A conspectus review on solar drying of wood: regional and technical contrivances

Fuel quality is an important measure to assess as conventional fuel resources have been depleted at an alarming rate over recent years. For centuries, wood-based biofuels have been used extensively as the primary fuel source for boilers or heating plant operations. In a heating plant scenario, operating temperature, moisture content, gas usage, emission controls, etc., play a significant role in fuel quality assessment. Additionally, the advent of solar energy and its popularity in drying applications has provided ample opportunities to explore wood solar drying. Hence, improving the wood-based biofuel quality by implementing solar drying strategies has caught research attention in recent decades. However, there is a lack of well-documented review on the classifications of wood solar drying systems and the various modeling and simulation approaches that evolved in recent years for their performance optimization. This work reviews extant wood fuel quality problems and regional and technical challenges worldwide. Further insights into the possible solutions (through modeling or simulation) to enhance wood-based fuel quality by adopting solar drying technologies are discussed briefly. Notably, a case study of real-time data assessment of wood chips as biofuel in a boiler plant in Miskolc, Hungary, is presented. The outcomes of this review would serve as a benchmark and aid industries and researchers in further exploring wood solar drying potential.