Wood Product Carbon Substitution Benefits: A Critical Review of Assumptions

Abstract:

There is growing interest in the role that forest biomass can play in substituting fossil fuels and non-biomass materials, a great deal of which is associated with the role of long-lived wood products in the construction sector. Often the climate change mitigation benefits of this substitution are presented and quantified in the form of displacement factors. Sathre and O’Connor (2010) employ a meta-analysis in which a displacement factor is quantified numerically as the reduction in emissions achieved per unit of wood used representing the efficiency of biomass in decreasing greenhouse gas emissions. The purpose of this review is to identify and assess the economic and technical assumptions in the forest carbon accounting and life cycle assessments that use displacement factors. Four assumptions are analyzed, which include: changes in harvest or production rates will lead to a corresponding change in wood product consumption, wood building products are substitutable for concrete and steel, the same set of products could be produced from increased harvest rates of a given area, and there are no market responses to increased wood use. After outlining these assumptions, we find that many studies assessing forest management or products for climate change mitigation depend on a suite of assumptions that the literature either does not support or only partially supports. We conclude that we need a better methodology to quantify the climate change mitigation benefits of substituting wood products for fossil fuel materials. Furthermore we identify opportunities to increase the potential use of wood products and minimize the effect of these assumptions.