Crop residues as energy sources: assessing the cost and energy feasibility of direct firing

Crop residue is a renewable resource that could supply various energy products to an agricultural region. The feasibility of such an effort depends upon the agricultural characteristics of the region, the use of current energy products, alternate conversion technologies, and the operation of the supporting activities which collect, compact, and ship the residue on its journey from the field to final disposition. This paper delineates the various issues and shows a method of feasibility analysis which provides a uniform means of assessment of costs and energy use of alternate systems. The method is applied to examine the feasibility of direct firing residue in selected coal-fired utility boilers in Minnesota. It is found that many county-plant-operation combinations exist where the current coal cost exceeds the as-delivered cost of an energy equivalent amount of residue, suggesting that residue is a potential alternative fuel for power generation.