Comparative Techno-Economic Analysis of Direct Sustainable Lithium Extraction from Brine: Solvent Extraction, Adsorption, and Combined Nanofiltration/Membrane Distillation−Crystallization

The rapidly growing demand for lithium, driven by the expansion of electric vehicles and renewable energy storage systems, highlights the need for cost-effective and sustainable extraction technologies. This study presents a techno-economic analysis evaluating the feasibility of three direct lithium extraction (DLE) methods for producing lithium carbonate from brine: solvent extraction, adsorption, and a combined nanofiltration/membrane distillation−crystallization (NF/MD). Key economic indicators, capital expenditure (CAPEX), operational expenditure (OPEX), net present value (NPV), rate of return on investment (ROROI), and payback period (PBP), were assessed across 11 lithium carbonate (Li2CO3) price scenarios ranging from $10,000 to $50,000/ton over a 15-year project lifetime. A sensitivity analysis was also conducted to determine how variations in chemical and consumable costs affect the economic outcomes of each method. The estimated CAPEX values are 5.5 M$ for adsorption, 5.6 M$ for NF/MD, and 8.5 M$ for solvent extraction, while the corresponding OPEX values are 3.9 $/kg for Li2CO3, 7 $/kg, and 7.5 $/kg, respectively. The results show that adsorption, due to its lower CAPEX and OPEX, is the most economically viable and remains profitable even under relatively low lithium price scenarios. Specifically, at a high profitability threshold of 40% ROROI, adsorption remains viable across all market prices, whereas NF/MD and solvent extraction require minimum Li2CO3 prices of approximately $14,000 and $18,000 per ton, respectively. Furthermore, sensitivity results indicate that a 40% increase in consumable costs results in a significant 38% decrease in NPV for solvent extraction, while adsorption remains highly resilient with only a 5% reduction. In contrast, solvent extraction performs poorly because of its higher cost structure.