Impact of agronomic treatments on fuel characteristics of herbaceous biomass for combustion

Miscanthus and switchgrass are two perennial grasses with the potential to replace coal in generating heat and electricity. Agronomic management practices such as nutrient fertilizer applications are required for crops to grow and thrive. However, some of the nutrients essential for biomass growth are also highly undesirable in the combustion process. A field-plot study was conducted to evaluate the impact of agronomic treatments on the quantitative fuel properties of the two grass species. Empirical indices were used to characterize samples for their potential to impact combustion quality as a function of the agronomic treatments. Ash content was significantly affected by harvest time (α = 0.05). Delayed harvest in the spring resulted in a significantly reduced ash content. Potassium (K) was the only ash mineral that was significantly reduced as a result of delayed harvesting; reduction in other ash minerals was varied. N-fertilization tended to increase combustion indices, suggesting improvement in biomass combustion quality when there is minimal fertilization for both plant species. More studies are needed to find alternative technologies to leach out other undesirable ash chemical constituents that adversely impact thermochemical combustion. The study provides a better understanding of how fuel properties of Miscanthus and switchgrass may be affected by agronomic practices.