2022 Annual Meeting
Properties of Hemp Stalk Residues and Potential for Value-Added Applications
Student Poster Competition Category: Materials Engineering and Sciences
Properties of Hemp Stalk Residues and Potential for Value-Added Applications
Hannah Severns, Hanah T. Rheay, Catherine E. Brewer
Department of Chemical and Materials Engineering, New Mexico State University
Hemp (Cannabis sativa L.) has been an important agricultural crop across the globe for thousands of years. Hemp production in the U.S. has only recently resurged following nearly 70 years of prohibition. Today, hemp is defined by U.S. law as C. sativa with a maximum allowable concentration of 0.3% total tetrahydrocannabinol (THC), a psychoactive compound. The current hemp industry is primarily driven by demand for cannabidiol (CBD) and other non-psychoactive cannabinoids in hemp, with most fiber and grain hemp products imported from countries with established hemp industries. The domestic focus on cannabinoid products and the lack of infrastructure for hemp fiber processing has led to most of the stalks and stems of high-CBD hemp crops (up to 70% of the total crop dry weight) being disposed of as waste. Although the fiber residues of cannabinoid hemp crops may not be suitable for traditional fiber applications, they still represent an underutilized feedstock with several potential value-added uses: solid biofuels; feedstock for bioethanol, paints, plastics, and sealants; building material bio-composites components, such as hempcrete; and paper or pulp additives. The choice among these value-added uses is dictated by the chemical composition of the lignocellulosic hemp biomass.
Following harvest, hemp stalks from high-CBD hemp crops grown in New Mexico are milled to obtain a homogenous residue for characterization. The homogenized residue is evaluated for lignin, cellulose, extractives, volatiles, moisture, and ash contents, as well as mineral and elemental (CHNS) compositions, and energy value. Characterization results will be compared against ideal feedstock compositions for the various downstream applications. In order to sustain hemp production in New Mexico, particularly for high-CBD production, it is vital to identify additional value-added products that can be obtained from a crop.