Simulation-based evaluation of supply chains for stump fuel

Abstract

Current concerns about climate change and fossil-fuel dependency have intensified interest in renewable energy and increased demand for suitable substrates. Softwood tree stumps could be a very interesting renewable fuel assortment, since large volumes of unutilized stump biomass are available. The stump-root system constitutes about 25% of stem volume. However, optimization of logistics issues within the supply chain of stump fuel is crucial in ensuring low procurement costs, particularly for transport and comminution operations. Bulky stumps can be transported and comminuted in different ways, and if the system is planned properly it can reduce the supply costs and help deliver a fuel at a competitive price. This study evaluated various systems for stump transport and comminution in terms of cutting unnecessary costs and making the systems more resource-efficient. A discrete-event simulation approach was applied, using the ExtendSim simulation software. Simulation results obtained using the model developed show large variations in system performance and system costs. The costs of the best and worst alternatives differed by around a factor of 2, irrespective of transport distance. The most cost-effective option proved to be crushing stumps into the ground and using a self-loading truck for wood fuel transport.

Keywords:

• tree stumps
• wood fuel
• logistics
• wood fuel transport
• comminution of stump wood
• supply chain
• discrete-event simulation