Feasibility of Solar-Enhanced Drying of Woody Biomass

Jyrki Raitila*, Eemeli Tsupari

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    20 Citations (Scopus)

    Abstract

    Sustainable biomass resources are limited and their utilization therefore needs to be more efficient. In addition, there is an urgent need for low-cost energy storage, particularly for solar energy. Drying considerably increases the calorific value of woody biomass, and the resulting dried biomass provides easy seasonal energy storage. The drying both improves the quality of the biomass and extends its storage life. To investigate the technology and feasibility of solar-enhanced drying, several drying experiments were conducted on wood chips in VTT’s 12 kWpeak convective dryer in Jyväskylä, Finland. Drying times varied from 3.5 to 27 h and the final moistures from 12 to 32 w-%. VTT’s experiments show that solar heat can be successfully applied to thermal drying of biomass. The moderate drying temperatures used (typically 20–50 °C) 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. In the experiments, best profitability was achieved by drying seasoned wood, for which a payback time of 12–17 years was estimated for a large scale system such as a biomass terminal. Based on the assumptions that technical improvements are made, the best drying efficiency reached in our experiments is achieved, and some investment subsidy is secured; scale-up is feasible. With these criteria met, the payback time of such a dryer could be brought below 10 years. This requires, however, that drying increases the selling price of wood chips.

    Original languageEnglish
    Pages (from-to)210-221
    JournalBioenergy Research
    Volume13
    Issue number1
    Early online date10 Nov 2019
    DOIs
    Publication statusPublished - 1 Mar 2020
    MoE publication typeA1 Journal article-refereed

    Funding

    The solar-enhanced drying studies were conducted as part of the Sustainable High Value Products from Low Grade Residues and Waste (WasteBusters) and Value-optimized Use of Biomass in a Flexible Energy Infrastructure (VabiSys) projects. The authors wish to acknowledge and thank the Finnish Funding Agency for Innovation (Tekes/Business Finland), our Finnish partner companies and VTT for providing resources for the project.

    Keywords

    • Bioenergy
    • Biomass drying
    • Energy storage
    • Solar energy
    • Wood chips

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