Forest biomass harvesting operations’ costs and production rates in the Florida Coastal Plain: a case study of two sites

As biomass energy becomes a key part of the renewable energy mix, optimizing biomass harvesting operations is crucial for ensuring efficiency, economic viability, and a sustainable energy supply. This study analyzed two biomass harvesting operations in the Coastal Plain of Florida, each employing rubber-tired feller-bunchers, grapple skidders, trailer-mounted knuckleboom loaders, and whole-tree woodchippers. While both operations produced wood chips, Operation A harvested material from a stand dominated by small-diameter trees, whereas Operation B harvested understory and unmerchantable trees from a mixed stand where merchantable stems were handled separately. The average productivity rates per productive machine hour (PMH) were 17 green tonnes for the feller-bunchers, 38 green tonnes for the skidders, and 64 green tonnes for the chippers. Low productivity of the feller-bunchers was attributed to the small diameter of harvested trees, with over 60% having a diameter at breast height (DBH) of 7.6 cm or less. Despite chippers having a low utilization rate (58.5%), feller-buncher capacity ultimately constrained overall system productivity. Chipping was the most expensive activity at $USD 105 per scheduled machine hour (SMH), followed by felling ($USD 102), skidding ($USD 98), and loading ($USD 92). Compared with the 2020 TimberMart-South Coastal Plain final-harvest cut-and-load reference rate of $USD 12.5 per tonne, biomass cut-and-load rates were $USD 2.3 higher in Operation A and USD $5.1 per tonne higher in Operation B, with lower costs in Operation A due to higher productivity. This study provides valuable insights into improving the economic efficiency and operational productivity of biomass harvesting systems while supporting the sustainable development of biomass energy.