Sustainable production of nanocellulose: Technoeconomic assessment, energy savings and scalability

Abstract

Nanocellulose is a promising biopolymer compound which is produced from pulp. However, the traditional approaches do not produce it in an energy efficient and sustainable way. The production of nanocellulose through moderate refining and froth flotation has the potential to reduce the traditional nanocellulose production cost. This technoeconomic analysis explores the financial profitability of using moderate refining followed by enhanced froth flotation technology at pilot scale (best case scenario) to produce nanocellulose in an affordable and sustainable way. With a 100% nanocellulose yield, the yearly the operational cost was $7312 AUD/ton nanocellulose for the best-case scenario. The 25-year NPV coming from discounted cumulative cash flow rate for best case scenario is approximately 9.5 million AUD (profit). From the sensitivity analysis it was revealed that the key driver behind profitability of nanocellulose production is Capital Cost and Labour cost. Lastly four different case scenarios are explored to examine the economic viability for commercial scale nanocellulose production. For a similar level of nanocellulose pulp quality development, there is an energy savings of approximately 5000 kWh/t (aspect ratio), 2000 kWh/t (fines) and 15,000 kWh/t (volumetric specific surface) in moderate refining combined with enhanced flotation at bench scale, when compared with extensive refining stand alone. There is minimal or no energy savings when flotation is used at a laboratory scale. Technoeconomic assessment for nanocellulose production at pilot scale was evaluated and compared with that of bench scale and it was revealed that moderate refining followed with flotation at pilot scale is most economical. The high ROI of 175.3% and NPV of $9.5 million for moderate refining along with flotation at pilot scale demonstrates flotation technology is worth investing for nanocellulose production at pilot scale.