TECHNICAL-ECONOMICAL COMPARISON BETWEEN COGENERATION, PELLET PRODUCTION AND THERMAL USES OF BIOMASS

摘要

he logistics for the collection of energy biomasses is a major constraint in areas with severernorography, lack of transportation infrastructures and dispersed land ownership. The use of small size units eases thisrnprocess for it reduces the extension of the gathering area. Nevertheless, small size means low electrical efficiency andrnhigh specific costs. Many yearly operating hours are required for making a small plant become a cost effectivernsolution. A difficult compromise must be settled, between the proximity of the plant to the woodland and thernpresence of a local heat demand, for a full exploitation of the power output.This paper discusses the idea of using thernheat surplus of a biomass-fired cogeneration unit to treat a share of the biomass and produce fuel like pellet, to bernstored and distributed for heating purposes. This form of thermal energy storage makes time and geographical shift ofrnheat utilization possible, also in small-scale applications. A technical-economical comparison is carried out andrndiscussed between the above mentioned system and a district heating supplied by a traditional biomass boiler, or arnconventional chip-fired cogeneration plant without pellets production. The economic profitability of different plantrnsolutions is investigated in some case-studies.