ENERGY BALANCE OF THE PRODUCTION AND USE OF MISCANTHUS FOR ENERGY PURPOSES, IN PORTUGAL

摘要

The aim of this study is to evaluate the energy balance of the production and use of Miscanthus forenergy purposes, in the pedoclimatic conditions of South Portugal. Combustion of the biomass was the processconsidered once it is largely implemented, industrially and commercially. Four different scenarios were considered;Scenario1) Biomass Power Plant (10MW); Scenario 2) Biomass Power Plant (0,1MW); Scenario 3) domestic systemfor the pellets combustion. Pellets are being produced in an unit at the frontier of the farm; Scenario 4) domesticsystem for the pellets combustion. Pellets are being produced in the field at the same time of the harvest.In all scenarios, energy efficiencies determined were higher than unit (Scenario 1: 14,1; Scenario 2: 12,9; Scenario 3:9,4; Scenario 4: 8,8) and the energy balances presented positive values. Scenario1 – Combustion of Miscanthus in aBiomass Power Plant (10MW), is the most advantageous. Conversion, irrigation, and, in the case of pellets use indomestic systems, transportation, were the factors that most contributed for the energy consumption. Irrigation andharvest date were the factors that mostly affected the energy efficiency of the system. No irrigation after the 3rd yearof the crop increases significantly the energy efficiency. To harvest in January, means a significant reduction of theenergy efficiency of the system.