Evaluating the use of renewable fuel sources to heat flue-cured tobacco barns

Abstract

The curing of flue-cured tobacco (Nicotiana tabacum L.) is an energy intensive process and represents a significant portion of the overall cost of production. Given the goal of the industry to reduce the environmental footprint of tobacco production and the energy demand of curing, attention has been directed to explore options for the use of renewable fuels for heating tobacco barns. A two-year study conducted at the Virginia Tech Southern Piedmont Center evaluated the effectiveness and cost of curing flue-cured tobacco with a wood pellet burner. Additionally, field studies were conducted to evaluate the feasibility of on-farm production of biomass fuel crops as well as on-farm manufacture of biomass fuel pellets. The first time use of a wood pellet burner with an air-to-air heat exchanger in a bulk curing barn proved to be a viable alternative to a conventional propane fueled burner. Curing cost averaged $0.05 with the pellet burner compared to $0.04 per kilogram of tobacco with the propane burner. The increase in cost was offset by a 90 percent reduction of CO2 emissions with the use of wood pellets. The use of low lignin grass varieties did have an impact on biomass pellet properties. Pellet testing revealed high ash and chloride levels which could be problematic using a high efficiency wood pellet burner. Full maturity harvest of annual grasses fertilized with 112 kg per ha N resulted in higher yields. However, fertilizing for maximum yield would increase the CO2 footprint for biomass fuel pellet production.