Conversion of Invasive Species Biomass to Energy and Biochar through Pyrolysis and Torrefaction

2015 AIChE Annual Meeting, Salt Lake City, UT

Session: TG004 Conversion of Solid Wastes to Energy and/or Product

Conversion of Invasive Species Biomass to Energy and Biochar through Pyrolysis and Torrefaction

Graham Hoffman, Andrea Y. Salazar, Catherine E. Brewer

Department of Chemical and Materials Engineering

Russian Thistle (Salsola tragus), which turns into “tumbleweed” when it dries, is an invasive species and poses a threat to surrounding native vegetation and ecosystems. In addition to competing with native plants for water and nutrients, tumbleweed creates fire and traffic hazards, dramatically reduces crop yields, promotes wind erosion of soil, and causes allergies when flowering. There have been numerous control measures tested but these have yet to give satisfactory results. Another invasive species that continue to cause problem in the drought-plagued western U.S. include Russian olive (Elaeagnus angustifolia) and salt cedar (Tamarix spp.). Salt cedar consume incredible amounts of water, draining both groundwater and waterway sources. Eradication projects have been conducted but are not on the scale required to remove salt cedar from the area.

In this study, we explore the use of slow pyrolysis and torrefaction to convert invasive species biomass to biochar and/or a stable, friable solid fuel that is suitable for co-firing with coal. We compare different torrefaction and pyrolysis conditions with respect to product physical and chemical properties, reaction complexity, and feasibility for implementation. The goal of this research is to provide a financial return for invasive species collection and removal.