This study explores the integration of biochar, derived from downed timber, into PLA-based plant containers as a strategy to reduce environmental impact and enhance carbon sequestration. By incorporating biochar as a filler, these containers have the potential to store carbon in soil after disposal, improving their sustainability profile.
A life cycle assessment (LCA) was conducted to compare plant containers made from PP, PLA, and PLA+Biochar across production, and end-of-life stages. The study evaluates the environmental impact of varying biochar content (10–90 wt.%) in PLA composites to determine optimal formulations. The system boundary follows a cradle-to-grave approach, incorporating production, collection, and end-of-life scenarios based on U.S. waste management data. The functional unit is 1,000 plant containers, each with a 3-liter capacity. Life cycle inventory data were sourced from literature, ecoinvent, and USLCI-NREL databases, with environmental impacts assessed using the IMPACT 2002+ method, emphasizing land occupation during end-of-life.
Results indicate that PP containers have the lowest global warming potential (GWP) during production, at 75.54 kg CO₂-eq per functional unit, compared to 160.86 kg CO₂-eq for PLA containers. However, adding biochar to PLA significantly reduces its overall environmental footprint, with GWP decreasing as biochar content increases. End-of-life analysis highlights additional benefits of PLA+Biochar containers, particularly in composting scenarios where biochar contributes to long-term carbon sequestration in soil. The GWP for PP, PLA, and PLA+Biochar containers (based on respective waste management routes) is 16.25, 23.32, and ranges from -0.51 to -27.52 kg CO₂-eq per functional unit, depending on biochar content. The findings suggest that PLA+Biochar containers with 40 wt.% or more biochar could outperform PP containers in terms of overall life cycle impact, presenting a viable and sustainable alternative for horticultural applications.