A comprehensive overview of the continuous torrefaction method: Operational characteristics, applications, and challenges

Throughout the history, the whole world have been concerned with the supply of energy and fuel. Today, technological advancements and the depletion of fossil fuel reserves have made countries to think about energy and alternative fuels that can be tapped in a more effective and sustainable manners. Several methods are available to address the imminent energy shortage, including diversification of the available energy resources. With the advent of biomass in large quantities at low costs, sustainable energy sources have opened up new possibilities. However, raw biomass is less suitable to use because of certain characteristics, such as low energy yield, high moisture content, and inadequate storage and processing. Due to these issues, pre-treatment has gained a lot of attention to convert these materials into fuels of value. Continuous Torrefaction is one of the most promising candidates for the pretreatment method of these materials that has sparked interests for researchers. During this treatment, the raw biomasses are exposed to a temperature between 200 and 300 °C under a controlled atmosphere that produces solid biofuels with elevated thermochemical features. An in-depth examination of continuous torrefaction, including its operational characteristics, applications, and challenges, is provided in this study. This research examines continuous torrefaction from the perspective of operational characteristics, applications, and challenges. In addition to the temperature, residence time, and feeding rate, several operating parameters will be evaluated in relation to continuous torrefaction, including how they affect the torrefied biomass's properties.