Techno-economics of lignocellulose biorefineries at South African sugar mills using the biofine process to co-produce levulinic acid, furfural and electricity along with gamma valeractone

Abstract

Lignocellulose biorefineries process biomass into ‘green’ chemicals and bioenergy and play a key role in sustainable bio-economies. Using sugarcane bagasse and trash feedstocks, biorefineries were simulated in Aspen Plus ® v 8.6 to generate mass and energy balances. Four scenarios with electricity and furfural as common products were generated. Scenario A in addition produced high volume, low value levulinic acid whilst scenarios B1 and B2 generated low volume, high value levulinic acid at varied feedstock capacities. Scenario C produced low volume, high value levulinic acid and bulk gamma valerolactone. The four biorefineries were also compared to a combined heat and power plant that only produced steam and electricity. Aspen Plus ® Economic Analyser and a discounted cash flow rate of return methodology were used to determine the economic feasibility of the bioenergy self-sufficient biorefineries annexed to a conventional South African sugar mill. Levulinic acid production via the Biofine process makes economic sense when produced for niche markets, due to the anticipated decrease in market prices when production volumes increase. Scenario (C) co-producing a low volume of levulinic acid (0.15 t h−1) together with 3.3 t h−1 furfural, electricity (14 MWh) and 6.8 t h−1 gamma valerolactone, was the most profitable. It attained an internal rate of return of 23% and 253 US$ million net present value at a 9.7% hurdle rate by matching chemicals' production volumes to market demands, to maintain high market prices for multiple revenue streams.