Quantification of Biomass Potential from Timber Stand Improvement (TSI) Operations in Hardwood Stands in North Carolina

Abstract

Across North Carolina, forest species composition has changed substantially over the past 35 years. Oak species have declined while other species, especially red maple and sweetgum have proliferated. This general trend is seen across the state of North Carolina, though each of the four physiographic regions of the state has different factors that contribute to the specie composition changes. Within oak stands, competition in the understory and midstory can significantly reduce oak regeneration. Mitigating competition with oak species through TSI can generate biomass for energy. This project explores potential connections between oak regeneration through conservation forestry and timber stand improvement operations that target red maple and sweetgum removals for biomass energy. This project quantifies small-diameter biomass of red maple and sweetgum trees in oak dominated stands across North Carolina. Biomass supply estimates typically focus on available residues from forest harvests or from overstocked stands. This report is the first to focus on biomass available from restoration activities in hardwood stands. The standing stock of small diameter red maple and sweetgum is approximately 18,000,000 tons in North Carolina, or 725,000 green tons on an annual basis. However, because harvesting biomass in stand improvement operations is expensive and because of the distributed nature of the resource, limited quantities of biomass will be utilized by our current biomass energy infrastructure. A supply model of the biomass facilities in the state shows that only 87,000 green tons could be utilized. The four facilities modeled in the scenario could produce 53,000 MWh of electricity from the available biomass. Utilization of all biomass in high efficiency thermal applications could yield 1,500,000 MWh-equivalent of thermal energy. A distributed network of biomass energy utilization, focusing on high efficiency thermal applications appears necessary to realize the full potential of North Carolina’s biomass resources.