Are compostable clamshells climate-better where composting does not exist? A streamlined comparative LCA of PET, PP, PLA and PHA food packaging under Lebanon's end-of-life conditions

Compostable bioplastics are promoted as low-carbon substitutes for fossil food packaging, but their benefit depends on end-of-life infrastructure that many countries lack. This study compares the cradle-to-grave climate impact of rigid clamshells made from PET, PP, PLA and PHA for cold food in Lebanon. There, 57% of municipal waste goes to sanitary landfills and 43% to open dumps, where much of it is burned. A streamlined LCA combines published eco-profiles, Lebanese electricity and waste data, and IPCC end-of-life methods across five scenarios, two biogenic carbon conventions and a 10,000-run Monte Carlo analysis. Under current conditions, PP has the lowest impact (41.2 kg CO₂ eq per 1,000 containers), followed by PET (58.9) and PLA (60.4), while PHA is highest (105.6). PHA's result is driven by methane from landfills and dumps, which accounts for 45% of its total. Bio-based options outperform fossil ones only under open burning, or when landfilled biogenic carbon is credited as storage, which lowers PLA to 31.6. Ideal composting does not let either bio-based material beat PP. The findings indicate that, in countries with weak waste systems, compostable packaging should follow, not precede, investment in organics collection, composting and landfill gas capture.