Agricultural Waste Processing into Briquette: A Sustainable Solution for Alternative Woodfuel Supply in Rural Areas of Bangladesh

Introduction

Agricultural waste biomass has been contributing as dominant source of total primary energy supply in rural areas of Bangladesh. Biomass in energy mix includes various types of agricultural wastes obtained from rice, wheat, jute, sugarcane, potato, oilseeds, maize, and groundnut crops. However, rather than agro-waste, woodfuel is preferable as fuel to the users in urban and peri-urban areas. The main disadvantages of the loose agricultural waste biomass are bulk in volume, variability in moisture content, heterogeneous in particle sizes and shapes and difficult to transport. There is an acute shortage of woodfuel in the country. There are two options to fill up the vacuum in the wood fuel supply chain, firstly to collect the woodfuel by exhausting the forest and, secondly to choose an alternative source as replacement of woodfuel. The first option has been committed in the country to meet the rising demand of woodfuel. However during recent decades densified agro-waste biomass (‘briquette’) has got attention as replacement of woodfuel in rural and peri-urban areas. At present only rice husk is densified into briquette and other wastes are ignored although, other wastes biomass also have potential for converting into briquette fuel. Biomass briquette is woody material with some advantages compared to woodfuel such as the uniformity in moisture content, density and strength, calorific value, and reduced volatile matter. Moreover, rice husk briquette is about 60% more thermally efficient than woodfuel in same cook stove. There is a potential of 3.0 million tonne of briquette fuel from rice husk only that could save 25 thousand hectare forest annually from ongoing deforestation process and could reduce 7.8 million tonne of CO2 emission as well. The potential of briquette fuel from different types of agricultural wastes and their socio-economic and environmental impacts are discussed in this paper.

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