Relationships between Major Constituents, Storage Conditions, and Higher Heating Values of Rice Straw

Relationships between higher heating values (HHVs) and major constituents (carbon, nitrogen, moisture, ash concentrations) of rice straw while examining storage conditions were investigated. Different storage periods and temperatures affect major constituents. To obtain high-accuracy predictions for HHVs, we analyzed the relationship between carbon and nitrogen concentrations, which is a better method than analyzing moisture and ash concentrations. HHV is calculated as 17007.89−9.17t+0.05T, where t and T are the number of storage days and biomass temperature, respectively, with coefficient of determination = 0.801 and significance level = 0.05. HHVs obtained from this relationship agreed well with those obtained using a bomb calorimeter, indicating that this relationship has the potential for use in estimating HHVs of rice straw.