A review of technoeconomic benefits of torrefaction pretreatment technology and application in torrefying sawdust

Abstract

Economic analysis of torrefaction process centers on assessment of the economic feasibility of the production and utilization of torrefied biomass using developed models such as costs of biomass, electricity, labour, investment, transportation etc. to evaluate the cost of biomass torrefaction. The increase in energy usage over the past century has raised concern over the energy insecurity and environmental unsustainability of current fossil fuel utilization; therefore, there is need for energy diversification. An attractive alternative is the biomass. However, the poor performance of raw biomass in energy generation further necessitate development of refined technologies to enhance its performance, particularly at low temperatures between 200–300 ℃. This study therefore reviews the technoeconomic benefits of torrefaction technology and reactors and its application in the pretreatment of sawdust. An overview of torrefaction technology, torrefied product characteristics, and economic analysis of torrefier reactor and torrefaction cost/ton were reviewed. From the review, torrefaction significantly improved the physical, combustion and performance characteristics of torrefied products, with comparable durability and storability to raw biomass. Comparing with other thermal pretreatment methods, torrefaction is an economical way of improving biomass properties.