Cost impacts of producing high density bales during biomass harvest

Bale density is the most important factor that influences the logistics cost of harvesting and delivering biomass to a biorefinery. Volume limited transport equipment carry a larger mass with denser bales. But denser bales require more power to be formed and more power to be transported. This paper compiles the published equations and data on bale density and power for making and hauling bales. The costs are also calculated for shredding and windrowing the chopped stalks and transporting bales to the roadside and from there to a biorefinery. The purchase price of implements are scaled to the increased power. The power requirement are used to calculate the purchase price of tractors. The analysis shows that the farm gate cost of baled biomass increases with density, and as expected the transport and storage cost decreases. Summing the farm gate and transport costs yields a minimum at which the bale density is optimum. This optimum density varies with the transport distance.