Assessing the integration of torrefaction into wood pellet production

• A simulation module for torrefaction of woody biomass is developed.
• The module incorporates the quality of biomass and its uncertainties.
• A real wood pellet supply chain is used as the case study.
• Integration of torrefaction into an existing supply chain is evaluated.
• Cost of torrefied pellet delivered to existing and potential markets are estimated.

In this study a dynamic simulation modeling approach is used to assess the integration of torrefaction into the wood pellet production and distribution supply chain. The developed model combines discrete event and discrete rate simulation approaches and allows considering uncertainties, interdependencies, and resource constraints along the supply chain which are usually simplified or ignored in static and deterministic models. It includes the whole supply chain from sources of raw materials to the distribution of the final products. The model is applied to an existing wood pellet supply chain, located in British Columbia, Canada, to assess the cost of delivered torrefied pellets to different markets, energy demand, and carbon dioxide emissions along the supply chain and compare them with those of regular pellets. In the presented case study, integration of torrefaction leads to lower delivered cost to existing and potential markets due to increased energy density and reduced distribution costs. In comparison with regular pellets, the delivered cost of torrefied pellets ($/GJ) to Northwest Europe is 9% lower. Also, the energy consumption and the emitted carbon dioxide along the supply chain are decreased due to more efficient transportation of torrefied pellets. Integration of torrefaction into the wood pellet production and distribution supply chain could result in less expensive and cleaner biofuel. The feasibility of such integration depends on the trade-off between the higher capital and operating costs and the reduced transportation costs.

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