Comparative Life Cycle Assessment of Algal Bioplastics and Polylactic Acid

The massive scale of plastic production and persistent plastic waste have intensified global efforts to develop sustainable bioplastics. Algal bioplastics, produced directly from whole algal biomass, are inherently biodegradable and do not rely on agricultural feedstocks, positioning them as a versatile and accessible alternative to commercially dominant bioplastics such as polylactic acid (PLA). To guide their advancement, a comprehensive evaluation of environmental impacts, material performance, and end-of-life behavior is needed. Here, we conduct a life cycle assessment to quantify cradle-to-gate environmental impacts of lab-scale algal bioplastics made from sugar kelp across eight impact categories and benchmark them against lab-scale PLA. To support transparent optimization, we perform hotspot analyses with alternative processing and energy scenarios while investigating data variability and sensitivity to quantify uncertainty in early design. Algal bioplastics exhibit on average 47% lower environmental impacts than the lab-scale PLA baseline (33–75% across eight categories), with comparable stiffness, improved flame resistance, and 94–99% biodegradability in seawater after 120 days as quantified by biochemical oxygen demand. By providing transparent data and methods and an in-depth discussion of limitations and challenges, we establish a comprehensive foundation for algal bioplastic design, supporting future innovation and scale-up of this emerging sustainable material class.