Techno-economic comparison of ethanol and electricity coproduction schemes from sugarcane residues at existing sugar mills in Southern Africa
Date
2014-07
Journal Title
Journal ISSN
Volume Title
Publisher
BioMed Central
Abstract
Background: The economics of producing only electricity from residues, which comprise of surplus bagasse and
50% post-harvest residues, at an existing sugar mill in South Africa was compared to the coproduction of ethanol
from the hemicelluloses and electricity from the remaining solid fractions. Six different energy schemes were
evaluated. They include: (1) exclusive electricity generation by combustion with high pressure steam cycles
(CHPSC-EE), (2) biomass integrated gasification with combined cycles (BIGCC-EE), (3) coproduction of ethanol (using
conventional distillation (CD)) and electricity (using BIGCC), (4) coproduction of ethanol (using CD) and electricity
(using CHPSC), (5) coproduction of ethanol (using vacuum distillation (VD)) and electricity (using BIGCC), and (6)
coproduction of ethanol (using VD) and electricity (using CHPSC). The pricing strategies in the economic analysis
considered an upper and lower premium for electricity, on the standard price of the South African Energy Provider
Eskom’ of 31 and 103% respectively and ethanol prices were projected from two sets of historical prices.
Results: From an energy balance perspective, ethanol coproduction with electricity was superior to electricity
production alone. The VD/BIGCC combination had the highest process energy efficiency of 32.91% while the
CHPSC-EE has the lowest energy efficiency of 15.44%. Regarding the economic comparison, it was seen that at the
most conservative and optimistic pricing strategies, the ethanol production using VD/BIGCC had the highest
internal rate of returns at 29.42 and 40.74% respectively.
Conclusions: It was shown that bioethanol coproduction from the hemicellulose fractions of sugarcane residues,
with electricity cogeneration from cellulose and lignin, is more efficient and economically viable than the exclusive
electricity generation technologies considered, under the constraints in a South African context.
Description
CITATION: Petersen, A. M., Aneke, M. C. & Gorgens, J. F. 2014. Techno-economic comparison of ethanol and electricity coproduction schemes from sugarcane residues at existing sugar mills in Southern Africa. Biotechnology for Biofuels, 7:105, doi:10.1186/1754-6834-7-105.
The original publication is available at https://biotechnologyforbiofuels.biomedcentral.com
The original publication is available at https://biotechnologyforbiofuels.biomedcentral.com
Keywords
Sugarcane processing industries, Sugarcane products, Sugar factories, High pressure (Technology) -- Cycle, Steam
Citation
Petersen, A. M., Aneke, M. C. & Gorgens, J. F. 2014. Techno-economic comparison of ethanol and electricity coproduction schemes from sugarcane residues at existing sugar mills in Southern Africa. Biotechnology for Biofuels, 7:105, doi:10.1186/1754-6834-7-105