Optimising cascaded utilisation of wood resources considering economic and environmental aspects

Cascaded wood utilisation could help to bridge the gap between the rising wood demand and fresh wood availability as well as contributing to a circular economy. However, the economic and environmental implications of cascading wood-based products are not fully known yet and are hence explored in this paper, considering both aspects simultaneously for the first time. The study focuses on the production of the following five products in an integrated system: medium-density fibre, oriented-strand board, particleboard, coated paper and wood pellets. Firstly, a multi-objective optimisation model has been developed to minimise the costs and greenhouse gas emissions of cascaded utilisation of wood. The ε-constraint method has been used to solve the model and derive Pareto optimal solutions. The latter have been used to select two cascaded-utilisation scenarios and compare their environmental performance with two other scenarios: current situation and the use of fresh wood only. The environmental impacts have been estimated using life cycle assessment. The results reveal that cascaded utilisation is more environmentally and economically sustainable than the current situation or the use of fresh wood. One of the scenario (Scenario 2) reduces the impacts by 1%-23% on the current situation; the global warming potential (GWP) is lower by 15%. However, the costs in this scenario are only 4% lower. In another (Scenario 1), the costs are lower by 24% but the reductions in impacts are more limited, ranging from 1%-8% relative to the Reference scenario with the GWP being only 1% lower. The cascaded use of wood also offers the potential to save up to 35% of fresh wood resources, thus contributing to a circular economy. Using only fresh wood (Scenario 3) is the worst option, increasing the costs by 13% while offering small or no environmental benefits in most of the impacts. These results will be of interest to the wood industry, forestry authorities and policy makers