Biofuels from stumps and small roundwood—Costs and CO2 benefits

In this study, we analysed and compared costs, primary energy use and CO2 benefits of recovering stumps and small roundwood from thinnings, together with logging residues. Small roundwood, chipped at a terminal or end-user, has a cost comparable to the chip system and a primary energy use comparable to the bundle system used for recovery of logging residues. The small roundwood system with roadside chipping is more expensive. As productivity in the cutting process improves, the small roundwood alternatives become more cost-effective. The stump system has costs in the same range as or lower than the chip and bundle systems. Forestry operations for stump and small roundwood recovery require considerable primary energy, but net recovery per hectare is much greater than for the chip and bundle systems, which means that more fossil fuel can be displaced per hectare of clearcut than with a chip or a bundle system. Stumps and small roundwood from thinnings can become as cost-effective as logging residues in the near future. Furthermore, when stumps and small roundwood from thinnings are also used to replace fossil fuels, the potential CO2 reduction will be about four times as great as when only logging residues are used with a traditional chip system.