. Samples of trunks and branches were collected from 34 forest species in an area of 10.15 ha located in the Cerrado region aiming for immediate analysis, i.e. the contents of ashes (ASH), volatile matter (VM), fixed carbon (FC), and higher calorific value (HCV). Data from dry and saturated mass were obtained in order to determine the basic density. The species presented values of VM ranging from 77 to 85.5%, ASH from 0 to 1%, FC from 14 to 23%, and HCV ranging from 18,282 to 20,121 GJ ton-1. A significant relationship was found between VM and FC (R2 = 0.9927) whereas no significant values were found between HCV and basic density. The average value of energy density considering the 34 species was 12,459 Mcal m-3. The estimated energy density of the area was 1,378,541 Mcal ha-1. The proposed model for calculating the energy density as a function of basic density favors energy surveys of areas to be explored since there is no need for calorific value analysis.

摘要：木材是欠发达国家能源结构的主要能源来源，在发展中国家亦占据重要份额，且在巴西的能源消费结构中排名第四。为此，本研究旨在构建塞拉多（Cerrado）稀树草原林区森林树种的能量密度预测模型。研究团队在位于塞拉多区域的10.15公顷样地内，采集了34种森林树种的树干与枝条样本，开展即时理化分析，测试指标包括灰分（ASH）、挥发分（VM）、固定碳（FC）与高位发热量（HCV）。通过测定试样的干质量与饱和质量，计算得到各树种的基本密度。供试树种的各项指标取值范围分别为：挥发分77%~85.5%、灰分0~1%、固定碳14%~23%，高位发热量介于18282~20121 GJ·t⁻¹之间。研究发现挥发分与固定碳之间存在显著相关性（决定系数R²=0.9927），而高位发热量与基本密度之间未呈现显著关联。34个供试树种的平均能量密度为12459 Mcal·m⁻³。该样地的估算能量密度为1378541 Mcal·ha⁻¹。本研究所提出的基于基本密度的能量密度计算模型，无需开展发热量测试即可用于待开发林区的能源勘测，可为相关区域的能源普查提供便利。