• Nebra, Sa
• Teixeira, Jcf
• Teixeira, Sfcf
• Ferreira, Ac

Abstract

Biomass, as a renewable energy source, has the advantage of being converted through physical, chemical or biological processes into useful energy such as heat, electricity or biofuels. In the specific case of forestbased biomass, it mainly consists of carbohydrates (cellulose and hemicellulose) and lignin, which represents one of the major renewable raw materials for bioenergy production. Despite the increasing interest in the forest biomass use, several barriers are limiting its market due to the high logistic costs, which in some cases represent almost 90% of the total bioenergy production cost. Thus, the supply chain cost of forest-based biomass for energy generation is an important factor affecting the selling prices of all wood biofuels and it affects its competition when compared with fossil fuels. Biomass logistics comprises several activities in the upstream and downstream phases of the supply chain: (1) harvesting and collection; (2) storage; (3) pre-processing; and (4) transportation. The main objective of this work is to analyse the complete supply chain of different forest-based biomass production and estimate the full cost structure and the biomass respective energy value. The analysis includes the estimation of the costs to harvest, store, preprocess and transport the biomass from forest to its end-use. The cost structure of harvesting, storage and pre-processing operations include the investment of machinery for a certain service period, the labour cost, the fuel costs and the harvesting productivity. The transportation cost depends on distances, transport option and load volume. Biomass can be collected in different forms and the harvesting costs of forest biomass vary mainly due to different working methods and distinct machinery used for cutting or splitting the biomass. Biomass can be stored at intermediate storage facilities or directly at the conversion facilities, whereas the type of storage depends on the biomass characteristics and the climatic conditions. Storing biomass at intermediate facilities enables handling and storing large volumes of biomass for long durations, but it also represents additional transportation costs. Additionally to the distance travelled or the quantity of biomass, the transporting cost is influenced by the number of rail or truck used and the actual routes taken by the vehicles. Biomass pre-processing includes operations such as sorting, chipping, grinding and densification. This processes increase transportation efficiency and improve the quality of the feedstock. A representative fraction of Portuguese primary forest biomass is used for energy production, followed by wood-based products and pellets industry. Wood chips, pellets and briquettes are used for bioenergy production. When compared, the pellets have a better balance concerning heating value (17 to 19 MJ/kg), energy density (11000 to 13000 MJ/m3) and price (150 to 200 €/ton). Total harvesting costs vary between 20 and 25 €/m3, depending on the level of mechanization felling. Load transportation costs can reach a value of 16.6 €/m3 © ECOS 2020.All right reserved.

Topics

• density
• impedance spectroscopy
• energy density
• phase
• grinding
• lignin
• wood
• cellulose
• densification