Life cycle assessment of facile applicable biodiesel production

• K 2 CO 3 is used as a heterogeneous catalyst for biodiesel production from WCO. • Methanol and K2CO3 have the highest environmental impact on biodiesel production. • The most significant impact category is climate change. • Human noncarcinogenic toxicity is one of the most significant impact categories. • The production of biodiesel based on K₂CO₃ is more economical and successful Biodiesel is crucial for mitigating fossil fuel depletion and reducing environmental impacts. Herein, this approach represents a life cycle assessment (LCA) of biodiesel production from waste cooking oil (WCO) utilizing potassium carbonate (K 2 CO 3 ) as a heterogeneous catalyst instead of potassium hydroxide (KOH) which is the most used catalyst in industry. However, KOH requires 20% methanol and 66% reaction time higher than K 2 CO 3 . Besides, KOH is used once, and produces impure biodiesel and glycerol. While, K 2 CO 3 has the ability to be used recovered and reused twice, which decrease the net required catalyst amount without significant decrease in biodiesel production yield, decreases the environmental burdens, and produces purer products. When using WCO or high free fatty acid (FFA) oils, K 2 CO 3 has the advantage of effective direct transesterification, while KOH requires post treatment process (esterification), which means extra usage of methanol besides the acid catalyst, which is commonly H 2 SO 4 , to decrease the FFA content and avoid the saponification reaction. Therefore, this research aims to quantify the environmental burdens of biodiesel production and compare the performance of K 2 CO 3 with that of conventional KOH. Using the ReCiPe method in SimaPro 9.5 software, the LCA adheres to ISO 14040 and 14044 standards. Key findings indicate significant impacts in climate change (0.274 kg CO 2,eq ), human non-carcinogenic toxicity (0.12 kg 14-DCB eq ), terrestrial ecotoxicity (0.536 kg 14-DCB eq ), and fossil resource scarcity (0.183 kg oil eq ). Methanol and K 2 CO 3 are identified as major contributors to environmental burdens. In contrast, KOH demonstrates a less environmental impact compared to K 2 CO 3 . The economic study revealed that, for producing 250 thousand tons of biodiesel per year, the total CAPEX needed to build up the plant is around 12 M$ for both catalysts. The results proved that using K 2 CO 3 leads to higher net profits. The study revealed that the biodiesel plant would achieve a remarkable net profit using any type of catalyst, with an advantageous economic indicator for K 2 CO 3 over KOH, proving the high profitability of using K 2 CO 3 as a catalyst.