Energy requirements for wood chip compaction and transportation

Wood chips represent one of the most popular biomass fuel in latest cogenerating plants and in small heatingsystems. This fuel, being characterized by low bulk density, requires high transportation costs. This obstacle canbe overcome by wood chips densification. The authors investigated the energy benefit of wood chips densification for transport operations for "short supply chain" as defined by the Italian government for the biomass fuelsubsidy scheme. Three different woods (poplar, chestnut and a mixture of spruce and eastern white pine) chipsand six different tractor's trailed trailers were investigated. The total specific energy (kJ kg-1) required totransport a defined quantity of wood chips, the energy saving ratio (%) from chips' compaction and the breakeven distance (km) between raw and compressed chips were calculated. The results highlights that densificationprocess of wood chips is an interesting opportunity to improve the transport energetic convenience. The benefitof wood chips densification is strongly affected by raw wood chips density values and by trailer characteristics:the benefit is maximum when the density of compressed wood chips to be transported attains the vehicle theoretical density