Beyond Economic Allocation: Investigating Alternative Coproduct Treatment Methods in Cotton Life Cycle Assessments

Abstract

Highlights The multifunctionality of cotton cultivation is analyzed using different coproduct treatment methods. Changes in life cycle impacts with different coproduct treatments are higher than uncertainty in global data. Cereal unit and biophysical allocation are shown to be robust alternatives to economic allocation. Abstract. Cotton lint represents the largest natural textile fiber production globally, and as organizations strive to reduce their upstream environmental impacts, robust cotton life cycle assessment (LCA) data has never been more important. A key characteristic of cotton is that during its cultivation, it produces an important coproduct – cottonseed, and thus the impacts of the cultivation are partitioned between the cotton lint and cottonseed. How the environmental impacts of cotton production are split between the products is critical for measuring the environmental impacts. This study evaluates the effect of different coproduct treatment approaches on the life cycle impacts of cotton and presents the issues and limitations of these approaches. Approaches include partitioning (mass, economic, biophysical, and cereal units) and substitution, sometimes referred to as system expansion. Results show that when accounting for uncertainty in allocation and inventory, the global warming impact of global average cotton lint ranges between -0.01 and 4.24 CO2/kg of lint at the 95% confidence interval. Comparing the coproduct treatment approaches for cotton lint, a mass partitioning perspective tends to yield the lowest impacts, whereas economic partitioning along with substitution can yield larger impacts in other categories. The more recent cereal unit and biophysical allocation methods are identified as robust alternatives to economic allocation, overcoming its common issues and limitations. This study helps organizations interested in cotton understand the underpinnings of each approach and how coproduct treatment plays a role in LCA results. It also serves as a foundational work on coproduct treatment in agricultural contexts. Keywords: Allocation, Coproduct treatment, Cotton lint, Cotton sustainability, LCA.