Assessment of hybrid greenhouse/hot air biomass drying in a briquetting process

Abstract

The use of forest biomass for energy purposes is expected to increase considerably in the coming future due to environmental concerns and fluctuating fossil fuel prices. Briquetting process allows valorization of loose woody biomass. Optimizing the process allows a higher cost effective production. For this reason, drying of biomass which is one of the most energy consuming and critical steps in the briquetting process should be addressed. Conventional dryers in such production lines are kiln or room dryers where heat is provided by burning part of the biomass. One alternative way to dry a wet material is by using solar energy inside greenhouses. This is a cheap and efficient method that saves energy. Based on a numerical model, this paper assesses the opportunity of using a greenhouse dryer in a briquetting process in Lebanon as an alternative to a conventional one. Solar drying depends immensely on weather conditions. For that reason, scenarios taking into consideration different compromises between the dryer size and its drying rate, and additional energy source during cold and humid days are studied. The results are compared to the conventional dryer energy needs. © 2018 University of Minho. All rights reserved.