Techno-economic and life cycle assessment of renewable diesel production via methane-assisted catalytic waste cooking oil upgrading

In this work, a techno-economic and life cycle assessment of a novel catalytic methane-assisted process for the production of renewable diesel has been performed. A systematic method for calculating catalyst production cost is engaged via CatCost utilization. The results are compared with commercial processes (hydrotreatment and alkali-catalyzed process) and other recently published research. The total capital investment in hydrotreating of WCO (hydrocracking of long chain fatty acids by hydrogen under high pressure and temperature) and alkalicatalyzed process (transesterification of fatty acids by NaOH to produce fatty acid methyl ester) are 39% and 97% more than that of the novel methane-assisted catalytic process, respectively. The consumed energy per unit mass of produced renewable diesel calculated from this innovative upgrading technique is 0.93 kW/kg of renewable diesel, which is remarkably lower than that for the aforementioned commercial processes. The production costs have also been investigated and it was found that using natural gas is noticeably cheaper than hydrogen employed for the hydrotreating process and NaOH and methanol used in alkali catalyzed process. The production costs for the methane-assisted catalytic process are 0.365 $/kg renewable diesel and for hydrotreating and alkali-catalyzed process, the production costs are 0.574 $/kg renewable diesel and 0.513 $/kg biodiesel, respectively. The economic results have also been compared with other research and it was found the total production cost of the new process is minimum, however total capital investment is a bit high. The results of the life cycle assessment (LCA) have also proved the advantages of the newly developed process because using NaOH and methanol in the alkali-catalyzed process and hydrogen in the hydrotreating process would have higher environmental impacts. The impact assessment showed that the proposed process contributes significantly to reducing global warming since CO2 eq results indicate that the proposed process emits remarkably less CO2 as one of the major greenhouse gases compared to other processes. For examining the risk of investment, the Monte Carlo simulation with 1000 iterations has also been conducted and the results manifest the high profitability of this process.