Direct combustion energy from crops and crop residues produced in Iowa

Abstract Energy values were determined via bomb calorimetry for various crops and their residues produced from single- and double-cropping systems in Iowa. The dry-matter energy values of this biomass were in the order of 16.3 ± 2.0 MJ/kg. Considering crop moisture conditions in the field at harvest, energy values of the “as is” biomass were about 12.0 MJ/kg, or slightly less. Energy available from harvestable corn residues in Iowa exceeded that of energy required from fossil fuels used in electrical generation in the state in 1978. Biomass from a proposed double- cropping system of rye and sorghum × sudangrass grown on less than 12% of the corn hectarage in Iowa, also could have supplied all the energy required to generate electricity in Iowa annually. Utilization of biomass for energy, however, must be balanced with conservation of the land and its productivity. Calculations suggested that up to 70% of energy required for electrical generation could still be obtained from corn residues after leaving adequate amounts of residue to conserve soil resources.