Life-cycle inventory of wood pellet manufacturing and utilization in Wisconsin.

Abstract This study summarizes environmental impacts of “premium” wood pellet manufacturing and use through a cradle-to-grave life-cycle inventory. The system boundary began with growing and harvesting timber and ended with use of wood pellet fuel. Data were collected from Wisconsin wood pellet mills, which produce wood pellets from a variety of feedstocks. Three groups of manufacturers were identified, those who use wet coproduct, dry coproduct, and harvested timber. Pellet mill data were weight averaged on a per unit basis of 1.0 short ton of “premium” wood pellets, and burdens for all substances and energy consumed were allocated among the products on a 0 percent moisture basis. Wood pellets produced from dry coproduct required 60 percent less energy at the pellet mill. However, when considering all cradle-to-gate energy inputs, producing wood pellets from whole logs used the least energy. Pellets from wet coproduct and dry coproduct used 9 and 56 percent more energy across the life cycle, respectively...