When we use wood products to displace other materials and avoid their fossil emissions, we speak of a substitution effect. Finland already boasts significant substitution effects, but they can be further increased by utilising forest industry side streams more extensively as raw material for products.
Elias Hurmekoski, a postdoctoral researcher at the Department of Forest Sciences of the University of Helsinki, leads a project focusing on substitution processes related to wood products and their climate impact. “Of all the climate impacts related to wood consumption, substitution effects may be the most abstract, since they refer to the fossil emissions avoided through the use of wood. We’ve known about substitution effects for 30 years or more, and there have been many attempts to calculate them. However, major gaps in information remain in the field.”
“In this project, we adopt a multidisciplinary approach, because we’re interested in both the fossil emissions avoided and market operations. We focus on preparing calculations and analysing the underlying assumptions, but the project also provides a more detailed estimate of the size of substitution effects.”
Substitution effects can be increased
“When calculating substitution effects, the essential data concerns the products that wood is expected to displace. There are thousands of potential products and thousands of purposes of use. We also have a host of products with the potential to be substituted by wood. It’s impossible to examine all the combinations, so we need to make a number of rough assumptions.”
Product portfolios can help to significantly increase substitution effects. Wood construction is a good example of this, and from a climate perspective, it is still one of the smartest ways to use wood.
“It can be challenging to calculate the substitution effect if you focus on a single product group. For example, if you examine a stand marked for final felling or a single tree, for example, part of it is log wood, while the rest is treated as pulpwood and other fractions. This makes it essential to analyse the use of side streams. They are currently used for pulp, energy production and chip boards, among other things. However, to maximise the substitution effect of wood, we should increasingly steer these side streams to products and postpone their use as energy until the end of their life-cycle.
Substitution benefits from textiles
“Textiles are a very interesting pulp-based product group. Their manufacture offers the potential for large substitution benefits. If the end use of pulp shifts from graphic paper to the textile business, this would be a very positive change for the climate. Wood-based products also offer many other benefits apart from climate aspects. Talking about textiles, the cultivation of cotton, for example, involves freshwater consumption and pesticide use, which pulp-based products do not.”
According to Hurmekoski, the packaging materials and chemicals used to displace plastic are other pulp- and side stream-based products that could generate greater average substitution benefits – greater efficiency from the same volume of wood, if you like.