Solar Enhanced Drying Improving the Woody Biomass Supply Chain

Sustainable biomass resources are limited, especially regionally. The energy content of sustainable woody biomass resources can be maximized through drying. On the other hand, there is an urgent need for low-cost energy storage applications, related to solar energy in particular. Biomass dried with solar energy could serve as a seasonal energy storage. It also improves the quality of biomass and helps preserve its quality. In order to study the technology and economy of solar enhanced drying, several drying experiments were conducted on wood chips and on hog fuel made from recycled wood in VTT’s convective dryer in Jyväskylä. VTT’s experiments show that solar heat energy can be successfully applied to thermal drying of biomass. The moderate drying temperatures achieved are advantageous for ensuring homogenous drying of wood particles and for preventing changes to the physical structure of the biomass and loss of volatiles. Due to the low efficiency of the system, still in its prototype phase, the calculated payback times were not highly attractive to the entrepreneur. The best experiment with drying seasoned wood resulted in the shortest payback time (22 years). With technical improvements and a better design, however, the efficiency of the dryer could be improved significantly. Our calculations show that if most of the heat could be utilized for evaporation, the payback time would be brought below 10 years.